Search found 34 matches

by madengr
Sat Mar 22, 2014 4:28 pm
Forum: General
Topic: APCO 25 trunking receiver
Replies: 6
Views: 27587

Re: APCO 25 trunking receiver

Here is an updated version for 3.7. Still UHD though, not gr-osmosdr.

https://dl.dropboxusercontent.com/u/495 ... _rec37.tar
by madengr
Tue Aug 06, 2013 8:30 pm
Forum: Tutorials and Examples
Topic: [Dead] kb3gtn's bladeRF setup guide
Replies: 11
Views: 63366

Re: kb3gtn's bladeRF setup guide

Cool thanks. Maybe I can get this thing to insmod when it boots.

BTW when everything is working, run volk_profile for a real speed-up in GNU Radio.

http://gnuradio.org/redmine/projects/gnuradio/wiki/Volk
by madengr
Tue Aug 06, 2013 8:13 pm
Forum: Troubleshooting
Topic: "Mirroring"/Ghosting and CF Peak
Replies: 16
Views: 51823

Re: "Mirroring"/Ghosting and CF Peak

Any recommendations on getting rid of the DC peak at CF? You can never get rid of it fully; it's DC imbalance in the I and Q channels due to LO feed through and actual DC imbalance in the electronics. It's the bane of direct conversion receivers, but you can work around it like so. See attached exa...
by madengr
Tue Aug 06, 2013 6:48 am
Forum: Troubleshooting
Topic: "Mirroring"/Ghosting and CF Peak
Replies: 16
Views: 51823

Re: "Mirroring"/Ghosting and CF Peak

Likewise. Have not been to IMS since we met last. I'll definetly be going next year.
by madengr
Tue Aug 06, 2013 6:42 am
Forum: Troubleshooting
Topic: "Mirroring"/Ghosting and CF Peak
Replies: 16
Views: 51823

Re: "Mirroring"/Ghosting and CF Peak

That you Lance (RF Dude)? Lou here.

lousyg, do those gains settings work? Last I tried I don't think they were all implemented. I think RXVGA1 tops out at 6 dB. I tried programming them in GRC, then read back the values in the CLI, and they did not match.
by madengr
Tue Aug 06, 2013 5:34 am
Forum: Troubleshooting
Topic: "Mirroring"/Ghosting and CF Peak
Replies: 16
Views: 51823

Re: "Mirroring"/Ghosting and CF Peak

To better show these two observables, I've created a screenshot and uploaded it here: http://i.imgur.com/67OCGLD.png You are sampling at 160 kHz with the filters set to 2.5 MHz. Those may be aliases rather than image due to I/Q imbalance. Set the filters to 1.5 MHz (minimum they go; they are really...
by madengr
Sun Aug 04, 2013 6:52 pm
Forum: Troubleshooting
Topic: Dropping TX samples?
Replies: 5
Views: 21077

Re: Dropping TX samples?

I also tried the experiment in reverse to see if RX samples were dropped, again at a 10 MHz sample rate. I set the RX LO to 1500 MHz and drove the unit with a 1501 MHz synthesized source. Then used a frequency translating FIR filter, decimating to 25 kHz sample rate, to center the 1501 MHz signal. T...
by madengr
Sun Aug 04, 2013 6:10 pm
Forum: Troubleshooting
Topic: Dropping TX samples?
Replies: 5
Views: 21077

Re: Dropping TX samples?

OK here I think you can actually see it. I set the baseband sinusoid frequency to 10E3/8192 Hz. This would provide a one second beat frequency; i.e. if the sample is dropping it should do so at a 1 Hz interval Then zero spanned the spectrum analyzer with a 1 MHz RBW and 1 Hz sweep rate, linear scale...
by madengr
Sun Aug 04, 2013 5:10 pm
Forum: Troubleshooting
Topic: Dropping TX samples?
Replies: 5
Views: 21077

Re: Dropping TX samples?

88% CPU load. Yes, constant results in just clean CW at CF. That means if the samples are being dropped, they are at least not being replaced with an arbitrary value, say full scale 0 or 1. When I'm sending a sinusoid, a 1.2207 KHz modulation on that tone would mean it's skipping every 8192 sample a...
by madengr
Sun Aug 04, 2013 4:28 pm
Forum: Troubleshooting
Topic: Dropping TX samples?
Replies: 5
Views: 21077

Re: Dropping TX samples?

If I give it a constant source instead of the sinusoid, and it were replacing a TX sample with an arbitrary value, I would expect to see the modulation on the carrier. That's not the case, the carrier is clean.