On 2007-03-07, SMS <scharf.steven@geemail.com> wrote:
> Dennis Ferguson wrote:
>
>> have a friend who lives in La Honda who was an AT&T customer for
>> a long time, and who now has Sprint service for the above reason. If there
>> are people in the Santa Cruz mountains who prefer Verizon they must
>> live further south, closer to Highway 9, where Verizon does have coverage.
>
> My experience is all with AC1. I do a lot of cycling and hiking
> throughout the Santa Cruz mountains, and the southern part of San Mateo
> county. In many of these areas I get only AMPS coverage. I have no
> handset with AC2, so I can't comment on AC2 coverage. I presume that its
> Verizon AMPS and not AT&T AMPS since I've never been charged roaming,
> and because I know that Verizon AMPS is used on most of the roadside
> call boxes on the roads that have call boxes.

Yes, I remember you also saying you weren't charged for roaming
on Cingular AMPS in Florida too. I don't know if you lead a charmed
life or if there's something wrong with my phone or PRL, but when
I've tried I got no service from Cingular AMPS on my AC2 Verizon phone
where my Sprint phone got it. I also have a friend who I think is a
Verizon customer who told me he once had to phone 911 back there when
is phone was getting service with no bars. He dialed 911 and the call
connected, but when he was done he said he now had an "Emergency Only"
all-bar analog signal. The only way he could get rid of it and make the
phone search for native service again was by powering the phone
off and on. I think his phone also didn't roam on Cingular AMPS.
I'd been assuming that anywhere Verizon (or Airtouch or PacTel)
didn't have towers the state just got AT&T (or Cellular One?) to
provide call box service instead, which might also explain why Cingular
would keep towers on that most of their customers can't use.

Note that I haven't had a phone for a while that would tell me who
the service is coming from, and my friend's use of Sprint service
doesn't necessarily prove anything since Sprint is fairly promiscuous
about roaming these days. I know for sure that my friend used to
use AT&T service back there, even though there's no digital Cingular
service now, that I lost service in there when I moved from Sprint to AC2
Verizon, and that the Verizon AC2 coverage map has big areas of white
where AC1 (and Sprint) think (and I know) there might be analog service.
If it were all Verizon AMPS, AC1 and AC2 wouldn't be different. I can
see no assumption that explains this better than that this is AT&T,
not Verizon, AMPS.

> What you have to realize about coverage maps is that if the tower has
> both digital and AMPS, then they will show that area as digital. However
> you'll get AMPS service for a much longer distance away from the tower
> than you'll get CDMA service (or GSM service for that matter).

This we'll probably need to disagree on, since I can't see a way it
could possibly be true. I have a paper somewhere from people at Qualcomm
which does a theoretical analysis to find that CDMA has an 11 db Eb/No
power advantage over FM AMPS (6 db for CDMA versus 17 db for FM); that
is (assuming not much sharing of the CDMA channel to boost No) a
200 mW CDMA phone should operate over the same distance as a >2W AMPS phone.
I admit this result is convenient for Qualcomm since we've all given up
2W phones for 200 mW phones. I also freely admit that Qualcomm has probably
made at least one other over-optimistic assertion about CDMA performance,
that FM is useable with less than perfect signal where CDMA might not be and
that I don't understand enough about the theory to critically evaluate
the assumptions which lead to 11 db. What I can tell you with great
certainty, however, is that a 200 mW CDMA phone will always get better
distance that a 200 mW AMPS phone, which is what we're comparing here.
+11 db is a huge enough theoretical difference that there is just no way
it could actually be a negative number in real life.

You might want to consider the possibility that, when you are getting
AMPS service but have lost the digital service, that what you are seeing
isn't the longer reach AMPS but rather AMPS from a different company,
like in the Santa Cruz mountains. Your phone seems to roam freely
to Cingular, Cingular clearly has sites with no GSM yet, and I think
your explanation disagrees with the physics.

Dennis Ferguson