4 Wire?

[Trinity-Explorations]

I would like to make our repeater a 4 wire so all units can TX/RX simultaneously. What kind of programming or equipment is required to do this?

We have a MSF5000 VHF 100 watt 151mhz and are applying for a VHF Conventional Analog License.

[tech020]

The repeater is capable of duplex (simultaneous TX/RX) but I am not aware of any VHF narrowband duplex portable radios. What you need is wireless duplex intercoms, not land mobile equipment.

[kb4mdz]

4-wire would be used to/from your dispatch point, like a full console, or even as simple as a 4-wire, full duplex tone remote.

[Trinity-Explorations]

Is this an actual wiring scheme? or is it programming? We need to invest in a narrowband repeater upgrade, we are working with our coordinator to fix that issue, but we use XTS3000 VHF Model I radios and would like to go 4 wire, we are using a Centracom Gold Elite computer and console.

[kb4mdz]

It's a wiring scheme between the (Centracom) console & the repeater, IF, (a big if) the console is connected directly to the repeater. However, if the console talks to the repeater with a 'control station' ( a fancy name for a mobile radio and an external antenna, at a building or another site), then making the repeater 4 wire probably won't gain you anything anyway.

But '4 wire' has no meaning with regards to the portable radios. The portables are half-duplex, in that they can only transmit, or receive, at any time, but cannot TX & RX simultaneously.

I'll have to draw word pictures to really make any sense.

[kb4mdz]

I'll assume you have the console connected directly to the repeater; it can be 2-wire, in which case what comes in the repeater's RX, goes down the wire to the console. If the console transmits, even while a user is still talking into the repeater, audio goes from the console to the repeater and out over the air, so the other users can hear. DEPENDING on how the repeater itself is set up, the audio from the RX goes out over the air (straight repeater) or the audio from the console gets priority, and goes out over the air, to other users. This also cuts off any audio coming thru the repeater's RX, and prevents it from going down the line to the console. Mixing the RX and TX audio on a single pair would make a difficult situation; since the repeater already is taking RX audio and routing it the the TX, via one path, if you also add a path where it goes into the 2wire telephone line, it could/would also couple around to the TX audio, resulting in very poor audio, unless a LOT of audio engineering is done to prevent that.

If you set up for 4 wire, 1 pair of wires will carry repeater's RX audio to the console, and the other pair of wires will carry audio from the console out to the be TX'ed over the air. This way, the Console, (if it's setup appropriately) can listen to what's coming in the RX , as well as being able to talk out the TX; very effective with a headset system at the console.

[Trinity-Explorations]

We are connected directly to the repeater with the Dispatch console ($2500 package from govdeals.com)

I see what you are saying about the 4 wire, i want a set up like NYPD uses where the dispatcher can TX and RX at the same time as the unit, if you ever listen to NYPD they have some kind of 4 wire where it is simultaneous TX and RX so the repeater doesn't tie up and everyone can hear without interruption

[ramal121]

I think I know what your thinking is, sort of.

A repeater is a full duplex device. By connecting it to a dispatch console via a 4-wire telephone circuit (separate transmit and receive paths), the console is also full duplex and can talk and hear at the same time. This is for the benefit of the dispatcher only. All the mobiles and portables can only transmit or receive, but not at the same time.

Here's my guess at your question. When dispatch has the repeater keyed and is chatting away, you would like a field unit to transmit through the repeater and have it where the audio is mixed and both dispatch and the field unit would be transmitted. At the dispatch end, since it is full duplex, it would be like a phone call for them and they would pause according to the field units calling in. All other receiving radios would hear the mixed audio and for them would be like evesdropping on a phone call. Interesting concept.

The rub is in the repeater. There is a priority hierarchy as to which audio is sent out the transmitter depending on the keying source. For example, if the repeater has wireline priority, a call from a mobile unit will be muted whenever the console keys up. There is no mixing of the two and I can't think of a repeater at this moment that will allow this.

Doesn't mean it can't be done with external repeater controllers, remote adapters and a little wizardry.

[kb4mdz]

Let's start with what kind of repeater you have; manufacturer, model, etc. How far physically is it from the console? Do you know the programming of the BIM card (Base Interface Module) in the console rack (often called the CEB rack; Central Electronics Bank)? You'll probably have to get that reprogrammed, too, as well as changing some connections to it.

[cabletech]

trinity--As been stated, the ONLY advange to 4 wire is for dispatch and even then the operators may not like it as it can be very confusing during high traffic times.

I also have to ask, are you the assigned radio tech for this system and have the authourty to make this kind of change?

On the other side of the coin, you are showing that you do not have the experance under your belt to do this change.

If the system is currently working as a 2 wire control system and is working the way it should, then leave it alone.

[cmdrwill]

Originally Posted by cabletech

trinity--As been stated, the ONLY advange to 4 wire is for dispatch and even then the operators may not like it as it can be very confusing during high traffic times.

I also have to ask, are you the assigned radio tech for this system and have the authourty to make this kind of change?

On the other side of the coin, you are showing that you do not have the experance under your belt to do this change.

If the system is currently working as a 2 wire control system and is working the way it should, then leave it alone.

A bit stiff Cabletech, you do not know IF it is working.. BUT this OP may have reasons not posted, let's wait to see what his reply is.

[Trinity-Explorations]

Our system is a private refurbed system. we are using it for our localized non emergency operations. The reason we wanted to use 4 wire is because we keep locking up our repeater during high use times with everyone stepping over each other.
The repeater is physically about 12 feet away from where the repeater is sitting.

We do not use techs as we maintain our own system unless something catastrophic happens to a piece of our infrastructure.

We would like to set up the 4 wire to make it easier for our dispatcher and field units to communicate.

And i only respond on weekends because i work all week long.

[Trinity-Explorations]

The make of the repeater is a MSF5000 VHF 100 watt

[R8000]

I have to agree with Cabletech.

I would strongly suggest you seek the help of a reputable local dealer. Your MSF is not narrowband compliant. That needs to be addressed asap. If your on the cheap, find a used MTR2000 with a wireline board.

It seems like to me you could easily hose things up quick. A reputable radio shop should be able to set you up pretty easily. Give one a call and crack open your wallet for a service call and build up a good reputation with them. Then in the future, they will also know what you have and can support you easier and faster.

I am not trying to talk down to you, but giving you advice before you dig yourself in too deep. The Centracom is one hell of a beautiful thing, but you can also easily make it a brick if you don't know what your doing. Blow it up and your repair bill will be several thousand dollars..easy.