Mike, Yes -- I disabled the video channel and it went away. I did not use it for the project.
I gave a talk on SDR and small systems -- it is available here: https://drive.google.com/file/d/0B0I7pqe_KM9tcExvY3RwOUdhOGc/view?usp=sharing Tom Kaminski On Mon, Nov 23, 2020 at 8:48 AM Mike Baranishyn <[email protected]> wrote: > Was this ever solved? > > On Monday, July 7, 2014 at 12:05:37 AM UTC-4 [email protected] wrote: > >> I have measured Beaglebone Black radiated energy around the 1575 MHz band >> that GPS uses with an SDR spectrum analyzer using GPRS on a MacBook Pro. It >> does not seem to be harmonically related to the BBB Clock. It is possibly >> related to the HDMI video circuit... >> >> Spectrum with BBB ON: >> >> >> <https://lh6.googleusercontent.com/-3UzV31XcvwM/U7obp6C432I/AAAAAAAAGn8/75NV0_4m3xY/s1600/Spectrum_BBB_On_GPS.jpg> >> Spectrum with BBB Off: >> >> >> <https://lh6.googleusercontent.com/-P9o5Wic5lpQ/U7ob62YIRVI/AAAAAAAAGoE/a3dg1JSmZyQ/s1600/Spectrum_BBB_Off_GPS.jpg> >> >> >> On Sunday, November 17, 2013 5:55:46 PM UTC-6, [email protected] wrote: >>> >>> Hello everyone, >>> >>> Sorry for the reposted message. I had posted this on the BeagleBone >>> group, but this is an issue with the BeagleBone Black. >>> >>> I am having some problems trying to use a GPS receiver with the >>> BeagleBone black. I connected a PMB-648/688 module to one of the BBB UART >>> ports. I can see the NMEA messages coming from the GPS receiver, but I >>> never get a valid fix. I doesn't report any satellites in view (GPGSV >>> messages). Not even if I leave it on my rooftop for a couple hours. >>> >>> Initially I thought it might be a problem with the GPS receivers, so I >>> tested them on my laptop. Every one of the receivers I have worked fine, >>> taking a less than a minute to get a fix from my window. >>> >>> The next thing i thought was that there might be some power supply noise >>> messing with the GPS receiver, so I tried powering the receiver by itself >>> (connecting the grounds of my receiver supply and the BBB). Surprisingly, >>> this worked. More surprisingly, it stopped working If I moved the BBB close >>> to the GPS receiver. >>> >>> This lead me to suspect that the BBB might be causing some RF >>> interference on the GPS frequency band. My next test was to have the GPS >>> receiver and the BBB powered independently. This confirmed my suspicion. If >>> I powered the GPS receiver, waited until it got a valid GPS fix, powered >>> the BBB, and placed the BBB close to the GPS receiver, the I would get the >>> same result as before. No GPS fix, no satellites in view. Since the two >>> devices are being powered with two independent power sources, then the BBB >>> must be causing some RF interference. I do not have a RF spectrum analyzer >>> to confirm this, but I do not see any other reason.I tested this with three >>> different BBB and 6 different PMB-648/688. I always got the same result. >>> >>> I tried the same GPS receiver on a Raspberry Pi and It works fine, so >>> that is what I am going to work with for the moment. But I really like the >>> BBB, and would love to use it for my application. Is there anything I could >>> do to fix this? >>> >>> I'm sure other people have used GPS receivers with the BBB. Can anyone >>> recommend a GPS receiver that works with the BBB? I'm looking for a >>> receiver that's approximately the same size (3cm*3cm) and price ($35-$40) >>> as the PMB-648/688. I'm getting the Adafruit Ultimate GPS soon, so I'll >>> report about that. >>> >>> Thanks! >>> >> -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to a topic in the > Google Groups "BeagleBoard" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/beagleboard/X_5oID-_g40/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/eb3028d4-701b-42e6-8270-b19fe32d1c27n%40googlegroups.com > <https://groups.google.com/d/msgid/beagleboard/eb3028d4-701b-42e6-8270-b19fe32d1c27n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAKewsAXhNA0-12zXE1%2BXV-PChQysKr5irJHQCJpYp4WHnPCVrQ%40mail.gmail.com.
