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righthalfplane / SdrGlut

SdrGlut is a simple software defined radio - using glut and glui for its interface
MIT License
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Frequency offset for up / down converters #12

Closed nmaster2042 closed 4 years ago

nmaster2042 commented 4 years ago

I'm using an up converter with my sdr for HF.

When I start Sdrglut, I chose a sdr and adjust frequency and sample rate.

I didn't find a way to enter an offset so I can read actual frequency when using up converter.

This would be useful.

righthalfplane commented 4 years ago

At first I thought that it was going to be difficult to do, but later I realized the changes that I put in for the RSPduo make it easy. It will be in the next release version or If you want to rebuild from the source, you can get it now. The "Frequency Offset" is now an option in the SDR Dialog menu.

nmaster2042 commented 4 years ago

I tried the offset, It doesn't works as I exptected. I think I have not well explained the purpose of my request, sorry. I have an up converter that has an offset of 125 mhz. On the offset option I set -125000000, but on software it doesn't change frequency I read on screen. On software side, up converter on, I want to tune to 10 Mhz, so I enter 10000000 on frequency and center frequency. And can read 10 mhz on graph window. On hardware side, considering the offset, to tune to 10 mhz, the actual frequency tuned would be 135 mhz. Here is the same use case but on gqrx: http://www.hagensieker.com/blog/page/?post_id=68&title=how-to-use-an-upconverter-with-sdr-in-gqrx

righthalfplane commented 4 years ago

Set the offset to +125000000 and hit the "Set Frequency" button that should give you what you want. It does not change the frequency, but tune to 10 MHZ and you should see what you want. If you set the "Frequency" to 10e6 the "Center Frequency" to 10e6 and the "Frequency Offset" 125e6 and hit the "Set Frequency" button that should set for use in offset mode. It just adds the "Frequency Offset" to the "Frequency" when it tunes. Once you have set the "Frequency Offset", you should be able to ignore it - all frequencies are converted.

nmaster2042 commented 4 years ago

OK. It's reversed compared to other sdr softwares, so I couldn't tune correctly. But it's not a real issue, just have to remember it. Will make more tests asap. Thank you very much.

righthalfplane commented 4 years ago

I flipped offset - I guess it makes a like more sense that way. Use -125e6 with the latest version.

nmaster2042 commented 4 years ago

I tried again, all is fine now, -125e6 as offset gives expected result.