Re: [Discuss-gnuradio] GPS L2C transmissions?
Maybe little bit off-topic in this list, but any of you have tried gpstk ( http://www.gpstk.org/bin/view/Documentation/WebHome)? I'm trying to use it in combination with gps-sdr. I'll keep you updated on my progress! BR, Carles On Sun, Aug 10, 2008 at 4:55 AM, Peter Monta [EMAIL PROTECTED] wrote: From my knowledge all the semi-codeless tracking algorithms are heavily patented, and hence cannot be found in textbooks or in any open forum. But the patents themselves contain pretty good descriptions of the techniques; also there is this paper: http://www.navcomtech.com/Support/Download/Optimum%20Semi-Codeless%20Carrier%20Phase%20Tracking%20of%20L2.pdf which summarizes all the options and adds a soft-decision refinement to Z-tracking. Some of the patents will expire pretty soon, probably before L2C is fully usable. There ought to be a fully open-source, geodetic-quality, dual-frequency (or tri-frequency once we have L5, or quad- or quint-frequency once we have Galileo and Glonass and accurate IGS orbits and clock ties for these other GNSS systems), software receiver. I have no real connection with any of this (just a hobbyist), but I'd enjoy having access to state-of-the-art timing and survey solutions. Finally snagged a dual-frequency antenna on Ebay a few weeks ago, so only software sits between me and centimeter positioning and subnanosecond UTC (or UTC(GPS) or UTC(IGS) anyway). Cheers, Peter ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] GPS L2C transmissions?
From my knowledge all the semi-codeless tracking algorithms are heavily patented, and hence cannot be found in textbooks or in any open forum. But the patents themselves contain pretty good descriptions of the techniques; also there is this paper: http://www.navcomtech.com/Support/Download/Optimum%20Semi-Codeless%20Carrier%20Phase%20Tracking%20of%20L2.pdf which summarizes all the options and adds a soft-decision refinement to Z-tracking. Some of the patents will expire pretty soon, probably before L2C is fully usable. There ought to be a fully open-source, geodetic-quality, dual-frequency (or tri-frequency once we have L5, or quad- or quint-frequency once we have Galileo and Glonass and accurate IGS orbits and clock ties for these other GNSS systems), software receiver. I have no real connection with any of this (just a hobbyist), but I'd enjoy having access to state-of-the-art timing and survey solutions. Finally snagged a dual-frequency antenna on Ebay a few weeks ago, so only software sits between me and centimeter positioning and subnanosecond UTC (or UTC(GPS) or UTC(IGS) anyway). Cheers, Peter ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] GPS L2C transmissions?
Hi Peter, maybe you could be interested on this: at www.gps-sdr.com there is a C driver for the USRP that manages a couple of DBSRX daughterboards, one centered at L1 and the other one at L2, just what you are mentioning for building a dual-frequency GPS software receiver. Cheers, Carles. On Fri, Aug 8, 2008 at 4:53 PM, Peter Monta [EMAIL PROTECTED] wrote: On the chance that there are GPS folks here that are familiar with the status of the new L2C signals: is there a currently-maintained list of which satellite is emitting what? In particular, PRN 29 seems to have no L2C (or at least none that I can acquire), while PRN 31 has a nice strong carrier (tracked with L2CM) but no NAV or CNAV data modulation---it's apparently sending only carrier. I'd like to find a signal with CNAV data. While I haven't tried it yet, the USRP should be capable of saving to disk both L1 and L2C using a pair of dbsrx daughtercards. That should permit dual-frequency receiver software. It would be nice to have a waveform-pair-to-RINEX tool to allow use of the various web services for dual-frequency solutions. Cheers, Peter ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] GPS L2C transmissions?
Peter: I've been tracking L2C this summer also. I can verify that there is NO DATA on any of the L2C capable SVs. The US Coast Guard has a great GPS status site at http://www.navcen.uscg.gov/. The GPS constellation status is listed at: http://www.navcen.uscg.gov/navinfo/Gps/ActiveNanu.aspx Block IIR-M SVs are L2C capable. Right now in my software receiver the USRP client can record L1 and L2C using a USRP with 2 DBS-RXs. Check out www.gps-sdr.com for more info. The L2C tracking capability will be included in the code after a couple more bugs have been ironed out. Feel free to email me directly if you need more help or info. -- [EMAIL PROTECTED] NASA Goddard Space Flight Center AETD - Mission Engineering and Systems Analysis Component and Hardware Systems Branch Mail Code 596, Greenbelt Rd. Greenbelt, MD 20771 (301) 286-6565 (301) 286-3823 (fax) ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] GPS L2C transmissions?
I can verify that there is NO DATA on any of the L2C capable SVs. Ah. I'd thought from the ICD that the only valid options were legacy data or new data. While I understand that this is all pre-operational, it would be nice to have some rough guidelines from the GPS people about what to expect with the on-orbit L2C signals over the next year or two. Check out www.gps-sdr.com for more info. Very interesting---thanks! Would you know if there are any open implementations of P/Y semicodeless? Cheers, Peter ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
RE: [Discuss-gnuradio] GPS L2C transmissions?
Peter: Yeah, it really sucks. If you look at IS-GPS-200D at table 20-VIII the 6 bit SV health message has a value that indicates L2C Signal Has No Data Modulation, unfortunately the Air Force is not following their own ICD. From my knowledge all the semi-codeless tracking algorithms are heavily patented, and hence cannot be found in textbooks or in any open forum. -Original Message- From: Peter Monta [mailto:[EMAIL PROTECTED] Sent: Fri 8/8/2008 6:50 PM To: Heckler, Gregory W. (GSFC-596.0) Cc: discuss-gnuradio@gnu.org Subject: Re: [Discuss-gnuradio] GPS L2C transmissions? I can verify that there is NO DATA on any of the L2C capable SVs. Ah. I'd thought from the ICD that the only valid options were legacy data or new data. While I understand that this is all pre-operational, it would be nice to have some rough guidelines from the GPS people about what to expect with the on-orbit L2C signals over the next year or two. Check out www.gps-sdr.com for more info. Very interesting---thanks! Would you know if there are any open implementations of P/Y semicodeless? Cheers, Peter ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
