VHF TRUNKING SCANNER

kd9000 · Post by **kd9000** » Thu Sep 16, 2004 9:38 pm

Does anyone know if the R.S. PRO-96 or Uniden BC-246T, BC-296D, BC-796D or other scanner will follow APCO-25 VHF digital and analog trunking? That's NARROWBAND 12.5 kHz VHF Trunking!

Thanks,
Ken

Cowthief · Post by **Cowthief** » Thu Sep 16, 2004 9:47 pm

Hello.

Some of the scanners will allow for the trunked frequency to be any range the scanner will allow.
I discovered this when a local company put up a UHF (450MHz) trunked system.

va3wxm · Post by **va3wxm** » Fri Sep 17, 2004 4:07 am

All but the BC246T will allow digital VHF trunking. The trick is you need to know the base frequency, spacing and offset numbers of the system you wish to monitor beforehand.

I use a BC796D to track the Ontario Provincial Police who are on a 3600 baud VHF Astro system.

EMS12 · Post by **EMS12** » Fri Sep 17, 2004 10:07 am

Is there any benifit to a VHF digital trunking system over a 800mhz Digital trunking system.

I know 800mhz has better penetration into bldgs and such but why would you want a VHF digital trunking system?

Whats the benifit?

Sorry to hijack thread

Cowthief · Post by **Cowthief** » Fri Sep 17, 2004 10:21 am

Hello.

Watt for watt, VHF has FAR greater range than 800MHz.
A 5 watt talkie can work a repeater 30+ miles away (2 meters).
800 MHz is line of sight, and anything green, be it a tree or just a large patch of tall grass sucks the signal away.

EMS12 · Post by **EMS12** » Fri Sep 17, 2004 10:47 am

Hello

So its just range? I mean I know that VHF is going to go farther than 800MHZ duh.

But I guess my guestion is why would you want a digital VHF system?

I guess I always thought of Digital trunking systems being 800mhz.

Notice I said digital. I know there are UHF trunking systems but the ones I have seen and listened to were analog.

A digital VHF trunking system seems over kill for a frequency that is traditionaly analog.

va3wxm · Post by **va3wxm** » Fri Sep 17, 2004 12:14 pm

I agree with you that it's probably overkill to go digital on something that's traditionally been analog.

Perhaps a lot of the infrastructure was there already? I know the radios and repeaters are completely different but coax is coax, antennas are antennas!

Range is definitely better on VHF than 800. You don't need to put in as many towers with a VHF system.

There's also the "security" aspect in that communications aren't in the clear like analog FM.

Or maybe it's just these public service agencies have buckets of cash to spend on new radios and Motorola, M/A Com, whoever comes along and sells them the latest and greatest?

kd9000 · Post by **kd9000** » Fri Sep 17, 2004 3:27 pm

It's my understanding that Montana, Wyoming and perhaps others will be going to VHF trunking with backwards compatibility to their legacy analog repeater systems (Can this be done? It's in their Specs) They also are looking for interoperability with Federal and Military systems.

Sound like a large order, but that's the plan. I travel to MT annually and monitor a lot, so while I'm in the market for a new scanner, I want one that's compatible. (Listen up Rat Shack [GRE] and Uniden)

Montana has a lot of existing VHF repeater sites, mountains and 800 MHz sucking pine trees.

Ken

OX · Post by OX » Sat Sep 18, 2004 12:35 am

They are probably going digital because of the DHS specifications and fund$. Yes, it doesn't really make sense to use VHF because the penetration inside a burning building or chasing a robbery suspect through a warehouse is less than required. Nobody thinks that stuff through though.

I wish I was estimating radio systems instead of Nurse Call systems. I'd have a bigger customer base to work from and could chase the morons out of business. hmmm

What a lot of places do when they get DHS funding is act like a 6 year old when you give them $5; they just blow it. And I know there are strings attached

Jim202 · Post by **Jim202** » Wed Sep 22, 2004 4:07 am

I have to disagree on the building penetration of 800 verses VHF. On many occations I have seen the police with their fancy 800 radios go into schools and try to use them. Nothing, yet the same location the fire department comes in and has no problems using their VHF repeated system. The cops can see each other in the hallways and can't talk.

Also the 800 signals have a much harder time with the vegitation than UHF or VHF. If you want the punch to be able to get in and out, 800 is not the best choice. If you get into hilly areas, 800 is not the best choice.

Many Public Safety agencies I know of are updating their radio systems to go to VHF or UHF trunking. The trunking gives many features that you can't get with regular analog systems. Just how the features are used depends on the system users.

Back to the main question of VHF abd 800. Given the choice for range and inside buildings, I will take VHF anytime. The State of Virginia is updating the entire state to a VHF trunking system. They are on a VHF repeater system right now.

Jim

nmfire10 · Post by **nmfire10** » Wed Sep 22, 2004 5:30 am

Doesn't trunking require very clear air? I mean, there is all kinds of crap on VHF from other users nearby since the band is so "full". I was always told that screws up trunking pretty bad.

trev_ca · Post by **trev_ca** » Wed Sep 22, 2004 7:36 am

nmfire10 wrote:I mean, there is all kinds of crap on VHF from other users nearby since the band is so "full". I was always told that screws up trunking pretty bad.

Hence the reason why digital is being pushed so much as it offers excellent narrowband operation ~6.25 kHz. VHF is congested, but so is the 800 band (ahem, iDen)

va3wxm · Post by **va3wxm** » Wed Sep 22, 2004 9:45 am

The only VHF trunking I've heard around here is our pseudo-provincial network. The frequencies are in the low 140's so spectrum wise they're somewhat removed from the crap in the 150-155 range.