Ctrl Panel & Main SP different freq.

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K3WKM
Posts: 5
Joined: Sat May 27, 2017 2:19 pm

Ctrl Panel & Main SP different freq.

Postby K3WKM » Sat May 27, 2017 2:30 pm

New to SDRUNO opened 3 RX...why do the RX for 01 and 02 show passband for different freq. than entered in the RX Ctrl.
Thanks for the help
73

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PG3
Posts: 29
Joined: Mon Nov 14, 2016 6:04 am

Re: Ctrl Panel & Main SP different freq.

Postby PG3 » Sun May 28, 2017 12:21 am

With a SR of 10 MHz and a DEC of 1 in the main window you have an IF bandwidth of 8 MHz. Each of your spectrum displays appear to be zoomed in and SCROLLED to different sections of the total IF bandwidth.

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K3WKM
Posts: 5
Joined: Sat May 27, 2017 2:19 pm

Re: Ctrl Panel & Main SP different freq.

Postby K3WKM » Sun May 28, 2017 10:15 am

OK thanks but the first issue is why in RX 01 and RX 02 is the RX control frequency different than what shows in Main sp 01 and 02?

If u understand the solution to my problem can u explain what and how I should be able to fix it?

Thanks
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K3WKM
Posts: 5
Joined: Sat May 27, 2017 2:19 pm

Re: Ctrl Panel & Main SP different freq.

Postby K3WKM » Sun May 28, 2017 10:26 am

OK so what do I do to fix it?

Thanks
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hfsdpk11
Posts: 18
Joined: Mon May 01, 2017 5:00 pm

Re: Ctrl Panel & Main SP different freq.

Postby hfsdpk11 » Sun May 28, 2017 1:35 pm

You can tune a VRX only within the sampling rate bandwidth centred on the LO of VRX0. In your case, VRX-0 sets the LO to 446.753637 MHz. and you're using a sampling rate of 10 MHz. That means the VFO tuning range of <ALL> VRXs is limited to 446.753637 +/- 5 MHz, or roughly 441.75 to 451.75 MHz. You are attempting to use VFO's of 147 and 162 MHz. in VRX1 and 2 respectively, however the LO and SR bandwidth will not allow you to do that. Instead, it will tune to wherever the VFO/LO math tells it to within the allowable BW (I'm too lazy to figure out why those particular freqs in your situation).

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K3WKM
Posts: 5
Joined: Sat May 27, 2017 2:19 pm

Re: Ctrl Panel & Main SP different freq.

Postby K3WKM » Sun May 28, 2017 2:10 pm

Thank you for the explanation....If I understand correctly that would mean you can not listen to two different freq. that are not within the 10 MHZ sampling rate.....my objective was to listen to two repeaters at the same time.....one on 2 meters the other on 70cm....(this can't be done is what I think u are telling me)....

I appreciate ur help....

73 Steve K3WKM
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hfsdpk11
Posts: 18
Joined: Mon May 01, 2017 5:00 pm

Re: Ctrl Panel & Main SP different freq.

Postby hfsdpk11 » Sun May 28, 2017 5:21 pm

I think you've got it. In essence, you can tune the VFO of any VRX across: LO +/- SR/2 but not outside of that. Since the RSP has only one LO, you're limited to the bandwidth around it and no more. Look on the VRXs as taking a chunk out of the passband provided by the LO and sampling of the ADC and then doing the demodulation/processing on that chunk.

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K3WKM
Posts: 5
Joined: Sat May 27, 2017 2:19 pm

Re: Ctrl Panel & Main SP different freq.

Postby K3WKM » Sun May 28, 2017 5:27 pm

Excellent...thanks for straightening me out!
73 Steve K3WKM
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