USRP B200 Measurements

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(Measurements of the USRP B200)

Revision as of 19:15, 8 April 2014


Measurements of the USRP B200

B200 output spectrum


The ODR-mmbTools have been used to generate a DAB transmission with the B200, which was connected to a R&S spectrum analyser.

Versions used:

The USRP B200 was connected over USB2.0 to a thinkpad T420, and was externally powered using a 6V laboratory power source.


All measurement data, parameter and spectrum plots are packaged together:

The meas-parameters.csv file describes the dabmod parameters

  • master_clock_rate
  • sample rate
  • gain mode
  • digital gain
  • analog TX gain

used for each generated image.


  • digital gain* of 1.0 or *gain mode* 0 lead to spurious signals.

This can be due to clipping in the digital domain.

Some *master_clock_rate* settings are better than others. The decimation factor N = master_clock_rate/sample rate is the important parameters.

For N = 5 (10240000), 6 (12288000), 10 (20480000) and 15 (30720000), we see ugly shoulders next to the transmission.

For N = 8 (16384000), 12 (24576000) and 16 (32768000) the ugly shoulders are not present. N = 4 and below doesn't work.

The analog *TX gain* has to be above 35, but at about 80 we start seeing the shoulders increase. The best value for this parameter has to be found experimentally, in a complete transmitter setup, but is likely to be between 70 and 85.


The best settings seem to correspond to

  • gain mode = 2
  • master_clock_rate = 32768000
  • native DAB sample rate of 2048000
  • digital gain = 0.8
  • tx gain at most 80

A real world will certainly offer us more insight into these parameters.

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