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Re: [Discuss-gnuradio] Channel measurements?

From: Johnathan Corgan
Subject: Re: [Discuss-gnuradio] Channel measurements?
Date: Fri, 25 Jul 2008 18:57:16 -0700

On Fri, Jul 25, 2008 at 6:12 PM, Nikhil <address@hidden> wrote:

> I'm curious -- in a channel sounder application what benefit, if any is
> there to performing the cross-correlation on the FPGA?  This is  assuming
> you are continuously transmitting the PRBS and computing the impulse
> response at the receive end at a rate that is consistent with variations in
> the channel (i.e. not continuously).

The channel sounder transmitter is sending the PRNG modulated BPSK at
32 Mchips/sec.  You need to do the correlation at this speed; it's not
possible to send that much data over the USB to the host.

A channel sounder in software would work for chip rates less than 4
Mchip/sec.  But that limits the resolution of your impulse response to
about 250 ns per bin, or 75 meters per bin in the spatial domain.

Johnathan Corgan
Corgan Enterprises LLC

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