Interoperability from the Car or Regional Dispatch Center

[tomasG]

The thread on whether or not CHP should go to trunking has sparked some excellent debate! Rather than add this in that thread I thought that a new topic was more appropriate.

Should interoperability be done at the patrol car level, at the regional dispatch center level, or both?

I actually believe that it should be done at both levels. My reasons for this are numerous, but first and foremost, officer safety. I believe especially after many spirited debates with my father who works for CHP that the patrol car radios need to be simple. Although the new breed of cop is computer savvy the new integrated system really seems to be a hauge-pauge of crap tossed together. It presents a major complexity for the officer and tecnical support nightmare. An officer should be able to operate the system with one hand while in a pitched gun battle in the middle of nowhere.

I believe that limited direct communications should be available from the patrol car and the hand-held. Instead of 700/800MHz hand-helds I believe that they should be P25 VHF trunking and that the CHP radio system should migrate to VHF. By using a trunked system talkgroups may be preconfigured at the RCC for the expressed purpose of communication with agency XYZ. The officer just changes the channel on his HT or mobile. Conventional channels like CLEMARS, NALMARS, and CALCORD would still be on the HT and mobile.

On-scene communications are done via HT and not inside the car and this is one key reason that I think that the proposed rats nest of interconnected junk in the trunk is ill-advised. When a CHP officer is on duty his primary mission is traffic enforcement and not building security. The rationale that I have read regarding CHP selecting 700/800MHz radios doesn't hold water since even Security Services Division is on UHF. The argument has been made that 800MHz radios have better building penetration and this is not entirely the case. Studies have shown that considering all factors VHF has a 20% edge over UHF and 800MHz primarily because of path loss. The occasional call to a DMV office for an arrest does not justify using 700/800MHz HT's. I have never seen a DMV office that is massive in size and to the extent that talking in and out on VHF doesn't work. Considering also that the vast majority of CHP's work is either in the three metro areas of California but far, far more in back country and roads less traveled, who is Chuck the Chippie gonna talk to? The CHP RCC needs to be built to hear Chuck and Chuck should be able to talk to XYZ just by selecting a channel. No Captain or above should be required to approve a patch as is the case in Los Angeles.

When building a communications network the given standard is a minimum is -40dBm signal strength. Most law enforcement systems are designed for HT operation by default. A 5-watt VHF HT can easily access a mountaintop repeater with ease. Hams do it daily. Should CHP go to a P25 VHF trunked system this would be accomplished with half the number of radio sites needed for an 800MHz system. Because the infrastructure would already be in place talkgroup patches to allied agencies could be accomplished without the patrol car being required as a relay. There can be many what-if's, but what if the CHP cruiser has gone over the side and the car is DOA? If all of the eggs are in one basket how then will Chuck the Chippie call for help?

This is just my take on it and I look forward to hearing yours.

 

[northzone]

When building a communications network the given standard is a minimum is -40dBm signal strength. Most law enforcement systems are designed for HT operation

-40dBm is a very strong signal (2,240 uv ), not a realist design parameter for a com system. The given minimum standard when building a communications network actually is -90dBm ( 7uv) . This allows for such things as building loss, portable antenna loss, etc. This is called the 95/95 rule, 95% coverage, 95% of the time. This is defined in APCO TSB-88 if you are interested.

 

[code3cowboy]

You throw out a lot of numbers and no sources/cites. If a cruiser goes over a cliff, chuck the chippie has bigger issues to worry about than who he can talk to.

You state "The occasional call to a DMV office for an arrest does not justify using 700/800MHz HT's. I have never seen a DMV office that is massive in size and to the extent that talking in and out on VHF doesn't work." Having chased my fair share of bad guys both into and out of buildings as well as along roads and into RF hell holes, I assure you not everyone runs into a single building that is not very large.

You should open your eyes to the CHP, no law enforcement in general, before spouting off. The CHP handles most of the old CSP duties including building security in Sacramento. I am guessing you have never been into the bowells of the State Capitol, but there are some spots where RF just will not make it. With a great system designed to get the RF around to everyone, the system works, but not as well as it could.

What would P25 trunking do for the CHP? The lo band system works fairly well, and in the areas where the lo band system has been rebuilt, it is freaking awesome.

During a gun fight, the officer should be more concerned about supressing threats, not ****ing around with an MDT or radio. Advising dispatch should be quick and easy by pressing the mic and stating "xx-xxx 11-99 11-99 shots fired". There should be no weight for a channel assaigment or god forbid a busy signal when Chuck the Chippie is getting blasted at by some crook with a stolen glock or mossberg.

Comparing hams to the Highway Patrol is like comparing a Cessna to the Joint Strike Fighter.

 

[ssd]

I see it this way. chp needs. A new up to dated radio system. Now I said it in the chp trs post. If they where to ues the calfire and f&g vhf sites to build a new p25 state wide trs. Or a smart zone system. It would work well for most of the state. Has vhf. And. Chp can keep the same set up for parts of the state were the vhf hi dos not work well. And so they can talk to uhf and 800. For sac and all the citys that do not have vhf. Then f&g would have a new leo to ask for help foem. Well hope some 1 in dgs is seening this

 

[tomasG]

@code3cowboy

I asked a question and stated my position. We can agree to disagree without being disagreeable. You chose instead to attack me and not the position I have taken.

Yes, I have 6 years of field experience in law enforcement and chose another path instead. The point of Chuck the Chippie going over the side was to illustrate how all the stuff in the trunk would then be useless. Agencies across the country are using trunked systems and officers don't complain of wiating for a channel assignment or a busy tone. Talkgroups are weighted. If you are more comfortable with a convential system, ok. I can work with that, too.

The question remains whether interoperability is best done from the patrol car, the RCC, or both. Your valuable insight would be appreciated.

@ssd: I am leaning in your direction and this is why I suggested a P25 VHF system that could use existing infrastructure and still modernize. Maybe even a hybrid in areas where lowband is still the only way.

 

[code3cowboy]

My problem is with your skewed view of the role of the CHP and apparent lack of understanding of what their officers do coupled with your lack of understanding of the processes and interfaces of interoperability gateways.

Connecting radios is now as simple as pressing a few buttons on a touchscreen or a box in your console.

The primary mission of a CHP Traffic Officer is traffic enforcement, there are throngs of CHP officers who go to work each day and do things other than Traffic Enforcement.

Officers do complain about busy signals and dispatch and the other guys "going digital". I left an agency who transitioned to a P25 system. It was a joke. They now have their own little island and have to use clemars, which any idiot with a scanner can hear, to deal with any surrounding agency or air support.

The answer to your question is neither. Interoperability is best accomplished by keeping your system consistent with those around you, and having both surrounding agencies channels and standard interagency channels in every radio, and ensuring every officer, dispatcher, firefighter, and other person knows of the channels and their use. Having remote bases your dispatch center can operate on the interop/interagency channels to keep them in the loop allows them to pop up wherever their officers are. Then your big operations do not tye up your patrol channels, and your "just on their side of the fence" ops do not require an act of congress to allow you to talk to your academy buddy who you are backing a block into his town.

 

[jim202]

Lets get down to the truth here. Radio Interoperability is not all about what radio system you have or
if it is in the vehicle or at the dispatch center. It's bottom line is rather "POLITICS". If you ever can
get past the "POLITICS", we would have a tremendously well working radio system.

What I am saying here, is that we have the equipment, we have the ability to program the radios,
we have the radio channels. What we don't have is the support of the top dog running the show
to use the technology. The top dog doesn't play well with his counter part in the agency next door,
so we don't get to use the "Interoperability" that is available in the radio systems today.

You solve the "POLITICS" and we will have the foot soldiers in the field being able to talk to everyone.

 

[tomasG]

@code3cowboy, who is not a police officer: The question remains whether interoperability is best done from the patrol car, the RCC, or both.

Suggesting that the CHP officer return to his patrol car to activate a channel by using a touch screen is not practical. I feel that using a trunked system, as are used nationwide without hearing calls of officers killed waiting for a channel assignment, and don't require digital (I don't know where your comment came into play) allows RCC to maintain talkgroups already assigned to an allied agency patch. Other mutual aid channels may remain on the officers HT. Orange County, Riverside and San Diego and Border Patrol use this approach already and it works.

Somewhat agreeing with you, I don't see LAPD going trunked because they might be the test case for busy signals. You seem to want CHP to stay on lowband while extolling the awesomeness of touch screens. Citing the needs (if they have any) of CPS as justification for spending $27,000 per car statewide seems a huge waste of money. Who is going to maintain the nightmare in the trunk? As K6CDO researched police agencies are spread across three bands statewide. What about fire departments, whom CHP needs to talk to as well? I believe that our taxpayer money would have been better spent on the mil-spec triband portables.

The answer to your question is neither. Interoperability is best accomplished by keeping your system consistent with those around you, and having both surrounding agencies channels and standard interagency channels in every radio, and ensuring every officer, dispatcher, firefighter, and other person knows of the channels and their use.

Huh? So you aren't in favor of CHP's junk in the trunk? How will CHP put interoperability on Chuck the Chippie's portable? And what if he goes on a really long foot pursuit and out of range of his car? He then ends up in another county and can't push the touch screen and now he needs VHF? With P25 and RCC based interoperability the officer could easily change channels and go direct instead of being tied to the patrol car.


@jim202: BINGO! I have listened to LAPD working a sniper call adjacent to the 110 freeway in Eagle Rock gang territory. They requested a patch with CHP and it took an hour for a CHP Captain to say no. In contrast, there are Los Angeles County interoperability, or mutual aid, channels that are used usually without asking or a quick phone call.

I think that limited interoperability in the car is good but better on the HT and at the RCC. CALFIRE has built an excellent conventional VHF system that favors HT operation. CHP can do the same. I was recently in some of the CHP vaults on 5,000 ft.+ mountaintops and do not see HT range as an issue. Maybe up north but I don't know - I haven't been there.

 

[northzone]

Somewhat agreeing with you, I don't see LAPD going trunked because they might be the test case for busy signals.

There is NO question LAPD is going trunked. The system bid proposals were due on Aug. 4th, 2010. If all goes as planned a vendor will be chosen next month. Do a search on LA-RICS.

http://la-rics.org/documents/LARICS_Brochure.pdf

 

[tomasG]

LAPD isn't close to even beginning their system. LASD on the other hand plans to go UHF trunked and got an entire new block of 480 frequencies. Too much is up in the air on LA-RICS and I personally feel that it is premature for any of us to know with certainty. I know that LAPD is planning on it but wow! That would be a tough system to build! There is rarely a second that goes by without traffic.

LA-RICS estimates $400 million for the entire county. LAPD alone would be at least that, wouldn't you agree? In fact, they estimate that their system alone will cost between $484 million and $604 million. I wish I could balance my checkbook like that. "Somewhere in between these two numbers..." LOL. I sure agree that southern California is long overdue. LA-RICS is an excellent example of a RCC-based interoperability system rather than the trunk of a car.

Members: LA RICS

Proposed: http://www.la-rics.org/documents/Radio_Interoperability_Project_Final_Report.pdf

 

[northzone]

LAPD isn't close to even beginning their system. LASD on the other hand plans to go UHF trunked and got an entire new block of 480 frequencies. LA-RICS estimates $400 million for the entire county.

Actually the document you cited is 4 years old, many things have evolved. LAPD and LASD are not building separate systems. LA-RICS has estimated the cost at $600 million. The bid is about to be awarded, it is going to happen. But were getting off-topic here so I will bow-out.

 

[tomasG]

Actually the document you cited is 4 years old, many things have evolved. LAPD and LASD are not building separate systems. LA-RICS has estimated the cost at $600 million. The bid is about to be awarded, it is going to happen. But were getting off-topic here so I will bow-out.

That was partly my point. LA-RICS continues to evolve and prices change. I believe that the cost will actually be far more than $600 million. The current LAPD system cost more than that and is conventional. But the P25 standard allows interoperability far easier than conventional and is RCC-based.

Back on topic, and you weren't that far off, how do you feel about interoperability in the trunk of each CHP car when things keep changing so much across the state? Not to mention that California is broke.

 

[northzone]

I think the mess in the car trunk will get much cleaner over time. Now that Harris builds a 4-band mobile (XG-100M) you really just need the lowband, the multiband, and the extender (which are very small). No need need for a scanner if you have a 4-band second radio.

The main reason for the 700mhz extender portable is to get more channels (currently planned for 16 extender only channels). There is a problem in areas like LA and the Bay Area. When an officer is out using his portable on a high spot, he may get into extenders of several different frequency colors. Also, the extenders turn other extenders off when they are turned on, this is also a problem for in-range other color extenders. The answer for the last 30 years has been to put a 100db pad in the extender receiver making them nearly deaf. The new extenders will not need to do this and will have a several mile range.

With the new channels they will be able to have different frequencies for the extenders for the different colors in a given area. If an officer changes frequencies (color) on the lowband radio the extender will automatically change to the correct extender freq for that color. I actually think after getting the kinks out this will serve their needs.

 

[zz0468]

Should interoperability be done at the patrol car level, at the regional dispatch center level, or both?

You left out the third level, which was mentioned by jim202 - politics. It's the politics that are, by far, the largest hindrance to any sort of interoperability.

Interoperability has become a post-911 buzzword that few people really understand. It's more procedural than technical. The ability to interconnect disparate radio systems has existed for decades, and it's not that complicated. Before anything else is done, agencies need to decide who they need to talk to, and what do they need to talk about. Then, and only then, can you determine the best mechanism to accomplish that goal.

But everyone has been lost in the glittery features of P25 and trunking and and the dreaded ACU1000. P25 is being sold as the perfect interoperability air interface, and I suppose in the digital world it'll do. But there are many, many, obstacles to inter-agency use of trunked systems, and only a concerted regional effort on the political level will solve it.

I believe that limited direct communications should be available from the patrol car and the hand-held. Instead of 700/800MHz hand-helds I believe that they should be P25 VHF trunking and that the CHP radio system should migrate to VHF.

Have you given any consideration to any of the possible reasons that CHP remains on low band? Is there enough CHP traffic to justify the expense and the frequency resources to build a trunking system? Are the needs of the metro areas the same as the rural areas? Do you really think one size fits all?

By using a trunked system talkgroups may be preconfigured at the RCC for the expressed purpose of communication with agency XYZ. The officer just changes the channel on his HT or mobile. Conventional channels like CLEMARS, NALMARS, and CALCORD would still be on the HT and mobile.

I've seen efforts to do just that fail miserably. The technical problems seem to center around insistence to use VOX type cross patching between systems, which makes it less than reliable. The operational problems center around the fact that there ends up being too many talk groups in the radio, officer and dispatcher awareness of what's where and how to get to it fades with time. So, when an event happens where inter-agency communication is desired, the hardware is there, and no one knows how to make it work.

When building a communications network the given standard is a minimum is -40dBm signal strength.

Good lord! Where on earth did you hear that? You missed the target by about 70 db. -40 is a convenient level when designing point-to-point microwave paths, but that's WAY FAR removed from reality.

Yeah, the higher the signal strength, the better, but modern radios have a threshold of about -120. No one can afford to put -40 dbm everywhere.

Most law enforcement systems are designed for HT operation by default.

Wrong. There is frequently a disconnect between what the users think it should be (like, HT operation), vs. what the engineers are told to design, vs. what is actually funded. Why do you think there are so many complaints out there about coverage?

Or do you ever hear about those? Clearly, you're not a professional in the field. Not a dig at all... just an observation based on this post.

A 5-watt VHF HT can easily access a mountaintop repeater with ease. Hams do it daily.

Yes, but hams become subconsciously aware of where the dead spots are and just deal with them without thinking. For public safety users, NO dead spots are acceptable, so the comparison is invalid.

Should CHP go to a P25 VHF trunked system this would be accomplished with half the number of radio sites needed for an 800MHz system.

Without proper engineering, blanket statements like this have no validity. There is no "rule of thumb" that states VHF takes half the sites that 800 does. There are too many variables you've left out.

Because the infrastructure would already be in place talkgroup patches to allied agencies could be accomplished without the patrol car being required as a relay. There can be many what-if's, but what if the CHP cruiser has gone over the side and the car is DOA? If all of the eggs are in one basket how then will Chuck the Chippie call for help?

In general, the more options that exist, the more different situations could be accommodated. But this also adds to complexity. If your hypothetical CHP car is DOA in one of the inevitable dead spots to the infrastructure, then disallowing any type of mobile interoperability solutions will hurt you.

What needs to be done is, agencies need to assess the type of situations that they're likely to encounter, decide who needs to talk to who, and about what, and build systems that actually fit the needs.

 

[tomasG]

I am not sure why the point-by-point when you are actually arguing with the plans of CHP.

CHPERS:

Replacement of radio system infrastructure such as base stations, mobile, and portable radios, and equipment for remote radio sites, as well as ensuring the CHP receives high-quality radio equipment in a competitive bidding environment.

Ensuring new radio equipment purchases are compliant with Project 25 communications systems standards which were created by public safety and federal communications professionals to help ensure future interoperability. The new radio equipment will enhance the Department’s operational
capabilities and help provide interoperability with local, state, and federal first responders.

The primary goal of the CHPERS project is to apply modern technologies and methodologies to enhance the CHP’s radio communications system while leveraging the existing infrastructure. To that end, DGS, in conjunction with the CHP, continues to refine the radio system design, operational and technical specifications for equipment, as well as identify remote radio vault site requirements, and apply for the acquisition of additional frequency spectrum.

Continue the acquisition of frequency spectrum in VHF high band for future integration/migration for better efficiency and area coverage.

I am unaware of P25 lowband equipment and CHPERS makes clear the intent to move to VHF highband and into P25 environment. That being the case I have simply stated my opinion. Personally, I like lowband. I love working 6 meters when it opens and even 10 meters. Now that cycle 24 is about to finally open you'll hear of many more complaints of "skip traffic." But lowband has not been friendly to CHP. It remains difficult and expensive to simulcast and radios aren't as available. All the junk in the trunk is a kludge method of interoperability. I don't like it but that's my opinion and why I have asked for yours. I ask that you not focus on my opinion but offer yours.

As for the -40dBm base output level system design, no one asked how. It isn't achiveed with one transmitter and some of you should know that. Pomona, for example, uses 5 simulcast repeater locations to do it, or close to it. It isn't difficult and perhaps my own words caused some of you to go down the wrong road thought-wise by assuming a wide area system. To that I'd agree that -40dBm is tough to achieve. But not locally. Locally it is done with antenna placement, antenna gain, power output and ERP. Some of you know this. 50-100 watts (easy to afford) and a 9dBd gain antenna at 60 feet (or lower) will easily achieve -40dBm for the target cell.

I absolutley agree that no dead spots are acceptable and this is why the high standard. Yet one of the posters in this thread insists that it is -90dBm and a 95% coverage 95% of the time and I say BS! I HAVE worked as a police officer, first in patrol in the military (not a field MP) and as a civilian reserve until an injury forced a career change. I have been in some pretty nasty situations and we didn't run back to our car to call for help. We used our HT's.

I've got to disagree with you about systems being designed for HT use. It is a fact. Mobile operation is easy and a 10 watt base on Lukens will cover much of Los Angeles nicely. But not to or from HT's. I chuckle at the CHPERS recommendation of going to 700/800 for extender use because it increases range from 400-500 feet to 1-2 miles. I hate to tell them but a 800MHz portable with a stub antenna ain't gonna do two miles in the city, and, the VHF portables would do more than that if they weren't limited to .25 watts for extender use and 1 watt for CLEMARS.

I also agree with you that CHP is spending a huge amount of money planning for interoperability in GG, L.A. and San Diego forgetting that back woods that comprise most of California.

See, this is why I lose it on the CHPERS plan -- it doesn't make technical sense. I don't have a problem with CHP staying on lowband and never had. I've just said that if they are going to move I'd lean towards P25 VHF. Excellent examples of systems (networks) designed for HT use are CALFIRE and U.S. Forest Service. They don't sit on the engine to fight the fire. A bad example is San Bernardino County desert and especially the mountain area. 800 in the mountains equals bad planning. Ironically, they switch to VHF to fight the fire and I am told that they are migrating back down to dispatch and tactical fire on VHF with CALFIRE and Forest Service. See the ULS for the new block assignments.

As far as RCC-based interoperability the ACU1000 served a purpose that has been exceeded. The proper way of interfacing, as some of you know, is with COR. Any ham that has built or worked with a repeater group knows that controllers are usually multi-port and COR operated. The WIN System is what? 120 linked repeaters or that's the goal and they're at like 75? Let's not sell hams short. I think the consulting companies charging millions to tell CHP what they need are full of it but I'm in school for it K.I.S.S. Keep it simple, stupid. Simple means for the RTO's and the officers both.

 

[zz0468]

I am unaware of P25 lowband equipment and CHPERS makes clear the intent to move to VHF highband and into P25 environment. That being the case I have simply stated my opinion. Personally, I like lowband. I love working 6 meters when it opens and even 10 meters. Now that cycle 24 is about to finally open you'll hear of many more complaints of "skip traffic."

So, you're writing from the perspective of a ham, and not from experience of having designed large public safety radio systems? That would explain a few thoughts that you have expressed. Not that your opinion isn't valid, or that this isn't an interesting thread, but there seems to be a few misconceptions you have, particularly about coverage.

But lowband has not been friendly to CHP. It remains difficult and expensive to simulcast and radios aren't as available. All the junk in the trunk is a kludge method of interoperability. I don't like it but that's my opinion and why I have asked for yours. I ask that you not focus on my opinion but offer yours.

ALL simulcast is expensive, if you're intending on doing it correctly. They are all maintenance intensive, some methods less so than others. Low band simulcast isn't particularly more difficult of expensive than any other band.

As for the -40dBm base output level system design, no one asked how. It isn't achiveed with one transmitter and some of you should know that.

Where I disagree with this is where you stated in your previous post that -40 was a specified MINIMUM signal level. -40 is a HUGE signal, and you're only likely to see that within a few miles of a site.

Real system design, and not internet conjecture, takes reality into account, the practical aspects of cost, site availability, and actual signal levels NEEDED. In an FM system, the level of signal required to produce an acceptable level of quieting in the receiver is a known quantity, as are typical land use losses that need to be taken into account. The end result is a whole lot less than -40 is delivered to the receiver, and that's quite acceptable. I'd love to know where you got that number.

Pomona, for example, uses 5 simulcast repeater locations to do it, or close to it. It isn't difficult and perhaps my own words caused some of you to go down the wrong road thought-wise by assuming a wide area system. To that I'd agree that -40dBm is tough to achieve.

Tough, and expensive, and I seriously doubt Pomona is getting -40 more than a quarter mile from any of their sites.

But not locally. Locally it is done with antenna placement, antenna gain, power output and ERP. Some of you know this. 50-100 watts (easy to afford) and a 9dBd gain antenna at 60 feet (or lower) will easily achieve -40dBm for the target cell.

Provided the target cell is small enough.

I absolutley agree that no dead spots are acceptable and this is why the high standard.

We agree here. But this is where we depart company in agreement. The police officer in the field wants 100% coverage. The system engineer wants to provide it.

Yet one of the posters in this thread insists that it is -90dBm and a 95% coverage 95% of the time and I say BS!

The problem is that radio propagation is statistical in nature. 100% coverage 100% of the time is a virtual impossibility in any practical system. Filling in that last 5% coverage area will create 95% of the cost of a system, and at some point the taxpayers back breaks, and they can pay no more. So a realistically acceptable specification (like 95/95) is produced, and a system is designed to meet it. And when budgets fall short, one of the first things to be sacrificed is signal density.

I HAVE worked as a police officer, first in patrol in the military (not a field MP) and as a civilian reserve until an injury forced a career change. I have been in some pretty nasty situations and we didn't run back to our car to call for help. We used our HT's.

This explains your perspective. It's a very valid point of view. Yes, I understand and agree that police officers use their HT's, probably more than their unit radio. You misunderstood my comment about systems not being designed for HT use. The SHOULD be designed the way officers use them, but the sad fact is, they frequently are not.

I've got to disagree with you about systems being designed for HT use. It is a fact. Mobile operation is easy and a 10 watt base on Lukens will cover much of Los Angeles nicely. But not to or from HT's.

Several times now, I have been called upon to reverse engineer existing systems to identify the cause of coverage complaints, particularly where HT use is concerned. In every case, what I've come up with is the fact that systems were essentially designed for mobile coverage, not portable coverage. This is the source of my previous comment.

What's frequently not taken into account is the approximate 15 db body loss from operating a portable on the hip with a speaker-mic, the 10-20 db of loss from operating inside a wood frame structure, the 30+ db loss from operating inside steel and concrete structures, and the additional losses from operating inside a vehicle. When you take all those losses into account, yeah, having -40 dbm on the street would make sense, and would be desirable, and you end up with -90 or -100 inside a house (if you're lucky) while you're on a call, a more realistic minimum specification. And THAT is the specification systems need to be designed for.

...Excellent examples of systems (networks) designed for HT use are CALFIRE and U.S. Forest Service. They don't sit on the engine to fight the fire.

They're not designed so much for HT use as you'd think. The primary difference is, CALFIRE and USFS firefighters are using their HT's in open territory, not in urban environments. And they DO have dead spots - many of them. It's just not as apparently critical as in a law enforcement situation where an armed suspect creates an immediate need for backup.

A bad example is San Bernardino County desert and especially the mountain area. 800 in the mountains equals bad planning.

A good example of 20/20 hindsight. At the time that, and similar systems, were put in, the peculiarities of 800 MHz propagation in forested areas wasn't as apparent. Another thing that happened with the advent of 800 MHz was the ubiquitous use of HT's that never previously existed. Officers had their VHF HT's, but it was a known quantity that coverage sucked, and they didn't depend on them the way they do now. Sadly, the design specification for many existing systems was created without the future knowledge of how those HT's were to be used.

Take a look at what Riverside County's PSEC project is doing in regard to the number of sites being constructed. That is a direct result of a design based primarily upon HT coverage. And even that will have some dead spots - I guarantee it.

As far as RCC-based interoperability the ACU1000 served a purpose that has been exceeded. The proper way of interfacing, as some of you know, is with COR. Any ham that has built or worked with a repeater group knows that controllers are usually multi-port and COR operated.

The ACU1000 is oversold as an ultimate interoperability solution, which brings us full circle in this discussion. Interoperability is 90% politics, and 10% hardware. And the ACU1000 is 10% of the needed hardware solution. So, you can see where it fits into the overall grand scheme of things.

The WIN System is what? 120 linked repeaters or that's the goal and they're at like 75?

There are better examples than that. Sytems with more sites, and more coverage that have been around for a lot longer.

Let's not sell hams short. I think the consulting companies charging millions to tell CHP what they need are full of it but I'm in school for it K.I.S.S. Keep it simple, stupid. Simple means for the RTO's and the officers both.

I don't sell hams short, I am one. But at the same time, when it comes to public safety communications, an amateur approach is not what is needed. It's a phenomenally complex problem, and a system engineer these days needs to be part engineer, part politician, and part financial wizard. He needs to be able to understand the needs of the end users, as well as the needs of the taxpayers buying the stuff, and those needs are often mutually exclusive.

 

[tomasG]

I am not approaching this as a ham at all. I simply drew parallels. But again, one shouldn't sell hams short. Many, many hams are professionals and design excellent systems. I am part of a repeater team right now covering 6 meters, 2 meters and 70cm with links from multiple locations. My perspective comes from numerous years in law enforcement and now as one working on an advanced degree in communications system design ("officially" known as Electronics, Electrical and Communcations Engineering from Cal-State.) My LEO experience was at the world's largest military base, Ft. Hood, where we worked and trained side by side with DOD Police, local and state police, and Federal. Not to be confused with a field MP, we were very active in a city of over 150,000 by day. Last years mass murder showed Ft. Hood in a positive light as far as our professionalism and capabilities.

With that aside, this thread isn't about me or a point-by-point dissection of my comments make it so. I do need to concede that I should not have used the word minimum and that is my error. But system design between 40 and 70 is not cost prohibitive. As was pointed out the APCO P25 DAQ standard is -90dBm. But digital is not analog. I just modeled Pomona again using their site located in San Dimas, a power output of 79 watts and a 9dBd antenna at 60 feet. As expected -40dBm was achieved that covered half the city. But Pomona uses 5 sites. They are actually a bad example because they are ICIS digital. Perhaps we can agree on -60dBm and call it even. Or agree to disagree and then have coffee.

But please, to the topic. We can go back and forth with boring numbers but I am very interested in opinions on whether or not CHP should use mobile, RCC or both for interoperability.

 

[zz0468]

...I do need to concede that I should not have used the word minimum and that is my error. But system design between 40 and 70 is not cost prohibitive.

That's a blanket statement that isn't necessarily true. It depends on the specifics. Trying to put -40 signal levels everywhere in a large county like, say, San Bernardino county, could well cost three quarters of a billion dollars. Doing it in a city like Pomona, not so much. It also depends on how many channels you're talking about. Single channel, fm, low band? Piece of cake. 28 Channels of P25 trunking? Cha-CHING!

So, the cost isn't defined simply as signal density in the service area. I'd also like to add that site acquisition and construction can easily exceed $500k per site - just for the dirt, the building, and the tower.

...I just modeled Pomona again using their site located in San Dimas, a power output of 79 watts and a 9dBd antenna at 60 feet. As expected -40dBm was achieved that covered half the city.

How did you model this? What software? What propagation model? Did you include land use data? Did you include any other real-world losses that actually occur, but aren't automatically plugged into the software? Be careful there. I have seen real systems built and advertised to overly optimistic coverage levels because the engineers didn't quite understand how the modeling software works.

But Pomona uses 5 sites. They are actually a bad example because they are ICIS digital. Perhaps we can agree on -60dBm and call it even. Or agree to disagree and then have coffee.

We can agreeably disagree over coffee. It's nearly impossible to make a blanket statement of an acceptable minimum coverage level because there are too many variables. No matter how much signal you try to put into an area, there will always be something that can absorb most of it, so the best you can do is come up with a statistical model (like 95/95). And you want to add up all the losses that you can, and try to build in enough margin to overcome a reasonable amount, for a reasonable cost.

But please, to the topic. We can go back and forth with boring numbers but I am very interested in opinions on whether or not CHP should use mobile, RCC or both for interoperability.

Certainly, back on topic. I look at it like a basket full of eggs. There's a million different reasons why the need for interoperability could arise, and not all of them are predictable. The more options one has, the more likely one has the tools on hand to adapt to the current situation. So, I always suggest both mobile and fixed assets for interoperability, with some overlap and redundancy.

The real bottle neck, as previously stated, will be politics and training.

 

[RolnCode3]

I don't know how an interoperability discussion got onto signal strengths, but it isn't my thing, so no comment on that.

However, I do have opinions on interoperability. The question really is what do you want to accomplish? If you want a patrol car to go anywhere in the state, all by itself, and talk to anyone, then you have to install lots of radios. And then put "HIGHWAY PATROL" on the side of it. I for one have NO problem with CHP's goal of outfitting their entire fleet with multiple radios, as long as the officers are capable of safely performing their jobs with the equipment installed.

If you want your cars to be able to individually assist on a perimeter or search in another local jurisdiction, then maybe you just need a compatible radio. Not much need to patch together radio channels if a single car can just switch to a different radio.

If you only want to coordinate on large scale events such as pursuits, officer involved shootings, riots, and natural disasters, then coordination at the communications center level is probably appropriate.

Of course, you can also have a hybrid: command staff/watch supervisors have specially outfitted cars where they report to a command post and each individually communicates with his/her own officers based upon joint command decisions.

 

[zz0468]

I don't know how an interoperability discussion got onto signal strengths, but it isn't my thing, so no comment on that.

TomasG made a statement that was egregiously in error, and me being the neurotic and pedantic techno-nerd that I am, had to correct it. =)

However, I do have opinions on interoperability. The question really is what do you want to accomplish? If you want a patrol car to go anywhere in the state, all by itself, and talk to anyone, then you have to install lots of radios...

...If you want your cars to be able to individually assist on a perimeter or search in another local jurisdiction, then maybe you just need a compatible radio. Not much need to patch together radio channels if a single car can just switch to a different radio.

If you only want to coordinate on large scale events such as pursuits, officer involved shootings, riots, and natural disasters, then coordination at the communications center level is probably appropriate.

Exactly. Which is what I was trying to say in my first post:

...Before anything else is done, agencies need to decide who they need to talk to, and what do they need to talk about. Then, and only then, can you determine the best mechanism to accomplish that goal...

It's this first step that consistently gets missed, so "interoperability" has become a huge waste of time and money.