DSDPlus Automatic RF gain control in FMP

[brian]

I'm interested to know if it's possible to have RF gain in FMP (FMP24, in my case) adjusted automatically. I don't believe there is, but want to verify I'm not missing anything. Note that I'm not referring to audio gain, but RF gain (signal strength).

More and more I'm using DSD+/FMP24 in a mobile environment. I find myself in areas with simulcast trunked radio systems frequently, and without a portable radio that supports simulcast, I find this to be a good solution. It also allows better logging capabilities of systems/sites that I don't frequently monitor.

I find that even with a decent band-specific antenna, gain has to be adjusted fairly frequently while mobile. Either strong signals from nearby RF sites overload the SDR receivers, or elevation changes and obstructions cause signal to drop. Seeing this is pretty insightful to understand why my scanners struggle with signal also.

Any suggestions (aside from buying an SDS or Unication)?

PS - when stationary, once it's dialed in, FMP/DSD+ functions extremely well most of the time. It's a great application.

 

[wgbecks]

There are no AGC functions built into DSD+ for RTL SDR's. Airspy devices have AGC modes built into their architecture, but FMPA only provides for the individual adjustment of the LNA, Mixer, and IF gain stages.

 

[brian]

Thanks. That's consistent with what I believed.

So some follow-up questions: is anyone else using DSD+ fastlane in a similar mobile use case? Do you find the same challenges to be present? Does anyone have any creative solutions?

 

[wgbecks]

Brian,

I've never attempted to run DSD+ FL mobile, but I suppose that you could configure it to do so to include the ability to
roam multiple sites with the lost control channel hunt setup. However, I have been doing this very same thing for a few
years now with Boatbod OP25 using RTL's and Airspy devices with good success.

The Boatbod rx.py application provides not only for multiple control channels, but more importantly, the ability to configure
use of a single NAC of 0x0 whereby a rx.py will accept the first NAC encountered each time the trunking logic acquires sync
on an active control that makes it easy to roam about a multisite system.

Of course, one can get a bit more sophisticated and employ scripting driven by I/O control functions (bttons) to tailor your
whitelists/blacklists and control channels on the fly as your driving about the system.

Bill