XTS2500 and 5000, P25 Quick Call II

[dustinw251]

I may be searching the wrong way but haven't found much info on it. I was recently made Fire Chief with my department back in October and I am looking for a way to streamline our radio usage for more coverage and better reception. We currently use XTS and XTL radios, 2500 and 5000 models of both. I see where these radios are capable of utilizing Quick Call II tones but will they use quick call 2 tones over the P25 trunked system specifically the Louisiana LWIN System. Granted I understand we wont have the Pager capability with the minitors we use now but if the same functionality will work with the 700 system on the radios and the radios will alert like a pager that would suffice. If this is Possible, has anyone here had dealings with this and how well does it work for you.

 

[krokus]

The analog tones are not supported on P25.

Direct Call could be used, to alert specific radios.

MPSCS is now supporting fire paging, which is growing in use, using Unication G4 pagers.

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[dustinw251]

So the quick call could only be used on conventional then?


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[GTR8000]

QCII in the XTS/XTL series only works on analog conventional.

If you need paging over P25 (conventional or trunking), the APX series now offers that feature (Tone Signaling)

 

[jeatock]

Generic short version:

Analog radios handle signalling based on audio tones in a defined pattern.
--QCII generally uses a 1-second+3-second audio tone pair.
--If a receiver decodes the "A" tone (usually for 0.5 seconds) then immediately (no pause) decodes 0.5 to 1.0 seconds of the "B' tone it behaves as programmed. (Minitor pagers alert for the duration of the "B" tone after decode)
--Other two-tone formats work in similar ways.
--A "Long tone" single audio frequency can be used for group or single agency alerting.
--MDC1200 and EIA 5/6-tone also use audio tones, but each "digit" is much shorter - EIA 5/6 "digits" are 0.066 seconds each).
--QCII (and similar) have a limited number of "addresses" (a couple hundred) and are considered a single agency (or station) signal. EIA 5/6 tone signalling sends a five digit number, and if specific RX masks or wildcard masks are used can signal everyone, a single agency, a single station, or an individual radio with the same data tone burst (100,000 addresses)

Digital radios react to specific data in the digital "sentence"
--Each digital format is unique (sometimes to a specific manufacturer) and are not interchangeable.
--A specific "word" or portion of the digital string contains signalling-specific data, and a receiver may be programmed to do something when it decodes that signal portion.
--Digital radios generally do not respond to audio tones in digital modes.
--Digital radios CAN have an analog mode that responds to audio tones, but that data typically is not carried over digital repeaters or base stations.

 

[dustinw251]

I guess my next question is, is there an efficient way to do signaling without having the quick call. That we could use to alert radios. Eventually i will simulcast vhf to use our pagers but i havent checked on pricing for that yet.


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[riveter]

Basic bottom line is that quik-call is a two-tone analog system that requires radios to decode precise audio frequencies for the two tones and decide they're the matching two tones to work.


The P25 digital waveform uses noise cancellation, error correction and vocoding that will slightly change the pitch of audio as it gets encoded and decoded at both ends (hence why voices sound a little different). If you ever hear patched two-tone paging over P25, you'll hear it's distorted by the vocoding and may warble or warp a little bit in pitch.

That warp is usually enough that a radio, even configured to trip to an audio tone decoded from p25, won't hear the correct pitch and won't alert.


And for your last question: are you looking specifically for signalling while operating P25? If so, then P25 over-the-air signalling is... well, that's exactly what's available. Group and individual paging is available via P25 and is transparent to the user: it's carried in the control channel stream on trunked systems or on data bursts in conventional P25 systems.

 

[902]

Actually, what happens with tones and noises is that the vocoder selected for P25 uses a table to correlate the sounds that are placed into it, then picks the symbol that most closely approximates the input and assigns a digital value for it. The early vocoders were designed for voice clarity. The tables more or less failed when something non-voice audio got into the vocoder. It did approximate the tones, but in most cases, the steady tone input sounded wobbly ("gollywobbles" - it's one of the definitions in Urban Dictionary, except it's not because of excessive BER, but because of the tables not having a way of reconstructing the sound exactly). It'll sound drunk, like wobbly siren noises or alert tones you might hear. So, two-tone paging in P25 just isn't going to work.

You want to go from 700 digital to VHF? Sounds retrograde, to me. You'd lose a lot of range, but then, you don't want people who are way out of position screaming down the roads. You'd also unnecessarily duplicate infrastructure and assume higher maintenance and operating costs. Budget for that.

Unication? You need to set up your system a special way to use those, and that might require special talkgroups just to be alerted.

Have you looked into the selective calling features for the radios?

Maybe the bigger question - Have you discussed your need with the radio system manager, or someone from the state who might have come up with a solution for user agencies with similar needs?

How do you get alerted right now?

 

[GTR8000]

So, two-tone paging in P25 just isn't going to work.

That is no longer true. The DVSI vocoder, in particular AMBE+2, has come a long way in the last decade.

The tones (both single frequency and DTMF) are detected and generated by the vocoder itself, rather than the vocoder incorrectly interpreting tones as "voice-like sounds".

The Tone Signaling feature (paging over P25) that Motorola has implemented in the APX series is quite robust and reliable. It functions well on both conventional and trunked P25, including over Phase II TDMA talkgroups. In fact, it functions better on TDMA due to tighter tone tolerances. Single tone, standard DTMF, and Knox format DTMF are all supported.

This has all been discussed here before, but I'm unable to find the thread where we posted the DVSI and Motorola documentation. In any case, it's no longer accurate to say "two-tone paging on P25 doesn't work". Quite the opposite, in some cases you achieve better results than you would on a noisy analog frequency.

 

[dustinw251]

That is no longer true. The DVSI vocoder, in particular AMBE+2, has come a long way in the last decade.



The tones (single tone and DTMF) are detected and generated by the vocoder itself, rather than the vocoder incorrectly interpreting tones as "voice-like sounds".



The Tone Signaling feature (paging over P25) that Motorola has implemented in the APX series is quite robust and reliable. It functions well on both conventional and trunked P25, including over Phase II TDMA talkgroups. In fact, it functions better on TDMA due to tighter tone tolerances. Single tone, standard DTMF, and Knox format DTMF are all supported.



This has all been discussed here before, but I'm unable to find the thread where we posted the DVSI and Motorola documentation. In any case, it's no longer accurate to say "two-tone paging on P25 doesn't work". Quite the opposite, in some cases you achieve better results than you would on a noisy analog frequency.

With that being said the xts and xtl series still do not support that though correct?


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[dustinw251]

Actually, what happens with tones and noises is that the vocoder selected for P25 uses a table to correlate the sounds that are placed into it, then picks the symbol that most closely approximates the input and assigns a digital value for it. The early vocoders were designed for voice clarity. The tables more or less failed when something non-voice audio got into the vocoder. It did approximate the tones, but in most cases, the steady tone input sounded wobbly ("gollywobbles" - it's one of the definitions in Urban Dictionary, except it's not because of excessive BER, but because of the tables not having a way of reconstructing the sound exactly). It'll sound drunk, like wobbly siren noises or alert tones you might hear. So, two-tone paging in P25 just isn't going to work.



You want to go from 700 digital to VHF? Sounds retrograde, to me. You'd lose a lot of range, but then, you don't want people who are way out of position screaming down the roads. You'd also unnecessarily duplicate infrastructure and assume higher maintenance and operating costs. Budget for that.



Unication? You need to set up your system a special way to use those, and that might require special talkgroups just to be alerted.



Have you looked into the selective calling features for the radios?



Maybe the bigger question - Have you discussed your need with the radio system manager, or someone from the state who might have come up with a solution for user agencies with similar needs?



How do you get alerted right now?

Right now our primary system is vhf conventional. The 700 LWIN system is our secondary system per say we just havent had the availability to alert from it so we normally use it for our BS channels more less.


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[GTR8000]

With that being said the xts and xtl series still do not support that though correct?

As I stated in post #4, only the APX series supports tone decoding over P25.

 

[dustinw251]

As I stated in post #4, only the APX series supports tone decoding over P25.

Thats fine then, I am ordering 4 of the 8000's this minth so at least incident command can use both systems without toting 2 radios. I will just have to keep the dept on vhf until we can possibly get another grant or the state does something different. I think ill have better odds with a grant than the state though .


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[GTR8000]

Make sure you order them with the QA09000 Digital Tone Signaling option. Last I checked it was around $110 per radio for that feature.

 

[902]

So much for moving away from two-tone to faster embedded signaling.

 

[GTR8000]

So much for moving away from two-tone to faster embedded signaling.

Sorry, but as much as I'm a fan of digital and all the fancy features that come with it, there is no easier and more efficient way to alert an entire group of radios than with good old fashioned two-tone paging.

Putting theoretical discussions aside, have you ever tried setting up call alert/page signaling on a P25 system in real life? It's cumbersome and quite limiting as compared to two-tone alerting. You have to setup lists of subscriber ID's you want as part of the group, and are often limited to just 100 subscribers per group. That doesn't work in a large volunteer organization where you may have 200+ members getting alerted.

So while digital embedded signaling sounds great on paper, in practice it's less than ideal when it comes to alerting large groups of radios simultaneously. In other words, two-tone paging (yes, even over P25) still has its advantages for Fire/EMS agencies.

Another factor to consider is that you can have trunked and conventional paging resources patched to get the best of both worlds. Consider our system, for example. ASTRO 25 TDMA system which has a permanent console patches that has Fire and EMS QCII alerts multicast over both the TDMA talkgroup and the conventional VHF/UHF resources. This allows the same tones to be used in both a Minitor pager as well as an APX subscriber, allowing for the greatest degree of flexibility.

Let's get back to reality, which is that not every agency can afford to purchase expensive digital subscribers for every member. Two-tone paging still very much has its place in the world.

Besides, it's just 4 seconds of tones, hardly an eternity. :wink:

 

[902]

Besides, it's just 4 seconds of tones, hardly an eternity. :wink:

Well... in my communications manager days, I deliberately shortened the B tone in the Model 25s because that confirmed structure fire usually took 45 seconds to alert every unit from every company and officers. If you were at the beginning of the stack, the stored voice would time out before the entire message could be recorded. I managed to shave it down some and hopefully step up the response by a few seconds.

Aside from money, our industry is measured in seconds. At some point, I'm sitting on the edge of my chair like, "Cripes! Where is it already?!" when we had that long train of tones. But then, a little further south of you, there are the "kingdoms of scripts."

"This is station KXX123, the radio station of the fire department of the Borough of Dogpile announcing an alarm of fire in the Borough of Dogpile, a signal 10-99 at..." rather than simply who, what, where, followed up by additional relevant information.

 

[krokus]

Sorry, but as much as I'm a fan of digital and all the fancy features that come with it, there is no easier and more efficient way to alert an entire group of radios than with good old fashioned two-tone paging.

Putting theoretical discussions aside, have you ever tried setting up call alert/page signaling on a P25 system in real life? It's cumbersome and quite limiting as compared to two-tone alerting. You have to setup lists of subscriber ID's you want as part of the group, and are often limited to just 100 subscribers per group. That doesn't work in a large volunteer organization where you may have 200+ members getting alerted.

With the Unication G4 & G5 pagers, you set up one new TalkGroup, that is just for alerting. (MPSCS is calling them a PageGroup, instead of a TalkGroup, as they are just for paging.) The pager alerts for any traffic on that PageGroup, and there can be many PageGroups in the pager.

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[krokus]

Well... in my communications manager days, I deliberately shortened the B tone in the Model 25s because that confirmed structure fire usually took 45 seconds to alert every unit from every company and officers...

Then there should have been group tones, say for whole stations, whole battalions, etc.

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[GTR8000]

With the Unication G4 & G5 pagers, you set up one new TalkGroup, that is just for alerting. (MPSCS is calling them a PageGroup, instead of a TalkGroup, as they are just for paging.) The pager alerts for any traffic on that PageGroup, and there can be many PageGroups in the pager.

I'm aware of how the Unication "alerts", and frankly, it's ridiculous. From a system admin standpoint, having to create a single FDMA talkgroup to mimic each traditional QCII group is a nightmare.

First of all, because the G4/G5 do not yet support TDMA, that means wasting system resources by forcing those talkgroups to FDMA. If you have limited RF resources, that can be a real issue.

Secondly, setting up consoles to steer dispatches to potentially dozens of trunked resources is nightmarish. So instead of steering tones to a single paging resources, now you've got to have dozens of trunked talkgroup resources on the console because each group requires its own FDMA talkgroup.

I won't even get into how cumbersome it is trying to patch these "alert" talkgroups to conventional resources, or how inefficient it is for users in the field to have to monitor/scan dozens of talkgroups if they want to hear dispatches for neighboring agencies, or the time wasted requiring dispatchers to switch between all of these resources when dispatching a large incident, etc.

The bottom line is that Unication should've figured out how to decode the tones over P25 like Motorola did with APX. It's all built right into the DVSI AMBE+2 vocoder, so it's not exactly some great mystery. :roll: