The following are only preliminary results of some tests I did today now that my STi has been updated with the public release of the new audio ramp-up firmware.
The following observations assume that the door opener frequencies are different enough so that the STi can "see" that there are two or more distant K band door openers. For those of you who are curious, it appears that the STi is capable of seeing different frequencies down to a resolution approximately 10MHz or the second digit after the decimal on the spec display. Thats pretty darned good, and it shows how much engineering went into the STi's M3 antenna design.
The STi now ignores extremely weakly detected K band door openers as long as two or more are being detected at the same time. This seems to be most effective for older K band door openers which used traditional Gunn oscillators which were manually tuned. Newer K band door openers use emitter plates (kind of like a phased array antenna) which tend to emit almost exactly on either 24.125 or 24.150 depending on the brand. Usually these newer K band door openers are "seen" as a single door opener by the radar detector.
Here is where the really neat new and undocumented changes in the firmware are. If the STi is detecting two or more K band door openers which have very similar intensities, then it will not alert to them until either their collective signal strength reaches 5 bars, or until one of their intensities is significantly stronger than the others.
If one detected K band door opener is very weak (signal strength of 1 bar) yet another detected door opener being detected which is somewhat stronger (maybe signal strength of 2 bars), then the STi usually will ignore them. Yet it seems that if the signal strength difference between the two exceeds a difference of 2 bars, then the STi will alert.
So, all in all a STi in Autoscan mode with the latest firmware code that features the new audio ramp-up is amazingly quiet around town. Yet you definitely want to switch to Highway mode once you hit the open road, especially if K band is still heavily used in your locale as is the case in my neck of the woods.
Well, what do you all think? Overall I was pleasantly pleased with the logic which Bel has chosen to implement in their latest firmware code.