MTR2000 VHF Base Cross Band to Low Band

[nick.dejohn]

OK.... I have been throwing this idea around for a long time and was wondering if it could be done and what I would need to accomplish it. Here is what I got, how it is currently setup and how I would like it to work in the end.

Our fire department has a Motorola MTR2000, 100 Watt, VHF Transmitter setup as a Base Station. We have a Motorola CDM750 42-50MHz Low Band mobile attached through a RICK Controller. At the present time we are cross banding the low band mobile, which is programmed with 2 low band frequencies; CH#1 RX/TX 46.180 RX PL CSQ / TX PL 141.3 and CH#2 RX/TX 45.880 RX PL CSQ / TX PL 141.3. The low band mobile is set to scan the 2 channels and whatever is received on the low band is re-transmitted in the VHF Base station. VHF is are regular operating band, in case anyone couldn't figure that out. If we were to transmit on the VHF Base Station frequency, it will revert the low band mobile back to CH #1. So, in the end CH #2 of the low band mobile is only capable of being received and not transmitted on.

My goal is to utilize the same VHF Base Station Transmitter and be able, with 2 separate PL's, transmit on the 2 low band channels at different times. I don't know if I will need two separate low band radios or if I can do it with one. I'm guessing that I can use a split PL for transmit and the same PL on receive. This way both low band channels will be heard on the same VHF frequency.

Now, does anyone think this can be done???? I have inquired to Arcom about a specific repeater controller that they make. I am awaiting a representative to get back to me to see if any of their products would do what I want. If anyone has any ideas for this project please let me know. Any help is greatly appreciated.

Thanks,

[RKG]

I believe what you want to accomplish can be done via Wildcard programming in a Quantar. In essence, you program an MPL table in the VHF base. You then program a Wildcard table so that, if PL#2 is received, an AuxIO line goes active; otherwise it is inactive. Then you attach this line to an AuxIO in the CDM radio used for channel steering.

The MTR2000 will do some of this, I believe, but it is a bit more awkward, both to program and to wire.

What I can't remember is how to program the CDM for channel steering.

[Dan562]

From your cross-band system description using the MTR2000 VHF Base Station and a CDM750 Mobile as a Control Base, all functional programming should be performed in the CDM750 "if" the Mobile unit contains Wildcard Scripting Tables. Since the unit is set-up for the receiver Scanning function, the Wildcard Tables would be scripted to detect activity on either the F1 or F2 Channel Carrier and PL for approxiamtely 3 second Delay or longer to automatically enable either the F1 or F2 Transmit Frequency Tables that corresponds to the Receiver Frequency being used. The MTR2000 Base Station doesn't need to perform any Wildcard functions.

Dan

[Will]

The MTR2000 Base Station doesn't need to perform any Wildcard functions.
Dan

Correct, most of the signals needed are available on the MARTI DB connector.

[HumHead]

My thought would be to go for a Zetron Model 38A with the auxiliary relay option (don't forget the special MTR2000 interface kit).

Interface the CDM750 to the MRTI connector, as Will suggested.

Set the Zetron 38 up for two tone sets- one "normal" i.e. "A" in "A" out, and one split i.e "B" in "A" out.

Enable the auxiliary relay output on the Zetron for the split tone only, and use it to assert a channel steering input on the CDM750's accessory connector.

Having said that, I would not be at all surprised to see some noticeable operational delays arising from both the scanning receive, and the steered transmit. You also obviously have to make some decisions regarding channel priority.

[nick.dejohn]

I have looked into the programming of the mobile and I do not see anything relating to Wildcard Scripting Tables. I have inquired to a company called Arcom who makes a repeater controller that, after providing them with the type of equipment that I have, state that I will be able to do what I want to do with the purchase of their controller. Their controller from the point of order to the point of installation and being operation is going to run around $800.00. Has anyone heard of this controller or this company and does anyone know what their integrity is? I'm looking for the cheapest, easiest and most efficent way to do this. However, if it can not be done to the point where it is going to function properly, than I am not going to waist the money and do it.

[thebigphish]

Thats because the CDM does not have any kind of wildcard scripting. Those feature sets are part of the MTR system, not the CDM line. There are some really good ideas for what you are trying already suggesting.

[edited for relevancy] fat fingers, sorry guys