Quickcall II problem; are low signalling frequencies bad?

[chipjumper]

In other words, is there a problem having low toning frequencies (audible tones...)? Ours are 339.6 and 378.6. Most of the other FD's in the area have higher tone frequencies. Price is not really a problem here, we just want it to work. Consist of 36sq. miles of rolling hills to flat land with a 60-70ft tower on the high upper right corner of the township.

Actually I just got back from a run that I only knew was dispatched cuz I was scanning the ambulance service's TRS and heard the call. I live across the street from our VHF remote site and never got the call! I have a "never failed" Minitor II and a Keynote. We have spent over 10g's to make it work in our township. This includes equipment upgrades, service calls, and a remote site built (at the firehouse). Our remote site actually sometimes goes down because the phone company allegedly likes to use the dedicated telephone radio link as a test line.

Later today we are having a special communications meeting to discuss some current and future issues with our equipment. Should we buy all new Minitor IV's and replace the "old" Minitor II's and Keynotes??? Test out different tones???

[Pj]

I remember reading a SRN some time ago advising that low end paging tones should be avoided. I belive it pertained to the Min2 and 3 or just the 3. If I recall correctly, I think they just said to avoid anything under 400 or 500 all together. I'll see if I can dig it up again.

[nmfire10]

Our remote site actually sometimes goes down because the phone company allegedly likes to use the dedicated telephone radio link as a test line.

Later today we are having a special communications meeting to discuss some current and future issues with our equipment. Should we buy all new Minitor IV's and replace the "old" Minitor II's and Keynotes??? Test out different tones???

IS your phone company SBC by chance? They like doign that here too. They will just randomly disconnect lines because they didn't hear any dial tone on it and figured it must not be used for anything anymore. Idiots.

Trust me, going from a Minitor II to ANYTHING is not an upgrade. DO NOT, I repeat DO NOT dump the Minitor II"s for Minitor III/IV pagers. They are inferior pieces of crap. The Minitor II is and probably always will be the best two-tone voice pager Motorola ever made. If you want to use higher tones, you can do that with the Minitor II.

[chipjumper]

Thanks guys, I'll bring up that there is a known issue with reeds under 500hz today. PJ - if you can find some more info i'd appreciate it. Thanks!

[PETNRDX]

I agree about the Min II. As long as they are not beat to death they are about as good a reciever as you're gonna get.
As for the phone company, get a copy of the service agreement with them. If they are playing around with your service, you have a good arguement to not have to pay, or at least get refunds, or credits for the service interuptions.
If that is not in the contract, negotiate it next time, or get another signal transport method. Even your own spread spectrum link mite be better.

[wavetar]

I've found two problems with lower tones when you start getting close to the 300Hz voice cut-off:

1) Phone lines really attentuate the level of the tone at or around 300Hz, since they are filtered to pass 300Hz-3KHz. So, if you're paging remotely, the low tone has to be cranked up to be decoded properly by the pagers...resulting in a higher tone (if used) to blast out well above 5KHz, and be very distorted. If paging locally (no phone lines), then this isn't an issue...but read on.

2) Many radios used to transmit the tones have filters set to cut out anything outside of the 300Hz-3KHz voice window as well. It will vary for different makes & models, but some of them have problems as high as 400Hz or so. This generally occurs when trying to use a MIC input, as opposed to a flat TX input.

Combine #1 with #2, and you have a real mess waiting to happen, regardless of what type of pagers are out in the field.

Todd

[Cowthief]

Hello.

SBC switched over a bunch of customers last fall to this cable.
The only trouble? signal corps had vacated the cable, as the thing was scheduled to be removed.
Ma bell was very upset when an entire section of some berg lost service.
After some research the SBC people found out that this was indeed a US army cable.
The error was real easy to make, as the cable was made by western electric, only at the terminating points did it say it was a military cable, but still.
And, why did SBC cut over the services?
The notes said that a cable was to be vacated, that cable.

[Pj]

Our town recently swtiched from VHF-Lo dispatch to UHF (repeater). This was done for a whole host reasons, but hey, that's how things turned out.

Hence, I no longer have my Minitor 2, and we all got Min4's. So far, I can't complain. They seem to be doing well so far...but we have a fairly good system in place.

[KC8NIY]

I would say that changing the tones would be the easiest resolution. I definately read some time ago as well about lower freq tones being an issue, but also can't remember where I saw it.

Consider that Manchester has a remote link, and I've never heard of any complaints or missed calls out of them. Then again, Augusta used to get toned 3 times before responding, but that was before their link as well as some staffing issues from what I gathered.

It wouldn't be to hard, nor expensive, to throw some new reeds in and reprogram the encoder.

EMD might have some suggestions as well.

[chipjumper]

Yeah, we have a remote site here in Salem as well as Manchester and Augusta. We have had several problems with SBC disconnecting the line. This is very pathetic. It seems like its a gamble every time we get a run (only 400 per year though) whether or not everyone will be activated. In fact, I'm willing to bet that there is always one person that doesn't get the call.

I will strongly review changing reeds, checking the Zetron encoder for consistancy, and making sure we have a balanced phone line!

Even though we don't get a lot of runs, when we do they are usually pretty serious. I'm writing an email right now to a high level person at our dispatching contractor explaining our difficulties...

[Karl NVW]

The answer depends on your encoder and how it is connected. ALWAYS use the paging encoder input if one is available on your console. In theory all paging tones should have the same deviation level so that all tones hit the decoder at the same level. However, microphone audio is sent "pre-emphasized," that is the highs are much stronger than the lows, all relative to 1 KHz. If you connect the paging encoder through a mic circuit, a 2000 Hz tone gets twice the deviation of a 1000 Hz tone. A 333 Hz tone gets on ly 1/3 the deviation, therefore only 1/3 the recovered audio level into the decoder.

Your department's low tones are probably down in the noise unless they are sent without pre-emphasis. Once more: ALWAYS use the paging encoder input if one is available on your console.

[chipjumper]

Karl, I believe this is how it works,

Tone is activated via Centracom II panel...somehow the signal goes to the Zetron encoder, output audio (any, voice or toned) goes through the magic SBC phone line to our MTR2000 base which transmits the received audio.

I talked to the big cheese today and it sound like they will test the encoder but we have to arrange testing for our magic SBC phone line of which is believed to be an unbalanced line.

I'm curious if we can have an external encoder installed next to our MTR2000 that can be activated by our remotely located central dispatch...

[Will]

'm curious if we can have an external encoder installed next to our MTR2000 that can be activated by our remotely located central dispatch..."

That would be possible and would correct for the phone line's lack of equalization.