[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Discuss-gnuradio] USRP for Radioastronomy

From: Matt Ettus
Subject: Re: [Discuss-gnuradio] USRP for Radioastronomy
Date: Thu, 23 Jun 2005 21:40:56 -0700
User-agent: Mozilla Thunderbird 1.0 (X11/20041206)

Marcus D. Leech wrote:
> Lamar Owen wrote:
>>How did you get the flatter baselines?  Was this through the DBS_RX or
>>baseband?  Did Charles see this?  :-)
> The DDC was set to -5.75Mhz.  Doesn't the TVRX produce a 5.75Mhz IF?
> Perhaps (rampant speculation, and apologies to everyone, especially Matt,
>   if I'm wrong) the 40ft 21cm feed produces an IF that's in the passband
>   of the TVRX, and that's what we're looking at.  Or maybe it's something
>   else entirely.

2 separate issues here --

Yes, this was recorded using the TVRX since the IF we were connected to
was at a very low level.

The reason the baseline was flat is independent of the daughterboard.
By sending 4 MS/s over the bus (4 MHz BW) and decimating by a factor of
4, you get the 1 MHz of BW you see in the figure.  Since we are looking
at the center 1 MHz, it is in the flat part of the passband.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]