Fire Station Alerting

[larrybl]

I wasn't sure where to post this, but decided that sence it involves a Trunked infrastructure, Centracom Consoles, and Astro Spectra radios, I'd try it here.

I have been experimenting with Call Alert to alert our 13 fire stations. We currently use a two tone decoder attached to each base radio, and use QCII tones from the Centracom console. Each decoder has an individual first tone, that is set to a individual QCII tone (only the first tone of QCII is used). The decoder's second tone is set the same for all stations, which allows sending one QCII to alert all stations at once.
Each QCII is set as an Icon on the Console, and safety protected.
The Stations Base radio speaker output, is routed through the decoders Normally Open relay, and is fed to a Bogan PA amp. When the correct QCII is sent over the Primary Fire Talkgroup, the decoder's relay is tripped, which sends the audio to the bogan. What is heard at the station is the second part of the QCII tone, and then the Dispatchers announcement. Then when the firefighters return they re-set the decoder. One advantage of this is if monitoring the Fire Talkgroup, you hear the QCII tones (an attention getter) before the announcement.
The reason I am trying Call Alert is the two tone decoders are hard to come by, and we may be going digital in the near future.

What I have been able to do so far.

I have set up four radios for Call Alert. I programmed the Console with the four ID's, and created a (All Call) group that Call Alerts all four radio at once. There are five Icons on the console, and each radio can be Call Alerted individually or as a group. So far everything is working as advertised, and an advantage already noted is the dispatcher receives an instant notification on whether the alert was successful or not. The only question for the Centracom Console I have is (how many radios can I add to a group for call alert before I cause a problem on the control channel)? I have observed System Watch when initating a group call alert, and each ID is sent sequentially, and the ACK response from each radio is returned. If I send a group call alert to 15 radios, there will be 30 ISW/OSW words in rapid sequence.

At the Radio end, I am running in to several problems. The sequence of events that need to happen are.
1. Dispatch Initiates a Alert Call.
2. Radio receives the call alert.
3. Units not at the Stations are able to be alerted.
4. An attention tone need to be heard within the Station's)
5. Radio speaker output passed to a paging amplifier.
6. Radio needs to be Reset both manually or after a time out.
7. Provision to manually route radio audio to amplifier (un-mute).

I am working with two types of base radios, the Analog Spectra, and Astro Spectra. I prefer to use the Astro Spectra over the Analog spectra for obvious reasons.
The Analog spectra Call Alert audio tones (3 periodic beeps) does not override receive audio. The Astro Spectra Call Alert audio tones (3 periodic beeps) does override receive audio, (a bad thing).

Item 4 is a small issue, I can not use the Alert audio tones (3 periodic beeps) generated by the radio, because it overrides the incoming audio. I have disabled the radios internal alert tones to prevent lost audio. Now I have two options available. An alert tone will need to be generated at the console, this would also remedy item three, as the units monitoring the primary talkgroup would hear this alert tone also. Another option I am looking in to is to have a small one-shot tone generating circuit that would trigger upon receipt of a call alert, and generate a .5 to 1 second tone to be fed into the PA amplifier aux 2 input at each station.

Item 5 would be no more than a small relay triggered by the H/L output of the radio, I would use the Light output, and set it to the max of 240 seconds, or unlimited, still needs more experimentation.

Item 6 is the most troublesome, the only way to reset the radio is to generate a PTT from the radio. The two options that I am working on is a manual (requires the firefighter to remember to press the ptt. Or a time out timer, that would provide a pulse at a pre-determined time to automatically reset the radio. This would be fed into the radio's microphone connector.

Item 7 would be no more than a by-pass switch across the speaker relay contacts.

As you can see I am looking at a fairly simple circuit to build, and to do it right I plan to add LED indicators for the various functions. The main requirements are: (in order of importance).

Reliable
Inexpensive
Expandable
easy to implement and maintain

Any help or suggestions would be greatly appreciated.

[wavetar]

Just a suggestion. We run a similar system here, with 17 stations. Each station has either an analog Spectra or Maxtrac as a receiving radio. All are hooked to public address amps, some of which are Bogan, some are not. We also use Centracom consoles. The system is SmartNet AMSS.

What was done in our case, was to set each radio on it's own talkgroup. So, there are 17 different icons on the Centracom screen, one for each station. The dispatchers use the built-in alert tones (#2, I believe...the hi/low tones) before each transmission to a station, as an 'attention getter'. If multiple stations require alerting, they simply use the Centracom's multiselect capabilites. This allows for a lot of flexibility as far as which stations you can page at the same time, and can change 'on the fly'. Monitoring with portable radios is as simple as adding the station talkgroup to the radios. No Call Alert resetting required either!

I will say that there were issues with trying to put all 17 stations into a multiselect. Resources would seem to 'lock-up' randomly. It was determined to be a SmartNet OSW limitation, not a Centracom issue. After some testing it was determined that calling around 9 or less always worked without issue. So, it was decided that calling all stations at once was a very unlikely need, and they were susequently broken into North & South multiselect groups of 8 or 9. They rarely ever call more than 3 stations at once anyway.

Something they didn't do, but easily could have was to program an announcment talkgroup into each station radio & then have the capability to call all stations at once, with only a single OSW.

Just somethings to think about. It's been running this way here for about 6 years now, and working great.

Todd

[RocketNJ]

What about a stacked page? Send out the Call Alerts followed by a QCII over the Announcement Talkgroup? Set up the firehouse radios and field units on the same ATG. This way the firehouse radios will unmute on call alert and then hear the QCII tones.

Just a thought.

George

[motorolamonster911]

This may not apply here. Each one of our 13 EMS stations has a GM300 and a power supply for an alert monitor/base station. When tones are sent from the Centracom it alerts the radio, which alerts a relay that turns on the bedroom lights, sounds a buzzer, and starts a timer. That timer is wired into the PTT so that after alert, it clears the Call Alert. We have and MDC Tx Signaling system that also sends the appropriate signal back to dispatch to confirm the radio alerted. If you have any more questions..feel free to PM or email fightfires4eva@hotmail.com

[Jay911]

I just saw this system set up in a new station near here.

Voice/audio path for alerting is on a UHF frequency. Most halls have relays to open the audio path, turn on lights, shut off the stove, etc., thru dedicated wirelines. This hall instead uses a POCSAG decoder to listen to the VHF alpha pager system that's also used alongside voice dispatching. When the decoder hears a certain string on a certain pager number, it does all the things the wireline system does.



--j.

[larrybl]

I wish to thank all for your replies. I have sucessfully interfaced a set of relays to the accessorie connector for the Horn/Light activation. The horn is set to 4 seconds, and light is set to Infinity. This allows for the triggering of an inhouse alarm for 4 seconds, and routes radio audio to a PA until the radio is re-set. I disabled the radio's internal alert tone feature to prevent the 3 call alert beeps. I looked in to the creation of single T/G's for each station, although interesting, I don't think it would be practical for our patuliclar setup. I also looked into piggybacking the QCII with the CALL ALERT, This also is not practical, You can Set a list that will call alert all 15 radios in less than a second, If you add QCII and do the check list page it would take several minuets to complete. The plan I have now is to have Dispatch send a Call Alert, then send a Alert tone, before his anouncement.

Thanks again.