Excessive squelch tail HT750 VHF/Lowband

[Anderegg]

I just purchased a lowband HT750 for monitoring the California Highway Patrol, and I am very pleased with the reception and voice quality, but very dissapointed in the very long, very loud squelch tail.

The CHP uses GE equipment in their vehicles, and I am assuming GE repeaters. I wasn't expecting Motorola PL silent decoding of the CTCSS, but I was expecting the normal quick chirp of static at the end of the transmission. Instead it sounds as if I were to depress the monitor button for around 300ms. To make the problem worse, the voice traffic is somewhat low, and the squelch tail is extremely loud by comparison, making it difficult to listen to traffic for extended periods as I need to.

A few minutes ago, I heard a couple of units talking to each other, with one being received with silent Motorola type PL termination, and the other with a rather normal squelch tail. Not sure if they were simplex, but they may have been. Is there a way to tune down the squelch tail for use on the non Motorola CHP repeater system? I am looking into the reverse burst TOC thing with my programmer, but wanted to see if I can somehow fix this issue. The radio will be used in a stationary location, with a strongish signal if that makes a difference for sugesting some options. Just to be clear, this is for decode only, not a transmission issue, and this is open squelch I am getting, not a noisy burst from the repeater.

I might want to add that the Motorola, even this cheap one, blows away all of my scanners, even when they are running a 4 foot long lowband whip vs the handheld antenna on the HT750!

Thanks!

Paul

[DPL]

Try changing the mute/unmute rule on the Conventional Personality --> Options screen. Change the dropdown box "Unmute / Mute Rule" to "And Unmuting / Or Muting." Right now it's probably set for standard muting.

Standard muting means that the radio waits for the PL decoder to indicate loss of PL before muting the speaker. "Or" muting means that the radio will mute the speaker on the loss of PL OR when the squelch closes. The squelch tail is longer with standard muting because the PL decoder has a delay to keep from accidentally muting on a weak signal. "Or" muting means that the radio will mute as soon as the squelch closes, even if the PL decoder hasn't indicated loss of PL yet. That will give you a shorter squelch tail.

[wx4cbh]

To add to DPL's post, if the transmitting unit doesn't have the requisite STE (Squelch Tale Eliminator) enabled at the end of its transmission, or the type and timing of the STE used by the transmitting radio doesn't match the STE standard that the Motorola is looking for, and you do have the receive STE turned on in your radio, you will hear a longer squelch burst in your receive audio when the carrier drops. This is because the receiver is waiting for the Motorola STE and it never occurs. In those cases, the squelch circuit audio closure timing is delayed and the white noise burst may very well be longer than what you consider normal. Without the receive STE turned on in your unit, the white noise burst in your receive audio at carrier drop will probably be shorter because the basic audio/squelch circuit timing for audio closure is now the only device in play and an STE has no part of that timing. The above in my post is a generic explanation and only applies in general. As for me, I usually set my unmuting/muting to AND/OR for less fatiguing monitoring, but the specifics of your particular experiences and preferences may be different.

[Anderegg]

Well this is strange, I noticed that 39.4, the main San Diego CHP repeater does the long squelch tail, but 39.8, the CHP Oceanside repeater is silent like a Motorola. My programmer tried every option in the CPS, including putting 39.4 into the channel that had 39.8 hoping that there was a setting in that channel that was working, but no use. Is there a way to "tune" or adjust the receiver in any way to shorten this annoying sound, not to Motorola PL quality, but simply to scanner like? If not, would there be an alternate radio I could replace this HT750 with to eliminate this annoyance.........it is really bad and hard on the ears.

Paul

[Anderegg]

Just a quick follow-up......the Oceanside repeater makes a slight hum at the end of the transmission, then clean silence, the San Diego one does not. I will assume the OS one is Motorola and the SD one is garbage!

Paul

[WB6NVH]

These systems are presently in a state of transition. The GE RANGR equipment in the cars is being phased out and replaced with Kenwood drawers controlled by a touch-screen system indirectly supplied by Rockwell Collins.

The portables are now EF Johnson 700 MHz P25 units which go to a Pyramid vehicle "extender" and out the low band radio. Older cars still in service have Pyramid 154.905 MHz extenders and use Motorola HT's, although I am not sure what happened today with the narrowbanding taking effect. They may have a temporary waiver while the VHF analog gear is phased out.

The stations are not technically repeaters. They are split-site remote bases with the capability of repeating the car traffic out on the dispatch frequency at the option of the dispatcher, as an audio patch. That's one reason the car audio part sounds, well, a bit poor in quality. The intent has been to now leave that function on all the time statewide but it still varies from region to region. I can't recall what base equipment is in use in your region and it's all being replaced anyway, if it hasn't been already. Originally it was a mixture of GE and Quintron and dated back to the late 1980's (as does the car stuff.)

I too have noticed that the STE operation on Motorola receivers listening to CHP channels is not uniform, depending upon the transmitter being monitored. Part of that may be the Motorola design that loosens the squelch as the signal gets weaker.

I presume you tried this with the STE feature turned off?

I don't recall having this problem with a GE radio and as far as I recall I have the STE turned on in those.

[Pj]

Actually, may be a Kenwood/Motorola deal. IIRC I think it only delt with DPL, but there is/was an issue between Kenwood's and Motorola's implentation of DPL (and/or PL) with squelch issues. I know this was discussed here on the batboard a year or three ago.

I only recall seeing this an issue with the Pro series radios and I also seem to recall that there was something in the newer CPS that mentioned Kenwood radios and had an option.

Either way, if the repeater is getting the squelch crash on their end of the system, your screwed no matter what. From what I recall, they are just patching the input side into the dispatcher transmit side and there isn't any true repeaters. Its just a patch (at least from my CA work experience with them).

[Pj]

I found this, and prob what I was thinking... I guess it would also help to make sure your using current firmware and CPS and give it a try, as needed: http://batboard.batlabs.com/viewtopic.php?f=1&t=9856

The compatibility issue surfaced when I added a Kenwood TK-762 radio to a fleet of Motorola radios. Immediately, I discovered that the Kenwood radio caused squelch crashes on all the Motorola radios, and the Motorola radios caused squelch crashes on the Kenwood. I brought in another Kenwood radio to test, and it reacted in exactly the same manner as the first. A bench check proved that the reverse bursts were exactly on spec, and both Kenwood radios muted silently between each other.

I dug into this topic with the help of engineers and technicians at both Motorola and Kenwood, and gradually realized that Motorola used a 120 degree phase shift for 180 milliseconds, while Kenwood used a 180 degree phase shift for 150 milliseconds. This difference is almost immaterial for mechanical reeds or simple tone decoders, but is easily discriminated by the digital signal processors used in the latest radio models.

Motorola has finally acknowledged this compatibility issue in the latest version of Professional CPS, HVN9025K R06.02.03. There is now a check box on the Personality Configuration - Advanced page that has a box labeled "Non-Standard Reverse Burst." When this box is checked, the radio will encode and decode the CTCSS reverse burst in the format used by Kenwood and other major radio makers. When unchecked, its default condition, the radio will encode and decode the CTCSS reverse burst in the Motorola format. I tried using this new feature on a brand-new HT-750, and I can say that it works perfectly. Since the feature is programmed for each personality, I can now use just one radio in either a Motorola or a Kenwood system, and it will mute silently in either.

I expect that Motorola will begin including this capability in all future RSS releases for all radios. It remains to be seen if Kenwood will offer a similar upgrade in their software. At this time, you must send a Kenwood radio back to a service center to get it flashed so that it will be compatible with the Motorola reverse burst. That's too much trouble for me!