XTS5k - audio quality difference in P25 with and without DES

radio-link · Post by **radio-link** » Sat Jan 20, 2007 6:36 am

Hi!

I experience a slight decrease in audio quality when switching from plain APCO25 (unencrypted) to DES-OFB. This should not happen, as the encryption happens when the signal already is digital, so what is the reason for that? I have made a sample, although in german language you should be able to hear the difference. The first transmission is in clear, the second one in DES-OFB...
http://dk5ras.dyndns.org/samples/APCO25.wav

CTAMontrose · Post by **CTAMontrose** » Sat Jan 20, 2007 6:46 am

what version host/dsp and emc are you running in the radios?

radio-link · Post by **radio-link** » Sat Jan 20, 2007 8:05 am

grem467 wrote:what version host/dsp and emc are you running in the radios?

Those are quite old 123abc radios, 2.20, encryption module 5.13 or something like that. With newer "true" XTS it sounds similar, but I do not have them by hands and can not verify the exact versions.

Bruce1807 · Post by **Bruce1807** » Sat Jan 20, 2007 8:28 am

I assume you mean DES-OFP
There should be no difference between encryption and clear in a digital system.
Now clear and securenet that was another story.
But with each DSP release the quality has improved.

radio-link · Post by **radio-link** » Sat Jan 20, 2007 8:43 am

Bruce1807 wrote:I assume you mean DES-OFP
There should be no difference between encryption and clear in a digital system.
Now clear and securenet that was another story.
But with each DSP release the quality has improved.

I mean DES-OFB, and as you can hear, there is an difference :( Securenet is another thing :)

Anyway, in case I can find someone who is willing to sell upgrade licences to germany, I will flash my old radios, too.

Bruce1807 · Post by **Bruce1807** » Sat Jan 20, 2007 9:11 am

Yes I listened to the audio and there is a difference.
firmware reflash should solve the problem.
It is strange that it is like that so im also curious on the firmware versions

CTAMontrose · Post by **CTAMontrose** » Sun Jan 21, 2007 6:09 am

i concur they need a firmware uplift worse than bad, however if they are ABC radios, he may have issues getting that accomplised thru motorola