Does anyone know why Cecil county abandoned their VHF tone out channel (155.5275) after going phase 2? As far as I know only fire chiefs/ ems personel were issued new unication pagers.
Cecil County Phase 2 system no analog tone out?
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boatbod
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That would be somewhat unusual if true. When our county switched over we kept the vhf pager freq and (months later) added p25p2 tone out and digital pager support. Even now, multiple years later, we still run both systems due to the price difference between a G1 and a G4/G5.
I’m a member at a station in Cecil. Can’t speak for all companies but we have enough G5’s for anyone who needs one. This is just my assumption but I think the analog tone-out was actually part of the old vhf pro voice and that’s why it was abandoned but I could be wrong.
My understanding is that when Cecil County transitioned to the statewide system and depreciated the VHF EDACS, the state would not allow their microwave connectivity to be used to connect the VHF transmitters for the analog paging system. So the county would've had to maintain a microwave backbone for a single-channel VHF system, and chose to switch to two-tone over P25 on the state system instead. All county volunteers are issues a G4 pager. There is also a county-sponsored Active911 account.
The most significant downside to this is no local back-up transmitting for the pagers if the radio system crashes. Whereas with the VHF system, each firehouse had a VHF base station with a simple tone encoder allowing locally controlled pager activations if the county system failed.
The most significant downside to this is no local back-up transmitting for the pagers if the radio system crashes. Whereas with the VHF system, each firehouse had a VHF base station with a simple tone encoder allowing locally controlled pager activations if the county system failed.
Perhaps the MW backhaul for the VHF system was EOL, but I think I would have chosen to upgrade and retain the VHF paging capability. The whole Cecil situation was so murky...
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I am sorry, I don't know where this information came from, but I think the first part of your comment is wrong, both MD First and MIEMSS allow T-1's on their microwave and I cannot imagine either entity telling Cecil Co. no (not saying they couldn't), but MIEMSS microwave carried their VHF EDACS system and I don't know why they couldn't hold onto a T-1 for VHF paging or even a voice DS0 on another T-1, for paging.
It’s gotta be cheaper to just simply buy G5’s at $650 a piece than to maintain an entire vhf paging system. Especially considering a Motorola Mintor probably costs between 400-500 new.
boatbod
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Minitors or G1s were about $350 last time I looked, compared to G4s at $650. Bulk purchase probably brings that price down a bit but even so it's a big premium to pay. Guess the economics all depend on how many pagers you need and what geographical area needs coverage.
Consider what it must cost to maintain a county wide vhf system though.
you’d need at least one tower site and two repeaters one for ops and one for tone out and everything that goes with it
Licensing
Bridges
Dispatch center equipment.
Like you said though double the cost of the pagers would add up too, honestly I though two tone over digital was dumb at first but it’s grown on me seems to work better than I thought it would. I just wish I sold them all those pagers.
boatbod
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P25 Ph2 paging works better than analog because the tones are transmitted digitally end-to-end and synthesized for audio playback in the receiver, so in essence it's a fully digital paging system even though you still hear traditional tones.
Certain tone frequency sets have to be used on digital though, correct? Analog paging seems to work fine in AACo.
Correct, there are limitations with the DVSI vocoders, and they are different for IMBE (FDMA) vs AMBE+2 (TDMA). The Motorola APX series, which has the Digital Tone Signaling option, has the charts of available tones in the CPS. I can dig them up and post them if you're interested.
I programmed the old analog tones in my G4 and the pager alerts just fine. Tried to get the setting out of a county pager but the have a password on them 😡. Cecil is very protective of their “proprietary information”. They also don’t like it when you tell them the programmed the pagers wrong. Lol
Okay here are the two charts, FDMA and TDMA. Note that because the AMBE+2 vocoder used on TDMA is more advanced, it allows for 91 possible tone groups/ranges vs only 72 with FDMA. Enabling QCII over digital often means that some existing tone sets have to be modified. I know of some instances where two fire departments have common A tones and the B tones were very closely spaced, which was fine over analog, but they wind up in the same tone group for digital decoding. No bueno.
There are software utilities that can use the audio output stream to ID the tone frequencies. I'm not sure how accurate it is, but using the charts mentioned above could help you figure out the pairs.
Unication has a similar chart in their pps, I don’t think there were any conflicts in Cecil since there isn’t many stations. I used the old analogue tones listed in the wiki for Cecil. My only issue is I did something wrong with the long tone I need to bump the timer up in my pager because it’s alerting sometimes when it shouldn’t. Factory on the unication was like 3 seconds I think I bumped it up to 5 and still getting false tones I went with 5 because that was factory for a kenwood radio. I think I need to bump that up to 6 or 7 and try again. I’ll be in Cecil this weekend I’ll try and experiment.
boatbod
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Yes, the AMBE+ analog tone detector in the originating end is specified to match tones centered on specific freqs but allowable within a range. When these are converted back to audio at the distant subscriber unit they will be played at the center frequency. The ultimate effect is that certain legacy Minitor tones are unavailable to use on AMBE+ because they overlap the detection range.
When Talbot Co began using P25 P2 tone-outs they had to redefine some of the fire and ems company tone pairs, so now we have one set used on VHF and a different set used on 700Mhz.
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