Batboard

OK. I know this has been a topic in the past. but has anyone done this and can they either talk me through it or do it for me. I have a Lic VHF freq for our (Very ) small PD and also are lic. on the 800 trunked system. But we are in a valley and have a hard time getting out with the mobile. let alone the portable. I was thinking of placing a cross band repeat at the PD and power it up when one of the uys goes on duty. anyone help?

DFC2

hello,

Where are you located??

southern ohio

OK give us some more info and help us understand.

Are you runnning VHF on mobiles and portables and trying to build a VHF patch into the 800 system?

Or are the mobiles on 800Mhz and you need more coverage out or what??

This will all play a part in to what you need to make in essence a crosspatch.

In addition what type of trunking system is it? APCO25, SmartZone, SmartNet, Type I or II, EDACS, what????

Also what are you using to create the crosspatch for equipment? Base station, repeaters, consolettes????

We need to know all of this information in order to make a good clean reliable patch and not some bubblegum/duck tape toy.

Please provide the info and then I am sure a lot of people can help you with this issue.

we are on an 800 trunked system county wide. out village is in a valley and have a hard time getting out. I am considering trying to use our lic. vhf freq to cross patch to the 800 system by putting a vhf mobile and a 800 mobile both programmed to our auth. freqs/talkgroups and placing it at the PD. the antenna's will be high enough to allow access to the system and village wide coverage on the vhf freq. and the hope is we can use a VHF portable to hit the link at the PD and get out over the talkgroup to dispatch. we will still maintain the mobile 800 radio in the cruisers. I am looking for a way of doing this. I do not know how to do this. that is the reason for asking here. I have seen that others have talked of this and made comments that they have done it. it does have to be cheep. and it is not going to be a full time link. only a few hours each day a few days a week.

dfc2

Problem with tieing a conventional control station to a trunking control station is you can't tell if you got a busy bonk or you're actually going through.

Pyramid makes a vehicle repeater designed for trunking systems. It monitors for channel aquisition and tells you it's ok to talk. It might be better to hook a VHF SVR-200 vehicle repeater up to the trunking control station and operate through that. You would essentially have a vehicle repeater installed at the base with an outside base antenna. You could even put a VHF power amplifier on it if 4 watts is not enough. This basicly accomplishes the exact same thing as a conventional VHF control station while handling channel aquisition and busy bonks. The SVR-200 is about $1,000 and software programable. It can carry the trunking control station's local microphone audio over onto VHF as well, so when a user at the control station is transmitting, it will go over both trunked and VHF.

Yes I am familure with all my options and the in car repeaters.... problem is we are a small village and we can not afford the cost of several vehicle repeaters for our vehicles....and on top of that the chief and the LT. respond at times in POV's. It must be cheep and it must be at the station and not in the cars. Our hope is to use our village maint freq and the trunked system. I can get spare VHF portables all day long. so that is not a problem. trunked radios are a little harder to get at a cheep price. so my hope was to use one of the inexpensive cables I have seen mentioned here from a type 2 maxtrac and a vhf maxtrac ( low power. 1 watt or less is all that is needed on the VHF side to reach our entire village. an antenna mounted higher up on our PD tower will be fine to get into the trunked system. even our cars have trouble at times depending on where they are in relation to the trunked systems tower ( several miles away) we have had to move the cars to get dispatch a few times on the lower end of town. there is no fix as far as the county system is concerned. they tell us there is nothing they can do short of building another tower and that would be on our dime...not going to happen. so either we put up with the trouble...big officer saftey problem. or I try one of the cheep fixes.

DFC2

Read my suggestion again. I'm suggesting you put ONE vehicle repeater on the tower and use that in place of a conventional vhf mobile on a power supply.

You have to look at a few things when doing a project like this.

1.) Range of system - I am sure your VHF channel has a power rating and height restriction on the freq. Some public works freqs which are simplex are some times listed as mobile operations only. Therefore, you need to check the restrictions of the license. In addition what happens if you are using a VHF portable and can not hit your crosspatch but they could hit the 800Mhz system.

2.) Now after you check the restrictions you may need to reclass the license as a crosslink repeater which may or may not happen with that freq. Once again a lot of simplex freqs are only that and can not be licnesed for higher wattage or repeater operation.

3.) What type of 800Mhz trunking system are you trying to access? Some have it so when you are in range you can always key it up as long as no one is talking. However, if you have a type of system where you need to hear an ack back like a type II etc.... you need to have that bounce back.

4.) What if you have to talk on a different talkgroup? How do you facilitate changing talkgroups?

5.) If it is a public works channel how are you going to handle with public works using it and police usgae at the same time?

My suggestion is this and is a simple one. I am sure you have 800Mhz trunked portables and I am sure that you can program an 800Mhz conventional channel into the portable.

So program an 800Mhz conventional radio and interface it into the trunking system. Therefore if you have your portables and mobiles and move out of the range of your system you then can switch channels back to trunking.

To answer the original question (without necessarily disagreeing with those who suggest that maybe that wasn't the proper question), we have successfully linked VHF (simplex) to 800 trunked via a device called the NIDA KR200. As Matt says, you do not get the "talk permit tones" signifying that the 800 channel grant has occurred, so you run some risk of talking into space, but the link does work.

The product by KR Nida Communications is the "RC200". I have one of those in use on our fire system. We are using all three ports on it to link:

1: Vega tone remote
2: Low band base
3: UHF Repeater

It links all three devices together giving us the low-to-uhf cross link and connects both to dispatch. It is somewhat like a R.I.C.K. but with three ports and little more advanced. It does work well and will do the job, but like you said you won't have the confirmation of it going through.

Well, I was close.

There is one limit we've found. We use the device to connect to three radios: one VHF, one UHF and one 800. We have found that only one of the radios should be channeled on a repeater frequency (i.e., sending on the input and listening on the output), because if two of the channels are on repeaters, the system will ping-pong when the repeaters unkey. However, this works for us because the incoming companies (either VHF or 800) use a "direct" channel for hitting out link (to our home UHF repeater).

Yea, definately. If you want to link two repeaters, you pretty much have to hardwire from the repeaters I/O.

There is a device designed for for linking a conventional channel into a Motorola system via a mobile radio that will wait until after the VHF radio de-keys before playing error tones over the air, meaning as soon as you let go of the button, you'll know if your call didn't go through.

I'll be damned if I can remember who makes it, though. If nobody else knows, I'll try and find it.

Futurecom.

http://www.futurecom.com

They're up here in Canada and their products are VERY well built. I'm working on one of their mobile repeaters right now and it's built better than most radios I've ever seen.

Yep, the RST Smartbridge was the device I was looking into a while ago for a similar situation.

There are a number of companies that have devices available today to link different radios together. It kind of depends on just how your going to use them. If your linking radios at a fixed location, like a tower site, then you may want to look at a couple of boxes. The selection will vary with the application.

Some of the choices are: (number given is up to how many radios can be connected with one device control box)

Communications Applied Technology, 5

Infinimode Systems, 12

JPS Communications, 12, can use an IP network

Link Communications, 10

Motorola, 8, uses IP network can link multi sites

SyTech Corp. , 16, uses IP network, can link multi sites

Now don't get me wrong, you can in many cases stack more than one device together to get more radio channels that can be interconnected. There are also other vendors than the above listed ones. Generally they are a networked based system and as such the price is much higher. Your no longer into a simple interconnect system.

Have played with the Sytech and found you can use it as a dispatch console if needed. It uses a touch screen display. You can have a number of different audio communications paths up at the same time functioning independent of each other. This is one of the questions you should ask when inquiring about any of these devices.

Ask what the list price is for the package. This can vary somewhat with the options that are installed. When I did my homework several months back, I found that the JPS device would cost about $10K more than the SyTech box. Compared the features and found a big difference. You need to put it all together for your application and see what you get.

I did find out that the Moto Bridge could not be stacked. If you needed more that just 8 channels, you had to install a router or switch and add a whole second box.

Ask about creating private networks. This is where you have a network or several networks and then you have maybe 2 users or channels that need to be able to listen to specific channels as well as talk just between them selfs.

J



[quote="mr.syntrx"]Yep, the RST Smartbridge was the device I was looking into a while ago for a similar situation.[/quote]

nmfire10 wrote:Pyramid makes a vehicle repeater designed for trunking systems. It monitors for channel aquisition and tells you it's ok to talk. It might be better to hook a VHF SVR-200 vehicle repeater up to the trunking control station and operate through that. You would essentially have a vehicle repeater installed at the base with an outside base antenna. You could even put a VHF power amplifier on it if 4 watts is not enough. <snip>

While on paper this is an EXCELLENT idea, the reality is this:

1. The SVR-200V has a TX PO of 2 watts, not 4.

2. If running an external amplifier with an SVR200, you've got to be very careful of the amplifiers specs, as the SVR200's priority sampling scheme switches the repeater from TX to RX every (x) seconds (variable). If the amplifier's TX/RX switching isn't fast enough, the amplifier will sit in transmit, and you'd never get into the thing.

Disabling priority sampling is just a BAD idea IMHO.

Not sure where I pulled that 4 watt figure out of. Moot point anyway if your going into an amp.

The priority sampling can, and probably should be disabled. It would serve little to no purpose.

Considering the application here appears to be Public Safety/Law Enforcement, let me pose this question:

What happens when priority sampling is disabled (causing the link to go only one way at a time, since these repeaters are simplex) and an officer finds himself in a "cover now" or worse situation? The officer has to wait for any busy condition to clear before he can key up, rather than just stomping down the mic and talking, hopefully covering any other unit that might be talking... Better to have some chance than none, in my opinion. The priority sampling would allow the officer to potentially be heard, as it's checking for any channel activity without waiting for the base station traffic to clear.

The priority sampling does have it's advantages of course. However, going without it is no different that having another mobile or portable unit talking or another base talking at the time an officer needs help. In other words, it is just as likely that Unit 2 will be talking on the air to dispatch at the same time that Unit 1 needs help. It's and statistical possibility regardless of this link or not. It's the nature of a simplex channel.

Well I was considering the traffic on the 800MHz side of things moreso than the VHF simplex link...

As well as the hang-time on the 800MHz side.