Re: [Discuss-gnuradio] High noise level reading GSM spectrum.

[Matt Ettus]

Marcus D. Leech wrote:
> Matt Ettus wrote:
> > There is no low pass filter.  Assuming that you are setting the gain
> > properly, then most likely problem is that you blew out the LNA in the
> > front, U4.  Static or strong signals can do that.  You could try
> > replacing U4, which is an MGA82563.
> >
> > Matt
> Matt, I thought that there *was* an LPF on the I and Q channels on the
> MAX2118, which is what set_bw() is all about.
>   The MAX2118 has programmable lowpass filters on the I and Q outputs,
> does it not?


Yes, it does have programmable lowpass filters, but he seems to have a 
problem on the front end.  If a baseband filter had a problem he would 
get terrible opposite sideband rejection, which doesn't appear to be the 
case from the picture.

Matt