Note this can also be triggered by connecting and/or disconnecting from the Windows machine using RDP.

Or, you know, cosmic rays, or phase of the moon.

If you select (File->Settings->Audio->Soundcard) another device, click OK, select your radio, click OK, then it starts working again.

Sure would be nice to have the program detect that decoding had stopped (waterfall stopped, left and right windows not updating, but green status bar continuing to cycle) and reconnect to the sound card. The I could leave my computer spotting to pskreporter when it's not in use. Or maybe there's a way for the program to select the sound card by name instead of by enumeration-pointer (or whatever), but that's past my expertise.

73, Willie N1JBJ

On Jun 21, 2021, at 6:02 AM, Bill Somerville <g4wjs@...> wrote:
[...]
the issue you describe is often due to MS Windows deciding to power down USB audio devices it thinks are not being used. You must disable the power management options for each USB Hub Device listed in Windows Device Manager under "Universal Serial Bus Controllers" (right-click device, select Properties, then Power Management, and uncheck the allow option).

Note that this is _EVERY_USB_DEVICE_IN_THE_SYSTEM_, not just your sound card, your unused BlueTooth interface going to sleep will cause enumeration, and might move your sound card...
I thought I had done this, but just went through them all, and not _all_ of them were set right. 🤷‍♂️

You also must disable the USB Selective Suspend option in the Windows "Power Options->Change plans settings (on the current plan)->Change Advanced Power Settings" open "USB settings", then "USB selecting suspend setting", and click the "Plugged in" option to select Disabled.

This was also not done on my machine, though it is now.

As Bob, G8HGN, points out, there is another issue with HDMI monitor connections. HDMI connections include a USB audio connection which too can be unexpectedly powered down when a screen-saver or power-saver function activates. I don't know of any settings to stop that other than making sure graphics card/chip power management settings for the monitor and screen saver are disabled, YMMV.

There are monitor/display settings in the power plan, I've set all mine to no power saving or maximum performance

The root problem is that USB devices are "hot-pluggable" and adding or removing a device, while the system is running, will cause all other devices to be re-enumerated, this can change device identities but Windows does not inform applications using them that they have been shuffled.

Note this issue affects audio devices but not virtual serial ports like those often used for CAT control, virtual serial ports over USB connections seem to be capable of blocking such power saving options, presumably because they are one-to-one connections and Windows can be sure when they are in use.

Thank you Bill!

73, Willie N1JBJ