a consistent absolute phase center correction model
J Geod(2007)81:781–798
DOI10.1007/s00190-007-0148-y
O R I G I NA L A RT I C L E
Generation of a consistent absolute phase center correction model for GPS receiver and satellite antennas
Ralf Schmid·Peter Steigenberger·Gerd Gendt·
Maorong Ge·Markus Rothacher
Received:30May2006/Accepted:18February2007/Published online:18April2007
?Springer-Verlag2007
Abstract The development and numerical values of the new absolute phase center correction model for GPS receiver and satellite antennas,as adopted by the Inter-national GNSS(global navigation satellite systems) Service,are presented.Fixing absolute receiver antenna phase center corrections to robot-based calibrations,the GeoForschungsZentrum Potsdam(GFZ)and the Tech-nische Universit?t München(TUM)reprocessed more than10years of GPS data in order to generate a con-sistent set of nadir-dependent phase center variations (PCVs)and offsets in the z-direction pointing toward the Earth for all GPS satellites in orbit during that period.The agreement between the two solutions esti-R.Schmid(B)
Institut für Astronomische und Physikalische Geod?sie, Technische Universit?t München,Arcisstra?e21,
München80333,Germany
e-mail:schmid@bv.tum.de
P.Steigenberger
Forschungseinrichtung Satellitengeod?sie,
Technische Universit?t München,Arcisstra?e21,
München80333,Germany
e-mail:steigenberger@gfz-potsdam.de
Present address:
P.Steigenberger
GeoForschungsZentrum Potsdam,
Telegrafenberg A17,Potsdam14473,Germany
G.Gendt·M.Ge·M.Rothacher
GeoForschungsZentrum Potsdam,
Telegrafenberg A17,Potsdam14473,Germany
e-mail:gendt@gfz-potsdam.de
M.Ge
e-mail:maor@gfz-potsdam.de
M.Rothacher
e-mail:rothacher@gfz-potsdam.de mated by independent software packages is better than 1mm for the PCVs and about4cm for the z-offsets. In addition,the long time series facilitates the study of correlations of the satellite antenna corrections with sev-eral other parameters such as the global terrestrial scale or the orientation of the orbital planes with respect to the Sun.Finally,completely reprocessed GPS solutions using different phase center correction models dem-onstrate the bene?ts from switching from relative to absolute antenna phase center corrections.For exam-ple,tropospheric zenith delay biases between GPS and very long baseline interferometry(VLBI),as well as the drift of the terrestrial scale,are reduced and the GPS orbit consistency is improved.
Keywords GPS·Satellite antenna·Receiver antenna·Absolute phase center corrections·GPS data reprocessing
1Introduction
Starting on30June1996,relative GPS antenna phase center corrections had been applied by most of the Anal-ysis Centers(ACs)of the International GNSS(global navigation satellite systems)Service(IGS;Dow et al., 2005)in order to allow for a non-spherical phase response of the tracking antennas.These corrections comprised mean offsets of the electrical antenna phase center com-pared to the physical antenna reference point,as well as phase center variations(PCVs)as a function of the ele-vation angle.
The correction values could be derived from GPS data collected over a short baseline with the reference antenna AOAD/M_T(Allen Osborne Associates Dorne
782R.Schmid et al.
Margolin T)at one end of the baseline and the antenna to be calibrated on the other end(Mader,1999).Cor-rections from relative calibrations had been used until 5November2006(Gendt,2006)despite the arbitrary assumption that the PCVs of the reference antenna were zero and other limitations of the procedure,resulting in systematic errors(Schmid et al.,2005a).
By the transition to absolute receiver antenna phase center corrections in November2006these problems could be avoided.Corrections that do not depend on a reference antenna can be obtained from two com-pletely independent approaches.Former calibrations in anechoic chambers(e.g.Schupler et al.,1994)were veri-?ed by?eld measurements over a short baseline using a robot capable of tilting and rotating one of the antennas (Menge et al.,1998).Although the results were in good agreement(Rothacher,2001),they were not immedi-ately adopted for general use,as their application was found to give a global GPS frame differing from very long baseline interferometry(VLBI)and satellite laser ranging(SLR)in scale by about15ppb(e.g.Springer, 2000a).
It was suggested by several people(e.g.Springer, 2000b,Rothacher,2001)that the neglect of the behavior of the transmitting antennas on-board the GPS satellites might explain the failure of the absolute phase center corrections for the tracking antennas attached to GPS receivers on the ground.Within the IGS,one standard offset of the phase center with respect to the center of mass per satellite block was used at that time(Kouba, 2003).
Nadir-or azimuth-dependent PCVs were completely ignored,although the antenna assembly of12helical elements on GPS satellites indicates non-perfectly hemi-spherical signal wavefronts(Czopek and Shollenberger, 1993).Since the effort of Mader and Czopek(2002)to calibrate a spare Block IIA antenna on the ground did not result in adequate accuracy,the satellite antenna characteristics had to be determined from the GPS data together with other geodetic parameters usually set up in global solutions.
However,this problem is singular due to very high correlations between station heights,tropospheric parameters and the offsets and PCVs of the tracking and the transmitting antennas(Springer,2000b).A solution is only possible if the terrestrial scale is?xed by adopting a set of?ducial coordinates for the tracking network and if absolute receiver antenna phase center corrections are taken from external calibration measurements.
Schmid and Rothacher(2003)demonstrated the possibility to estimate nadir-dependent PCVs for the satellite antennas by adopting the International Terres-trial Reference Frame2000(ITRF2000)scale(Altamimi et al.,2002)and absolute robot calibrations for the track-ing antennas.Also,the existence of azimuth-dependent PCVs could be veri?ed(Schmid et al.,2005b).As the ionosphere-free linear combination LC had to be formed in order to eliminate the ionospheric refraction,their satellite antenna corrections referred to LC.
Whereas the latter work was limited to phase center corrections for the three different satellite blocks (Block I,II/IIA,IIR),Ge and Gendt(2005a)pointed out that it was not suf?cient to use block-speci?c correction values.Due to signi?cant differences between individual satellites,mainly in the offset in the z-direction point-ing toward the Earth,satellite-speci?c corrections are necessary.However,time series for satellite-speci?c off-sets from the reprocessing of global GPS networks(Ge et al.,2005b,Steigenberger et al.,2006)showed trends and long-periodic signals caused by inconsistencies in the scale de?nition and the orbit modeling.Therefore, long time series are essential in order to get the best possible mean phase center corrections for all satellites available.
In order to ful?l the recommendation from the2004 IGS Workshop and Symposium in Bern,Switzerland, to assemble a consistent set of absolute phase center corrections to allow for a test phase amongst the ACs (Schmid et al.,2005a),the Technische Universit?t München(TUM)and the IGS AC located at the Geo-ForschungsZentrum Potsdam(GFZ)decided to repro-cess tracking data since the of?cial start of the IGS in 1994,and to combine the results from two independent software packages using different strategies.
At the same time,the Jet Propulsion Laboratory (JPL)succeeded in deriving PCV maps from post-?t tracking data residuals of the antennas on-board the Jason-1and GRACE(Gravity Recovery and Climate Experiment)satellites for both the carrier-phase and code pseudorange data types(Haines et al.,2004).Those maps are two-dimensional(depending on nadir and azi-muth angle),but are only available for the GPS satellites active since2002.
A transition from relative to absolute antenna phase center corrections implies several positive aspects.As the modeling of one of the various elevation-dependent effects is improved,GPS results are less dependent on the selected elevation cut-off angle(Schmid et al., 2005b).Furthermore,any correlated parameter should bene?t.For example,Schmid et al.(2005b)demon-strated a signi?cant reduction of tropospheric zenith delay biases between GPS and VLBI,and Ge et al. (2005b)illustrated the stabilization of the global ter-restrial scale.
At the same time as absolute phase center correc-tions were adopted,the IGS began to consider the effect
Generation of a consistent absolute phase center correction model for GPS receiver and satellite antennas783
of radomes that protect receiver antennas from envi-ronmental impacts.Although it is well known that the impact of radomes on the phase center position can amount to several cm(e.g.Braun et al.,1997),it was more or less ignored up to November2006(Schmid et al.,2005a).
In particular,ignoring radomes has a dramatic effect on vectors between co-located techniques,the so-called local ties(Ray and Altamimi,2005,Ray et al.,2007). However,these vectors are the crucial links for the combination of the different space-geodetic techniques. Since calibrations for several combinations of antenna and radome in use are missing,and since some com-binations are not even‘calibratable’,this problem will persist.
This paper describes the compilation of the consistent absolute antenna correction?le for the IGS test phase. After a short introduction to the receiver antenna cor-rections,different satellite blocks and software packages used(Sect.2),we present several problems and spe-cialties in connection with long time series of satellite antenna offsets(Sect.3).
In Sect.4,the satellite antenna PCV results from GFZ and TUM are compared,yielding block-speci?c correc-tion curves.These values serve as the basis for the deter-mination of satellite-speci?c z-offsets that have to be referenced to a given epoch due to considerable trends in the time series(Sect.5).Finally,we demonstrate how the estimation of troposphere and orbit parameters,sta-tion coordinates and the terrestrial scale bene?t from the new phase center models(Sect.6).
2Input data,software packages and strategy
2.1Receiver antenna PCVs
The receiver antenna phase center information that was ?xed for the work presented here is identical to the corrections contained in the?le igs05_1365.atx (available at ftp://https://www.wendangku.net/doc/a513612490.html,/igscb/ station/general/pcv_proposed/)except for several radome calibrations(see below).As well as the satellite antenna information,this?le contains abso-lute calibration values for154different receiver antenna types in total.These comprise106antennas without a radome and48combinations of an antenna with one par-ticular radome.Among the106different antenna types, there are only32that possess robot calibration results including both zenithal and azimuthal PCVs(Menge et al.,1998).However,these32antennas include most of the types dominating the IGS tracking network.
In order to generate a complete set of phase center corrections for tracking antennas,the robot calibrations had to be complemented by results from relative?eld calibrations(Mader,1999).The latter had to be con-verted to absolute corrections by adding the difference between the absolute and the relative values for the ref-erence antenna AOAD/M_T(Menge,2003).Equations(1) and(2)give the conversion formulae for the phase center offset(PCO)and the PCVs,respectively.The rel-ative PCVs for the reference antenna are omitted from Eq.(2),as they are assumed to be zero.
PCO abs=PCO rel+(PCO abs(AOAD/M_T)
?PCO rel(AOAD/M_T))(1) PCV abs=PCV rel+PCV abs(AOAD/M_T)(2)
As the relative?eld calibrations are limited to eleva-tion angles above10?due to the error budget of low-elevation observations,naturally the converted PCVs also only extend down to10?.In contrast,robot PCVs are measured down to0?elevation.
It has to be noted that the calibrations for antenna/ radome combinations were not added to the?le igs05_wwww.atx(wwww:GPS week of the last?le modi?cation)until major parts of the work presented here had been?nished.In the case of a radome mounted at a site,the calibration for the antenna without the radome was used.This had also been the convention within the IGS for many years(Ray and Altamimi, 2005).
However,it may be expected that the consideration of radome calibrations will have minor in?uence on satel-lite antenna corrections.As Sect.4and5will show,the GFZ and TUM estimates agree very well although the tracking networks are different,and thus include differ-ent antenna/radome combinations.
2.2Satellite blocks
According to the Navstar GPS Joint Program Of?ce (2004),the space segment of the GPS system consists of six different satellite blocks(cf.Table1).However,the last Block I satellite(SVN10)was decommissioned on 18November1995and the?rst Block IIF satellite will not be launched before2008.That means that the cur-rent constellation consists of four different blocks(II, IIA,IIR,IIR-M).However,for our paper,Block IIR-M (M stands for modernized)could not be considered,as the?rst satellite was only launched on26September 2005.
As can be seen from Table1,the GPS operators do not distinguish between the conventional Block IIR
784R.Schmid et al.
Table1Of?cial satellite block designations(Navstar GPS Joint
Program Of?ce,2004),space vehicle numbers(SVNs)and manu-facturers
Satellite block SVNs Manufacturer
Block I1–11Rockwell International Block II13–21Rockwell International Block IIA22–40Rockwell International Block IIR/IIR-M41–61Lockheed Martin Block IIF62–73Boeing
Prototype12Rockwell International Table2IGS designations for the Block IIR satellites and the
corresponding SVNs(Marquis and Reigh,2005)
Satellite antenna type SVNs
Block IIR-A41,43–46,51,54,56 Block IIR-B47,59–61
Block IIR-M48–50,52–53,55,57–58 Unsuccessful launch42
satellites and the modernized representatives of the same block as regards the space vehicle number(SVN). Moreover,the last four Block IIR satellites that were launched between December2003and November2004 were retro?tted with the improved satellite antenna panel designed for the Block IIR-M satellites(Marquis and Reigh,2005).
For this reason,the IGS decided to subdivide the con-ventional Block IIR satellites into two subgroups called Block IIR-A and Block IIR-B(see IGS naming conven-tion rcvr_ant.tab available at ftp://igscb.jpl. https://www.wendangku.net/doc/a513612490.html,/igscb/station/general/).The classi-?cation of the three different subgroups of Block IIR is given in Table2.For the remaining satellite blocks,the of?cial designations are used.Finally,it has to be noted that the antenna panels on-board the Block II and IIA satellites are supposed to be identical,just like the pan-els on-board Block IIR-B and IIR-M.
2.3Estimation strategies
The reanalysis performed at GFZ to derive the antenna phase center models is based on the GFZ activities in the framework of the IGS TIGA(TIde GAuge benchmark monitoring)project(Sch?ne,2004).From the global network of more than300stations handled and cleaned within the TIGA reprocessing(Zhang et al.,2005),about 100well distributed stations were used.TUM repro-cessed a global GPS network in cooperation with Dres-den University of Technology(DUT;Steigenberger et al. 2006).Due to the high correlation between satellite antenna PCVs and PCOs,raw PCVs were estimated that correspond to the following sum:
PCV raw(φ)=PCV min(φ)+?z·(1?cosφ)(3) The raw PCVs were?nally converted into minimum PCVs and a z-offset forcing the PCV curves to be as?at as possible(Ge and Gendt,2005a).More details on the modeling and processing are given in Table3.
3Estimation of satellite antenna phase center corrections
3.1Attitude-related systematic effects
Horizontal satellite antenna offsets are sometimes highly correlated with the orbital elements.For example, depending on the position of the Sun with respect to the orbital plane,a small change of the horizontal PCO can easily be compensated by a change of the center of mass in the opposite direction.Therefore,the accuracy of the estimated horizontal offsets depends on the behavior of the attitude control of the GPS satellites,whereas the attitude control system is in?uenced by the orientation of the orbital planes with respect to the Sun.
Figure1shows the geometry of the Earth-?xed sys-tem,the orbit system and the satellite system(accompa-nying tripod of the satellite position).The elevationβ0 of the Sun above the orbital plane is given by
β0=90?
?arccos
?
?
?
?
sin i·sin?
?sin i·cos?
cos i
?
?·
?
?
cosδ ·cosα
cosδ ·sinα
sinδ
?
?
?
?
(4) with the right ascensionα and the declinationδ of the Sun as well as the inclination i and the right ascension of the ascending node?of the GPS satellite.
According to Montenbruck and Gill(2000),the pre-cession of the ascending node˙?of a satellite(assuming a circular orbit:e=0)is given by
˙?=?3πJ2
T
R e
a
2
·cos i(5)
with the orbital period T,the semi-major axis a,the inclination i,the radius of the Earth R e and the oblate-ness J2.Inserting the corresponding values of the GPS satellites gives a rate of˙?GPS=?14.1?/year.
This means that the annual period inβ0caused by the periodic terms of the right ascension and declination
Generation of a consistent absolute phase center correction model for GPS receiver and satellite antennas785
Table3Estimation strategies used by GFZ and TUM
GFZ TUM
Number of stations About100(from more than300TIGA
stations)
195(about40–160per day)
Time interval1January1994–1March20051January1994–31December2004
Software EPOS.P-V2(Earth Parameters and Orbit
determination System;Gendt et al.,1999)Bernese GPS Software Version5.0(modi-?ed;Dach et al.,2007)
Data Zero-difference GPS carrier-phase and code
pseudo-range observations Double-difference GPS carrier-phase and code pseudo-range observations
Sampling rate5min3min Elevation cut-off angle7?3?
Weighting Elevation-dependent(weight w=4·cos2z,
if zenith angle z>60?,else w=1.0)Elevation-dependent(weight w=cos2z with zenith angle z)
Ambiguity?xing Recently improved strategy resolving97%
of all ambiguities in the global network
(Ge et al.,2005c)Ambiguities resolved in a baseline-by-base-line mode;strategy depending on the base-line length(Steigenberger et al.,2006)
Station coordinates Fixed to the reference frame IGb00
(Ferland,2003)No-net-rotation and no-net-scale condition for the IGb00stations;thus,scale?xed to IGb00
Orbits24-h orbital arcs;initial orbit positions
and velocities,?ve radiation pressure
parameters of the model described by
Beutler et al.(1994)and pseudo-stochastic
pulses at12UT for each satellite estimated 24-h orbital arcs;six orbital elements,?ve radiation pressure parameters of the model described by Beutler et al.(1994)and pseudo-stochastic pulses at12UT for each satellite estimated
Earth rotation Daily pole and length of day parameters Set up at2-h intervals;pole coordinates esti-
mated freely except for blocking of retro-
grade diurnal terms(Hefty et al.,2000);the
?rst UT1–UTC parameter constrained to
its a priori value(IERS Bulletin A;Luzum
et al.,2001)due to correlations with the
orbital elements
Ionospheric refraction First-order effect eliminated by forming the
ionosphere-free linear combination LC;
higher-order effects not corrected for
First-order effect eliminated by forming the
ionosphere-free linear combination LC;
second-and third-order effects modeled
according to Fritsche et al.(2005)
Tropospheric refraction A priori hydrostatic and wet delay modeled
with the Saastamoinen(1973)model and
a standard atmosphere(pressure derived
from station height,temperature derived
from latitude and season);mapped to the
zenith with the corresponding Niell(1996)
mapping functions;zenith delays at4-h
intervals and gradients in north-south and
east-west direction at12-h intervals esti-
mated as piece-wise constant offsets using
the hydrostatic Niell(1996)mapping func-
tion A priori hydrostatic delay modeled with the Saastamoinen(1973)model and the stan-dard atmosphere described by Berg(1948) with a reference pressure of1013.25hPa at the ellipsoidal reference height of0m; mapped to the zenith with the hydrostatic isobaric Niell(2000)mapping function computed from NCEP(National Centers for Environmental Prediction)z200data (height of the200hPa pressure level;Saha et al.2006);zenith delays at2-h intervals and gradients in north-south and east-west direction at24-h intervals estimated as con-tinuous piece-wise linear functions using the wet Niell(1996)mapping function
Satellite antenna PCVs Satellite-speci?c,nadir-dependent estimation;φmax=14?;1?-resolution;a priori values
from Schmid and Rothacher(2003);?xed to result from Sect.4when estimating PCOs
(Sect.5)
Satellite antenna PCOs A priori values:?z I=2.1965m,?z II/IIA=2.3384m,?z IIR=1.3326m(Schmid and
Rothacher2003);?xed when estimating PCVs(Sect.4)
Receiver antenna PCVs If no PCVs are available below a10?elevation for the receiver antenna(see Sect.2.1),
observations are corrected with the value given for10?
of the Sun is superimposed with an oscillation due to the secular perturbation of?.The beat period is360?/ (14.1?/year)≈25.5years.The limits of variation for the maximumβ0-angleβ0,max due to this beat frequency is given by the inclination of the GPS satellite i and the obliquity of the ecliptic 0:
786R.Schmid et al.
Fig.1Elevation of the Sun with respect to the orbital plane: Earth-?xed system(X EF,Y EF,Z EF),orbit system(X SAT,Y SAT, Z SAT),satellite system(R,S,W).Right ascension of the ascend-ing node?,argument of latitude u,inclination i,argument of latitude u0and elevationβ0of the Sun. symbolizes the Sun,?the satellite
|β0,max,min|=i? 0≈31.5?
(6) |β0,max,max|=i+ 0≈78.5?
The elevation of the Sun for all GPS satellite orbits for the year2003is displayed in Fig.2.The satellites in orbital plane B show the largest variations;those on plane E the smallest.The formal errors of the estimated horizontal offsets versus the elevation of the Sunβ0are plotted in Fig.3.The formal errors show a similar behav-ior:the largest formal errors occur for orbital plane B; the smallest for orbital plane E.In addition,the formal errors of the satellites with largeβ0-angles are larger for the y-offsets than for the x-offsets.These effects can be explained by the behavior of the GPS attitude control system.
The GPS attitude control system has two major tasks: (1)the transmitting antenna has to be pointed toward the center of the Earth(nadir direction)and(2)the vec-tor perpendicular to the solar panels has to be pointed toward the Sun.For Block I and Block II/IIA satellites, there is a third condition:the angleαbetween the Sun and the satellite’s z-axis(see Fig.1)has to be between 0?and180?.Block IIR satellites do not have that limita-tion anymore,thus the angleαmay vary between0?and360?(Springer,2000a,Hugentobler et al.2003). The compliance with these conditions is permanently controlled by Sun and Earth sensors and adjusted by the attitude control system.
?80
?60
?40
?20
20
40
60
80
β
?
a
n
g
l
e
[
d
e
g
]
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
A
B
C
D F
E
Fig.2Elevation of the Sunβ0with respect to the orbital planes (A–F)for all GPS satellites in2003
During periods with the angle between the along-track direction and the satellite’s x-or y-axis close to 0?or180?,the decorrelation of the horizontal satellite antenna offsets and the along-track direction is a severe problem.This situation can occur during periods where the elevation of the Sun above the orbital plane is large. The anglesγx between the x-axis and the along-track direction andγy between the y-axis and the along-track direction for one satellite with small(SVN54,orbit plane E)and one satellite with large(SVN30,orbit plane B)variations of theβ0-angle are shown in Fig.4.
Only in the case of a largeβ0-angle,an angleγy close to0?or180?occurs over longer periods of time;γx behaves differently.This geometry-related effect explains the larger formal errors of the y-offsets esti-mated during periods with largeβ0-angles visible in Fig.3b,whereas the maximum of the formal errors of the x-offsets is smaller(Fig.3a).
Also,during eclipse seasons(angleαbelow about 14?,see Fig.1),systematic effects arise when the solar panels cannot be oriented toward the Sun.To stabilize the satellite’s attitude,the satellite starts to rotate with a rate of up to0.12?/s(Bar-Sever,1995)around its z-axis. As the y-offsets are close to zero,they are only slightly biased by this unmodeled rotation.
In contrast,the x-offsets of the Block I and Block II/IIA satellites(of?cial IGS x-offsets of21.0and 27.9cm,respectively;Rothacher and Mader,2003)suf-fer heavily from this systematic effect,as one can see in Fig.5.The mean x-offset for SVN37(Fig.5),includ-ing the eclipse seasons,is29.7cm.The corresponding offset without the eclipse seasons is32.7cm.Including data from eclipse seasons causes a systematic under-estimation of the x-offsets(e.g.,3.0cm for SVN37). Therefore,these periods should be excluded when deter-mining mean offsets.
Generation of a consistent absolute phase center correction model for GPS receiver and satellite antennas 787
Fig.3Formal errors of the horizontal offset estimates versus elevation of the Sun β0for 2003
?90?4504590
β0
[d e g ]
060120180
γX
[d e g ]
2003
2003.5
2004
2004.5
2005
60120180
γY [d e g ]
Fig.4Elevation of the Sun β0together with the angles γx between the x -axis and the along-track direction and γy between the y -axis and the along-track direction (each with one value at 0:00UT per day)for SVN 30(solid line )and SVN 54(dashed line )
3.2Correlations with orbit parameters
Besides the eclipse seasons,further periodic signals are present in the horizontal offset time series of all GPS satellites (independent of the block type)as well as in the z -offsets.The spectra of the offset time series for SVN 37are shown in Fig.6.
The peaks in these spectra are related to the orien-tation of the orbital plane with respect to the Sun.Due
to the precession of the ascending node ˙?
(see Eq.5)the time-period T R between the same orientation of the orbital planes with respect to the Sun is shorter than one year:T R =
2π
2π?˙?
GPS ·1year ·365.25days ≈351.5days
(7)
Even after one sixth of this period,the constellation of the six orbital planes has approximately the same ori-entation,though the individual orbital planes differ.The main period of T R =351.5days and its integer fractions T R /n ,n =2,...,6are clearly visible in the spectra of the horizontal offsets in Fig.6.
For the z -offsets,the peaks are not as sharp as for the horizontal offsets,but most periods are also present in the vertical offset spectrum (Fig.6).The amplitudes of the different periods vary from satellite to satellite.The amplitude of this signal also depends on the maximum value of the β0-angle.
3.3Correlation with the global terrestrial scale As already mentioned in Sect.1,there is a high correla-tion between the satellite antenna phase center z -offset and the scale of the terrestrial reference frame,i.e.the station heights.According to Zhu et al.(2003),a change in the z -offset by ?z for all satellites will result in a station height change ?r of ?r ≈?0.05·?z ,
(8)
i.e.,a change of ?z =10cm will change ?r by ?5mm.
Thus,the estimation of satellite antenna phase center corrections is only possible,if the terrestrial scale is ?xed.However,this means that the scale from GPS remains doubtful as long as PCOs and PCVs are not available from independent calibration techniques.
788R.Schmid et al.
Fig.5Horizontal offset time series for SVN 37(PRN 07).The eclipse seasons are gray-shaded .The maximum elevation of the Sun above the orbital plane β0,max steadily increases after 1996.This is re?ected in increasing amplitudes of the peaks in the y -off-set time series,particularly after 2000,when the absolute values of the maximum β0-angle are larger than 50?
012345670
1234567A m p l i t u d e [c m ]
Frequency [1/y]
X?offset
012345670
0.5
1
1.52
A m p l i t u d e [c m ]
Frequency [1/y]
Y?offset
012345670
1
23456
7A m p l i t u d e [c m ]
Frequency [1/y]
Z?offset
Fig.6Amplitude spectra of the antenna offsets for SVN 37
3.4Insuf?cient accuracy from short time series The GFZ and TUM estimates show a signi?cant trend in the z -offset time series (mean values of ?2.2and ?2.5cm/year,respectively;cf.Figs.10and 11later).This trend is caused by errors in the vertical rates of the refer-ence frame realization IGb00(0.8mm/year;Ray et al.,2004).For the combined solution,the trend has been corrected for (see Sect.5.2).
In addition to the effects described above,other sig-nals seem to be present in the offset time series whose origin is not yet known.Due to all these systematic effects,short (below 1year)time series are not ade-quate to determine mean PCOs.Averaging over long
(multi-year)time series and excluding certain time periods (e.g.,eclipses)helps to mitigate these effects.
4Satellite antenna phase center variations
As shown in Eq.(3),there is a high correlation between nadir-dependent PCVs and the PCO in z -direction.Fur-thermore,azimuth-dependent PCVs that are not consid-ered here are highly correlated with the x -and y -offset (Schmid et al.,2005b ).As long as the values for the PCO and its variations are used in a consistent manner,the partitioning of the overall phase center correction into PCO and PCVs is arbitrary.
We decided to de?ne the satellite antenna PCO such that the PCVs are minimized over the whole range of the nadir angle.Another possibility would be to mini-mize the PCVs for nadir angles above about 10?,where most of the observations are made,in order to keep the error as small as possible for those ignoring the PCVs.In addition,it had to be decided whether block-or satellite-speci?c values should be determined for the phase center corrections.It turned out that the daily and weekly estimates for the PCVs of one speci?c satellite (see Fig.7)as well as the mean PCVs for each satellite of one speci?c satellite block (see Fig.8)agree almost perfectly if satellite-speci?c z -offsets are allowed for in each 1-day solution.
It has to be noted that these daily z -offset estimates may differ considerably from day to day (see Fig.10).In order to reduce the number of model parameters,
Generation of a consistent absolute phase center correction model for GPS receiver and satellite antennas
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10
12
14
?10
?8?6?4?20246
8Nadir angle [°]
S a t e l l i t e a n t e n n a P C V [m m ]
Fig.7175weekly PCV solutions for SVN 43(Block IIR-A),each computed by GFZ from at least 4daily solutions
02468
10
12
14
?15
?10
?5051015
Nadir angle [°]
S a t e l l i t e a n t e n n a P C V [m m ]
Block IIR?A
Block IIR?B
Fig.8Satellite-speci?c PCV solutions from GFZ for all Block IIR-A and IIR-B satellites together with the respective means indicated by circles
the satellite-speci?c PCVs were averaged (unweighted)in order to get block-speci?c ones,while keeping the satellite-speci?c PCOs.Due to the relationship between PCVs and the PCO (Eq.3),it would also be possi-ble to de?ne block-speci?c z -offsets and to shift all the phase center differences between individual satel-lites to satellite-speci?c PCVs.However,many more parameters would then have to be determined.
In a ?rst step,mean PCVs were computed for each individual satellite by GFZ and TUM from all data available (SVN 43is shown in Fig.7as an example).Afterwards,both institutions separately averaged (unweighted)those values for each individual satellite block (Block IIR-A and IIR-B are shown in Fig.8).In the case of GFZ,the mean standard deviations for one single PCV value from this averaging are 0.7mm for Block I,II/IIA and IIR-A and 0.3mm for Block IIR-B.
These ?gures,as well as the graphs for the latter two blocks shown in Fig.8,indicate that the modern-ized antenna panels on-board the latest satellites (cf.Sect.2.2)are of high quality as they show the smallest variations between individual satellites.Furthermore,the comparatively large PCV values for Block IIR-B make it clear that satellite antenna PCVs have to be taken into account for high-precision applications.
Finally,the block-speci?c PCVs from GFZ and TUM were averaged to get the ?nal result given in Fig.9and Table 4.The error bars displayed in Fig.9characterize the difference between the two independent solutions from different software packages.The mean differences are 0.6mm for Block I,0.3mm for Block II/IIA,1.1mm for Block IIR-A and 0.2mm for Block IIR-B.
Except for several values of Block IIR-A and the peak at 1?of Block I,the agreement is rather excel-lent.The mean block-speci?c PCV values were ?nally ?xed when reprocessing the complete GPS data once again,in order to derive best possible satellite-speci?c z -offsets (see Sect.5).It should be pointed out that all satellite antenna parameters,PCVs and PCOs,refer to the ionosphere-free linear combination LC,as it was not possible to estimate separate corrections for L1and L2.
5Satellite antenna phase center offsets
5.1Phase center x -and y -offsets
Although Sect.3contains several aspects concerning the satellite antenna offsets in the x -and y -directions,they are not considered in detail here.On the one hand,the deviations from the nominal values did not appear to be signi?cant in most cases,and on the other hand,
2
4
6
8
10
12
14
?15
?10?505
10
15Nadir angle [°]
S a t e l l i t e a n t e n n a P C V [m m ]
Block I
Block II/IIA
Block IIR?A
Block IIR?B
Fig.9Mean LC PCVs for all GPS satellite blocks with error bars indicating the difference between the GFZ and the TUM solution
790R.Schmid et al.
Table4Mean LC PCVs(mm)for all GPS satellite blocks
Nadir angle(?)01234567891011121314 Block I?1.0?2.6?1.2?0.90.5 1.4 2.0 2.0 1.70.5?0.1?0.6?0.7?0.6?0.3 Block II/IIA?0.8?0.9?0.9?0.8?0.40.20.8 1.3 1.4 1.20.70.0?0.4?0.7?0.9 Block IIR-A?6.1?5.2?3.3?1.0 1.4 3.5 4.7 4.9 4.1 2.80.8?1.0?2.1?2.1?1.4 Block IIR-B/M10.710.18.0 4.60.5?3.8?7.5?9.7?10.3?9.5?7.4?4.10.3 6.012.1
Fig.10Satellite antenna
z-offset time series from GFZ
(weekly means)and TUM
(daily solutions)with station
coordinates?xed to the
IGb00reference frame,both
based on the mean PCVs
(gaps in the TUM series are
due to the exclusion of eclipse
seasons)
it would only make sense to take them into account if azimuth-dependent PCVs were also considered.The only satellite that could be identi?ed to have a horizon-tal offset differing considerably from the nominal value was SVN23,which has a problem with its solar panels (Hugentobler et al.,2003).
5.2Trend in the z-offsets and the scale of the
reference frame
Figure10shows,as an example,the z-offset time series for GFZ and TUM with respect to the corresponding mean PCVs.One can see a trend in the offset amount-ing to about20cm after10years and a seasonal?uc-tuation.The reason for the seasonal pattern is not fully clear.Major candidates are local multipath or unmod-eled loading effects,which may amount to several mm in the station heights,unmodeled effects in the satellite orbital models,and de?ciencies of the troposphere map-ping functions(cf.Boehm et al.,2006).However,the in?uence of those effects on the PCO can be removed (reduced)by taking an average over a longer(multi-year)time interval.There are no signi?cant changes in the PCOs depending on the PCV model used.
The mean z-offset trend over all satellites is?22.0±0.1and?24.8±0.2mm/year for GFZ and TUM,respec-tively,if the scale is?xed to IGb00.This trend of about 2cm/year can be explained by the reported error in the mean vertical velocity of IGb00of0.8mm/year(Ray et al.,2004).The scale drift of0.15ppb/year between GPS reprocessed results using absolute phase center information and IGb00(see Table8)would also roughly correspond to1mm/year in the station heights and hence to roughly2cm/year in the z-offset(cf.Eq.8).In another TUM solution,where a reference frame reali-zation of our own was used,no signi?cant z-offset trend (?1mm/year only)could be detected.
For comparing the GFZ and TUM results and for forming mean values from different solutions,the signi?cant trend,caused by the scale rate in the IGS realization of ITRF2000,has to be corrected for.By ref-erencing all the individual satellite z-offsets to a given epoch(2000.0),no scale change in the reference frame, especially if it depends on the changing satellite constel-lation,should be obtained anymore.A general constant bias may still exist,but for various applications,like sea level monitoring,a scale trend is much more trouble-some.
5.3Determination of satellite-speci?c z-offsets
To get better insight into the behavior and the reliability of the derived satellite antenna phase center z-offsets, daily estimated values are used instead of stacking the
Generation of a consistent absolute phase center correction model for GPS receiver and satellite antennas791 Table5Antenna z-offset differences(mean and standard deviation)between various solutions for the speci?c satellite blocks(I,II/IIA, IIR-A and IIR-B)and for all satellites(reference frame always?xed to IGb00)
Solution1Solution2Differences(cm)
AC PCV AC PCV I II/IIA IIR-A IIR-B All
TUM mean TUM TUM13±82±3?2±31±22±4 GFZ mean GFZ GFZ?13±111±3?6±42±4?1±6 GFZ GFZ TUM TUM18±47±47±22±27±5 GFZ mean TUM mean?7±176±33±42±24±6
normal equations and solving for a global parameter. In the latter case,also the trend resulting from the scale drift of the reference frame would have to be considered. Therefore,the simple but robust method of estimating daily offsets with a subsequent derivation of the mean offset and trend was selected.
The daily offsets have a formal error of about1.5cm and the resulting mean offset and the offset trend esti-mated from the time series have errors of a few mm and mm/year,respectively,depending on the length of the time series.These formal errors are rather optimis-tic and do not re?ect the accuracy as the comparison between the results of the two software packages and different estimation strategies shows(Table5).As known for a long time,the scale in the reference frame varies between solutions of the software packages (Altamimi et al.,2002)and this will also in?uence the differences in the estimated offsets.
For the individual satellites,the z-offset trends from the GFZ and TUM solutions are shown in Fig.11.The formal errors of the trends are in the range of 2–5mm/year and the agreement between GFZ and TUM is in most cases at the level of1cm/year.Sup-posing that we have the same cause for the trend,e.g. IGb00,in all satellite offset series,it is of course much more stable(formal error of0.1–0.2mm/year)to derive a common trend for all satellites.
Before generating the?nal combined solution,the effect of the given PCVs—AC own or mean—on the offsets was tested.From Table5and Fig.12,it can be seen that the changes by switching from AC own to the mean PCVs is not signi?cant,and the overall change of a few cm is within the noise level of the procedure. The larger scatter for the Block I satellites is caused by the fewer observations used.The overall difference between the mean solutions of GFZ and TUM,4cm and a scatter of6cm,demonstrate the high quality of the results(Table5).
The mean z-offsets for the different blocks are,as already known from the IGS standard for the relative antenna model(Rothacher and Mader,2003),rather different(Table7).Also within one block,the peak-to-peak difference between individual satellites reaches
Fig.11Trends for satellite antenna z-offsets for individual satel-lites from GFZ and TUM using own PCVs and?xing the reference frame to IGb00.Only satellites with more than2years of data are shown.The formal trend error is in the range of2–5mm/year values of60and70cm for Block IIA and Block IIR, respectively(Table6).
There is especially a signi?cant difference between the newer and the older Block IIR satellites(see Sect.2.2),similar to what we have seen for the corre-sponding PCVs.Therefore,mean block-speci?c values for the z-offsets cannot reasonably be de?ned,and thus we recommend the introduction of satellite-speci?c off-sets.It can be assumed that those,in addition,absorb the differences between satellite-speci?c and block-speci?c PCVs to some extent,as PCOs and PCVs are tightly connected.
792R.Schmid et al.
Fig.12Satellite antenna z-offsets from GFZ and TUM for differ-ent PCV models and reference frames used.The TUM solution based on an internal reference frame is shifted by+20cm.The formal offset error ranges from2to6mm
5.4Comparison with NGA values
The National Geospatial-Intelligence Agency NGA (formerly NIMA)uses a set of satellite antenna PCOs that differs from the IGS conventional values.We can-not say anything de?nite about the origin of these values, but most likely they are the result of calibration mea-surements by the manufacturers on the ground.It is also unknown for which frequency they were measured. For Block II/IIA,only a block-speci?c mean offset is given,whereas for Block IIR satellite-speci?c values can be found on the NGA website(https://www.wendangku.net/doc/a513612490.html,/GandG/sathtml/).
If the mean block-speci?c z-offsets from the com-bined GFZ/TUM solution are compared with values from NGA and the IGS relative model(cf.Table7), enormous differences appear between the diverse satel-lite blocks,but particularly between the three models. The GFZ/TUM and the NGA models agree in the fact that the Block IIR-B satellites have the smallest z-offset of all existing GPS satellites.However,there is a very big difference as regards Block II/IIA and Block IIR-A:the Table6Mean LC antenna z-offsets(cm)and differences(cm) between GFZ and TUM for all satellites active between1994and 2005
SVN PRN BLK Mean Diff
09G13I174.1?28.1 10G12I174.814.5 11G03I168.6?9.3 13G02II253.0 1.7 14G14II264.411.4 15G15II231.27.3 16G16II236.4 2.3 17G17II225.3 5.2 18G18II238.9 3.9 19G19II274.4 2.6 20G20II241.611.4 21G21II234.4 1.9 22G22IIA226.7 4.9 23G23IIA257.5 6.9 24G24IIA245.510.3 25G25IIA229.5 5.4 26G26IIA230.7 6.2 27G27IIA247.2 2.4 28G28IIA220.58.7 29G29IIA235.2 6.8 30G30IIA246.68.7 31G31IIA210.7 4.5 32G01IIA220.19.1 33G03IIA261.9 4.3 34G04IIA227.9 6.1 35G05IIA246.3 5.5 36G06IIA267.6 6.9 37G07IIA222.08.2 38G08IIA240.5 4.8 39G09IIA234.09.9 40G10IIA238.97.0 41G14IIR-A117.8 4.3 43G13IIR-A120.30.6 44G28IIR-A91.17.1 45G21IIR-A130.0?0.4 46G11IIR-A97.18.2 51G20IIR-A115.4 1.9 54G18IIR-A113.3 4.1 56G16IIR-A130.7?5.4 47G22IIR-B79.2 5.2 59G19IIR-B66.8 2.2 60G23IIR-B60.2?1.6 61G02IIR-B61.4 2.1 (SVN space vehicle number,PRN pseudo-random noise number, BLK satellite block designation)
Table7Comparison of the mean satellite antenna z-offsets(cm) from GFZ/TUM with NGA values and the relative IGS model Block GFZ/TUM NGA IGS
I172.50–85.40 II/IIA239.6095.19102.30 IIR-A114.46158.850.00 IIR-B66.90?1.000.00 GFZ/TUM model detects a difference of+125.14cm between the two blocks in contrast to?63.66cm in the NGA model.
Generation of a consistent absolute phase center correction model for GPS receiver and satellite antennas
793
90
95100105110115120125130135
S q u a r e s : G F Z /T U M z ?O f f s e t [c m ]
Space vehicle number
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44
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152154156158160162164166
168
T r i a n g l e s : N G A z ?O f f s e t [c m ]
Fig.13Comparison of individual antenna z -offsets (cm)for all Block IIR-A satellites:the GFZ/TUM offsets are represented by squares with the scale on the left ,whereas the scale for the triangles representing the NGA values is given on the right
The comparison with the relative IGS model shows that the proportion of the offsets to each other agrees well for the ?rst three blocks,indicating that the val-ues used by the IGS until November 2006are relatively consistent,even though Ge et al.(2005b )outline that the Block IIR-A offset should be about 40cm smaller.However,the relative IGS model did not account for the offset difference between Block IIR-B and Block IIR-A as detected by the other two models:?47.56cm (GFZ/TUM)and ?159.85cm (NGA),respectively.If this dis-crepancy had also been ignored for the Block IIR-M satellites to be launched,a considerable change of the global terrestrial scale would have had to be expected.A closer look at the individual z -offsets of the Block IIR satellites shows that the new GFZ/TUM model and the NGA values are quite consistent.Figures 13and
60
65707580S q u a r e s : G F Z /T U M z ?O f f s e t [c m ]
Space vehicle number
47596160
?9
?5
?1
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T r i a n g l e s : N G A z ?O f f s e t [c m ]
Fig.14Comparison of individual antenna z -offsets (cm)for all Block IIR-B satellites:the GFZ/TUM offsets are represented by squares with the scale on the left ,whereas the scale for the triangles representing the NGA values is given on the right
14show the satellite-speci?c offsets of the two mod-els for Block IIR-A and Block IIR-B,respectively.The individual satellites are arranged according to the size of their GFZ/TUM offset.In order to compensate for the different mean values (cf.Table 7)as well as the differ-ent ranges of values,a bias and a scale were allowed for in the representation of the two offset models.Except for SVN 45and SVN 60,the agreement is almost perfect in consideration of the fact that the TUM estimates for the Block IIR offsets differed from the GFZ ones by 2–3cm.
6In?uence on global GPS parameters
To study the in?uence of different antenna phase center corrections on global GPS parameters,four solutions covering the time interval from 1January 1994to 31December 2004were computed with completely identical settings,except for the PCVs and z -offsets used (Table 8).
The processing scheme is identical to the TUM strat-egy described in Sect.2.3,except for three differences:(1)neither PCVs nor PCOs were estimated,(2)the scale was not ?xed to IGb00and (3)the hydrostatic isobaric mapping function was computed with ECMWF (European Centre for Medium-Range Weather Fore-casts)z200data (available at http://mars.hg.tuwien.ac.at/～ecmwf1/Z200/).
The relative PCV model used by the IGS until Novem-ber 2006was introduced for solution A.Solution B uses an older absolute PCV solution by TUM with block-spe-ci?c offsets .Solution C is based on the TUM contribu-tion to the combined GFZ/TUM PCV solution labeled D.The latter solution is the only one taking into account the in?uence of several antenna/radome combinations.6.1Troposphere parameters
The comparison of common parameters derived by different space-geodetic techniques allows an assess-ment of the effects of different modeling approaches for technique-speci?c effects like antenna PCVs.The tropospheric zenith delays resulting from the GPS solu-tions A,B and C were compared to a VLBI solution computed by Deutsches Geod?tisches Forschungsinsti-tut (DGFI,Tesmer et al.,2004).Identical a priori zenith delays for each station together with the Niell (1996)mapping function were used,both for GPS and VLBI.The theoretical difference in the tropospheric zenith delay due to the height difference between the GPS antenna and the VLBI telescope was corrected for with
794R.Schmid et al. Table8Global11-year GPS solutions using different PCVs and z-offsets together with their scale offset and drift with respect to IGb00 on1January2000
Sol.Antenna model Offset(ppb)Drift(ppb/year) ID PCVs Type Sat.PCVs z-off.Rec.PCVs Radomes with respect to IGb00
A IGS Relative–b z– 1.200.34
B TUM Absolute b b a–?0.650.18
C TUM Absolute b s a–?0.100.12
D GFZ/TUM Absolute b s a x0.250.15
(b block-speci?c,s satellite-speci?c,z zenith-dependent only,a zenith-and azimuth-dependent)
Fig.15Tropospheric zenith
delay biases between GPS
and VLBI for24co-located
stations.The theoretical bias
due to the height difference
was corrected for.The mean
biases(indicated by
horizontal lines)are
+5.3±3.5mm for relative
PCVs(solution A),
?2.5±3.2mm for absolute
PCVs with block-speci?c
z-offsets(solution B)and
?0.8±3.2mm for absolute
PCVs with satellite-speci?c
z-offsets(solution C)
the Saastamoinen(1973)model(accurate to1mm for height differences below about20m).The biases between GPS and VLBI for24co-located stations are shown in Fig.15.The largest mean bias(+5.3±3.5mm) occurs for relative PCVs(solution A);it can be reduced by more than a factor of two to?2.5±3.2mm by switching to absolute PCVs with block-speci?c z-offsets (solution B).
A further improvement can be achieved by introduc-ing satellite-speci?c z-offsets(solution C):the bias can again be reduced by a factor of three to?0.8±3.2mm. The tropospheric zenith delay biases of the eight sta-tions participating in the continuous2-week CONT02 VLBI campaign(Thomas and MacMillan,2003)show an astonishingly good agreement with the11-year time series(see Thaller et al.,2006).Remaining biases might be caused by changes in the antenna/radome constella-tion of the individual stations,by local multipath effects or by VLBI-related effects.6.2Global terrestrial scale
Scale offset and drift with respect to IGb00of the four different global solutions are listed in Table8.The solu-tion using relative PCVs(solution A)shows the well-known large offset(1.20ppb;cf.Altamimi et al.,2002) and also a large drift of0.34ppb/year caused by the erroneous standard offsets,especially for Block IIR, and the satellite constellation changing with time(Ge et al.,2005b).Both values are reduced by a factor of about two for solution B with absolute PCVs and block-speci?c z-offsets.
Solution C has the smallest scale offset as well as the smallest drift due to the fact that the same software package was used,both for the estimation of the PCVs and the computation of the global solution.The com-bined GFZ/TUM PCV set used for solution D causes a slightly larger offset and drift than in solution C,but the reduction of the scale offset compared to solution A by
Generation of a consistent absolute phase center correction model for GPS receiver and satellite antennas795
a factor of almost?ve is a signi?cant improvement.The remaining scale drift of0.15ppb/year re?ects the error of the IGb00(0.8mm/year)mentioned in Sect.5.2.
6.3Orbit parameters
An improved modeling of the satellite antenna phase center also affects the orbit quality.The root mean square(RMS)of a3-day orbit?t through three1-day orbital arcs was used to quantify the internal orbit con-sistency of the daily solutions.The mean RMS reduction within the11-year time interval for each individual satel-lite when switching from relative PCVs(solution A) to absolute PCVs with block-speci?c(solution B)or satellite-speci?c z-offsets(solution D)is shown in Fig.16.
The Block IIR satellites,especially the Block IIR-B satellites,show the largest improvement in orbit consis-tency as they possess the largest PCV values(cf.Fig.9). Due to the fact that no distinction was made between Block IIR-A and Block IIR-B for solution B,the improvement for the Block IIR-B satellites mainly shows up when comparing the solutions A and D(Fig.16).
Fig.16RMS reduction of3-day orbit?ts through three1-day orbital arcs:a relative PCVs(solution A)versus absolute PCVs with block-speci?c z-offsets(solution B),b relative PCVs (solution A)versus absolute PCVs with satellite-speci?c z-offsets (solution D).Due to their small number of observations,Block I satellites were excluded
In the comparison of the solutions A and B,the two Block II satellites with the largest z-offsets(SVN14and SVN19)show a degradation of the RMS and for two Block IIA satellites with also large z-offsets(SVN23 and SVN36)the RMS does not change.By additionally taking into account the z-offset variations within the different satellite blocks,the RMS reduction improves by a factor of about two for Block II/IIA and by a factor of1.4for Block IIR-A,emphasizing the importance of considering individual z-offsets.
6.4Station coordinates
The mean coordinate changes between the solutions A and D for the whole11-year time interval are shown in Fig.17.Systematic effects due to different reference frame realizations of the two solutions were removed by a three-parameter similarity transformation(trans-lations only).The changes in the horizontal component range from?8to+6mm for the north and from?5to +5mm for the east component.
A major part of these changes might be caused by considering azimuth-dependent receiver antenna PCVs for solution D that are neglected in solution A.The
Fig.17Histograms of the mean coordinate changes between the solutions with relative(solution A)and absolute PCVs(solution D).Geocenter differences were removed by a three-parameter similarity transformation
796R.Schmid et al.
large mean change in the height component of+6mm is primarily related to the scale difference between the two solutions(offset on1January2000:0.95ppb,drift: 0.19ppb/year).The spectrum of changes in the station height ranging from?7to+18mm is much broader than for the horizontal components.Especially some stations with calibrated radomes show large height changes.
To study the in?uence of radomes in more detail, an additional solution was computed which is identical to solution D,but neglects the radome calibrations.The largest differences with up to±10mm occur in the height component.The horizontal component also changes by up to±8mm for some stations.Stations equipped with the Trimble antenna TRM29659.00and the UNAVCO radome UNAV show differences of about5mm in the north component and6–8mm in the east component.
A part of these changes is caused by de?ciencies in the calibration procedure for the antenna with radome: whereas for the antenna without radome a robot cal-ibration including zenith-and azimuth-dependent cor-rections is available,the values for the antenna with radome are converted from relative?eld calibration results including zenith-dependent corrections only.The neglect of the azimuth-dependence of the PCVs in com-bination with the effect of the radome are the reasons for the signi?cant horizontal as well as vertical(about 10mm)displacement of the stations using this antenna.
For the Ashtech antenna ASH700936C_M with SNOW radome,both calibrations(with and without radome) are available with zenith-and azimuth-dependent cor-rections.As stations using this antenna show a shift of about5mm in the east component,one can con-clude that the SNOW radome has a signi?cant azimuth-dependent in?uence.Since the number of calibrated antenna/radome combinations in our network is small (calibration available for only20out of92radome sta-tions),the mean coordinate changes are rather small: 0.25mm for the north,?0.04mm for the east and 0.68mm for the up component.
7Outlook
For the de?nition of the GPS satellite antenna parame-ters within the new absolute IGS antenna model named igs05_wwww.atx(available at ftp://igscb.jpl. https://www.wendangku.net/doc/a513612490.html,/igscb/station/general/),the results from GFZ and TUM were taken to form the mean val-ues the new model is based upon.Both ACs,together with other IGS ACs,will monitor the satellite antenna models on a regular basis.As soon as signi?cant changes will be detected,an update of the IGS antenna model will be considered.
Especially important is the determination of antenna parameters for newly launched satellites.Their estimated antenna parameters over a few days or weeks will be tested against already existing ones.If its PCVs ?t to one of the existing groups,only a z-offset will be derived based on the block-speci?c PCV values.Oth-erwise,a new group will have to be de?ned.Until the release of new of?cial values,the users have to apply block mean values.
This paper only describes the generation of the antenna models for the GPS satellites.In the meantime, the Center for Orbit Determination in Europe(CODE) reprocessed about15months of data to derive consis-tent corrections for the GLONASS(and GPS)satellites on the basis of a combined GPS/GLONASS analysis (Schmid,2006).Since the absolute antenna model con-sisted of correction values for all active GNSS satellites, it was ready for the adoption as the new standard by the IGS.
A similar procedure will be necessary for the upcom-ing Galileo system.Even if the Galileo provider will calibrate the satellite antennas before launch,experi-ence with GPS has shown that those values have to be con?rmed by in-orbit analysis results and possibly adapted to the estimated models.
Furthermore,it is desirable that azimuth-dependent satellite antenna PCVs are analyzed in more detail together with the corresponding x-and y-offsets.The single elements each GPS satellite antenna consists of can clearly be identi?ed depending on the azimuthal direction(Schmid et al.,2005b).If additional ACs would generate such results,they could be combined with the JPL maps(Haines et al.,2004)in order to get a new IGS standard.First investigations have shown that sta-tion coordinates may be changed by1–2mm in global solutions and that the quality of GPS orbits could be improved by about half a mm,if azimuthal PCVs were considered.
As the latter numbers are rather small,there seems to be more need for action on the part of the receiver antenna.On the one hand,of course,each new antenna type has to be calibrated before use within the IGS net-work,but on the other hand there are also a lot of com-binations of antenna and radome pairs in use that were not calibrated until now.In these cases,the calibration for the antenna without a radome is used.The conver-sion of relative?eld calibrations(see Sect.2.1)that are limited to elevation dependence and that cannot pro-vide PCVs below10?elevation is another suboptimal, temporary solution.
This means that there is still a big demand for receiver antenna calibrations,also for antennas that are removed from reference frame stations to allow for an improved
Generation of a consistent absolute phase center correction model for GPS receiver and satellite antennas797
reprocessing.All future calibrations should be per-formed in an absolute way in order to get full models, either by the calibration robot from Hannover(Menge, 2003)or,maybe,by an automated chamber calibration the University of Bonn is working on(G?rres et al., 2006).The best would be,however,to avoid radomes wherever possible and to reduce the number of differ-ent antenna types within the IGS network.
The IGS switched to the new absolute antenna phase center model simultaneously with the switch to an IGS realization of the new international terrestrial reference frame ITRF2005(http://itrf.ensg.ign.fr/; Altamimi et al.,2007)on5November2006(Gendt, 2006).As a consequence,a discontinuity was observed in all IGS product time series.
However,this discontinuity will be recti?ed by the complete reanalysis of all historic GPS data planned within the IGS(Steigenberger et al.,2007).In any case, users should avoid mixing results from solutions using different phase center conventions.Needless to say that the four constituents of the model,namely the PCOs and the PCVs for the receiver as well as the satellite antennas,should only be used consistently.
Acknowledgments We thank Dr V.Tesmer(DGFI)for the analysis of the VLBI data,Dr J.Boehm(Vienna University of Technology)for providing the ECMWF z200data and Dr G. Wübbena(Geo++GmbH)and his group for the kindness to make the absolute robot calibration results available to the IGS.The TUM/DUT GPS reprocessing project was funded by the Deut-sche Forschungsgemeinschaft(German Research Foundation). References
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505操作说明
505操作说明 一、505一般介绍 （一）505转速控制器的键盘和显示器 505转速控制器的操作屏由操作面板上的键盘和显示器组成。显示器具有二行，每行显示14个字符，用于以英文显示运行参数和故障报警查向参数。此外，还有30个键，提供丁505调速面板上的全部操作。汽轮机的控制操作不需要附加的控制屏，每个汽轮机控制功能都能通过505转速控制器的面板执行。 （二）505键盘上：各个键的功能 1）键盘中央的大菱形键，在其四个角上带有箭头。 ←→(左右翻动)使编程或运行方式下的功能块显示左移或右移。 ↑↓ (上下翻动)使编程或运行方式下的功能块显示上下移动。2）SELECT(选择键) 选择键用于505显示器上行或下行变量的选择控制。@符号用于指出哪一行(变量)能通过调整键ADJ来进行调整。只有当上、下行都为可调变量时，SELECT键和@符号才能起作用。当显示器只显示一个变量时，SELECT 键和@符号的位置将不起作用。 3）ADJ(调整键) 在运行方式中，“▲”增大可调参数，“▼”减少可调参数。 4）PRGM(编程键) 当505处于跳车状态或停机状态时，用该键选择编程方式。在运行方式中，该键用于选择程序临视方式。在程序临视方式中，能浏览所编制的程序但不能修改。 5）RUN(运行键) 从505画面显示(CONTROLLING PARAMETR／PUSH RUN OR PRGM)状态触发汽轮机运行即启动指令。 6）STOP(停止键) 一旦予以确认，触发汽轮机控制停机(运行方式)。能过通过服务方式设定值(在“键选择”下来取消“STOP”指令。
7）RESET(复位键) 对运行方式的报警和停机状态作复位／清除。在停机后按该键还可使调速器返回到(CONTROLLING PARAMETR／PUSH RUNORPRGM)状态。 8）O／NO： 输入O／NO或退出。 9）1／YES： 输入1／YES或投入。 10)2／ACTR(执行机构)： 输入2(编程方式)或显示执行机构位置(运行方式)，按“下翻箭头”显示输入执行机构的电流。 11)3／CONT(控制参数)： 输入2(编程方式)或显示控制参数(运行方式)，按“下翻箭头”显示505的最近—次跳车原因、达到的最高转速和就地／远程状态。 12)4／CAS(串级控制)： 输入4或显示串级控制信息(运行方式)，未使用。 13) 5／RMT<远程控制)： 输入5或显示远程转速给定值控制信息(运行方式)。 14) 6／LMTR(阀位限制器)： 输入6或显示阀位限制器信息。 15) 7／SPEED： 输入7或显示就地转速值(二选一，选最高值)和转速设定值。 16) 8／AUX(辅助)： 输入8或显示辅助控制信息(运行方式)。 17) 9／KW(负荷)： 输入9或显示KW／负荷或第一级压力信息(运行方式)。 18)CLEAR：
[整理]DCSSU-25操作手册
LOCK ON 中文讲解课程 本章节主要讲解苏系战机起飞操作步骤 飞机起飞步骤大体分为三个部分 一：启动发动机 二：滑出停机坪上跑道 三：起飞 首先是启动发动机的步骤， 我们所实用的机型是 SU-25T ， 只所以不是 SU-27 ， 是因为 SU-27T 是 LOCK ON 中操作步骤比较复杂的机型， 它的启动步骤包含其他机型的启动步骤， 同时也 有所复杂，所以我们用 SU-25T 来讲解飞机的启动步骤 现在我们在 SU-25T 的座舱里可以看到飞机的所以仪表都处在关闭状态， 因为主电源是关闭 状态，我们通过 Shif+ “ R “键打开飞机的主电源，注意仪表开始有变化，观察气压高度计，我们通过 Shif+ “ - “和 Shif+
“ = “将气压高度计归零，这是 SU-25T 在 LOCK ON 中的标准 操作步骤，至于为什么要将它归零，我也不知道！好，一切仪表正常，准备启动发动机，我们按 Ctrl+ “ L “键点亮翼灯，向塔台表明我们要启动发动机，确认节流阀收到低按键盘右侧 （空格右边第 2 个键）文斗丝间和 HOME 键，让发动机启动，注意发动机的转速表开始变 化，发动机已经启动， SU-25T 是双阀战斗机，目前版本的 LOCK ON 当中的所有可用机型 都是双阀，所以我们可以单独的启动左发动机和右发动机，通过按 ATT GR+HOME 键来来 启动左发动机，通过 Shif+HOME 键来启动右发动机，目前版本的 LOCK ON 中 SU-25T 以 及 SU-25 的启动步骤是相同并且是最复杂的，其他大部分机型的启动步骤中，进入座舱后， 电源本身是打开的，仪表也不需要矫正，直接启动发动机即可，现在我们回到 SU-25T 的座
IE安全漏洞及防范措施
IE安全漏洞及防范措施 摘要 谈到联网的计算机，就能想到它百纳海川的资讯，可以在网络的世界里找到自己想了解到的，自己想探索到的新知识，但是要想了解到这些资讯我们需要借助到一个工具，这就是我们每一个人都熟悉的----IE浏览器。技术的进步，离不开知识的传播。时代的需求就是我们的责任，我们要抓住信息时代的脉搏，在Internet飞速发展的今天，互联网成为人们快速获取、发布和传递信息的重要渠道，从而倍受人们的重视。互联网上信息的查找又要通过浏览器的浏览来实现，所以希望通过对IE浏览器的安全漏洞和防范措施的探讨让大家对网络及网络资源搜索的认识以及浏览器的各个功能。 关键词：IE浏览器/漏洞/措施
IE Security vulnerabilities and preventive measures ABSTRACT The PC is popular and the brilliant Computer-Culture is developing rapidly by drived of the Financial globalization,Assimilation of information and the Industrial knowledge-ization.Studying computer knowledge is becoming a consciousness action for many back-hoping people in the Boundary of the century.There are many progresses in the information industry,the time of the network and so on.We can see that more person's work and life are never left by a computer.It isn't left the spread of knowledge by technological progress.The demanding of the time is our responsibility.In the days of the internet developing fastly,we should catch the pulse of it,make the internet become a basilic channel that make people getting,issuancing and passing the news at a rapid rate.And then made the internet receives people's emphasis increasingly.One looking for the information by the browser's browsing,so I hope everyone should increasing Browser vulnerabilities and preventive measures and all kinds of functions of the browser by my paper. Keyword: Internet Explorer /vulnerabilities/measure
505调速器说明书
一、引言 505/505E是以微处理器为基础的调速器，适用于单执行机构或双执行机构的汽轮机控制。调速器采用菜单驱动软件以引导现场工程师根据具体的发电机或机械驱动应用要求对调速器进行编程组态。本说明书主要介绍调速器的工作原理、系统构成、面板操作。由于英文版手册存在不断增加和更改内容等方面的因素，使用woodward505/505E时，还请参考随调速器提供的woodward正式英文版手册。 二、505/505E的工作原理及系统介绍 505/505E电子调节器比一般液压系统控制精度高，自动化水平大大提高，热电负荷 自整性也高，它能实现升速（手动或自动），配合电气并网，负荷控制（阀位控制或功频 控制），抽汽热负荷控制及其它辅助控制，并与DCS通讯，控制参数在线调整和超速保护 功能等。能使汽轮机适应各种工况并长期安全运行。 2.1基本原理 并网前在升速过程中，转速闭环为无差控制，505/505E控制器将测量的机组实际和给定转速的偏差信号经软件分析处理及PID运算后输出标准电流信号给电液转换器，电液转换器接受调节器输出的标准电流信号，输出与输入电流信号相对应的调节信号油压。调节信号油压经液压伺服机构放大，控制油动机活塞移动，通过调节杠杆，改变调节汽阀的开度，调节汽轮机高压段、低压段的进汽量。从而减少转速偏差，达到转速无差控制，当转速达到3000r/min，机组可根据需要定速运行，此时505/505E可接受自动准同期装置发出的或运行人员手动操作指令，调整机组实现同步，以便并网。 机组并网后，如果采用功率闭环控制，可根据需要决定505/505E使机组立即带上初负荷，DEH实测机组功率和机组转速作为反馈信号，转速偏差作为一次调频信号对给定功率进行修正，功率给定与功率反馈比较后，经PID运算和功率放大后，通过电液转换器和油动机控制调节阀门开度来消除偏差信号，对机组功率实现无差调节，若功率不反馈，则以阀位控制方式运行，即通过增加转速设定，开大调节汽阀，增加进汽量达到增加负荷的目的。在甩负荷时，505/505E自动将负荷调节切换到转速调节方式。机组容量较小时建议可不采用功率闭环控制。 在机组带上一定电负荷后可根据需要带热负荷，投入抽汽控制。505/505E控制器根据机组工况图对机组电负荷及抽汽压力进行自整控制。
员工入职资料表格汇总26387
入职资料登记表 申请职位：入职日期：年月日 基本资料 姓名性别民族出生年月 学历身份证号 联系电话身高体重政治面貌 是否有驾照及类型婚姻及生育状况 户口所在地现居住地 紧急联系人联系电话 电子邮箱社会统筹情况□养老□医疗□失业□生育□工伤□公积金 教育背景 起止时间毕业院校专业学历/学位教育性质 □统招□函授□自考□其他 □统招□函授□自考□其他职业资格证书或其他相关证书： 时间工作单位、职位离职原因工作 经历证明人姓名及联系方式 家庭关系姓名年龄工作单位职务联系方式主要
关系 招聘渠道：□网络招聘□员工推荐（员工姓名）□人才市场□其他方式其他是否有朋友、亲戚在我公司工作？□是，请说明：□否 其他说明事项： 公司承诺：此资料将进入公司人才库严格保密，并仅作招聘使用。为全面了解您的优劣势，安排合适的岗位 使您扬长避短，请您认真、完整、如实填写。 本人承诺：本人授权公司向本人曾任职的公司、介绍人或咨询人查询所有记录，且申明以下提交的一切资料 绝对真实，如有不实，可作为被公司辞退的理由，而公司无须做出任何赔偿。 填表人确认签名： 新员工录用工资确认表 姓名录用部门录用岗位入职时间年月日发放日期每月20 日，遇节假日顺延薪酬标准执行①试用期工资：元/ 月；转正后元/月。 第种； 本岗位工资按公司规定暂实行足额发放。②实行年薪制 ③其他 年薪元，试用期工资：元/ 月；转 正后元/月；余额根据公司内部规定发放。 ①社会保险 福 利 待 遇③其它补助自年月开始缴纳社会保险。（备注说明：） 补贴①： 试用期发元/月；转正后发元/ 月。
补贴②： 试用期发元/月；转正后发元/ 月。 以上信息由人力资源部填写，填写人签字确认： 确认日期：年月日人力资源部主管领导意见： 确认日期：年月日领导签批确认： 确认日期：年月日 以下信息由新入职员工填写 新入职员工身份证号码 银行卡号 开户行 以上薪资及福利内容本人已经知晓，身份证号码、银行卡号、开户行信息由本人自已填写，并确保 信息准确无误；因自已填写错误造成的损失由本人承担一切责任。同时本人承诺对自已的薪资福利绝 对保密，如自已泄露愿接受公司的一切处理，直至解除劳动合同给予辞退。 新入职员工确认签字：确认日期：年月日 本表一式一份，仅供人事部与新录用员工核对薪资福利信息用，在经领导核定并经新录用员工签字 备注说明 确认后作为发放工资的依据。领导核定签批后原件留存于财务部门，人力资源部留存复印件。
Mrbayes中文使用说明
< >内为需要输入的内容，但不包括括号。所有命令都需要在MrBayes >的提示下才能输入。 文件格式： 文件输入，输入格式为Nexus file（ASCII，a simple text file，如图）： 或者还有其他信息： interleave=yes 代表数据矩阵为交叉序列interleaved sequences nexus文件可由MacClade或者Mesquite生成。但Mrbayes并不支持the full Nexus standard。 同时，Mrbayes象其它许多系统软件一样允许模糊特点，如：如果一个特点有两个状态2、3，可以表示为：(23)，(2,3)，{23}或者{2,3}。但除了DNA{A, C, G, T, R, Y, M, K,S, W, H, B, V, D, N}、RNA{A, C, G, U, R, Y, M, K, S, W, H, B, V, D, N}、Protein {A, R, N, D, C, Q, E, G, H, I, L, K, M, F, P, S, T, W, Y, V, X}、二进制数据{0, 1}、标准数据（形态学数据）{0, 1, 2, 3, 4, 5, 6, 5, 7, 8, 9}外，并不支持其他数据或者符号形式。 执行文件： execute
ZOOM505Ⅱ效果器中文说明
面板各部位名称（图1） ---------------------- | | A1 | | 存储键●| | 音色| |●+参数值（编辑时）/组的更换↑ | | | | | | | | 编辑键●|------| 灯|------|●-参数值（编辑时）/组的更换↓ | *|* | | 踏板1 | 踏板2 | ---------------------- 后侧各插孔意义（图2） --------------------------- | 1 2 3 4 | | ◎◎ ZOOM ◎◎| --------------------------- 1、→电吉他 2、→9V变压器电源 3、→外接踏板 4、输出插口→音箱或耳机 三、原厂的24种音色 尽管鲜有人使用，但还是有必要说明一下，这是你进行各类音色设置的最直接参照，在此基础上修改会事半功倍。
A组 1-适合于SOLO的失真2-带延迟效果的原音 3-适合于节奏的失真 4-极度失真的重金属 B组 1-适合SOLO的浅失真2-带哇音的过载失真 3-带飘忽效果的原音 4-带和声效果的原音 C组 1-适合节奏的浅失真 2-带和唱效果的原音 3-重金属效果的失真 4-略带飘忽的电原音 D组 1-另外一种过载失真 2-带镶边效果的FUNK 3-闪烁回音的浅失真
4-木吉他的仿真效果 E组、F组 进行了设置,原厂音色记不清了. 四、演奏中变换音色的方法 1、基本的 连接好以后，接通电源（或装电池，接上吉他即开。505没有电源开关。）根据需要踩（踩一下即可）踏板1或踏板2，你将看到组、号的逐次变换，这时，就出现了相应的音色。 非演奏中，比如分段录音时，还可以使用图1中的“组的更换键”，这样，每次按一下，将变换一个组，而组号不变。 2、锁定音色 A、锁定一组：进入该组，按住“编辑键”不放，2秒钟后进入锁定组的状态，再次按住不放，2秒钟后自动解锁。 B、锁定单一音色：同上，所不同的是按住“存储键”。 五、直通和调弦功能 将踏板1和踏板2同时踩下后，进入直通状态，此状态中可以调弦。弹响一个音后，505将自动显示该音的首调唱名，同时，有一个闪烁的小灯，这是该音的标准位置指示灯，其他闪动的灯与此平齐时，显示的唱名和你的弹奏音音高一致。
su简单中文使用手册范本
CWP软件的安装与简单使用手册
CWP软件的安装 一．在LINUX下建立用户CWP，在CWP下建立目录path，将源文件cwp.su.all.37.tar.Z 放 二．到path目录下，并建立bin文件夹 三．在CWP用户主目录下显示隐藏文件，修改.bash_profile 文件，在已有的export之后另起一行，分别添加 export CWPROOT=/home/CWP/path，再于 PATH=$PATH:$HOME/bin后添加 ：/home/CWP/path/bin:/home/CWP 退出保存 四．从终端中分别输入 cd path zcat cwp.su.all.37.tar.Z | tar –xvf- … 待终端中反映完毕，分别输入 cd src make install make xtinstall make mglinstall make utils make xminstall make sfinstall 这期间可能有系统安装所等待的时间，不用急，但凡遇到yes/no，一路y下来即可。四．为了检查是否安装完毕，在终端中输入 Suplane > data.su Suxwigb < data.su & 若出现一个简单的图像，则成功！
CWP软件的简单说明 一、文中涉及的命令全部以小写形式，均可在终端窗口下输入，以次获取自述帮助。先说几个命令：suplane和suxwigb，more。 suplane作用是产生一个简单的零偏移距su文件，suxwigb是一个典型的X—windows 绘制图形工具，如例子： suplane > data.su suxwigb < data.su more < data.su 比较全面的了解它们，请在终端中输入suplane , suxwigb ,more 。 二、关于DEMOS的应用所有DEMOS必须把文件拷到用户根目录下，而后依照readme 文件中的执行顺序，在终端中输入文件名。注意目录下的文件变动。 三、在执行DEMOS文件时，如果想清楚了解程序执行过程，请输入 more programname 由于水平有限，这里的谬误很多，希望大家能在偶尔翻看时，多多留心，发现并改正，衷心希望能和大家一起学习。
spyglass中文使用说明
望远镜用户指南
概览............................................... (5) 关于本指南 望远镜 概观 按钮 手势 最多显示头---（HUD）的 工具和手段 入门................................................ (17) 版本和功能 硬件和软件兼容性说明............................................. (17) 启用定位服务 设置最多望远镜 开始标记和跟踪对象............................................. . (22) ViewVinder ................................................. . (23) 设置颜色 设置最多的HUD 快速切换 HUD的操作模式 缩放 指南针................................................. (28) 校准
增强现实和三维罗盘............................................. .. (29) 寻找目标对象 设置最多罗盘 罗盘定位模式............................................... .. (32) 罗经................................................. .. (34) 开始使用罗经............................................... .. (34) 确定启动轴承............................................... .. (35) 漂移和调整 全球定位系统................................................. . (37) 设置最多的GPS 获取GPS数据 设置单位 查找................................................. .. (39) 概观 按钮 快速目标标记 添加目标 管理目标 寻找和跟踪 在地图上观测地点的目标............................................. .. (47) 跟踪................................................. .. (48) 设置跟踪
505控制器使用方法
505 控制器使用方法 一、505 控制器常用键功能： PRGM ——编程RUN ——运行RESET——复位 STOP――停止（需要按YES或NO键确认） F1――报警F2――超速实验［F2+ADJ （上升）］ SELECT——选择SPEED——速度 AUX——功率限制KW——功率（负荷）显示 CLEAR ――清除ENTER――回车（确认） EMERGENCY SHUTDOWN ――紧急停机 二、PRGM ――编程键一般情况下用户不能动，一般由厂家和DCS 设计单位联合来完成编程，编程时设计有密码。 三、通常模式下启动（505 面板操作） 通电一一505控制器自检（约1分钟）——自动跳到CONTROLLING PARAMETER——如果有报警（F1键红灯亮），按F1 键观察报警条目。报警包括（MPU FAILED 转速传感器故障、CASCADE INPUT FAILED 阀前压力传感器故障、KW INPUT FAILED 功率传感器故障、OVER SPEED超速等） 自动启动： 1. 启动前应按RESET 键复位报警，F1 红色灯熄灭，方可 启动。启动前保证主汽阀处于全关状态 2. 按RUN 键运行，505 转速设定值按照编制的程序上升到500rpm ，此时调节阀门逐渐全部打开。
3. 逐渐打开主汽阀冲转，当转速达到500rpm 设定值时，调节阀门回缩到某一稳定位置，505 接替控制，按预先编制的低暖机时间进行暖机。 4. 暖机时间达到时，505 自动控制转速上升到1200rpm，按预先编制的高速暖机时间进行暖机。 5. 暖机时间达到后，505 将自动控制转速越过临界转速而逐渐达到3000rpm 后稳定运行。 手动启动： 1. 启动前应按RESET 键复位报警，F1 红色灯熄灭，方可启动。启动前保证主汽阀处于全关状态。 2. 按RUN 键运行，505 转速设定值按照编制的程序上升 到500rpm ，此时调节阀门逐渐全部打开。 3. 目标转速设定：通过按SPEED 键找到SETPT 后，按ENTER 后，直接输入转速设定值，再按ENTER 确认，此时逐渐打开主汽阀，转速就会按照设定值进行升速。（此后每次转速目标值都如此进行设定） 4. 暖机时间设定：若需要延长暖机时间，可通过按SPEED 键找到STATUS后，按NO键终止自动顺序，从而人为延长暖机时间。当按SPEED 键找到STATUS 后，按YES 键又可以恢复到自动顺序控制状态，505 将按照编制好的程序继续自动控制。如果希望减短暖机时间，可通过SPEED键找到SETPT后，按方向键立刻提升或降
SketchUp教程[指南]
SketchUp教程[指南] SketchUp? 草图大师 由于SketchUp直接面向癿是设计过程而不是渲染成品,不设计师用手工绘制构思草图癿过程徆相似,因此SketchUp癿目标是设计师做设计而不是制作员作图。 5、快捷键设置 L W O 线段漫游平行偏移 A ALT+` V 囿弧透明显示量觇器 N ALT+2 D 多边形消隐显示尺寸标注 空格键 ALT+4 SHIFT+T 选择贴图显示三维文字 E F2 H 橡皮擏等觇透规规图平移 M F4 SHIFT+Z 移动前规图充满规图 S F6 F9 缩放左规图回到下个规图 J B K 路径跟随矩形绕轰旋转 Q C P 测量囿添加剖面 T F ALT+1 文字标注不觃则线段线框显示
Y X ALT+3 坐标轰油漆桶着色显示 鼠标中键 G F3 规图旋转定丿组件顶规图 Z R F5 规图缩放旋转后规图 F8 U F7 恢复上个规图推拉右规图 I 相机位置 ，3，分割线段 如果你在一条线段上开始画线,SketchUp会自动把厏来癿线段从交点处断开。例如,要把一条线分为两半,就从该线癿中点处画一条新癿线,再次选择厏来癿线段,你就会収现它被等分为两段了。 ，4，分割表面 要分割一个表面,叧要画一条端点在表面周长上癿线段就可以了,
有时候,交叉线不能按你癿需要迕行分割。在打开轮廓线癿情冴下,所有不是表面周长一部份癿线都会显示为轳粗癿线。如果出现返样癿情冴,用直线工具在该线上描一条新癿线来迕行分割。SketchUp会重新分析你癿几何体幵重新整合返条线。 ，5，直线段癿精确绘制 画线时,绘图窗口右下觇癿数值控制框中会以默认单位显示线段癿长度。此时可以输入数值。 输入长度值 输入一个新癿长度值,回车确定。如果你叧输入数字,SketchUp会使用当前文件癿单位设置。你也可以为输入癿数值指定单位,例如,英制癿(1’16”)戒者公制癿(3.652m) 。SketchUp会自动换算。 输入三维坐标 除了输入长度,SketchUp迓可以输入线段终点癿准确癿空间坐标。 绝对坐标:你可以用中括号输入一组数字,表示以当前绘图坐标轰为基准癿绝对坐标,格式 [x, y, z]
505操作简单介绍
操作指南 简介 键盘和显示器 505E的服务面板由调速器面板上的键盘和LED（发光二极管）显示器组成。LED显示器可以显示2行（每行24个字符），用来显示运行参数和故障检测参数，使用的语言是简单的英文。通过505E前面板上的30个按键可以实现全部的控制操作，操作控制透平时无需另外的控制面板，所有的透平控制功能都通过505E的前面板执行。 下面针对每个键的功能作以说明。具体有些说明请参见505E说明书操作流程图（第五章），里面详细介绍了每个功能键下的菜单，如何操作，请仔细阅读。 SCROLL（翻页键）：键盘中央的大菱形键，菱形的四个角上各标有一个箭头。 ?，?（左、右翻动）：在编程或运行模式下使功能块显示左、右移动。 ▲，▼（上下翻动）：在编程或运行模式下使功能块显示上、下移动。 SELECT（选择键）：用于505E显示器上行或下行变量的控制选择。符号@用于指示哪一行（变量）能通过调整变量（动态、阀门标定模式）时，才会使用SELECT键和@符号来决定哪一行的变量可北调整。当显示器上只有一个可调整参数时，SELECT键不能改变@符号的位置。 ADJ（调整键）：在运行模式下，▲增大可调参数，▼减小可调参数。 PRGM(编程键)：当调速器处于停机状态时，用该键可进入编程模式。当
调速器处于运行模式时，用该键可进入程序查看模式。在程序查看模式下，程序只能看，不能修改。 RUN（运行键）：当机组准备就绪后，按RUN键发出一个透平运行或启动的指令给505E. STOP（停止键）：一旦给予确认，触发透平控制停机（运行模式下）。通过服务模式设定（在“键选项”下）可以禁用STOP命令。 RESET（复位键）：用于复位、消除运行模式下报警和停机。在停机后按该键，还能使调速器返回到（Controlling Parameter /Push Run or Prgm）状态. 0/NO:输入0/NO:回退出。 1/YES:输入1/YES或投入. 2/ACTR(执行器):输入2或显示执行器位置(运行模式下). 3/CONT(控制参数):输入3或显示当前的控制参数(运行模式下);按“向下翻页”键显示调速器的最后一次跳闸原因、条件存在图的优先权（steam map priority）\达到的最高转速、就地/远程状态(如果使用的话). 4/CAS(串级)：输入4或显示串级控制信息（运行模式下）. 5/RMT(远程):输入5或者显示远传转速给定控制信息(运行模式下). 6/LMTR（阀位限制器）：输入6或者显示阀位限制器信息（运行模式下）。7/SPEED(转速)：输入7或显示转速控制信息（运行模式下）。 8/AUX(辅助)：输入8或显示辅助控制信息（运行模式下）。 9/KW(负荷)：输入9或显示KW/负荷或第一级压力信息（运行模式下）。
Sketchup快速完全入门手册
Sketchup 快速完全入门手册焦志鹏1024 https://www.wendangku.net/doc/a513612490.html,
写在前面： 子曾经曰过：“工欲善其事，必先利其器”，两年前，我第一次接触su，中午收到别人从qq 上传来的su5.0，当时的感觉就是“这么小的软件”，当天下午了解了su 的大部分功能和基本用法，这时的想法是“果然是个小软件”…… 当时认为已经完全了解了su 的我在两年后的今天，却仍然不敢对任何人说：“学su？不会你找我！” 这就是su……
目录 第一篇初识su 第二篇su 全局概述 第三篇su 功能详解 第四篇su 的材质和组件第五篇su 使用技巧
第一篇初识su 这一篇可以算作一个前言，讨论一些似乎看起来和su 没有关系，但实际上密不可分的问题。 一、关于su 的适用范围 以我所接触的人们来说，使用su 的人大概可以分为四类“建筑设计”“室内设计”“景观设计”“工业设计”，总的来说，每一类人里都有高手，也许每个人都在使用中有所感受，这里我只说说我的一家之言。 建筑设计 据我所知，su 被引入cad 行业，最早就是在“建筑设计”中被使用的，以我的观点看，su 作为建筑设计的模型制作工具，可以说是比较合适的。 首先说说它的优点：第一，它的操作界面非常友好，相对于“三视图+相机视图”的模式，su 在人机交互界面上有着让人难以抗拒的友善感，在三维操作方面，也显得很灵活；第二，它的工具功能简单，操作方便，我一直认为，软件工具不怕多，就怕复杂，一个工具解决一个基本问题，多个工具组合解决复杂问题，这一点su 还是很不错的，在su 的工具栏里，只要单击就可以使用这个工具，单击不区分左右键，没有二级工具集，不弹出预设值对话框，一切都是顺序发生的，这一点对新手非常重要；第三，它的模型对简单体块的修改、查看非常方便，对建筑方案的前期推敲非常有利；第四，它的模型是单一文件，包含所有的贴图、块等元素，交换方便。 其次我们也要面对它的缺点：su 最大的问题可以归结为两大类：程序内核本身先天的孱弱和与生俱来的功能的缺失，有这些问题本身并不可怕，真正让你感到不幸的是我要告诉你在可以预见的将来，我们对这两点无计可施，具体的问题会在后面陆续提及。说到具体的问题，有如下几点：第一，su 的性能和执行效率非常低下，我可以毫不客气的说它可以荣登我所用过的所有软件中“性能最差”的宝座；这是由它的内核决定的，这里我们不谈这个，第二，su 在设计上也存在很严重的问题，首先，su 的精度不够，su 的精度在长度上只能精确到小数点后1 位，既0.1，当你绘制一条0.11 单位长度的线时，你会发现在模型信息中这条直线的长度前添加了约等于符号“~”，也许你会说没有人会画这样的线，但是在有曲线相交的情况下，这种线是有可能存在的，su 在面积上只能精确到0.01，也就是说面积小于0.01 单位的面永远无法封面；第三su 设计上另一个缺失就是在su 中没有贝斯曲线，su 处理曲线只能将曲线转变为多段直线处理，换句话说su 不能处理曲线方程，比如在cad 里用spl 命令绘制的曲线，就是贝斯曲线，这种曲线导入su 后，将被转化为多段线，这样一些原本在cad 中交叉的线在su 导入的过程中就会断开，导致不能封面（其实cad 在处理spl 时也比较头疼，比如你可以试试，cad 里spl 无法延伸），而事实是更残酷的，实际上su 在处理任何曲线都是以多段线的形式处理的，因此cad 中的任何曲线，包括圆、圆弧、多段线中的弧都将无一幸免；第四，当你知道了su 连曲线都处理的如此狼狈，那么su 弱的可怜的曲面建模能力也就不足为奇了，很多人都在埋怨su 的曲面能力，但很少有人知道su 曲面能力弱是因为su 无法处理贝斯曲线，更没有人知道不能处理贝斯曲线实际上也是其精度不够的必然结果。 说了这么多，总的看起来好像su 的缺点比优点要多，但是在实际应用中，我们只有在真正关注绝对精准的尺寸的施工图中才会遇到我上述各种缺点，因此，虽然它有很多不足，但仍然是当今非常热门的建模软件。 室内设计 用su 做室内设计的朋友们，可能会比用su 做建筑设计的朋友们更能感受我刚才说过的那些缺点，这是因为室内设计比建筑设计更关注细节，更容易遇到上述的那些不足，由于su 的性能不高，在场景复杂的情况下难以操作，由于su 的精度不够，一些细节的部分无法表达，由于曲线是多段线的形式，一些平滑曲面的效果必然会消耗大量的系统资源，曲面建模能力不足，也使很多设计中个性的亮点难以表现。总的来说，su 做室内设计，除了上手方
505E安装和操作手册
Installation and Operation Manual安装和操作手册 505 Digital Governor数字调速器for Steam Turbines蒸汽汽轮机with Single 单一or Split-Range部分范围Actuators调节器 Volume 1 Manual 85017V1B 第五章505运行操作 Run Mode Architecture运行模式体系结构 The 505 is designed愿意to be interfaced界面上with through通过a user-friendly用户界面友好的，用户容易掌握使用的service panel,维修面板 discrete and analog离散模拟input/outputs or Modbus communications.通讯Basic program基本程序 architecture体系结构is illustrated in Figure 以插图说明见5-1. When the control is powered up 加电and after the brief下达CPU self test自检测has been completed完成, the control displays a ready status就绪状态 (Controlling Parameter调节参数/Push Run or Program). The 505’s normal operating正常工作architecture is divided分成into two sections到两部分零件: the Run Mode and the Program Mode. The Program Mode is used to configure the 505 for the specific application专用应用程序and set all operating parameters工作参数(see Chapter 4). The Run Mode is simply仅仅the normal 正常 turbine operation mode工作操作方式and is used to view operating parameters and run the turbine. A Service Mode预检（服务）模式is also同样available可用to make制做additional另外附加的on-line adjustments调整机构 while the unit装置is running. See Volume 2 for information on the Service Mode. 505愿意从界面上通过用户的友好界面进行服务与维修。其基本程序体系结构为离散模拟输入/输出与Modbus通讯（插图说明见5-1）。当控制电源加电与CPU下达自检测完成后，控制面板显示ready status就绪状态(Controlling Parameter调节参数/Push Run or Program)。505正常工作体系结构分为两部分，即：the Run Mode and the Program Mode（设置全部的工作参数见第四章）。运行模式仅为正常工作操作方式与用户去浏览工作参数和启动汽轮机。预检（服务）模式同样可用需制做另外附加的调整机构，当装置运行时可以在服务模式上看见容积信息。
sketchup快捷键(中文版与英文版)
sketchup快捷键（中文版与英文版） 中文 编辑/撤销 Ctrl＋z 编辑/放弃选择 Ctrl＋t 编辑/辅助线/删除 Alt＋E 编辑/辅助线/显示 Shift＋ Q 编辑/辅助线/隐藏 Q 编辑/复制 Ctrl＋C 编辑/剪切 Ctrl＋X 编辑/全选 Ctrl＋A 编辑/群组 G 编辑/删除 Delete 编辑/显示/全部 Shift＋A 编辑/显示/上一次 Shift＋L 编辑/显示/选择物体 Shift＋H 编辑/隐藏 H 编辑/粘贴 Ctrl＋V 编辑/制作组建 Alt＋G 编辑/重复 Ctrl＋Y 编辑/将面翻转 Alt＋V 编辑/炸开/解除群组 Shift＋G 查看/工具栏/标准 Ctrl＋1 查看/工具栏/绘图 Ctrl＋2 查看/工具栏/视图 Ctrl＋3 查看/工具栏/图层 Shift＋W 查看/工具栏/相机 Ctrl＋4 查看/显示剖面 Alt＋，查看/显示剖切 Alt＋. 查看/虚显隐藏物体 Alt＋H 查看/页面/创建 Alt＋A 查看/页面/更新 Alt＋U 查看/页面/幻灯演示 Alt＋Space 查看/页面/删除 Alt＋D 查看/页面/上一页 pageup 查看/页面/下一页 pagedown 查看/页面/演示设置 Alt＋：查看/坐标轴 Alt＋Q 查看/X光模式 T 查看/阴影 Alt＋S 窗口/材质浏览器 Shift＋X 窗口/场景信息 Shift＋F1 窗口/图层 Shift＋E 窗口/系统属性 Shift＋P 窗口/页面设置 Alt＋L 窗口/阴影设置 Shift＋S 窗口/组建 Shift＋C 工具/材质 X 工具/测量/辅助线 Alt＋M 工具/尺寸标注 D 工具/量角器/辅助线 Alt＋P 工具/路径跟随 Alt＋F 工具/偏移 O 工具/剖面 Alt＋/ 工具/删除 E 工具/设置坐标轴 Y 工具/缩放 S 工具/推拉 U 工具/文字标注 Alt＋T 工具/旋转 Alt＋R 工具/选择 Space 工具/移动 M 绘制/多边形 P 绘制/矩形 R 绘制/徒手画 F 绘制/圆弧 A 绘制/圆形 C 绘制/直线 L 文件/保存 Ctrl＋S 文件/保存备份 Shift＋N 文件/打开 Ctrl＋O 文件/打印 Ctrl＋P 文件/导出/模型 Ctrl＋M
505操作步骤
一、自动启机操作 505E按组态好的参数自动从零转速开始完成暖机，过临界等过程(要求调门严密性良好情况下)。 l、外部条件已经具备，如高压油泵及一台电控油泵已启并油压正常，电动主汽门关闭, 将自动主汽门开启，按505E “Reset”(或DCS上的“505E复位”，作用是清除各项报警信号)，检查高压调门处于全关状态，旋转隔板油动机处于全开状态。 2、按规程完成启动前的工作, 将电动主汽门旁路门开大,按505E(运行)“RUN”键（或DCS上的“外部运行”），则高压调门缓慢开启，从零转速下开始按步骤冲转。包括500rpm低速暖机(冷态停留15分钟)，在过临界转速(1400~1800rpm)时，自动提高升速率(10r/s)升速过临界，过临界后升速率下降，并冲转至高速暖机2400rpm，(冷态停留15分钟)，高速暖机完成后，自动升速至3000rpm。 3.机组冲转后, 根据机组缸温决定是否进行1200 rpm中速暖机。操作见第7条人为干预。 4.自动开机时, 注意高压调门应缓慢开大, 如发生快速上升, 机组转速飞升, 应立即果断停机。 5. 开机时, 如发生旋转隔板关闭,应立即果断停机. 6. 自动开机过程中, 为防止机组转速快速上升, 机组转速飞升, 可按6(LMTR)键, 翻菱形上下键, 在显示屏中显示SPEED ？？？？rpm/ HP LMT SETPT ？？．？？%, 调整调门限制值,用ADJ键设定高调门开度＜30%(或直接设定为30%)。根据高压调门开度,随时调节调门限制开度值。 7.热态启动，505E自动判断机组状态（停机2小时内），此时启动无500rpm低速暖机与2400rpm高速暖机,机组直接从0rpm 升至3000rpm。在自动起机过程中，可按ADJ增减键人为干预，按下ADJ键(中间部位)后, 505E则在当前转速下维持，此时可手动按ADJ键的▲或▼人为操作继续升减转速，也可在(速度)Speed栏下翻菱形上下键至状态栏Start(启动)，按1（Yes）键后将人为冲转切换至自动升速程序，（在过临界时不要人工干预）。 二、手动启机操作： l、外部条件已经具备，如高压油泵及一台EH油泵已启并油压正常，电动主汽门及旁路门关闭, 将自动主汽门开启，按505E “Reset”(复位键)，检查高压调门处于全关状态，旋转隔板油动机处于全开状态。 2、按505E面板上运行键“RUN”，此时高压调门自动全开，而旋转隔板油动机仍处于全开位置，则设定转速自动升至2800rpm后维持，(实际转速因未进蒸汽，转速仍为零)，在此条件下缓慢开启电动主汽门的旁路门进行冲转，在完成冲转暖机与过临界转速升至2800rpm 后，505E自动接受控制，再开大电动主汽门的旁路门时, 高压调门向关的方向关小, 转速不再上升, 表示高压调门已控制转速，检查转速控制情况良好后, 打开电动主汽门，关闭电动主汽门旁路门, 按ADJ键增加转速至全速3000rpm,或直接设定转速为3000rpm,待机组转速维持在3000rpm后，通知电气并网。 三、并网带负荷： 在3000rpm下，505E接受并网信号，则505E设定转速会从当前值(如3000转)自动增加约5rpm，而实际转速与电网周波相同，约3000rpm，按“+/-(DYN)”键可看到在并网前的(脱网)Off-Line, 并网后变成(并网)On-Line，505E设定值在并网同时自动增加约5rpm, 是为了将机组带上一定初始负荷的防止逆功率。并网后按ADJ增减设定转速来增减电负荷(3000-3150rpm对应零负荷至满负荷)。 四、供热抽汽的投入： 在电负荷带30MW时, 按“．(Ext/ADM)”键可进入抽汽栏，投入抽汽控制热负荷。