From: "Dr Thomas A Clark (W3IWI)" Date: 28 Aug 1998 06:38:09 Subject: [IGEXMail-0003] Goddard IGEX site ****************************************************************************** IGEX Electronic Mail 28-Aug-1998 06:38:09 Message No 0003 ****************************************************************************** Author: "Dr Thomas A Clark (W3IWI)" Subject: Goddard IGEX site This is to give you advanced notice that we will be contributing an additional dual-frequency GPS+GLONASS station for IGEX. We had not previously "registered" this with IGEX since we were not certain that we could make it happen. Here are some details -- we will send the official participation form soon: SITE: NASA Goddard Space Flight Center, Greenbelt MD SITE NAME: GODZ -- GODZ uses the same antenna as the GODE IGS station, so all station parameters will be the same as already in IGS database. [I'm typing this at home and don't have the NASA or DOMES numbers readily available.] ANTENNA: GODE's AOA/JPL Dorn-Margolin Choke Ring equipped with 8-port high-isolation power splitter. SITE NOTES: GODE/GODZ is collocated with VLBI, SLR & PRARE systems (but not DORIS) at the NASA Goddard Geophysical & Astronomical Observatory (GGAO). GGAO has a large number of geodetic monuments associated with the various geodetic systems at GGAO. The GODE name means GODdard East GPS marker. GODZ (Z meaning Z-18) is chosen to provide a unique site name for the Z-18 data. [Note -- for a few days, I think we will have a second Z-18 occupying the GODW (West) monument, 22 meters from GODE/GODZ, in case anyone wants to do dual-receiver short-baseline tests.] Sponsors: Joint activity of the NASA/GSFC Space Geodesy Program and Ashtech Receiver: Ashtech Z-18 Frequency Reference: Today it is running with the Z-18's internal crystal. Next week it SHOULD be running with the same VLBI Hydrogen Maser that runs the normal IGS GODE TurboRogue and MV-3 VLBI, and that provides site-wide time/frequency reference for the various NASA SLR systems at GGAO. Status: Mark Bryant (Ashtech), Chuck Kodak and I got GODZ running mid-day Aug.27. Data is logged in real time to a Windows95 PC and the entire operation can be run remotely. We should have the operation running smoothly next week and will provide the GODZ RINEX files directly to CDDIS. As soon as the data flow is established we will announce the availability of the Z-18 GPS+GLONASS data via IGEXMAIL. Dramatis Personae: Tom Clark & Chuck Kodak (NASA/GSFC) Mark Bryant (Ashtech) Two additional notes: (1) We have run Carrol Alley's (Univ. of Maryland) 3S GLONASS/GPS receiver on the GODE antenna in the past. His receiver is currently at the factory being updated and Carrol has not indicated when it will be returned to him. I anticipate that if/when he does get it back, he will want us to connect it the GODE antenna. So we MAY be able to contribute data from an additional receiver sometime during IGEX. (2) Bruce Schupler and I made initial measurements on the standard D-M choke- ring antenna (AOA TurboRogue version) in our new GSFC anechoic chamber over the entire GPS+GLONASS L1 & L2 frequency bands. Preliminary results (showed at the Spring AGU meeting) indicate that the phase center varies linearly and smoothly with frequency, and that the antenna heights have ~85 microns/MHz slope over the entire L2-to-L1 frequency range. We have additional anechoic chamber time scheduled in mid-Sept. to perform additional tests and verify the phase center slope. Tom Clark mailto://clark@tomcat.gsfc.nasa.gov