From stefan.schaer at aiub.unibe.ch Mon Mar 12 04:19:15 2007 From: stefan.schaer at aiub.unibe.ch (Stefan Schaer) Date: Mon, 12 Mar 2007 12:19:15 +0100 Subject: [IGSMAIL-5574]: Three new GLONASS-M satellites active Message-ID: <45F53733.3090109@aiub.unibe.ch> ****************************************************************************** IGS Electronic Mail 12 Mar 04:19:27 PDT 2007 Message Number 5574 ****************************************************************************** Author: Stefan Schaer Dear IGS/IGLOS colleagues, We got confronted with first IGS/IGLOS tracking data of the three new GLONASS-M satellites launched on 25 Dec 2006, namely: R14 (715) on 06 Feb 2007 (day 037) R10 (717) on 15 Feb 2007 (day 046) R15 (716) on 16 Feb 2007 (day 047) See also: http://www.aiub.unibe.ch/download/igsdata/y2007/odata_glonass_d037.txt http://www.aiub.unibe.ch/download/igsdata/y2007/odata_glonass_d038.txt http://www.aiub.unibe.ch/download/igsdata/y2007/odata_glonass_d046.txt http://www.aiub.unibe.ch/download/igsdata/y2007/odata_glonass_d047.txt With these three new satellites, the GLONASS-M constellation now consists of 7 satellites: R06, R07, R10, R14, R15, R23, R24. Remark: We observed a minor GLONASS tracking data anomaly on days 043 through 045: a particular receiver model reported R14 incorrectly as R10. The CODE GNSS orbit products include currently up to 47 satellites (31 GPS plus 16 GLONASS). The following GLONASS satellites may be declared as active (not all of them are marked usable): R01 (796) R02 (794) R03 (789) R04 (795) R06 (701) R07 (712) R08 (797) R10 (717) R14 (715) R15 (716) R18 (783) R19 (798) R21 (792) R22 (791) R23 (714) R24 (713) Inactive are: R05 (711) R17 (787) R20 (793) Note that the GLONASS status page (dated March 9, 2006) does not yet reflect the mentioned satellite constellation change: http://www.glonass-ianc.rsa.ru/pls/htmldb/glonass.collectors_content.get_cys_en_as_txt The three new GLONASS-M satellites are still marked unusable. This is the reason why corresponding tracking data is available just from a subnetwork of AIV tracking receivers. None of the Ashtech Z18 receivers did recognize one of the new GLONASS-M until now (they seem to track currently at most 10 of 16 GLONASS satellites). More alarming is the fact that R15, transmitting on frequency channel 0, is sampled solely by one IGS/IGLOS receiver model (Trimble NetR5)! At CODE, we perform POD for R15 on the basis of one single Trimble NetR5 receiver baseline. In this context, the following questions arise: - Are specific receiver models able to track R15 after it becomes marked usable? - What about negative frequency channel numbers to be expected in the (near) future? - Is it possible to upgrade the firmware at legacy receiver models to allow sampling of GLONASS satellites transmitting on frequency channel numbers 0, -1, ..., -7? Additional remark: Trimble NetR5 receivers, when configured for AIV tracking, are able to exclusively provide R15 observations. However, they use to provide also observations (often incomplete observation records) with respect to, e.g., R05, R17, R20, observations which must be considered fictitious. This problem is irrelevant to our analysis, but important when comparing satellite tracking data availability between the various GNSS receiver models. Best regards, The CODE AC Team