Re: [Discuss-gnuradio] how to learn of decimation rate in general_work() ?

[George Nychis]

On Wed, Feb 8, 2012 at 7:34 PM, Ian Buckley <address@hidden> wrote:

Just to confirm, the USRP2/N2x0 ADC samples at 100MHz.  (The DAC output however runs at 400MHz, its fed samples at 100MHz and it has built in 4x interpolation which may be the source of confusion).

On Feb 8, 2012, at 4:12 PM, Tom Rondeau wrote:

On Tue, Feb 7, 2012 at 5:37 PM, George Nychis <address@hidden> wrote:

Hey George,

You can use the relative_rate data member of the blocks. Setting the decimation actually sets the relative_rate to 1.0/decimation. You can get this value with the accessor function "relative_rate()".

Hey Tom,

 

Using this I can get the decimation rate, but is there a way to get the rate of samples from the ADC?  That way I can compute the real clock time in-between samples.  For the USRP2, despite the ADC running running at 400Msps, it's rate through the FPGA is actually 100Msps, right?

Actually, I think the ADC is running at 100 Msps, which I think you can get with the "get_clock_rate(mboard)" method. The rate that they come across is then determined by the decimation rate. You can query sample rate from the USRP via the UHD with the "get_sampl_rate()" method.

Great, thanks a bunch for the info Tom & Ian!  I'm using UHD, so I will use get_sampl_rate()