Quantar Transparent P25 Encryption - DUI3000 help?

[seleong]

Hello!

Steve here in Southern California. I am running a dual-mode VHF amateur Quantar and just got a DIU3000 that I hope to interface with it. My goal is to prevent transparent encryption pass-through with the addition of the DIU3000. I am curious if anyone any "words of wisdom" that might help me with interfacing the DIU with the Quantar. The whole issue cropped up when some local hams found out that they could pass encrypted traffic on the Quantar in P25. When asked to cease the encrypted traffic, they ignored the request and I had to turn off the P25 capability. I hope to turn it back on, but only if I can control the key with the DIU. I wish I has a newer UCM for the DIU but only have an old DES-XL module that it came with. Any help would be greatly appreciated. Thanks very much! Steve

[delvis]

Im pretty sure that as long as the quantar is configured as a repeater and it receives the correct qualifiers, then it will pass whatever audio, the subscribers handle the decoding. So a DIU by itself would not stop it.

[xmo]

One of the primary applications of the DIU is to interface dispatch consoles to digital capable channels.

As such, it is often desired to have a "coded" indication available on the console. To accommodate that feature, the DIU can be programmed to activate a "Mode" output line to reflect the current channel state.

So - in your case, I would co-locate the DIU with the repeater and connect them with V.24. I would then program the DIU to assert the "Mode" line on receipt of coded signals.

I would then connect that mode output line to a wildcard input on the station and program it to disable repeat - or change to analog only operation if someone tries to use secure.

Actually, thinking further, I think I would have the wildcard simply do a transmit inhibit. That way, the repeater would stop transmitting if anyone tried to use secure and then as soon as an incoming signal was clear coded or analog - bingo the transmitter would be re-enabled. Coded won't repeat - everything else does - all automatic with no intervention required from the control operator.

Also - if you wanted to - you could hook a small message module to the DIU console input and whenever someone tries to use coded - have it play back someone speaking in a stern voice - narrating the appropriate FCC rule!

[xmo]

Upon further reflection - rather than a stern voice - I think I would recruit a really sweet sounding YL to record something like:

"We're sorry. It appears that you may have inadvertently attempted to transmit with encryption enabled.

In accordance with FCC rules governing the amateur radio service, this repeater does not support encrypted operation.

Please recheck your coded - clear switch and try your call again."

[Astro Spectra]

Pulling pin 12 of the 50 pin Cinch telco connector to ground will inhibit the repeat function. This pin is pulled up to +5VDC and you need get it below 0.5V to inhibit.

[seleong]

XMO,

Thank you very much for you great explanation and suggestion. I think I better try the v.24 hardware solution before I search for the YL for the appropriate recording...

Very cool. I am curious if there might be some logic I could add to the solution to only key the repeater if a proper/loaded key is received...???

Again, many thanks for your help!

Steve