Encryption Question

[PHOENIX_SCANNER]

Why is it that certain agencies have encryption on their radios, yet rarely use it?

Besides the human reasons (forgot to turn it on), ignorance, etc.

What TECHNICAL reasons are there for not being able to use encryption at times (other than one or more involved doesn't have encryption capability).

I remember years ago when PPD was analog uhf for surveillance, they would sometimes say "I am out of range for B" which meant they couldn't use encryption, but why would that be? If the radio works, why wouldn't the encryption work?

 

[EncryptionMan]

The repeater can not pass encryption (The radios are new or not designed to work with that repeater system in encryption mode IE: new radios older repeater, Brand conflict, Etc.) So they may be able to use two radios (mobile or portable) while using encryption but must be in simplex or direct mode.

Some departments only chose to use it for sensitive information or for surveillance.

Some departments do not allow it to be used for incident related communications because its off the repeater (that can not pass it) and have no way to record it .

 

[prcguy]

Because range is reduced in digital encrypted modes and digital in general. Motorola DES and DVP really reduces range and APCO25 is better, but not as robust as analog FM.
prcguy

 

[EncryptionMan]

Because range is reduced in digital encrypted modes and digital in general. Motorola DES and DVP really reduces range and APCO25 is better, but not as robust as analog FM.
prcguy

That is if they are operating in simplex or direct mode. That would have no effect if they were operating on a repeater which passes digital and their form of encryption. I'm not really sure if the "P25" IMBE vocoder offers any real advantage for distance. I have issues with it when just a few buildings are in the way. I don't have any real proof of this but IMBE was not chosen because of the clarity over distance. You have much better results operating in analog encrypted and that is how most of the time at least in my experience departments programing their "digital" radios to operate in simplex or direct using encryption and analog voice. But that really goes WAY beyond the orig. question... If I come across any a document that backs my statements up ill post it but I speak from personal experience operating in and programing both modes and feedback from those that operate them.