Firefighters distrust of digital radio system grows

[Samuel]

Steve-

I agree there are some upgrades that could be done but I don't think thats gonna happen this year with the financial situation the county is in. The point that I was trying to make is that while there are some changes that could be made overall it is a good radio system and the county didnt buy half a system so to speak as some jurisdictions (like DC) have nor did they just use the footprint of their old system. Believe me I agree with adding some things to improve coverage. My pet pieve is certain places in the mall. As for the "bonks"...I think we have plenty of frequencies its an operator issue that everyone on the same talkgroup is tryin to talk at the same time which regardless of training seems to happen when you have high stress incidents. As for the county stepping up and fixing it...they cant do that till they know its an issue and until this incident I had never talked to anyone on our fire side that had any real complaints about the system. The line staff may know where the dead spots are but if no one calls OIT and tells them then they cant fix it. I think there has been a lot of complaining to each other instead of OIT. I know on the police side this is the case ;-). Keep in mind that the dispatcher heard Kyle's mayday call...his radio got out. So while its certainly a tragedy it is factually incorrect to say he died because of a faulty communications system.

DISCLAIMER: I am in no way associated with the management of the system. I only use it.

 

[HogDriver]

I'm sorry to say that it apperars that the digital systems are still really in the testing stage even though many departments have made them fully operational without any analog backup...at the public safety officials endangerment. I hope that this becomes widespread and serves as a wakeup call to the 'ill-enformed' officials that have purchased these systems.

 

[wendallb]

Our county is talking about digital radios which would put our department in the mix and we are in the country. This could be disaster waiting to happen. Thanks for the report.

 

[SABRE46]

Happy to say that we are on VHF analog with no plans to go to any sort of trunked system. Works like a charm

 

[SLWilson]

It Might Not....

Our county is talking about digital radios which would put our department in the mix and we are in the country. This could be disaster waiting to happen. Thanks for the report.

I say again, it MIGHT NOT be a disaster IF it is done correctly so your system has STREET LEVEL COVERAGE on the trunked system OR if you use an 800Mhz ON SCENE FIREGROUND frequency that everyone can go to once there.

But even with that, I'd di some basement testing, building PENETRATION testing etc BEFORE I gave up what is working now!

Steve/KB8FAR

 

[LouisvilleScanMan]

From the article...

"But Chris Lougee, vice president with LMR vendor Icom America added that, scientifically speaking, digital signals penetrate buildings better than analog signals. "I'm puzzled by that problem," he said. "All of our testing shows that a digital signal produces a higher-quality signal in noise conditions than an analog signal."

The fact that thier scientific calculations and tests and the real world performance of the radios are vary different tells me that they do not know enough about this technology to be throwing to out left and right to public safety agencies as a "communications cure all" . Doing so is irresponsable and dangerous.

"In most cases, it is a very political and sensitive position to abandon expensive technology and go back to something that is old," said Daryl Jones, owner and president of Telecommunications Engineering Associates, which manages public safety systems throughout the San Mateo area in California."

Save face or save lives, hmm tough decision.

"The perception of quality of communications in my opinion is much lower on trunked radio systems because it's always based on a comparison of what an agency had before," Jones said. "If they are coming off an analog system that provided 100% coverage and go to a digital trunked system that has different characteristics and less coverage, it's going to be worse."

IT IS WORSE!!! If you are using a system (analog or otherwise) that works fine and switch to a system that has the problems and flaws that P25 does then it's not just in opinion but is IN FACT worse.

"However, others say the problems have to do with training, as digital systems operate differently than analog. For instance, digital systems require key-up time, forcing first responders to hold down the transmission key longer before they can begin talking. "It's a long and arduous process to educate police and firemen to change the way they have always communicated," Jones said."

That's right, just pass the buck.

 

[chrismol1]

Why did these companies just release these radios without a lot of real world tests? I mean geeze, they should know that the top systems are being purchased by town and governments that have money to spend on these and that they are used in emergency applications. If only they could figure it out before releasing or make the analog system better some how.

 

[SABRE46]

Because we live in a world now that just assumes everything will be ok when the exact opposite is true. This includes people that put products in the market that just assume they will work good enough. These are the same people that have never been on a fire scene or crime scene and have no idea what kind of havoc is going on or what that havoc does to disrupt communications...

 

[SLWilson]

Again....

Why did these companies just release these radios without a lot of real world tests? I mean geeze, they should know that the top systems are being purchased by town and governments that have money to spend on these and that they are used in emergency applications. If only they could figure it out before releasing or make the analog system better some how.

That is the whole issue.....

From the standpoint of an Amateur Radio operator, using the "radio theroy of operation" common sense should tell EVERYONE this simple thing.

That is, when you go UP in frequency (most have moved completely away from low band which has the BEST building penetration you'll EVER get) first to VHF which gives you slightly less penetration.

Then, take UHF. If you look at the power levels on low band, vhf hi band and UHF you'll see that they KEEP DROPPING the power output of the mobiles and portables.

When you het to 800 Mhz, even LOWER power levels, and SHORTER antennas.

Why would anyone with good common sense make a statement that "digital" on 800Mhz penetrates better than VHF Lo/Hi bands?

Our county sheriff uses a VHF Hi band and a repeater system. They have in-car "mobile radio extenders" that are UHF. As long as they are "in the open" they get decent range away from their cruiser from this setip. But, the minute they go into a concrete building (like the emergency room at our hospital) they have no use of the MRE's....

So, just imagine using an 800Mhz MRE how much their range would be cut!

Lastly, I'll say that IF you build enough frequencies into your 800Mhz trunked system, place the towers in such a way that gives you street level coverage, EVERYWHERE you need to go, it will be OK....

But, then again, I'm NOT an engineer. I've just been using VHF Low and hi band systems since 1978. UHF since the mid 90's and have seen first hand how they all operate!

Now, I'm using 800Mhz trunked radio and see how it works. Built correctly, it IS OK.....

Steve/KB8FAR

 

[redneckfireman]

redneckfireman

its a shame the feds are pushing all this digital trunked junk, they are pushing on louisiana as well, even though they should have learned after the 2 big hurricanes hit louisana & flooded everything and all the phone systems were out this junk will not work in times most needed our fire chief is fighting this stupid crap they are trying to do

 

[richardc63]

From the article...

"But Chris Lougee, vice president with LMR vendor Icom America added that, scientifically speaking, digital signals penetrate buildings better than analog signals. "I'm puzzled by that problem," he said. "All of our testing shows that a digital signal produces a higher-quality signal in noise conditions than an analog signal."

The fact that thier scientific calculations and tests and the real world performance of the radios are vary different tells me that they do not know enough about this technology to be throwing to out left and right to public safety agencies as a "communications cure all" . Doing so is irresponsable and dangerous.

"In most cases, it is a very political and sensitive position to abandon expensive technology and go back to something that is old," said Daryl Jones, owner and president of Telecommunications Engineering Associates, which manages public safety systems throughout the San Mateo area in California."

Save face or save lives, hmm tough decision.

"The perception of quality of communications in my opinion is much lower on trunked radio systems because it's always based on a comparison of what an agency had before," Jones said. "If they are coming off an analog system that provided 100% coverage and go to a digital trunked system that has different characteristics and less coverage, it's going to be worse."

IT IS WORSE!!! If you are using a system (analog or otherwise) that works fine and switch to a system that has the problems and flaws that P25 does then it's not just in opinion but is IN FACT worse.

"However, others say the problems have to do with training, as digital systems operate differently than analog. For instance, digital systems require key-up time, forcing first responders to hold down the transmission key longer before they can begin talking. "It's a long and arduous process to educate police and firemen to change the way they have always communicated," Jones said."

That's right, just pass the buck.

I'm sorry but there is no "one answer is correct" to this debate. There are that many factors impacting radio communications in confined spaces that no-one can say with any authority that digital or analogue radio will be better than the other.

Prior to the last APEC Conference in Sydney I was tasked to test radio coverage in certain interior locations where the heavy hitters like President Bush would be attending. One of these was the Sydney Opera House. Using a handheld on the government's Smartzone/ASTRO system I tested comms using first an analogue talkgroup, and then a digital talkgroup from a variety of locations within the building. The base end was using a common aerial on the top of a building some 1-2km away. Quite simply the DIGITAL talkgroup FAR out-performed the analogue to the point where in one location I had unusable analogue comms but 100% digital comms. The difference blew the firefighters I had with me away...

Another benefit of digital is acoustic feedback when operating analogue simplex- try putting two radios next to each other using analogue FM and then try it using C4FM the same way. This has been our firefighters' biggest complaint for eons- and using C4FM fixes it.

Ambient noise has always been an issue & always will be an issue. Deal with the noise problem first... voice transducer technology still has a way to go.

That's my experience.

Cheers,


Richard

 

[loumaag]

its a shame the feds are pushing all this digital trunked junk, they are pushing on louisiana as well, even though they should have learned after the 2 big hurricanes hit louisana & flooded everything and all the phone systems were out this junk will not work in times most needed our fire chief is fighting this stupid crap they are trying to do

<rant>
The "feds" are not pushing "digital trunked junk". They are pushing P25 digital, they don't care if it is trunked or VHF/UHF/800, and the reason they are pushing is so that Joe Blow from department A can talk to Sam Sham from department B on the same type of radio no matter who sold it to the department. Of course they have to have a common channel, but that goes without saying. Your fire chief needs to stick to fighting fires, because he (and you) apparently don't have a lot of communication electronics skills. </rant>

I have seen a lot of nonsense posted in this thread along with some thoughtful posts.

Yes, it would seem that Motorola should do some fixing on their radios, background noise should indeed be filtered out, but maybe that has a lot to do with the previous insistence of the users that microphones be more sensitive so a user can talk from a foot away (stupid and lazy). I am also a firm believer that fire ground (indeed any tactical situation) channels should never be part of trunked system or rely on a repeater that is more than a couple of blocks away. A mobile repeater in a communications command vehicle on the scene (with an appropriately raised antenna) is the solution for that; failing that solution, stick with simplex operations. Coverage for simplex is simple, a 5 watt radio should be able to cover any fire scene (other than large outdoor ones); yes, it may not be able to be heard by scanners miles away, but really that is not what we are talking about in this thread.

Digital/analog arguments are not the same thing. Since obviously several vendors (read all but one) don't have problem dealing with background noise in a fire environment, then really digital would be a better choice. Why? Because it is indeed better, clearer, and either works or doesn't. Analog gives the illusion it works better because you can hear it "disappear" into the background noise level; however, the digital signal is still 100% readable when the same frequency/power level analog signal is lost in the noise.

Think about this for a moment, it was not too many years ago that fire fighters going into a fire didn't have a radio with them at all. And yes, I think that real world testing is important but I also believe that progress is necessary and budgets are a reality that everyone has to live with.

 

[AZScanner]

Good thread. Recently the Phoenix Fire Department also had concerns about our new radio system and set out to do some testing of their own. Here's an excerpt from their tests:

Testing
Testing was developed to determine if the application of this technology was
appropriate. The testing was performed over an eight-week period. The testing provided
an opportunity to test alternatives to the trunked radio system. Testing was performed
using the Trunked Radio System, 700/800 MHz Analog Simplex, 700/800 MHz Digital
Simplex and VHF Simplex radios. The tests were conducted in 30 buildings that
consisted of the five different NFPA construction types. Approximately 1,500 talk paths
were tested. The same test participants were used throughout the testing to provide
consistency in the grading process. Results of the tests showed an overwhelming
preference for analog (versus digital) modulation. Performance differences between the
frequency bands were negligible in the analog mode. Digital modulation and Trunked
Radios had a higher failure rate and the audio quality scored below the ratings in analog
mode.

But wait, there's more:

During the testing process, NIST (National Institute of Standards and Technology)
became aware of the Phoenix Fire Department testing and asked to participate. A team
from NIST spent a week doing radio signal measurements and determined that
predicting in-building coverage is a difficult proposition. The NIST measurements
showed large signal variations, often greater than a factor of two over the limited
distance of a single floor in the structure. This information contradicts vendor claims that
buildings within certain geographical areas should have specific decibel strengths in
order to have adequate in-building communication.

Wow... no foolin. Whodathunkit?

Trunked radio systems have factors that negatively affect safety issues related directly to firefighting operations. These factors are:
1. Repeated System -The radio must be in contact with the system infrastructure
to complete communications with any other radio. This causes radio&#8217;s operating
in some buildings to lose communication with command and crews operating on
the emergency scene.
2. In-Building Coverage -The system infrastructure provides varying levels of inbuilding
coverage and does not provide coverage in all buildings.
3. In-Building Treatment- Buildings that do not have interior coverage must be
identified and have communications equipment installed. The cost of identifying
and treating all affected buildings is cost prohibitive. Also, while this equipment
provides communications in a normal environment it may not survive the hightemperatures during a fire.
4. System Delays - The trunked system has inherent system delays (0.5 &#8211;
1.0seconds) that are required to allocate system resources to make a radio call.
These delays are not tolerable in some time sensitive operations for public
safety.
5. System Failure Modes - The system has modes of failure that allow users to
communicate but may isolate users operating on a single talk-group from one
another during emergency operations.
6. System Capacity - The system does not have the same call handling capacity
system wide. In addition, other system users creating high traffic loads may
cause the system to become overloaded and give busy signals to firefighters
and police officers operating on the emergency scene.
7. Radio Equipment -The Project 25 radios are complex and utilize software to
interact with system infrastructure. Different versions of software have caused
inconsistency in radio performance.

Now here's where the rubber meets the road:

Based on testing conducted in buildings within Phoenix, and the experiences of other fire departments, we recommend the use of 700 or 800 MHz simplex channels with analog modulation specifically for firefighting during hot zone operations. Simplex channels provide incident commanders and firefighters a safe and consistent communications system that is not dependent on infrastructure in order to speak to other units on the incident. A network of receivers and transmitters will be needed to provide the wide-area component of the simplex system necessary to allow the communications center to communicate with field users. The Computer Aided Dispatch system will assign the appropriate type of channel based on the incident type. It is recommended that the trunked radio system be used on incidents and for tasks (such as Dispatch, EMS, Command Structure Expansion & Logistical Coordination) that are lower-risk and appropriate for this type of system.

There you have it. Analog simplex. The report did go on to state that in very low signal situations 700 MHz digital outperformed analog but the test users still preferred the 700Mhz analog signal and it performed best overall. It's also interesting to note, for the naysayers in the group who claim firemen should stick to fighting fires, that these tests were not conducted and measured with fancy service monitors and portable laptops spewing graphs and propagation computations but rather they were conducted by real people who actually stood in the parts of the building where a firefighter would go, with a portable radio in hand, and the results were measured by the human ear which is where it counts. This is exactly the sort of testing I'd expect from a firefighter. "I don't care what the goddamned salesman and/or radio wizard says, I want to hear it for myself!" Good for PFD - glad to see at least someone in city government still has a brain.

Feel free to read the full PFD report: http://phoenix.gov/FIRE/radioreport.pdf It's rather enlightening and poses some serious questions as to whether we really needed this digital radio system or not.

-AZ

 

[richardc63]

<rant>
The "feds" are not pushing "digital trunked junk". They are pushing P25 digital, they don't care if it is trunked or VHF/UHF/800, and the reason they are pushing is so that Joe Blow from department A can talk to Sam Sham from department B on the same type of radio no matter who sold it to the department. Of course they have to have a common channel, but that goes without saying. Your fire chief needs to stick to fighting fires, because he (and you) apparently don't have a lot of communication electronics skills. </rant>

I have seen a lot of nonsense posted in this thread along with some thoughtful posts.

Yes, it would seem that Motorola should do some fixing on their radios, background noise should indeed be filtered out, but maybe that has a lot to do with the previous insistence of the users that microphones be more sensitive so a user can talk from a foot away (stupid and lazy). I am also a firm believer that fire ground (indeed any tactical situation) channels should never be part of trunked system or rely on a repeater that is more than a couple of blocks away. A mobile repeater in a communications command vehicle on the scene (with an appropriately raised antenna) is the solution for that; failing that solution, stick with simplex operations. Coverage for simplex is simple, a 5 watt radio should be able to cover any fire scene (other than large outdoor ones); yes, it may not be able to be heard by scanners miles away, but really that is not what we are talking about in this thread.

Digital/analog arguments are not the same thing. Since obviously several vendors (read all but one) don't have problem dealing with background noise in a fire environment, then really digital would be a better choice. Why? Because it is indeed better, clearer, and either works or doesn't. Analog gives the illusion it works better because you can hear it "disappear" into the background noise level; however, the digital signal is still 100% readable when the same frequency/power level analog signal is lost in the noise.

Think about this for a moment, it was not too many years ago that fire fighters going into a fire didn't have a radio with them at all. And yes, I think that real world testing is important but I also believe that progress is necessary and budgets are a reality that everyone has to live with.

Hi Lou,

Very well said. Unfortunately the very same people who write off any differing view as the opinions of idiots (refer to a number in this thread), they are the very ones who have shut their minds and would refer to play Dueling Reports. Heck, I can find a report that would justify just about anything- doesn't make them right. If people want to form a view do what I do- TEST. We can't test every scenario (almost) but this irrational opposition to digital modulation does the industry no good whatsoever.

Regards,


Richard

 

[RadioMarkW]

Hi Lou,

Very well said. Unfortunately the very same people who write off any differing view as the opinions of idiots (refer to a number in this thread), they are the very ones who have shut their minds and would refer to play Dueling Reports. Heck, I can find a report that would justify just about anything- doesn't make them right. If people want to form a view do what I do- TEST. We can't test every scenario (almost) but this irrational opposition to digital modulation does the industry no good whatsoever.

Regards,


Richard

You state Dueling reports, it seems to me that the vast MAJORITY have found problems with digital modulation at fireground sights. They were well documented and hardly seem IRRATIONAL! Did YOU even bother to read them or were YOU "irrationally apposed" to any of "Their Tests"?!?!??!

And your comment about " doing the INDUSTRY" no good, what about the firefighters having to use these radios. Sounds like you do not care a whit for them. They are the ones putting their LIVES on the line, NOT the radio Techs. !!!!!!!!!!

This is a big issue and you are not the only one making interesting comments, my favorite by far is anouther "Radio Tech." who states "If they are coming off an analog system that provided 100% coverage and go to a digital trunked system that has different characteristics and less coverage, it's going to be worse."

Well I would say when going from ANY kind of system that currently provides 100% coverage to one that does not, any SANE person will indeed name the new system inferior.

Oh, and I DO support digital technology, when it works it is phenomenal and has GREAT potential. It just is NOT the answer to EVERYTHING!!!!!!

Oh well, so much for my "Irrational Rant".

Regards,

 

[Smerri]

The article is itself is a year old.....

The article itself is less than a week old.

Anything beneficial to contribute?

 

[Samuel]

Just a thought but since every one is talking about personell safety....One reason some departments with trunked systems are hesitant to use a simplex channel for their tac ops is that you loose your emergency button function. I think that if you use a VRS then you may be able to still have it but I am not sure.

 

[AZScanner]

Dueling reports. I like that.

Let's bottom line it. You're a firefighter and you've just arrived at a burning building. You are handed a digital radio that works in-building about 70% of the time. You still wanna go in and fight the fire? Me neither. And those are pretty good odds from a gambling perspective. But when you're talking about whether or not you go home to your family at the end of your shift, those odds are no where near good enough. Being a firefighter is dangerous enough - we don't need to up the ante by giving them crap radios that don't work.

And I'm aghast that some people in this thread have actually argued "well firefighters didn't always have radios inside burning buildings". They didn't always have breathing apparatus and firehoses either! Should we go back to the days of a wet rag over your mouth and a bucket in your hand? Of course not. Neither should we expect that our firefighters, who have come to rely on the ability to effectively use in-building fireground communications, should now be asked to use a tool that has been proven in the field to be ineffective and could potentially lead to the loss of life. They have rightly decided that until these problems are addressed & corrected they will remain on VHF analog where the risks of communications loss are substantially lower.

Understand this: This report wasn't compiled by a bunch of railfoaming scannerheads screaming "They took away are scannerz!" It was compiled by a major metro fire department, folks. I think it's a safe bet that they know more about fireground communications than a bunch of armchair quarterbacking radio enthusiasts don't you?

Heck, I can find a report that would justify just about anything- doesn't make them right.

Sigh.. or not.

-AZ

 

[Jay911]

I'm both a radio enthusiast and a firefighter, and I have no problem saying that regardless of whatever studies can be/have been done that say digital is better/just as good/irrelevant compared to analog, my experiences lead me to demand analog simplex as my link to the outside world when I'm in a life-hazard situation. Seventy percent might be a good gambling rate, as AZscanner says, but professionals designing radio systems mandate 99.995% or higher in most cases. I've seen proposals/requirements for systems that must maintain 99.995% channel access/grant on portable radios regardless of their location, from standing still to speeds of up to 200kph (~120mph).

As mentioned, 700/800MHz signals have poorer penetration characteristics (into buildings et al) compared to lower frequencies. Low band UHF never caught on in any of the areas I've lived or visited, so I can't compare that to anything, but I do know I can get VHF "high" signals 10x better than I can get UHF (400) signals, which are again 5-10x better than 800MHz signals, at least in my area. What I'm trying to say is that I'm not one to try to muddle the analog vs. digital argument in with the issue of different bands having more power/strength inherently. However, on the same system, using the same 800MHz frequencies, I can routinely very clearly hear analog comms in "fringe" areas where ASTRO IMBE comms end up having at least 40% dropouts and missed phrases/sentences/conversations. This can be paralleled with a firefighter inside a building, as that becomes a "fringe" area of its own on most systems, where adequate redundancy and overlap in terms of tower signal has not been accomplished.

This whole thing should be as simple as can be: Conventional simplex involves firefighter A shouting "help me" into his radio. It is transmitted, regardless of the modulation or other audio properties, to all those around him, including firefighter B in the command post, who is able to get him help. Trunked or repeatered signals involve firefighter A shouting "help me" into his radio, which then has to transmit the signal to a repeater/tower any number of miles away, where the signal is then retransmitted to an output frequency, and transmitted over a wide area. It may or may not reach the command post and firefighter B, especially if a tall building is blocking the CP's "sight" of the repeater/tower, etc. Furthermore, if the signal coming from the tower is weak or interrupted/blocked, the modulation/audio properties may prevent it from being heard at all.
Which situation sounds simpler? Which situation do you think I and my brothers and sisters would prefer to be in?

 

[SLWilson]

Well Said!

I'm both a radio enthusiast and a firefighter, and I have no problem saying that regardless of whatever studies can be/have been done that say digital is better/just as good/irrelevant compared to analog, my experiences lead me to demand analog simplex as my link to the outside world when I'm in a life-hazard situation. Seventy percent might be a good gambling rate, as AZscanner says, but professionals designing radio systems mandate 99.995% or higher in most cases. I've seen proposals/requirements for systems that must maintain 99.995% channel access/grant on portable radios regardless of their location, from standing still to speeds of up to 200kph (~120mph).

As mentioned, 700/800MHz signals have poorer penetration characteristics (into buildings et al) compared to lower frequencies. Low band UHF never caught on in any of the areas I've lived or visited, so I can't compare that to anything, but I do know I can get VHF "high" signals 10x better than I can get UHF (400) signals, which are again 5-10x better than 800MHz signals, at least in my area. What I'm trying to say is that I'm not one to try to muddle the analog vs. digital argument in with the issue of different bands having more power/strength inherently. However, on the same system, using the same 800MHz frequencies, I can routinely very clearly hear analog comms in "fringe" areas where ASTRO IMBE comms end up having at least 40% dropouts and missed phrases/sentences/conversations. This can be paralleled with a firefighter inside a building, as that becomes a "fringe" area of its own on most systems, where adequate redundancy and overlap in terms of tower signal has not been accomplished.

This whole thing should be as simple as can be: Conventional simplex involves firefighter A shouting "help me" into his radio. It is transmitted, regardless of the modulation or other audio properties, to all those around him, including firefighter B in the command post, who is able to get him help. Trunked or repeatered signals involve firefighter A shouting "help me" into his radio, which then has to transmit the signal to a repeater/tower any number of miles away, where the signal is then retransmitted to an output frequency, and transmitted over a wide area. It may or may not reach the command post and firefighter B, especially if a tall building is blocking the CP's "sight" of the repeater/tower, etc. Furthermore, if the signal coming from the tower is weak or interrupted/blocked, the modulation/audio properties may prevent it from being heard at all.
Which situation sounds simpler? Which situation do you think I and my brothers and sisters would prefer to be in?

You stated that very well!
Steve/Gallia 911