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Re: [Discuss-gnuradio] filter ssb

From: mike revnell
Subject: Re: [Discuss-gnuradio] filter ssb
Date: Sun, 08 Jan 2006 19:16:19 -0700
User-agent: Mozilla Thunderbird 1.0 (X11/20041206)

Chuck Swiger wrote:

At 10:34 AM 1/6/2006 -0700, you wrote:

In continuing efforts to learn how to use gnuradio and the USRP I've continued banging on the code I posted previously.

Extending the length of the ssb demod filter scheme to 1023 taps seems to make it useful, at least for listening in on the ham bands. I've also added AM demod using the complex modulus block.

AGC is a far richer field than I ever imagined. There are ever so many parameters to tweak.

The attached tarball includes a reasonably functional and complete HF radio.

If deemed suitable for examples it may be included there.

I don't have a web site to put it up on but if anyone else has such be my guest.

Mike - I love it!  Your most recent attachment with complete gui was
just added to cvs gnuradio-examples/python/aps/hf_radio/


Glad to hear it.

In the interest of full disclosure I note the following.

In poking around some more on the net I've learned that the basic approach is known in the literature as the Hartley image-reject receiver. In this instance the I and Q channel mixers are in the DDC in the USRP. The low-pass filters and hilbert transformer are implemented in the translating filter. As noted in my writeups in the files the hilbert transformer is implemented as a complex pair with 45 degrees each rather than the more usual hilbert transformer with matching delay.

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