Re: [psas-avionics] Tuesday latenight updates (mostly GPS news)
For generating pseudonoise, NOAA helpfully posted some Matlab code: http://www.ngs.noaa.gov/gps-toolbox/MPsimul.htm The "bigger" sample I took is only 196MB in raw I/Q sign/mag binary format. But that turns into 3.1GB in complex 32-bit floats. I tried compressing a few different ways: 3.1G gpslog_big-outside.floats 196M gpslog_big-outside.raw 181M gpslog_big-outside.raw.gz # gzip --best 181M gpslog_big-outside.raw.7z # 7z -mx=9 179M gpslog_big-outside.raw.bz2 # bzip2 --best Compressing by almost 10% is pretty surprising to me. It doesn't seem like the fixed frequency spurs (at DC and -400kHz) would be enough to account for this. Maybe some of the aliasing artifacts could be compressed? I don't have a good place to post this file at the moment. Recommendations? I'll have it with me on a thumbdrive for the capstones Thursday, Friday hackday and Sunday lab hours. -- Kenny -+---+++-++---+--+-+-++--++--+-+-++--+++-+++-++-+++---++--++ On Wed, 2015-06-03 at 12:14 -0700, Jamey Sharp wrote: > On Jun 3, 2015 7:44 AM, "Kenny" wrote: > > + The STM32 which controls the MAX2769 (GPS baseband receiver) now > > dynamically configures the MAX according to instructions received by > > debug scripts so we can test all the configurations we want without > > reprogramming the STM32 each time. > > I was skeptical about whether this would be worth the engineering > effort, but Theo's time spent building it already paid for itself last > night. Excellent idea. > > > + Kenny joined the party to help transmit a sweeping sine wave +/- > > 2MHz around GPS baseband using HackRF. Samples received from the > > MAX2769, converted and viewed in baudline showed the same sweeping > sine > > wave (with noise and other artifacts). This turned out to be a good > way > > to test poorly documented configuration settings and lay to rest > > bit-order questions. > > I disagree. It was a *great* way to test. ;-) We now have confidence > about the meaning of most of the MAX2769 registers, and we know the > entire signal path on the jGPSv3 board is functioning! > > I have two next steps in mind for testing: > > First, someone (Nathan or me probably) should generate one GPS > satellite's pseudonoise sequence in a file. We should test feeding it > into soft-correlator first, which ought to report a strong signal from > that satellite at 0 Doppler shift. Then we should feed the same signal > through HackRF, record it with jGPSv3, and try feeding *that* to the > correlator. If that doesn't work, I don't know what's wrong; bad noise > maybe? If it does work, we can also try simulating some Doppler shifts > and adding varying amounts of noise in GNU Radio. > > After that: don't we know some folks who make GPS satellite > simulators? We're ready to ask them for help. > > In parallel, I think it's time to do the other engineering tasks we > need: send the COTS GPS data to Ethernet simultaneously with the MAX > samples; log it all to disk on the FC; stream the COTS data to the > ground; and log it all to SDCard on the STM if we're going to do that. > > I suspect that's mostly on Theo's plate, but anyone who's interested > in the microcontroller firmware or flight computer software could > help. > > > + Jamey said we could fly with this configuration and probably > figure > > out how to tease satellites out of the logged data later. > > I won't swear there's anything to tease out. I just think at this > point we've mitigated most of the risks of hardware problems. So if we > decided to fly with the hardware in this state, I'd feel pretty > comfortable that we'd done our due diligence toward getting useful > science out of the flight. And I think I should shift to focusing on > roll control and overall system engineering details. > > > + For fun, Kenny collected a larger sample outside from the > MAX2769, ... > > Could you post that larger sample somewhere? How big is it? And out of > curiosity, do any of the general purpose compression algorithms (gzip, > bzip2, etc) manage to compress it at all? (If they do we've probably > screwed something up, so that would be good to know.) > > Maybe we can try feeding the sample into the GNSS-SDR code we looked > at last fall, as another check. I think that's a good task for K if he > has time; he had that code running successfully IIRC. > > Jamey > smime.p7s Description: S/MIME cryptographic signature ___ psas-avionics mailing list psas-avionics@lists.psas.pdx.edu http://lists.psas.pdx.edu/mailman/listinfo/psas-avionics
Re: [psas-avionics] Tuesday latenight updates (mostly GPS news)
On Jun 3, 2015 7:44 AM, "Kenny" wrote: > + The STM32 which controls the MAX2769 (GPS baseband receiver) now > dynamically configures the MAX according to instructions received by > debug scripts so we can test all the configurations we want without > reprogramming the STM32 each time. I was skeptical about whether this would be worth the engineering effort, but Theo's time spent building it already paid for itself last night. Excellent idea. > + Kenny joined the party to help transmit a sweeping sine wave +/- > 2MHz around GPS baseband using HackRF. Samples received from the > MAX2769, converted and viewed in baudline showed the same sweeping sine > wave (with noise and other artifacts). This turned out to be a good way > to test poorly documented configuration settings and lay to rest > bit-order questions. I disagree. It was a *great* way to test. ;-) We now have confidence about the meaning of most of the MAX2769 registers, and we know the entire signal path on the jGPSv3 board is functioning! I have two next steps in mind for testing: First, someone (Nathan or me probably) should generate one GPS satellite's pseudonoise sequence in a file. We should test feeding it into soft-correlator first, which ought to report a strong signal from that satellite at 0 Doppler shift. Then we should feed the same signal through HackRF, record it with jGPSv3, and try feeding *that* to the correlator. If that doesn't work, I don't know what's wrong; bad noise maybe? If it does work, we can also try simulating some Doppler shifts and adding varying amounts of noise in GNU Radio. After that: don't we know some folks who make GPS satellite simulators? We're ready to ask them for help. In parallel, I think it's time to do the other engineering tasks we need: send the COTS GPS data to Ethernet simultaneously with the MAX samples; log it all to disk on the FC; stream the COTS data to the ground; and log it all to SDCard on the STM if we're going to do that. I suspect that's mostly on Theo's plate, but anyone who's interested in the microcontroller firmware or flight computer software could help. > + Jamey said we could fly with this configuration and probably figure > out how to tease satellites out of the logged data later. I won't swear there's anything to tease out. I just think at this point we've mitigated most of the risks of hardware problems. So if we decided to fly with the hardware in this state, I'd feel pretty comfortable that we'd done our due diligence toward getting useful science out of the flight. And I think I should shift to focusing on roll control and overall system engineering details. > + For fun, Kenny collected a larger sample outside from the MAX2769, ... Could you post that larger sample somewhere? How big is it? And out of curiosity, do any of the general purpose compression algorithms (gzip, bzip2, etc) manage to compress it at all? (If they do we've probably screwed something up, so that would be good to know.) Maybe we can try feeding the sample into the GNSS-SDR code we looked at last fall, as another check. I think that's a good task for K if he has time; he had that code running successfully IIRC. Jamey ___ psas-avionics mailing list psas-avionics@lists.psas.pdx.edu http://lists.psas.pdx.edu/mailman/listinfo/psas-avionics
[psas-avionics] Digi-Key order today
Hey! Need anything for the rocket from Digi-Key? I'm ordering today. Let me know by 5pm! Andrew -- --- Andrew Greenberg Electrical and Computer Engineering Portland State University http://www.ece.pdx.edu/ a...@ece.pdx.edu C: 503.708.7711 --- ___ psas-avionics mailing list psas-avionics@lists.psas.pdx.edu http://lists.psas.pdx.edu/mailman/listinfo/psas-avionics
[psas-avionics] Tuesday latenight updates (mostly GPS news)
Into the wee hours, we kept on doing stuff. * Gavin and Andrew wired up the FDT custom Uninterruptible Power Supply without melting any fingers in the process. I'm sure it was much safer than it sounded. * David(?) fired up the Geiger counter on picam2 and received data! So we have another cool thing that is ready for launch. * Kenny set up Splunk on the NUC and configured ground based systems to do remote logging. It even integrates with Nagios so when something goes down, the Splunk search for that host/service is a click away. * Theo and Jamey hacked on GPS stuff + The STM32 which controls the MAX2769 (GPS baseband receiver) now dynamically configures the MAX according to instructions received by debug scripts so we can test all the configurations we want without reprogramming the STM32 each time. + Python test scripts were overhauled to send our best known configuration to the MAX2769 and take a short sample. Even more magic was added to automate testing many different configurations. + Kenny joined the party to help transmit a sweeping sine wave +/- 2MHz around GPS baseband using HackRF. Samples received from the MAX2769, converted and viewed in baudline showed the same sweeping sine wave (with noise and other artifacts). This turned out to be a good way to test poorly documented configuration settings and lay to rest bit-order questions. + After running through all the settings and deciding we understood most of them to be what they should be, the correlator still wasn't able to pick up anything in an outdoor test. + Jamey said we could fly with this configuration and probably figure out how to tease satellites out of the logged data later. It is starting to look like the MAX2769 configuration is about as good as it can get. We just need to look at the data harder. + For fun, Kenny collected a larger sample outside from the MAX2769, returned to the basement while converting it for GNURadio, played it back through the HackRF in transmit mode and watched to see if the nearby COTS GPS receiver could lock. No position lock, but I wasn't watching the data stream to see if it was able to see any satellites at all. Some attenuators and a direct connection might help. Other people did stuff too! Like rebuilding an RCS controller board and ordering parts. I didn't keep track of all the cool things so please correct my fumbles and add your news. -- Kenny -+---+++-++---+--+-+-++--++--+-+-++--+++-+++-++-+++---++--++ smime.p7s Description: S/MIME cryptographic signature ___ psas-avionics mailing list psas-avionics@lists.psas.pdx.edu http://lists.psas.pdx.edu/mailman/listinfo/psas-avionics
