Re: [Discuss-gnuradio] subdev args for LF-TX

[Josh Blum]

On 05/04/2013 01:22 PM, Wolfgang Buesser wrote:
> Hi I am using a usrp1 populated with 2LF-RX and 2LF-TX daughterboards.
> 
> I am trying to learn how to use this hardware with the 'new'
> uhd-interface.
> 
> I am trying tx_waveforms. Using --subdev A:A or B:A I can select the two
> daughterbords. But how can I select a single output on either of the 2
> boards?
> 
> I always get signals on both outputs of either board - irrespective of
> wether I specify --subdev A:A, A:B or A:AB
> 

Well, we should be driving zeros into one of the DACs inputs:
https://github.com/EttusResearch/uhd/blob/master/host/lib/usrp/usrp1/usrp1_calc_mux.hpp#L95

Are you setting a non zero center frequency? There is no CORDIC in the
usrp1 TX chain, so if you set a center frequency, the DAC would actually
perform the mixing, and you would see something on both outputs.

-josh

> Thanks
> 
> Wolfgang
> 
> 
> 
> 
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