Re: Dah-de-bleedin'-dah.

On 8 Mar, 22:51, fistfull-o-sparks <fistfull-o-spa...@xxxxxxxxxxxxxx>
wrote:
On Mar 8, 1:41 pm, "Ian" <i...@xxxxxxxxxx> wrote:

You show your lack of knowledge of radio and digital modes very well.
Digital and analogue will be affected by flutter...

"Flutter" = A product of the combined effects of doppler shift and
fading due to multipath constructive and destructive interference.

(Just thought I would add that for any technically minded persons
reading this thread)

:-)

Flutter in digital system results in delays or even worse Jitter =
variable delays in transmission. Means that a 2 minute "over" could
results in an unpredictable delay at the end of transmission. The guy
transmitting has to wait patiently for a random period of time - could
be 20 seconds - before the other guy starts transmitting. Changes are
he'll jump in before that to ask if his message was received and chaos
ensues. Oh and the guy at the end is reliable on proper procedure and
hand "over" other wise he might think a delay was the other guy
passing over. Sloppy procedure doesn't work on a digital voice system.

The reality is that for digital systems to work (for speech), you need
very low noise channels. Works ok for text, file transfers and the
like where the traffic is character based and predictable - error
correcting works quite well for this but not for voice. So you can
bounce a digital system off the moon as long as it's short and
pedictable text, you haven't got a hope in hell if it's voice. The
Analogy is with morse and voice. In noisy conditions you get a
callsign and a QSL in reply over the space of a few minutes. In clear
channels you can convey more information in a much shorter period of
time with voice/video both which are inherent asynchronous unlike data
(or morse). Synchronisity is the key.


10-10 de g1lvn
------------------------------
Amateur Radio: Social Networking since 1987
.

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