[TrunkCom] while we are on the subject of encryption

[JETorres]

On Nov 7, 2006, at 12:34 PM, JERRY NONE wrote:

> I hope that the radio scanner makers keep up with the
> technology.  Does anybody know if this would be
> backwards compatible. Could a system be P-25 Mixed
> Mode and P-25 TDMA or 100% P-25 and P-25 TDMA? '


As far as I know, yes, they should be backwards compatible, the  
format of the CCh should stay virtually the same as far as scanning  
is concerned, etc. But once a whole county or agency is totally Phase  
2 compatible then I'm not sure if they could just totally "ditch" the  
Phase 1 part or not.....



>
> What exactly are the differences between CDMA, FDMA, &
> TDMA?  Which one is better for Public Safety / Public
> Service?
>


I suggest you google each one since it could get fairly technical and  
in-depth. Basically is ways to "crunch" more voice paths in the same  
or lesser bandwidth.

FDMA = Frequency Division Multiple Access, which is mainly what we're  
using now, one channel on a pre-determined bandwidth i.e. 25kHz or  
12.5kHz.
CDMA = Code Division Multiple......, which is what many cellphones  
use today and it digitizes/compress each voice path and assigns it a  
"code" to identify it, hence you can fit more conversations in a  
channel. AKA spread-spectrum, aka frequency-hopping sort of....
TDMA = Time Division Multiple....., basically it separates voice  
paths in time slots instead of codes to identify and route each. You  
can also fit more, up to four more conversations per channel than  
with FDMA.

That was all grossly over-simplified but like I suggested, best to  
google it or "wiki" it for better explanations and theory.


> Would making systems go P-25 TDMA make them more like
> TETRA or NOT?


Personally, I don't think so.....