Ettus B210 external reference how to?

Today I tried to set a ppm value to correct the 950 Hz offset on 70 cm, but I failed obvious due to that problem SatNOGS client V2.x / SoapyRTLSDR: setting Freq Correction (PPM). SoapySDR does not like the corr value and will not load firmware into the B210.

I have got a GPS reference but I don’t know how to enable the input connector for the external reference with SatNOGSclient.

Any hints?

73, Norbert

Unlike the RTLSDR, the B210 device does not provide PPM correction, accordingly for UHD devices function frequency_correction() not implemented at Soapy API.

You can try to pass parameter clock_source="external" for SoapyUHD using the --dev-args ( SATNOGS_DEV_ARGS )

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That seems to work. I added the parameter without quote marks! No failure warning. Have to check that. It’s fun to play around with this Linux stuff. I learn new things every day!

73, Norbert

Hello again!

I just checked the frequency offset of the Ettus B210 with internal and external reference using the 23 cm beacon DB0VC which is obviously locked to GPS or another reference signal. A fellow ham did check the beacon frequency with his GPS-locked sig gen like I did with my CMU200.

With the external reference the B210 offset is +2,7 kHz on 1296,920 MHz and of course +900 Hz on 70 cm.
With the internal reference the offset is -80 Hz on 1296,920 MHz.

I just found a new problem…

73, Norbert

It is wondering how the same offset for similar frequency was obtained when measured with an external reference and earlier with an internal reference.

I checked the frequency offset of the my own Ettus B210 (see GR flowgraph ) using the Motorola R-2680 + GPSDO Trimble 57963 as external 10MHz standard:

  • offset is -1,0 kHz on 437,8 MHz with internal reference;
  • offset is -14 Hz on 437,8 MHz with external reference.

Hi Alexander,

I don’t know how I came to the 950 Hz offset on 70 cm. Maybe a typo… 95 Hz!
Yesterday I checked the offset with SDRConsole which to my surprise has a switch to enable the external reference of the B210.

I use the Precision GPS Reference Clock by Leo Bodnar. No problems with my OpenHPSDR-TRX and Kuhne XVTR.

I will check the B210 a with reference source at work on tuesday.

73, Norbert

So, it mean, your B210 has internal reference not worse then GSPDO? How, then, can be explained the measurement results with external reference? IMHO, there is an mistake in the interpretation of the measurement results.

What I figured out is that seemingly I have a problem using the external reference depending on the uhd firmware version. I will do some more testing during the next days, before I do write more comments. I don’t want to worry others more than neccessary :slight_smile:

A few minutes ago I got a ver good cw signal from Raavana-1, beat frequency 1,6 kHz

Thanks for your comments! 73, Norbert

Zero Beat and Offset in CW

Maybe it will be useful - log for my B210:
Executing: /opt/local/Library/Frameworks/Python.framework/Versions/3.7/bin/python3.7 -u /Users/admin/GRC/USRP/

[INFO] [UHD] Mac OS; Clang version 11.0.3 (clang-1103.0.32.62); Boost_107100; UHD_3.15.0.0-16-ga3ece4f2
[INFO] [B200] Loading firmware image: /opt/local/share/uhd/images/usrp_b200_fw.hex…
[INFO] [B200] Detected Device: B210
[INFO] [B200] Loading FPGA image: /opt/local/share/uhd/images/usrp_b210_fpga.bin…
[INFO] [B200] Operating over USB 3.
*[INFO] [B200] Detecting internal GPSDO… *
[INFO] [GPS] No GPSDO found
[INFO] [B200] Initialize CODEC control…
[INFO] [B200] Initialize Radio control…
*[INFO] [B200] Performing register loopback test… *
[INFO] [B200] Register loopback test passed
*[INFO] [B200] Performing register loopback test… *
[INFO] [B200] Register loopback test passed
[INFO] [B200] Setting master clock rate selection to ‘automatic’.
*[INFO] [B200] Asking for clock rate 16.000000 MHz… *
[INFO] [B200] Actually got clock rate 16.000000 MHz.
*[INFO] [B200] Asking for clock rate 36.864000 MHz… *
[INFO] [B200] Actually got clock rate 36.864000 MHz.

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I used GnuRadio and a quick and dirty spectrum & waterfall flowgraph on my laptop to check the beacon frequency with external reference enabled. All is fine with the B210!

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