TRX-2: Encrypted NXDN??

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sparklehorse

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May 15, 2003
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Portland, Oregon
Hi.
I have one, small-town public safety agency in my area that uses NXDN. It's VHF, single channel. OK, it's a repeater, so technically two channels. Yesterday after the fixed updates were released, I was receiving their NXDN signal OK. A little broken, but mostly fine. Today zilch. I'm wondering if they turned on encryption. They're still active on their frequency. I've got my BCD436 parked on it as an analog channel and can hear the motorboat sound of their signal. And at the same time my TRX-2 shows 4-5 bars, so I'm sure the TRX is getting enough signal. But it does not decode it. I've checked and double checked all my settings. I tried re-updating the CPU and DSP. I even pulled the card out, re-formatted and re-programmed it. Nada. I downloaded all the NXDN frequencies from my four local counties using AggieCon's web page (thank you for that) just to see if anything NXDN was working. I have gotten a couple NXDN hits, not as many as I expected, but it proves the radio can still decode this mode. I even tried changing the mode on my target channel to DMR and also P25 just for grins, but still no dice. Anyway, can NXDN be encrypted? If so, is this radio handling it the same way it handles encryption on P25? I have mine set to TONE for encryption, and it works fine on P25, but I'm not getting a tone when my target channel is active. I just can't figure out why this channel was working fine yesterday, but today it's toast.
Thanks for the help!
.
 
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buddrousa

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Premium Subscriber
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Jan 5, 2003
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Location
NW Tenn
Hi yes NXDN has a basic encryption just like the DMR has.
Have you went over your programming to make sure it is still set to NXDN?
 

RayAir

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Dec 31, 2005
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1,796
NXDN can be encrypted using the built in 15 bit digital scrambler or by installing DES or AES boards (additional cost).

I'm not sure how the TRX handles encrypted DMR, or NXDN. I would set the scanner to pass encrypted voice.

It would be great if you could try to receive that signal with DSD+ to see if it is indeed encrypted, or if it's a scanner issue.

Here is a video of DSD+ decoding very narrow NXDN voice with a sample at the end of how the 15 bit digital scrambling would sound:
https://youtu.be/yf3t9uhZQfs
 

rustynswrail

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Joined
Dec 5, 2004
Messages
158
While I am sitting on the other side of the world and don't know your specific circumstances, I can relate a similar situation here.

During the week when RF traffic was highest, a distant DMR system could not be received. On weekends when the RF dropped off, no problem loud and clear.

There is of course other environmental influences. The weather can have an effect on how well you receive a signal, if at all. Even on VHF and UHF. And while encryption maybe the cause it might not be. You may have to delve further into your problem. Directional antennas could resolve the situation.

Just a thought...

R
 
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