Washington, D.C. - Big city fire depts balk at new digital radios
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Before jumping on the "Blame Motorola" bandwagon, it sounds like there are many variables about this incident we don't know.
By far, the biggest question is...why were they on a trunked system for fireground operations ? That's not Motorola's fault.
We also don't know how the trunked system is setup, locations of sites, known dead spots...etc.
If the system was put in by Harris or EFJ, would everyone be quick to blame them ?
It sounds like to me, Motorola is not the culprit here. Suing them is not the proper way to go about this. I would first look at the policies and protocols of that agency about fireground operations.
If you want to sue someone, how about going after DVSI. They invented the vocoder P25 uses, the heart of making P25 work. Although I think that'd be a bit silly, since you check out P25 on the ole Wiki at Project 25 - Wikipedia, the free encyclopedia looks like it has the "thumbs up" from all these boards and associations who call the shots for public safety ?
By far, the biggest question is...why were they on a trunked system for fireground operations ? That's not Motorola's fault.
We also don't know how the trunked system is setup, locations of sites, known dead spots...etc.
If the system was put in by Harris or EFJ, would everyone be quick to blame them ?
It sounds like to me, Motorola is not the culprit here. Suing them is not the proper way to go about this. I would first look at the policies and protocols of that agency about fireground operations.
If you want to sue someone, how about going after DVSI. They invented the vocoder P25 uses, the heart of making P25 work. Although I think that'd be a bit silly, since you check out P25 on the ole Wiki at Project 25 - Wikipedia, the free encyclopedia looks like it has the "thumbs up" from all these boards and associations who call the shots for public safety ?
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My point was/is, that the digtial voice you are hearing is beyond that the squelch fade already.... The error correction and technology allows voice recovery slightly beyond that squeclch fade. This is the same reason why you can decode a MDC1200 packet on an analog system but cannot hear the voice thru the static. The digital packet can still work (slightly or better) than the voice will carry.
I am very familar with the CSP system. Its still by far much better than the low band system where troopers were talking to Texas DPS to get wreckers when they were only 5mi from the barracks...or when they had to put the car radio repeat on to hear radio transmissions on car stops as the extenders didn't work half the time..thats if the car radio heard the troop at all..
PJH, I concur with your statements completely. As a matter of fact, IMHO I believe that the error correction is so good that the people designing the systems are stretching the wide area coverage per site, FAR beyond what would have been acceptable for analog signal coverage. Correct me if I'm wrong, the higher the frequency, (generally) more sites would be needed to cover the same area with analog right? Therefore with digital, less infrastructure = lower system cost. Bottom line, lower bids gets "your foot in the door so to speak."
There are other issues related to digital clarity. Specifically, the decoder. It's well documented that the APCO25 Phase I has it's issues decoding high ambient noise with voice. Supposedly APCO25 Phase II is going to fix that. (We'll see).
However, I can tell you that I've used non-APCO25 Motorola digital radios and with 1 watt of power and have had better coverage and in building penetration @ 900 Mhz than with 4 Watts analog @ 460 Mhz. The digital worked far better than the analog in every case. Vertically and horizontally.
Not sure which digital encoder they used in these radios, (DTR-550) but there were no issues with high ambient noise levels either.
I used to be one that didn't want anything to do with digital radios. But now I know that the problem isn't just that the radios are digital. The specific problems are system design (signal levels at the receiver), the type of digital encoding used and cancelling out the noise before it is fed into the encoder.
And that doesn't take into account the proper training and radio discipline of the end users. That's a whole different subject.
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I would be curious to know what systems these agencies worked on before they jumped to a P-25 trunked radio system and what kind of training subscribers used when they were issued their new equipment. A trunking system functions completely different to a simplex system- a repeater for that matter is much different than simplex.
For regular fireground comms- whether they are digital or analog- we should be switching over to simplex tactical channels. Too many times I have seen end users frustrated that they could not talk to someone 100 yards away on the radio because they don't realize they are trying to bounce their signal off of a repeater 25 miles away!
As far as I am concerned, many of the issues brought up in this article are simply failure to plan and sufficiently train personnel on comms use.
For regular fireground comms- whether they are digital or analog- we should be switching over to simplex tactical channels. Too many times I have seen end users frustrated that they could not talk to someone 100 yards away on the radio because they don't realize they are trying to bounce their signal off of a repeater 25 miles away!
As far as I am concerned, many of the issues brought up in this article are simply failure to plan and sufficiently train personnel on comms use.
I prefer simplex on the incident scene as well. However, all mechanical/electronic devices have their operational limits. Let's say in a hi-rise scenario when you need to talk to someone on the 78th floor from the lobby, the operational limits of any portable radio analog or digital have do doubt been exceeded in the simplex mode.
We were operating at an incident the other day where the crews were 20+ floors up, the system repeater was not within range, and the lobby control couldn't talk to the guys on the 22nd floor on simplex. I was standing in the street at the command post and could hear both of them fine. Sometimes you just have to resort to the "human" repeater to get the message through. But to expand on that scenario, the crews in the building were unknowingly talking over each other at times. Using analog as we were, I was able to get some bits and pieces of each message. I wonder if in that same scenario using digital, would the signals just cancel each other completely or would something actually get through. Even in a scenario like this, busy transmit inhibit wouldn't have helped.
And I also heard that the new P25 Phase II standard was being held up because of some problem with simplex (direct) communications. From what I gather the TDMA doesn't work that way.
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To answer some questions...
The codec for standard P25 simplex, conventional, Motorola SmartZone and Phase 1 systems is the same. Its all IMBE. Phase 2, Motorola TRBO and Opensky uses the AMBE codec. Both developed by DVSI. ProVoice uses IMBE, but with a little different implementation which makes it incompatible with the P25 standard, and is not sold as a P25 compliant radio.
Phase 2 is complete. Its being rolled out in PG County right now. The current R6 firmware for the APX radios brings them up to Phase 2 compliance IIRC. Previously Motorola was rolling this out as a pre-Phase 2 system, but now it should be Phase 2 compliant IIRC. I haven't kept up on it.
There really isnt any additional user training needed for trunked users unless they have implented advanced features. To the user, its still press button and talk. Nothing special at all. The analogy for trunked vs repeater vs simlex doesn't really apply, and isn't that complicated. A trunked system just assignes a repeater to a talkgroup per request....almost no different than say a PL steered community repeater if you want to think if it that way.
Again, unless using advanced features such as private call or dynamic regrouping etc...press, talk, listen.
The codec for standard P25 simplex, conventional, Motorola SmartZone and Phase 1 systems is the same. Its all IMBE. Phase 2, Motorola TRBO and Opensky uses the AMBE codec. Both developed by DVSI. ProVoice uses IMBE, but with a little different implementation which makes it incompatible with the P25 standard, and is not sold as a P25 compliant radio.
Phase 2 is complete. Its being rolled out in PG County right now. The current R6 firmware for the APX radios brings them up to Phase 2 compliance IIRC. Previously Motorola was rolling this out as a pre-Phase 2 system, but now it should be Phase 2 compliant IIRC. I haven't kept up on it.
There really isnt any additional user training needed for trunked users unless they have implented advanced features. To the user, its still press button and talk. Nothing special at all. The analogy for trunked vs repeater vs simlex doesn't really apply, and isn't that complicated. A trunked system just assignes a repeater to a talkgroup per request....almost no different than say a PL steered community repeater if you want to think if it that way.
Again, unless using advanced features such as private call or dynamic regrouping etc...press, talk, listen.
Right. Assuming that you are not using the radio in simplex mode. And as for the codec, I thought that due to the narrower bandwidth of TDMA vs FDMA it was encoding at a different (lower) rate to facilitate the change. Is that not correct? I know that in other applications, the lower rate encoded, the worse the audio gets.
Interesting info on the DVSI Site: DVSI Products VC-55™
fwoodruff
Member
digital radio
digital radio is garbage compared to analog,as far as that goes digital tv on antenna is garbage compared
to analog when it rains the reception takes a dump,police and fire do not need nor do they need a radio system that they can not trust and digital can not be trusted,analog is the best way to go,but the goverment
is pushing this down every ones throat,I just wonder who is getting paid off,they should have left the analog tv alone it was fine,but they have to make every one go digital,digital radio is junk,digital tv is junk,they know it.
digital radio is garbage compared to analog,as far as that goes digital tv on antenna is garbage compared
to analog when it rains the reception takes a dump,police and fire do not need nor do they need a radio system that they can not trust and digital can not be trusted,analog is the best way to go,but the goverment
is pushing this down every ones throat,I just wonder who is getting paid off,they should have left the analog tv alone it was fine,but they have to make every one go digital,digital radio is junk,digital tv is junk,they know it.
lol wut????
System engineering is a huge component of this problem. I operate a mixed-mode 800 MHz public safety trunked system. When my jurisdiction went from UHF to 800, we tripled the number of repeater sites initially, and added as required to get suitable coverage. Too often, I've seen agencies who just replace what they have without looking to see what the effects of the band shift will be for coverage. Today, we have fire agencies who use analog talkgroups for fireground comms, agencies who use digital talkgroups for fireground comms, and agencies who use analog simplex off the system. As the system operators, we don't dictate to the users how to handle their fireground operations. We let them decide what works for them, and support them by programming their radios to meet their needs.
IF anything, a major technical component of the Phase 1 digital issue is that none of the P25 trunked equipment manufacturers originally made it possible for the technician to properly set mic gain in the mobiles and portables. Out of the box these radios are set up with so much amplification that an officer in a patrol car can reach over to the mic on the dashboard, push the PTT without picking up the mic from the clip, and in a normal level of voice speak and be heard quite well by all listening to the transmission. [This, of course, is amusing when the officer has a K-9 partner who gets chatty while the officer has the radio keyed, and everyone has to ask for repeats because the dog is louder than the officer.] As a result, when the officer is standing on a roof under an orbiting helicopter, or the firefighter is wearing a mask or using a power saw, the background noise is often as loud as the voice of the radio user.
After pointing this out to some manufacturers we are now starting to play with improved mic gain levels, better vocoders (such as AMBE), and radios with improved noise cancellation techniques. So far, my technicians (and users) are pleased with the improvements - but there is still work to do.
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