I have downloaded the new firmware 1.08.07 and cannot reproduce the problem. 1.08.07 works exactly the same as earlier firmware, and I see no delay, nor any significant change in the noise that sometimes precedes or follows some digital transmissions.
I monitor both Motorola Type II Smartzone APCO P16 3600-baud control channel system with anolog and P25 Digital audio, and also a very complex with multiple Motorola APCO P25 9600-baud CQPSK systems with only P25 audio.
I have posted on other lists a procedure that greatly reduces the so-called motorboating noise. Since I've always run with this tuning procedure (on earlier firmware as well as the current) it's possible that a change in the firmware is more apparent to those who don't follow this fine tuning procedure.
<cross post>
There are some initially-confusing things about the P25 Decode Threshold
level. The manual gives very adequate instructions about how to use
the AUTO setting, I thought. But I'll provide some insight:
The level numbers are an index into a table of thresholds for decoding
the digital data. Higher numbers are more permissive (the thresholds
for decoding are wider) while smaller numbers tighten the threshold
ranges. The optimum range depends on how the technicians have set up
the system you are trying to receive.
DEFAULT
Means a Level (Index) setting of 8. Thresholds don't change. Must
likely you can do better.
MANUAL means you control it all -
Hold Func and press the scroll knob twice to get the screen.
Adjust the setting with the knob until you get the best result for
any given SYSTEM.
The radio will remember this setting for that System and use it
every time it has to decode digital audio.
AUTO means the radio attempts to fine tune the P25 audio transmission
thresholds during receive. You can generally see it doing this. During
the beta test, we convinced Uniden to implement a slight change to the
"Auto" functionality. Specifically, we noticed that it was starting
over at the default setting and then trying to correct it again at every
transmission; sometimes this meant it took a long time to settle in.
We went thru a couple of iterations, requiring at first - Set the
threshold with MANUAL and then AUTO would use that as a starting point.
This was cumbersome, and soon changed to the ability to control the
starting point while in AUTO mode by using FUNC-SCROLL while viewing the
decode screen. Whatever you set at this point will be remembered FOR
THIS SYSTEM as the starting point for the auto-tuning function for
subsequent trransmission ON THAT SYSTEM.
Incidentally, we did suggest the ultimate -- for the radio to
automagically remember this on its own, continually refining it and
picking a better starting point if it could. But the engineers thought
it would results in too many writes to the EEPROM, which has a generous
capability for making changes to the programming, but the limit would be
reached if every P25 audio transmission resulted in a write.
Now I can offer a slight refinement (courtesy of a very helpful Engineer
at Uniden): If you're having trouble with a P16 (Moto type 2) system
decoding digital P25 audio, slightly offtune the automatic setting.
Frequently the radio will auto tune to a setting that is halfway between
the values that you can set manually. For example, it might finally
settle to a low threshold of 1.41, but you can't set the starting point
to that, you can only make it 1.40 or 1.42. Well, the trick that helps
stop the motorboating is to pick the tighter threshold side. In the
example, instead of picking 1.40, pick 1.42 (that's a tighter
threshold). (Think of it as similar to setting the squelch tighter for
a conventional channel.) Even if you auto-tune to an even value, like
1.42, pick the next tighter value (1.44) to start at.
Works for me. Cuts out 80% of the motorboating that occurred prior to or
after a transmission. YMMV. You guys having trouble with motorboating
on the San Mateo system should definitely try this.
</cross post>
