EFJ 5100 priority scan

[hailstonewrangler]

The radio seems to clip about 1-2 seconds off of the begining of a transmission on a non-priority channel when scanning. There is only 7 channels in the scan list, the priority channel is set to the selector knob, and I have tried different priority rates with no luck.

Is there any thing that can be done to reduce the clipping?

Thanks.

[flat4turbo]

Is this on a trunked system or conventional channels?

If conventional, it sounds like you have to tweak the values for the scanning Loopback A and Loopback B values in the Per System configuration screen for the defined conv object. If the values are too low, then a combination of finding TX activity, plus CTCSS/DCS/NAC decode times might be keeping the audio from coming through cleanly.

Also, check how many channels are Priority 1 vs Priority 2 in the Priority Scan definition screen.

[hailstonewrangler]

All of the channels are conventional with some being digital/conventional mixed mode and having ctcss on the recieve. It is the channels with the ctcss that seem to be clipped the most.

I have tried adjusting the priority lookback time from .25 up 1 second. I have not tried any values higher than that. I would like to have it set at .25 to reduce the amount of a priority transmission that gets clipped, but that is where the clipping of the other channels occured the most.

The only priority channel is the channel that the selector switch is on.

When I switch the radio from selective squelch to normal squelch it does improve sometimes, other times it still clips the same. I have the ctcss set, because the radio seems very prone to recieving interference.

I am starting to get frustated by the fact that I have a high end radio that is getting out scanned by a $90 scanner.

[Intrinsically Safe]

The 5100 has a harder time decoding CTCSS/DCS than it does the carrier. That is why there 2 timers (a and b)
A is of course is your priority sampling and B is your CTCSS decode sample. This timer in effect waits how long the radio will check the carrier after an incorrect CTCSS tone was detected. If your Rx channels in your scan list all have different CTCSS tones this will cause havoc. I woul generally make this timer higher, probably around 3.5 to 4 seconds and see if it helps.
If you have your priority A set too fast that can cause issues with the vocoder when scanning digital channels, especially in the older 5100s (pre version 4.x.x) without the new vocoder. It seems the vocoder cannot sample fast enough and keep the audio in spec, you will get some warbling in the Rx audio.
With 7 channels in the list I bet the radio is struggling if the A timer is less than .5 seconds.
Also what version of Firmware is in your radio. They did some scanning improvements a while back and maybe an update is in store.
Just my observations and experience with 'em

I.S.

[hailstonewrangler]

Setting the Priority B to 4 seconds has helped quite a bit from what I can tell on the channels that have ctcss. I also set Priority A to 1 second, but it still seems to want to clip about a second off of the simplex channels.

It is an older EFJ with a firmware of 1.18.15 .

The scan list looks like this

1. Mixed mode repeater w/ RX ctcss of 100.0
2. Mixed mode simplex w/o RX ctcss
3. Mixed mode repeater w/ RX ctcss of 100.0
4. Conventional simplex w/o RX ctcss
5. Conventional simplex w/o RX ctcss
6. Conventional repeater w/o RX ctcss
7. Conventional narrow band repeater w/ RX ctcss of 123.0
8. Mixed mode narrow band simplex w/o RX ctcss
9. Conventional RX only w/o ctcss

I think that the clipping is now being caused by the variety of different RX modes, so not much more can be done.

Thanks again for the quick responses!

[flat4turbo]

Yeah,

I have my Loopback B set to 2.5 and my A to 1 sec and there will always be some noticeable delay due to the progression of the freq scan compounded with the tone decode times. If it were a smartzone system, the priority jump would be instantaneous and voice loss would be more in the ms range.

Cheers,
f4t

[Intrinsically Safe]

In trunking the radio doesn't have to load the synthesizer with every freq like conventional scanning does. It only has to load the control channel freq, and that takes ms. I have heard that it takes about 180 ms just to load the synthesizer, then about 125 ms to check for carrier, and if there is a CTCSS tone another 80 ms. So to scan just one channel in conventional it takes over .25 second.
I know early on the 'tick' heard when the radio was sampling the priority channel while Rx'ing another call was very pronounced but they found some way to speed up the scanning and now it isn't as bad. This change was made about 3 years ago. That is why I asked about the code versions.

I.S.