"Dial-Up" Tone Remote Control?

[Babylon 5]

We are running a radio system that is basically two-wire tone remote control of widely dispersed simplex radios.

Party-line style, appropriate users share the two-wire line to get access to the towers they need, and talk to users from different responsibility groups.

This means everything from Gold Elites, Zetron 4010s, T5600s & T1604s are all paralleled up as needed.

As you can imagine, the two wire leased line costs are significant, but due to the rural nature or the system & simplex use, it is the only way to go.

Now the problem – we have about 20 other sites that are too far away geographically, as well as having low hours of yearly usage – that make it economically unfeasible to run leased lines.

These 20 remote sites do have PSTN (poor quality, modems barely run 14.4 and drop a lot!) and are presently accessed through teleconnect (Zetron Model 35a at each site).

As you can imagine, the simplex vox keying is almost unmanageable, and integrating the remote site to more than one dispatch phone is unworkable.

What we are looking for is an add on system that could bring in these towers “On-demand” through the PSTN, provide positive PTT from the dispatch side, and appear as standard Tone Remote control devices to the various consoles.

Any advice or experience out there?

[Dan562]

What I have read in your system description appears that you need a microwave system as your backbone to the simplex two-way system eliminating your leased line expense. The microwave system would probably pay for itself in two years. If your current Telco pairs are that bad .... which wouldn't surprise me, why would you think regular Telco lines would provide any better quality or service for your very remote applications?

I'll bet there are people on this Batwing message board who maintain Statewide Public Safety systems that are still using Microwave systems for their local and rural sites. These people could provide the up front and long term cost $$$$ versus system reliability and maintainability. I think you've come to a crossroads to consider upgrading your system. The entire system is only as good as the weakest link.

Dan

[nmfire10]

Look at it this way. You have three choices:

1. Telco pairs. This would include standard tone remote and any kind of Voice-Over-IP using the internet since that would have to come in on the same phone lines. If the phone lines suck, neither will work right. Even if the phone lines don't suck, the phone company usually makes up for by being generally stupid.

2. RF point-to-point. You could do this with microwave and that is ideal. A little less expensive is lisensing another VHF or UHF frequency as a link, putting a link radio at each end and aiming some yagi's at eachother. May or may not work depending on height and distance.

3. You could use a sat. uplink, beam it up to space and back down. While possible, if phone lines are "really expensive", this is probably not an option on the radar.

[Babylon 5]

Thanks for the replies guys.

Without getting of track, our permanently connected sites are indeed a mixture of leased line, microwave and rf links.

The "dial-up" sites that we have are located so far away, and used so little, that economically it is unfeasible to build or lease an infrastructure to connect them.

An example of a "Dial-up Tone Remote" from Vega corp. can be found at the following link:


http://dvservices.com/download/C-550-RP ... remote.htm


The problem with this device is that:
1- its a Vega (not bashing, but I'd be happier with Zetron etc.)
2- it is a single control point, and I need to share control on parrallel TRC's

Any other thoughts would be welcome!

Thanks

[xmo]

Vega is now part of Telex [If that helps inspire additional confidence] and their offices are now at Lincoln, Nebraska.

http://www.vega-signaling.com/index.htm

I don't see why you couldn't solve this problem the 'do it yourself' way. You would put a simple phone patch at each remote site - configured to answer on the first ring. That would connect to either a tone controled base station or a tone remote adapter connected to a local control station.

If someone dials your station by mistake it won't do anything unless they send tone remote keying to it. I suppose someone could accidentally discover that they could dial that number to monitor the station's receiver, but that's a fairly low probability.

At the console end you need a way to dial the number and then bridge the line to the remote or BIM as the case may be - there is your real challenge since you have several different control point types.

For the Centracom, I would use the DPI [Direct Phone Interconnect] card, but I think I would use standard BIM firmware and program it as a tone control base, then access the DPI off-hook function with Aux I/O programming. You could set up a pre-programmed [page] button with DTMF signaling and the base station's phone number.

To access the station your dispatcher would click the off hook icon, hear dial tone, click the station phone number icon, and once the station answers the radio resource would work just like any other.

If you had smart stations [like MSF5000] they have a transpond function so you could even have an icon that would send a tone up to the station which would then answer you back so you could check to see if you are connected.

If the call gets dropped - the telco should go back to dial tone - or an off-hook warning message / tone.