[FedCom] Questions

joe baeza [email protected]
Fri, 24 May 2002 17:18:11 +0000




Hi, 

I hate to be the messenger of bad news, however, Customs Air in San Diego uses coded comms with both fixed-wing aircraft and their A-Stars helos on a regular basis.
Joe

>From: [email protected] 

>Reply-To: [email protected] 

>To: [email protected] 

>Subject: Re: [FedCom] Questions 

>Date: Thu, 23 May 2002 18:43:01 EDT 

> 

>In a message dated 5/23/02 11:13:57 AM Central Daylight Time, 

>[email protected] writes: 

> 

><< Why can't most (if not all) surveillances with aircraft talk coded? 

> Does it have something to do with synchronization?? >> 

> 

>I don't recall ever hearing aircraft, particularly helicopters using DVP/DES. 

>As near as I can figure (and I'm certanly no expert), it might have something 

>to do with the rotation of the main rotor. 

> 

>I know a lot of electrical energy is produced by a spinning rotor, so perhaps 

>there is too much noise for DVP/DES to function, i.e. to deconstruct an 

>analog transmission, convert it to digital and send it off, or vice versa. 

>That may also be one of the reasons that the military went with 

>frequency-hopping radios rather than encrypted radios in their helos. Of 

>course frequency hopping is also more resilient to SIGINT attempts. 

> 

>I also wonder if it's a matter of all the other noise in the RF spectrum. 

>Look at your average congested area: a cacaphony of spurious junk. 

> 

>164.5500 (167.9 PL) (simplex) was in use in the skies over Chicago the other 

>day. It's ordinarily encrypted, but obviously this wasn't possible this time 

>out. 

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