Audio Holes during scanning.

EddieC · Post by **EddieC** » Tue Jan 06, 2004 6:45 am

I'm trying to eliminate, or at least reduce to a tolerable level, audio holes. I have HT1250's used by Safety personel to monitor a plant-wide Emergency channel while they do their work during the day on as many as 15 other frequencies. The Emergency personality is progammed to alert and unmute when it receives the proper A-B tone sequence. In order to increase reliability, I set this channel as a priority one channel on the scan list with 'Selected' as the only other on the scan list (not set as second priority).

This, of course, results in audio holes in the traffic on the selected personality. I ran the scan sample time up to one second to reduce the frequency of the holes, but the guys still complain about it. Is there anyway to further reduce the holes or eliminate them all together, while still ensuring that the radio will alert despite ongoing traffic on another frequency?

The Emergency personality is set up to unmute with proper PL (Standard/Standard) OR QCII.

Thanks!
Eddie Cranford

Post by **alex** » Tue Jan 06, 2004 6:48 am

This is an interesting one.

Whats your console back end setup like?

Any chance you can use a MDC broadcast to accomplish the same thing?

That might be a bit better than QCII for those radios, and requires less audio time.

The Waris series radios (in my oppinion) take forever to reliably "lock" on frequency and kick whatever decoders into action. You could change the QCII timing on the console so that it would hold the A time longer (I think).

HOw about some more information. Is this a trunked system? Conventional? Could you key up on ALL the channels and dump the tones? (that seems like real overkill)

Just thoughts.

-Alex

EddieC · Post by **EddieC** » Tue Jan 06, 2004 7:37 am

Interesting wasn't the first description that came to my mind

Instead of a console, the tones will be sent via portable. This was required because the safety personel who will initiate the alert are on the move in a truck or on foot 90% of the time.

QCII was selected over MDC because the Emergency Brigade (our in-house fire fighters and EMT's) carry Director II series voice pagers when they are not carrying their radios. The A-B tones for the pagers match the selected QCII Call Alert tones.

I've noticed the lock-on timing problem... increasing the Pre-Time on the sending portables helped with that. I've got it set at 500mSec and it seems to work OK.

Here are more details about the system so far:

Portables used in the system are HT1000's, MT2000's, HT750's, HT1250's and HT1250LS (bought by mistake by an administrative type... our system is strictly conventional). All of the portables will be set up to alert. Waris series will alert and revert.

Voice pagers are carried by personel who don't always carry a portable.

The 'Emergency' channel is UHF w/PL repeated by a Motorola MSF 5000 45Watt repeater station. The repeater has a reverse patch (MRTI-1000). The only console access to the station is a paging moden that is being obsoleted by the system change (no one will be there to use it).

The other interesting part of the problem is that the Emergency personel will be answering phone calls through the personality that they monitor 95% of the time... the 'Coordinator' channel. The 'Coordinator' channel and the 'Emergency' channel share the same frequency (same repeater) but have different PL's! (I'd love to get my hands on the guy that made that decision

!)

Each department in our plant has a radio (mixture of bases and portables of different model) that monitor the Emergency channel, but are not part of the alert scheme... there is a plant wide alarm system for that.

Thanks for any advice... I've been sweating over this for a couple of weeks. I even had to set up an autodialer to call the head safety guy's cell phone when an alert is initiated.

Thanks,
Eddie Cranford

Post by **alex** » Tue Jan 06, 2004 8:06 am

Well, I was going to ask if this works reliably on the Jedi portables, and then I stopped and had to think - they won't send QCII pages. Else, I could see a feisable solution would be to make sure every emergency worker has the jedi portables, and give the Waris POS's to the other folks.

MDC won't work because of the afore mentioned need for the Minitors.

I'm guessing that the phone channel is so that if someone calls for an emergency - everyone hears the phone call, and a qualified person can answer it.

I wonder if setting the scan time on the portables would help at all. Have you looked into trying that? I kept all my Waris stuff on 750ms check times, but I wasn't using QCII. Most of the stuff I monitored was with MDC as the RX personality, since I carried a QCII pager.

Just more suggestions.

-Alex

EddieC · Post by **EddieC** » Tue Jan 06, 2004 12:42 pm

Yeah, I've had some transmission problems with the Waris radios. They don't seem to get the same range despite a solid 4 Watts at the antenna port. Maybe it's an antenna design problem? This has cropped up recently... up until then they seemed comparable to the Jedi's.

I ended up taking the scanned channel off priority one and setting it as a non-priority. Most of the traffic on these radios will be on the channel that shares the frequency. Alerts won't go out until that frequency is clear, so all of the pagers will get it and most of the other portables will as well.

Thanks for your help!
Eddie

Post by **alex** » Tue Jan 06, 2004 1:50 pm

Are you using the "cone" style antenna's on the portables? They have a SRN out on them, and your supposed to buy the old GP300/MT1000/HT600 style antenna's to replace the "sleek non working" versions.

Maybe try swapping some of them around and check the performance. I had a VHF 1550XLS for a while, never really had too may problems with it.

-Alex

EddieC · Post by **EddieC** » Wed Jan 07, 2004 4:39 am

By cone, do you mean stubbies? If I get one in with a stubbie it gets tossed and I reinstall a whip. As a general rule, those things seem to be a bad idea. Is the SRN posted anywhere on the net? I'd love to read it.

Thanks,
Eddie

Post by **alex** » Wed Jan 07, 2004 7:13 am

I don't have access to get the tech notes, but I'm almost 99.999% sure there was something a while ago (I want to say ~2 years ago) that stated you should switch the antenna's, and the radios started shipping with the older GP style antenna's.

If you look at this page: http://www.motorola.com/cgiss/portables/ht1550xls.shtml the HT1550XLS shown in that picture has the older "cone/sleek/aerodynamic" whatever you want to call it antenna that shouldn't be used.

However, if you like the style and grace - don't care about performance, that antenna is for you.

I don't know if the SRN was specific to a band, but I believe all of those antenna's are in the same boat. If your using VHF you probably shouldn't use a stubby antenna regardless.

-Alex

EddieC · Post by **EddieC** » Wed Jan 07, 2004 9:41 am

All of our stuff is UHF. The antenna in the link looks like the VHF version of the ones that came on the HT1250LS's a couple of years ago.
These are the antennas I replace with whips:

I just noticed that the design of the whip has changed also! The one pictured at our vendors website looks different from the last batch I bought. You can see that at Wireless Communications. They do make BNC adapters for the Waris series, I have a couple in a drawer. If forced to carry one of these radios (I carry a modified vertex), I would put a better aftermarket antenna on it.

Thanks,
Eddie

kcbooboo · Post by **kcbooboo** » Thu Jan 08, 2004 7:21 am

Just a suggestion, and it may not be desirable. Could you disable the PL decode on those scanning portables for the emergency channel? When the radio scans around, it must sit on each frequency for a while to make sure that any signal has the right PL. If you can make it plain old carrier squelch, it won't have to sit on that channel more than a few milliseconds before going on to check another freq, thus making your audio "hole" much shorter.

The obvious downside to this method is that the portables will now hear and stop scanning on any activity on that channel, but if they're inside a building, and not likely to hear anything else on that freq except the emergency stuff you want, that may be acceptable.

Bob M.

EddieC · Post by **EddieC** » Thu Jan 08, 2004 10:24 am

kcbooboo wrote:Just a suggestion, and it may not be desirable. Could you disable the PL decode on those scanning portables for the emergency channel? When the radio scans around, it must sit on each frequency for a while to make sure that any signal has the right PL. If you can make it plain old carrier squelch, it won't have to sit on that channel more than a few milliseconds before going on to check another freq, thus making your audio "hole" much shorter.

The obvious downside to this method is that the portables will now hear and stop scanning on any activity on that channel, but if they're inside a building, and not likely to hear anything else on that freq except the emergency stuff you want, that may be acceptable.

Bob M.

Thanks for the suggestion. Under normal circumstances that would help. However, I'm right on the fringe of another license holder for that frequency. I have a feeling their antenna might be higher than the coordinator allowed and we get periodic interferance from them. At one time the Emergency radios were on receive CSQ and transmit PL (to protect the repeater). I had to put them all on RX PL when we started getting interferance. I would call the FCC, but I inherited a mess when I took this job and would rather not have them looking around too much... at least, not yet. Besides, I don't know for sure that we were the first license holder for that freq pair.

Thanks again,
Eddie