Business Comms (analog w/ secondary - P25 or DMR/TRBO)

Business Communications (analog w/ 2ndary usage on P25 or DMR/TRBO digital)

I’m designing a two-way radio system for a new client. We have agreed on going VHF vs UHF, and it will consist of VHF repeaters & VHF simplex. Their property consists of 500-acres, most of which is mountainous by semi-dense woods, rock ledge cliffs (i.e. similar to a rock quarry) and low spots & hills.

We recently did a (simplex only) radio test on the property – VHF & UHF, and VHF performed the best. We tested VHF analog, VHF P25 and VHF DMR/TRBO and the winner was actually P25 digital having worked past the outer edge of the analog coverage and outperformed the DMR/TRBO portable radios when they got garbled and P25 continued to work. Though at times when we tested and I got no response on any portable radio I was calling out, I had to use my VHF mobile radio to establish comms, so mobile-to-portable worked best, but we are designing portable-to-portable coverage. That is where our VHF rptrs will come into play, to get the communication from one end of the property to the other and furthermore, penetrate the rock ledge cliffs and hilly woods of trees.

The comms proposal:
1. 95% of the business communications will be analog, and the important department channels will have a VHF repeater system (i.e. 50-watt rptr on a 30’ tower or bldg rooftop within the property).

2. The VHF simplex will be for secondary usage (i.e. parking lot staff, private chat-chat, concession & food stands, etc).

3. A discussion came about privacy, individuals listening in on their channels, and issues with the security staff being monitored while on-duty by outsiders and/or those possibly wishing to trespass. So I talked about P25 digital (which we ourselves internally use quite frequency {P25 simplex only}) and we have been beta testing some DMR/TRBO mobiles & portables for the past several months to understand DMR more. When the client asked what is the best way to prevent listeners is, I explained that DMR uses privacy codes from a pick list and P25 requires a key loader and you make up your own security key and it is at the top of the list, and public safety uses P25. This led to the next topic, the local towns (EMS, fire & police) are all VHF and if we went DMR 100% & no analog, it would be an interoperability issue. If we went 95% analog, and put the 2 or 3 important departments on P25 mixed mode, they can talk among themselves in P25 encrypted, and when an analog only staff person calls in for assistance in analog, the staff on the P25 will hear the radio message. So we see a benefit to P25 by using mixed mode as well. With DMR/TRBO there is no mixed mode, it’s either an analog channel or digital channel. So if we are in a digital, and someone calls in analog, you wouldn't hear the message unless we switched our radio channel to analog. As most of us know, the only effective way to communicate encrypted these days is via digital mode, not in analog mode. We have previously tried analog rolling code encryption option boards and 2 brands failed to function/work 100% of the time, so we sold them all off.

The high level departments would be using P25 digital for internal ops, a few with full-time encryption, and others on a radio button on/off basis. So the plan is to purchase P25 portables for the upper level management (maybe talking ~7 portables) and ~75 analog only portables for the rest of the business staff.

I am aware that P25 is slightly more expensive than DMR/TRBO radios, but it would not be that many radios and at least any P25 radios would be compatible with local public safety. I do wish to stay away from NexEdge or IDAS as those digital formats are not compatible with anything local. I'm trying to make the VHF system concept simple & interoperable with local public safety.

The radio channel plan is about 21 channels so far between rptrs & simplex.

Last item: What I have been tinkering with..... I find a local business and their FCC license shows DMR/TRBO emissions. I can simply program in their VHF frequency into my DMR/TRBO mobile (set up as a base) and data enter 16 channels starting with color code "0" and all the way to "16" and when they talk I simply put my mobile in scan mode and it stops on the color code they are using. So now I can listen to them just like I was on their radio system. So this is the reason why I'm shying away from DMR/TRBO because if I can figure out anyone's DMR time slot and color code in less than 1 hour of listening. So much for them having privacy and anyone can still listen in (unless their radio shop enabled either "basic privacy" option & selected a pick list code, or the "enhanced privacy" option.

Any comments, feedback or thoughts? Please share....

Just go all digital, on DMR. If you buy other than Motorola, you should be able to get AES 256 encryption. Hytera, and Tait both make good gear. Not sure why you want to mess with running both analog and digital. Steer clear of P25, you are not looking at a 'bit more expensive' you are looking at double the cost.


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For a 500 acre site a 50 watt repeater is overkill. 5watts after the duplexer at 30 feet into a Sinclair/DB/Comprod 2 element folded dipole will more than cover 500 acres. You are trying to cover less than a square mile(640acres)

Not being rude, but you seem a bit out of your depth. I believe you would be best served finding a radio shop to help engineer this system.

Also scanning DMR is not as simple as guessing colour code. You also need to know what slot and what TG the radio you are listening to is using.


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cmpsa said:

I am aware that P25 is slightly more expensive than DMR/TRBO radios, but it would not be that many radios and at least any P25 radios would be compatible with local public safety. I do wish to stay away from NexEdge or IDAS as those digital formats are not compatible with anything local. I'm trying to make the VHF system concept simple & interoperable with local public safety.

Click to expand...

A couple of comments here, take them as what they are, free info from a guy on the internet……


A P25 radio is going to be twice as much (at least) as a DMR/TRBO radio.

What makes you think that the radios need to be compatible with public safety systems? Earlier you were looking at UHF and VHF, and didn't seem concerned with compatibility with other radio systems in the area. Unless you are operating a state recognized law enforcement, fire or ambulance agency, it is extremely unlikely that any other public safety agency is going to permit them to access their system.

Getting licensed for 21 frequencies on VHF might run into some issues with the frequency coordinator. If you are going to need to run more than a few repeated channels, you'd likely be better off looking at a trunked system. Using a couple of channels on a trunked system would easily support hundreds of radios, and everyone would get the benefit of the repeater system. Simplex is useful in some instances, so I'd encourage you to get a simplex channel or two, but with a well designed trunked system, you won't need much.

As for your testing, sounds like you did a pretty good job. Doing simplex to simplex over 500 acres with the terrain you described can be difficult. This is where repeaters/trunked system would shine.
I run a couple of VHF, UHF and 800MHz system for a research university. We are on 2000+ acres in similar terrain as yours, costal redwoods, rolling terrain with old quarries, and lots of concrete/rebar/steel constructed research buildings. VHF works well for our PD and Fire department, but our trunked system is 800MHz, and it works very well, probably looking at 97% coverage or better. What is really important is in building coverage. We have places where the 800MHz system will easily outperform the VHF system.

Also, don't rule out any brands or protocols this early in the game. While NXDN/iDAS/NexEdge might not be as popular as the others, they all do analog, which is about as universal as you are going to find. You need to look at what functions you need, what the total price of ownership is, and what your local support structure is like. MotoTrbo works great, I trialled a system before I purchased. I ended up going with NexEdge due to much better local support. The 2 time slot function of Trbo is nice, but do keep in mind that if one repeater goes down, you've lost 2 voice traffic channels, not just one.

Make sure you look at total cost of ownership of the radios themselves. Some radios might seem cheaper on the surface, but can get expensive really quick when you start looking at accessories, batteries, etc.

Local support is going to be -extremely- important. Does't matter what system you get, you will need support. If you buy a system that isn't well supported in your specific area, you are going to have a real headache on your end. Talk to the local shops and see what their skill levels are.

Also, make sure you look into frequency coordination first. You need to find out what you can get licensed for in your area. 21 channels of VHF might not be a problem in your area, but it would be impossible where I am.

Trunked systems can give you a lot of functionality that you won't be able to with conventional systems.

Don't get too hung up on encryption. It can be useful, but it isn't always necessary. Our PD runs analog VHF in the open. They can run encryption, but don't choose to. Hasn't really been an issue. As for parking/security guys, there are really bigger issues you need to be concerned about. If you can add encryption functions easily to your system, then go for it, but don't focus on it too much.

Type of business: Motorsports Park / race track / motor speedway

I just realized I left out what type of business in my post. Sorry about that. I'm sure it would help you all understand what I was trying to explain. It's basically an automobile race track/motor speedway, not for NASCAR racing but for all other types of auto racing, and non-racing as well. NASCAR specifically uses "Motorola XPR series" DMR/TRBO radios in analog mode & TRBO mode, and they are licensed on solely UHF. Some of the governing bodies for their type of racing are currently using VHF freqs already, and their local public safety are on VHF tool. So hence why we picked VHF. On a side note since this is a race track, a ton of dual-muff headsets wired to the portables will be used too. So noise might be an issue when trying to communicate.

The facility will have its own internal fire dept/rescue ops, first-aid/medical ops and public safety dept.

The proposed channel plan (still being designed/edited):
Ch1 Emergency (Rptr-analog)
Fire Dept Ops (Rptr-analog/P25) dual mode
Fireground (simplex-analog)
EMS/Medical Ops (Rptr-P25 ENC) dual mode
EMS/Medical TAC/Helipad (simplex-P25 ENC)
Public Safety Ops (Rptr-P25 ENC) dual mode
Public Safety TAC1 & TAC2 (simplex-P25 ENC)
Admin Ops (Rptr-analog/P25) part-time ENC (i.e. for sensitive discussions)
Ops / ProShop / Souvenirs (Rptr-analog)
Facilities & Maintenance / Concessions & Food (Rptr-analog)
Parking Ops (Rptr-analog)
Parking TAC (simplex-analog)
Spare 1-5 (simplex-analog)
Interop - UHF (simplex-analog)
Interop - Public Safety (simplex-analog)

Racing Radios:
Race Track Ops (Rptr-analog)
Race Control Ops (Rptr-analog)
Race Control Flaggers/Marshals (Rptr-analog)
Race Control 2ndary (simplex-analog)
Media/Video Production (Rptr-analog)
Rental Radios 1 thru 25 (simplex-analog)


So the "interoperability with local public safety folks" was being thought out so the local municipal fire & police depts can communicate directly on the business' radio system (in analog, as some have P25 ports & mobiles and other just have analog only ports & mobiles).

So, I counted 11 repeated channels. If all completely separate, you are looking at quite a combiner system to make that happen, and that won't come cheap.

This is the sort of application where a well designed trunked system might work better for you. You'd be reducing the number of repeaters you'd need, and reducing the number of ports on your combiner/multi-coupler system. When pricing out good quality radios for your non-public safety users, you'll likely find that the good ones will already support some type of trunking, so you won't see much cost increase there. Repeaters and combiner systems are expensive, so reducing the number there will keep costs reasonable. Also, the part I mentioned above about the frequency coordinator is really something you need to carefully consider. Before going much farther with this, you need to figure out what you can get. You listed 57 separate frequencies above (simplex+repeater input+repeater output), and I think you will find it's going to be very difficult to convince a frequency coordinator that you need that many channels without going to a trunked system.

Even without the frequency coordinator issue, the sheer cost alone would really push towards a trunked system. The trunked system I run has about 60 different talk groups on it, and we do all that with a total of 4 voice channels.

I'd strongly recommend keeping your fire and medical stuff analog. There isn't any real benefit by taking these to P25, and it may just be creating interoperability issues. Yes, I read the part about the surrounding agencies having P25 radios, but getting all those radios programmed up on your system isn't going to be easy. Encryption isn't necessary for emergency medical services, HIPAA doesn't require that for emergency communications.

P25 codec noise issues have been mostly solved, but on a race track, you might be pushing it a bit. Analog with noise canceling mics and headsets might be a better choice. There was a thread here a while back about a guy wanting to set up radio systems for use a concerts. There were a lot of good posts there about what worked best.

Law Enforcement on P25 would likely work fine, but it's going to add costs. Again, P25 on it's own doesn't do anything to increase interoperability.

The other thing to consider about interoperability with surrounding public safety agencies is that designing your entire radio system around that isn't necessarily the only way to do it. Since most of the users you listed above have zero reason to talk to a local fire or police department, it just isn't necessary to design the whole system that way. Unless you are expecting a huge interagency response, providing a few handhelds to local agencies might be cheaper and easier. Also, don't rule out patching. From the looks of things, you'll need some sort of dispatch function. A good dispatch console could easily patch local agencies in with your system as needed.

I'd consider a digital trunked system for everything, with maybe a single analog repeater for law enforcement, one for fire, and one for medical to cover interoperability. I think it's fairly safe to say that any radio out there capable of digital trunking is going to be able to do analog conventional just fine.
The other option would be to put non-public safety users on one band, and put your public safety users on a couple of VHF analog repeaters. People manning a concessions booth don't need direct communications with law enforcement, medical or fire. No reason to force them all onto the same system. Most importantly, don't try to guess what the public safety folks need. Talk to the guys on the ground and find out what they want. You may be surprised at what they ask for. Also, talk to the medical and fire guys, it could be that they could do fine having just one channel, and may actually want it that way for ease of communicating. I've found it can be extremely difficult to get public safety users to do something as seemingly simple as changing the channel to talk to another agency. Often they'll just want dispatch to handle the traffic.

Also, take a close look at UHF again. Chances are you might have a better chance of getting this many frequencies on UHF. VHF is pretty congested in many urban areas, and with the non-standard repeater splits you could end up with, setting up your combiner system could be a headache and could get very expensive if there are closely spaced channels. Having nice even offsets makes life a lot easier.

The other big benefit to a trunked system is access control. With the number of individual radios you are probably looking at, some will get lost or stolen, or just plain disappear. Being able to block those from accessing the system can be a very valuable option

NXDN (Kenwood) offers "Mixed mode", and is very affordable. You can talk Digi (With or without ENC) or analog, and with mixed mode, the user can hear either type of transmission.

Hytera DMR would allow you DMR at a much lower price. They can be used in mixed mode, but with the digital, you will get the asset of having a 2 timeslot "trunk" system. Thus allowing multiple talk groups to use it, and have 2 talk paths at the same time. They new RD622 (25watt) with a mobile duplexer, good feedline, and resonable antenna will more than cover your area of operation on portables. Also, some of the portable models support bluetooth and vox. The included encryption will provide you with secure communications, without having to pay for added security like other manufacturers. We have 9 of these linked over IP and they work great.

Hello All:

I have a business meeting on Sunday, and my idea has changed from a P25 digital system to DMR/TRBO. I'm going to some more testing this Sunday w/ analog -vs- TRBO and see.

So I'm guessing the final choice will be a TRBO system, some simplex and bunch of rptrs. I will report back on things in a week or so.

I greatly appreciate everyone posts here with feedback.. It appears that the radio official group is currently operating on VHF, which is good as that means I can stick to my original idea - VHF.

Some more insight.... I install and maintain thousands of MOTOTRBO radios across a couple hundred locations in the US and Caribbean. Your setup is a good case study on a 3 or 4 repeater (with a spare repeater in the rack) MOTOTRBO Capacity Plus trunking system. I would recommend a combiner, but not required in this case. I would also get one or two more repeater pairs than you need in case of interference. This would give you 6-8 simultaneous voice paths, which would cover you pretty well. I strongly recommend getting as many people onto the system as possible as this makes initiating ALL CALLS (lost kids, BOLOs, etc) and channel planning more straight forward. You can add/subtract talkgroups without changing the underlying equipment configuration. It would also make it more difficult to scan. Furthermore, if you want to add some sort of Public Safety Interoperability, then a low power control station on your system hard wired to a public safety control station allows for easy interop, there is a cheap cable on ebay we use to patch TRBO to other Moto analog radios. TT