On Tue, Jan 7, 2014 at 7:11 PM, Marcus D. Leech <[email protected]> wrote:

>
> Try reducing the amplitude to 0.7.  Another possibility is that your
> computer can't keep up.  If you are using one of the standard programs, are
> there U's printing in the terminal?
>
>  Matt
>
>  Also, what RF gain are you setting?  Does it exceed the maximum input
> level of the spectrum analyser?
>
> Are you connected directly, or with an antenna?
>
>
>
> On Tue, Jan 7, 2014 at 3:03 PM, Jonathan Fox 
> <[email protected]>wrote:
>
>>  A colleague and I are sending a simple signal in GNU Radio (sine wave,
>> 1 MHz, amplitude of 1) to the USRP sink and have the center frequency at
>> 500 MHz. The N210 USRP is hooked up to an Agilent spectrum analyzer. On the
>> analyzer we are seeing a weird phenomena every two seconds. At first we see
>> the carrier frequency and two sidebands from the sine wave (see attached
>> normal.gif). Then after two seconds we get two bursts of multiple harmonics
>> (see odd.gif).
>>
>>  The question is, why is this happening? Does the phase of the 1
>> KHz signal become discontinuous before or after being sent to the USRP?
>>
>>  Thanks,
>>
>>  Jon Fox
>>
>> _______________________________________________
>> USRP-users mailing list
>> [email protected]
>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>
>>
>
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>
> --
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortiumhttp://www.sbrac.org
>
>
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I don't recall seeing any U's but I can recheck tomorrow. The gain on the
USRP was set to -2. The USRP was connected directly with an SMA cable. The
analyzer is an Agilent E4440A, the Analyzer is rated for at least 1 Watt on
average, 100 Watt on a peak pulse (with the built-in attenuator in use).
While I am not ruling out the maximum input I thought the N210 tops out at
0.5 Watts due to FCC regulations.

Thanks

Jon
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