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Re: [Discuss-gnuradio] Carrier offset on DBSRX.

From: Marcus Leech
Subject: Re: [Discuss-gnuradio] Carrier offset on DBSRX.
Date: Tue, 27 Mar 2007 21:40:30 -0400
User-agent: Thunderbird (X11/20070221)

Trond Danielsen wrote:

Okay, I think I understand. But still, when inspecting the signal with
ursp_fft.py, the signal is not at baseband, but offset by approx.

I use the DBS_RX for radio astronomy, and I use a narrowband calibration signal (not from a precision source, but within a few Khz). That signal shows up in my FFT display within a few Khz of where it should be. I never see any errors as large as 500Khz, that's for sure, and I've used 3 different DBS_RX boards over the last couple
 of years.

Also, 21cm emissions from the galactic plane are usually within 200Khz of 1420.4058Mhz, and that's where they show up, so I'm reluctant to believe that in *general* observed frequencies can be off by as much as 500Khz.
 Something else is wrong.

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