On 08/09/2018 11:19 AM, Brett Killion via USRP-users wrote:
Hello,
I have a N210 with a UBX-40 daughtercard. I am outputting a moderately
low power 250KHz wide BPSK signal. If I set the center frequency
anywhere in the direct conversion path (500 MHz-6 GHz) the output is
beautiful with no spurs (see Above_500.png for a SpecAn screenshot)
and a power of -48 dBm. If I tune anywhere below 500 Mhz, the output
is just awful. The power of the signal drops to -65 dBm and there are
huge spurs almost 20 dB stronger than my signal (see Below_500.png).
My gain is set to 0 and I am not producing a strong signal so
saturation is not the problem. The spurs are at 72 MHz and multiples
thereof. They do not change when I move the frequency around below 500
MHz, they are static. I am using an external 10 MHz reference which
has been verified to be good.
I have read elsewhere on here that the Max2871 is "very touchy" and
works best with a clock rate of 20 Mhz, which is great, but I can't
change the daughterboard clock rate on the N series.
What's the work around for getting usable functionality out of the N
series with the UBX (or do I just have a busted daughterboard)?
Thanks!
- Brett
Does your N210 *also* have a GPSDO, and if so, are you using the
recommended beefier power supply?
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