Tuning with FlexControl keeps going and going and going and going.....

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  • Question
  • Updated 4 years ago
  • Answered
This has been a problem since the first release. When getting to the edge of the panadapter window, if you keep tuning with the knob, it appears to buffer tuning input and the window will continue to scroll/tune down the band for quite a while after you stop tuning input. Sometimes it seems that it will never stop until you tune back in the opposite direction.

I haven't seen anyone else report this, so I wonder if I am the only lucky one? I would like tuning to stop when I stop supplying tuning input, and not continue to unload buffered tuning commands, as this results in overshoot 100% of the time and is very annoying.

I can supply video if need be of the problem.
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Michael - N5TGL

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Posted 4 years ago

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Tim - W4TME, Customer Experience Manager

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Official Response
We are aware of the issues with the FlexControl, but currently it is working as designed.  The FlexControl sends tune commands to the radio when the knob is rotated and the amount of frequency tuned is dependent on the slice tune step size.  The radio is properly tuning when it receives a tune command from the FlexControl.  Tuning the radio is not an instantaneous action, as the radio hardware has to tune and the GUI must update the high resolution panadapters and the slice position.  When you are at the edge of the panadapter, even more GUI operations are taken because both the panadapter and the slice are being tuned.  More on this in a minute.

As Stu has noted, the FlexControl uses an emulated com port on a USB interface.  Comports have deep FIFO buffers by default that can store a lot of tune commands.  If you rotate the knob quickly, it senses that it is being turned quickly and informs SmartSDR which will tune in larger tune steps; this is the accelerated tuning algorithm.  Buffers have to partially fill before being emptied.  By making the com port FIFO buffer smaller, there is less "queuing" of tune commands which mitigates the radio getting tune commands after you have physically stopped turning the knob.

Also, as Michael noted, a fast graphics card also helps, since the GUI is having to do a lot of multiple display renderings as your tune quickly and even more that happen at the edge of the panadapter (pan edge tuning).  Several people have compared this to PowerSDR and say it works better.  The logic in SmartSDR is essentially the same as what is used in PowerSDR.  The only difference is that there is a lot more radio tuning actions happening with a 6000 since there are "two degrees" of tuning freedom (slice and panadapter) and the GUI is having to perform a lot more rendering operations per tune command.

We have several issues logged in our bug tracker to look at this operation and see if there is anything that can be done to make tuning smoother at the band edges and when tuning wide jumps in frequency when the knob is quickly rotated.  In the mean time, to mitigate the run on tuning, refrain from spinning the knob and set the FIFO buffer to a smaller size (http://helpdesk.flexradio.com/hc/en-us/articles/202118458-How-to-Mitigate-FlexControl-Latency