Re: [Discuss-gnuradio] Impulse response USRP DAC<->ADC

[Matt Ettus]

Per Zetterberg wrote:
> Hi All,
>
> I connected the DAC of the USRP directly to the ADC (basic db, 50ohm cable),
> 2MHz sample-rate. The impulse responses I get are:
>
> h1=[0,-2,2,-7,8,-6,314,479,-47,-161,-124,-103,-79,-63,-50,-39,-29,-23,-17,-1
> 4,-13,-9,-7,-5,-4,-3,-3,-2,-1,-3,-3];
> h2=[0,-1,-1,0,-2,2,22,274,208,-77,-79,-71,-53,-46,-36,-28,-23,-17,-15,-12,-1
> 0,-7,-5,-4,-4,-3,-4,-2,-2,-2,-1,-2];
>
> Where h1 is with "set_adc_buffer_bypass" and h2 without it. Does this make
> sense ?
>
>   

Yes, this looks reasonable.  You are seeing a hole at DC because of the 
low frequency cutoff of the transformers.  If you used the LFRX and LFTX 
instead of the BasicRX and BasicTX, you wouldn't see the hole there.

Matt