Transmission1

Has anybody any experience of linking 2 DMO Repeaters together? I currently have a CM9000 dual carrier repeater that has a variable uplink split.

I was wondering if this would link to a single frequency DMO repeater such as the MTM5400 or Sepura SRG series.

If anybody has any experience of doing this please let me know.

The idea is to have repeaters 20 miles apart to expand handheld coverage between the two.

Could try asking these guys Gareth, I don't think they overlap on the same frequency but interesting none the less.

There are currently 12 licensed ham tetra repeaters in Germany!


https://translate.google.co.uk/translat ... t=&act=url

Facebook group " DB0DMO TETRA HAM Repeater".

Hello Nokiaman2002,

As you have a CM9000 can you tell me please, do CM9000 radio main-units have any form of "trap" in them. By that I mean either a micro-switch or photo-cell that dumps the programming/stuns them if the case lids are removed ?
I gather at least one other well-known manufacturer's tetra radio cases have that form of protection for the programming.
Thanks in anticipation. May need to pick your brain in the near-future...

Rob.

Yes they do have a hidden pin switch that I found out the hard way while trying to pinout the interface cable for the head so "Don't take the covers off "

Second that, yes they do!

Hello Moj and Morgan306,

Thank you for that info, I wondered if what I had heard was a myth, obviously not.
Just a few questions to you both as you may be able to shine some light for me.

a) Is that form of protection fitted only on the emergency-services version or also on the civilian and older Dolphin models ?
b) Does the operation of that "pin-switch" kill the radio for evermore (and how) or does it just dump the programming or firmware, so a re-program will bring it back into use ?
c) How does it dump the programming ? ... if it is "volatile RAM" it must have a battery in it, so if not connected to 12v for a couple of days, that would have the same effect.
d) If it is "non-volatile RAM" or "flash", how does the switch cause the programming to be dumped ?

Anything you can pass-on will be very useful. I was hoping to use one because of the facility to control other radios (stimulated by the beginning of this thread and another on here).

Rob.

This is probably of no use to you whatsoever as I don't recall the make or model, but a repeater (I think it was a DOLPHIN but not sure) I saw many years ago had a micro-switch that fired when the lid came off, but apparently that didn't kill the box in any way, it just sent a tamper alarm via a text to a terminal. Maybe they can be configured to do different things or nothing at all in the software?

Other than that useless info, sorry, I have no idea about this stuff.

This also may be of no use whatsoever, I don't know anything about these repeaters but if you look at a typical business class PC like a Dell etc. (something you may be more familiar with) you can see what is possible.

The BIOS settings are stored in a battery backed memory. One tiny CR2032 button cell will typically last for over 10 years.

Inside the case is a microswitch that can be configured in the BIOS to flag an on-screen alert at boot time if anyone has opened the case and allowed the microswitch to open.

On the motherboard is a 2 pin jumper. Short those 2 pins, even for an instant, and all of the user configurable BIOS options stored in that battery backed memory are deleted causing the system to return to its defaults. Similarly, disconnect the battery momentarily and the same thing will happen.

It's not too difficult to imagine how these repeaters might be protected using a combination of similar techniques...

I can't answer what it does I'm afraid. I have opened a CM9000 in the past just out of curiousity, and it worked as it should afterwards on DMO at least. It may just dump encryption keys, the K key, or all of them. Gareth may have an idea, if he comes back to his thread?