Re: [Discuss-gnuradio] PNG's of a neutral hydrogen observation at PARI with a USRP.

[Matt Ettus]

> 
> I have a TVRX (and a basic RX/TX pair) on my personal unit; the PARI unit is 
> outfitted with two basic RX and two basic TX.  The TVRX can do 70MHz direct; 
> I might try that at some point.  There's a significant electrical storm here 
> now, so I have everything disconnected.... :-)

Actually, you can do 70 MHz directly into the BasicRX.  Just set
everything like you are using a 6 MHz IF (70-64=6).  No need to use the
ICOM R8500 at all.

> As to the DBSRX, I mentioned to Charles Matt's statement of the 'less than 
> 8dB 
> noise figure' and Charles wasn't real impressed;  need pretty good 
> amplification ahead of it to get a useful noise temp.  We have a few front 
> ends with less than 3 dB NF here, and we will soon have better.  No cryo 
> here, yet.

The DBSRX is not intended to be used for RA applications without an LNA
in front of it.  Besides, even if it had a 0 dB NF, you would still have
to run the coax from your feed all the way to it, which could be 10+ dB
of loss.

The DBSRX is even has a connector for providing LNA bias over the coax.

Matt