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Fwd: [Discuss-gnuradio] My SRP - Problem deciding on the RF Front End de

From: Prasanna Rao
Subject: Fwd: [Discuss-gnuradio] My SRP - Problem deciding on the RF Front End design.. need help.
Date: Wed, 22 Aug 2007 22:51:03 +0530

---------- Forwarded message ----------
From: Prasanna Rao <address@hidden>
Date: Aug 22, 2007 10:49 PM
Subject: Re: [Discuss-gnuradio] My SRP - Problem deciding on the RF Front End design.. need help.
To: Chris Albertson <address@hidden>

Hello Chris,
  Firstly I thank for your sincere advice..
  Microtune devices seem to have a high IF at around 25+ MHz which far too much for my requirement. Do they provide lower-IF devices..? i gues they do, but cant find locate them on their site.

  As for the ADC output, I would be using a DDC to down-convert the samples to the baseband spectrum. By that way I can have just one common IF at say 10 MHz for various types of information channels including FM AM audio. But yes, the fast data stream required in processing TV signals may need a UDP-like mode of data transfer..

 A small doubt I have here is, can I use the cable TV device to downconvert audio AM-FM channels? I guess we can.. kindly advice..



On 8/22/07, Chris Albertson <address@hidden> wrote:

--- Prasanna Rao <address@hidden> wrote:

> Hello everyone,
> I am planning to implement a small software-defined radio with a
> bandwidth
> of say 50-300 MHz at first. The system should be able to receive AM,
> FM, PM
> signals over the mentioned RF spectrum with upto 10MHZ baseband
> information.
> This would require an IF of at least around 11-12MHz. Can u ppl help
> me in
> choosing an appropriate RF front-end design for the hardware system?

So you are not interested in HF bands or weak signals? and you
want to "see" a 10Mhz bandwidth signal.
I think these strong, broadcast makes your job a LOT easier.
I've read about
people using tuners designed for cable set top boxes.  "Microtune"
makes a bunch of these that cover your range.  I think you just hook up
one of these microtune devices to an ADC that samples at about 30M/Sec
and 10 to 12 bits per sample.  At 30M/sec you don't need quadrature
clocks or QSD or anything like what SR40 does

The big issue will be how to get that data stream into the computer.
If it were me I'd format the data is UDP packets and put it on a
Gigabit Ethernet cable.  UDP is very easy being a one way stream
with no handshaking involved

Chris Albertson
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