[FedCom] clear comms = training & Encrypted aircraft

[Chris Parris]

Absolutely right Ben!

Over the years I've been able to correlate surveillance activity,  
both clear and encrypted, to many real world events. I've even known  
people involved in the operations (on the law enforcement side, not  
the suspect side) and was easily able to prove that adage about clear  
communications being only training as totally wrong...

You also bring up another interesting aspect about encryption that I  
have noticed over the years. I've monitored many surveillance  
operations in which all the participants on the ground were using DES  
or AES encryption on a simplex frequency, but the observation  
aircraft was always in the clear, analog mode. I was never able to  
confirm why this was with the particular agencies, but I always  
thought it was due to the background noise of the aircraft making the  
encrypted voice even harder to understand that usual. Recently I was  
able to copy some surveillance traffic in which everyone was using  
P-25 radios, and again the aircraft was not encrypted. The IMBE  
vocoders in the aircraft radio were just going nuts with the  
helicopter turbine noise in the background, trying to digitize the  
whine and rotor noise. It was interesting to hear how any sort of  
background noise on a digital system can be problematic for some of  
the users. My guess is that the same situation could occur when  
trying to use digital encryption on an analog channel. One of the  
laws of unintended consequences, I guess... :-)

- Chris


On Nov 11, 2007, at 6:55 AM, Ben Russell wrote:
>
> I can assure you that is not the case.  I have linked several big  
> ops heard in
> the clear on FBI, DEA, and ICE channels to press releases and news  
> articles
> about major busts.  With the newer radios, I'm always surprised  
> that radios are
> not set with the encryption strapped (full time on). On the local  
> FBI digital
> repeater it is usually the aircraft side of a surveillance that  
> turns up in the
> clear.  Every now and then, a ground unit can be heard, but it is  
> uncommon.
>
> Ben