04 Mar 08 01:57, Richard Webb wrote to Roy Witt:

 TW>> Tell that to the San Diego Sheriffs Department that let Motorola
 TW>> convince them to put digital Radios in their Helicopters only to
 TW>> find that when they transited faster then about 100 MPH the radios
 TW>> ceased Functioning.

 RW>> Which wasn't due to the digital signals being lost at 100mph. Those
 RW>> satellites sent to different planets use digital radio and their
 RW>> signal isn't lost as they travel at speeds hundreds, if not
 RW>> thousands of times faster than 100mph.

 TW>> Becasue of the Doppler Effect.
 TW>> They removed them al and went back to the Analog radios.

 RW> Their problem might have been due to multipath as well.  I've read
 RW> plenty of horror stories about multipath and digital signals. IT
 RW> seems that analog is a bit more forgiving, whereas digital won't be
 RW> able to sort out those signals bouncing off buildings, nearby hills
 RW> etc. and get the real one .

I've noticed a difference in how you find a digital signal vs the days of
analog TV signals with this HDTV I've got. Your aim can be off a few
degrees and the analog signal will be snowy, but with the digital signal,
you won't see any difference. If your aim is more than a few degrees off
with the digital signal, you'll see some pixel fading in the picture, but
the sound is normal.  They really need an S meter for aiming.

 RW> Our spacecraft in ROy's example isn't going to have problems with
 RW> multipath as that local TV station would, or that cop in the parking
 RW> garage.

It can have a doppler problem, but the digital receiver should compensate
for that. Remember, you don't need 100% of the digital information to
complete a message.

                R\%/itt



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