How to change the LO frequency

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captcha
Posts: 4
Joined: Fri May 19, 2017 5:26 am

How to change the LO frequency

Postby captcha » Wed Jul 05, 2017 6:20 am

Is there a way to change the Local Oscillator frequency whilst the program is running?

What I've been doing now is to click on the frequency in the waterfall where I want my LO to be, and then STOP the receiver and close SDRuno. Upon re-starting the program the LO is then sitting on the frequency I clicked. This is a very clumsy (but working, maybe a bug?) procedure. Is there a way to change the LO with some kind of button or shortcut? I tried holding down Shift and Alt and raising my left foot, but none seem to work..
Last edited by captcha on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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octave9
Posts: 59
Joined: Sun Feb 19, 2017 7:54 pm

Re: How to change the LO frequency

Postby octave9 » Wed Jul 05, 2017 11:26 am

Slightly easier than your way would be to; set the LO where you want it by adjusting the tuned frequency with the scroll wheel, in the MAIN SP window (or VRX window) while hovering the pointer over the digit you want to change. You'll see that the indicated LO changes in sync with your scrolling. When LO is where you want it - then click the LO LOCK button in the MAIN window. Now the LO will stay where it was and you can tune around it within the limitation of the sample rate set.

You'll need the 'Show F Dial' option enabled in the Main SP windows settings to see the LO (and tuned frequency) in the Main SP window.

I believe the 'holding down Shift and Alt and raising the left foot' method only works on alternate Tuesdays if there's an R in the month.

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captcha
Posts: 4
Joined: Fri May 19, 2017 5:26 am

Re: How to change the LO frequency

Postby captcha » Fri Jul 07, 2017 6:16 am

Oooh.. nice.. That worked beautifully.

Thanks for that.

The 'Show F Dial' option was already set. This must be the default as I'm still finding my way around the interface and haven't messed too much with all the settings.

That leaves me wondering, would the behaviour I described (LO is set to whatever receive frequency the user had set when the software is closed) be interpreted as a bug or as a feature?
Last edited by captcha on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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hfsdpk11
Posts: 28
Joined: Mon May 01, 2017 5:00 pm

Re: How to change the LO frequency

Postby hfsdpk11 » Sun Jul 09, 2017 4:07 pm

I've found that having two RX windows open is more effective for independent control of the LO and VFO. Leveraging off the fact that RX-00 is the only one that can control the LO, I have that RX open solely for moving the LO frequency. The second window is RX-01 which is used for VFO tuning and signal filtering/management. This method allows tuning the LO and fixing the VFO range without messing with the LO LOCK control and fiddling back and forth with RX-00.

The only downside is that you have to re-enable RX-01 whenever stopping SDRU processing (the STOP/PLAY) button and then re-starting. A stop-start cycle will requre (a) re-enabling RX-01 by clicking the red/green button in MAIN and (b) re-tuning the RX-01 VFO frequency since it will reset to the LO frequency when it starts up.

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