[Discuss-gnuradio] Minimum value for center frequency step size

[Karim El Defrawy]

Hi,
I am using a FLEX2400 transceiver daughterboard and was wondering what's 
the minimum step size that I can use to set the center frequency.

I tried steps down to 500KHz and I could tell the difference between the 
generated carrier frequency of a sine wave on an oscilloscope.

When I tried lower steps I was not able to see any difference in the 
generated frequency.
Thanks,
Karim



Sebastiaan Heunis wrote:
> Hi
>
> Can anyone please suggest a setup that I can use to test the maximum
> value of samples?  I know that we have 16bit signed values.  Looking
> at the ADC interface on the USRP, we sign extend each 12-bit sample
> and add 3 zeros to the right.  This should give us a maximum value of
> 16376 for samples?
>
> I tried using a BasicRX daughterboard.  I have a function generator,
> inputting a 20MHz, 10dBm signal into the db.  In my app I mix this
> down to 100kHz using the cordic.  I also decimate by 16.  The PGA gain
> is set to 20dB.  The FPGA build is the standard 2rx/2tx with hbf.  The
> maximum sample value that I get with this is 8635, so I'm using about
> half of the ADC's dynamic range.
>
> Sebastiaan