Re: [Discuss-gnuradio] GRC FFT Block Question

[mehmet kabasakal]

Hi Marcus,

May i ask you how you calculate the freq error i.e. 12.5 ppm ?
Is there a formula?

Mehmet.

2011/5/11, Marcus D. Leech <address@hidden>:
> On 05/11/2011 07:57 AM, Tom Rondeau wrote:
>>
>>
>> Mehmet,
>> You are seeing the frequency drift of the oscillator in both the
>> transmitter and receiver. They will never be perfectly accurate. You
>> should probably test your block using a simulation setup. That is, tie
>> the transmitted signal straight to the receiver in GRC and bypass the
>> USRPs altogether to make sure your block is correct.
>>
>> If you are looking for a symmetrical signal, you could then use your
>> calculation as the error value in a control loop to correct your
>> frequency offset :)
>>
>> Tom
> With the range of observed values given by Mehmet, it looks like a total
> frequency error of about 12.5PPM, which is pretty darned good.
>
> --
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org
>
>
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