TRTM> The only times CDMA or GSM-TDMA hybrids should have any problem is 
never.
TRTM> They never get static or anything like that, just when there is a very 
lo
TRTM> signal strength it sounds kind of funny.  But it never sounds horrible,
Here in the Charlotte area (BellSouth Mobility DCS), the signal strength
does not have to be all that poor to experience garble (that "kinda
funny" sound you mentioned), which seems to me to be a degradation of
the sampling rate used in the A/D conversion process, from what my
previous experiences with A/D conversion and digital encryption tell
me.
Ours is a GSM system... I would guess that they are using PCM for the
A/D conversion, but I wonder what the sampling rate is? As good as it
sounds, I'd have to guesstimate a rate of around 45-50Kbits/sec. or
better. For it to degrade to the point it does (before it drops your
call), I estimate that the sampling rate drops to 4800 or lower.
As could be expected at 1900 Mhz, range isn't much better than
line-of-sight to a cell site. I have two cell sites about 1/2 mile on
either side of me, and the signal strength, even outside, leaves a lot
to be desired - at this time.
What gets me is that they boast seamless coverage along the interstates
and in my general area, yet I experience a LOT of dropped calls as
opposed to being handed off to another site. And, as your post
mentioned, echo suppression seems to be a BIG problem.
Given the attenuation that results from carrying a handheld in a vehicle
(the problem is only worse at 1900 MHz), I expect to see external
antennas available for GSM phones soon.  In the meantime, I'll try a
passive radiator glass-mount for AMPS.  Surely it couldn't HURT...
My overall summary of GSM PCS: If I didn't get a FANTASTIC airtime plan
for selling the bloody things, I wouldn't have one!  For it to go over
at all, it will HAVE to get better than it currently is.  SOON.
For brief calls (90+% of my calls), if I'm not talking business or
paging someone, gimme my local 2-meter repeater with autopatch every
time.
FM clarity, 10-50 mile range (100+ miles plus up on the Blue Ridge
Parkway with NO roaming fees), and even though I DO support the club
that operates them here, they're open which means I don't have to pay if
I don't want to. I can live with a 3-minute limit on such calls and
everyone knowing what I'm saying.
Later... KF4ICR@juno.com
 * SLMR 2.1a * Me worry? Sysop and I are real close and..... NO CARRIER
                                                                              
                 
--- GEcho 1.11+
(1:379/1)
---------------