|
|
The Telecom Digest for May 3, 2010
Volume 29 : Issue 122 : "text" Format
Messages in this Issue:
Re: IEEE article on GSM interference affecting GPS landing systems (Sam Spade)
Re: IEEE article on GSM interference affecting GPS landing systems (Michael D. Sullivan)
Re: IEEE article on GSM interference affecting GPS landing systems (Steven)
====== 28 years of TELECOM Digest -- Founded August 21, 1981 ======
Telecom and VOIP (Voice over Internet Protocol) Digest for the
Internet. All contents here are copyrighted by Patrick Townson and
the individual writers/correspondents. Articles may be used in other
journals or newsgroups, provided the writer's name and the Digest are
included in the fair use quote. By using -any name or email address-
included herein for -any- reason other than responding to an article
herein, you agree to pay a hundred dollars to the recipients of the
email.
===========================
Addresses herein are not to be added to any mailing list, nor to be
sold or given away without explicit written consent. Chain letters,
viruses, porn, spam, and miscellaneous junk are definitely unwelcome.
We must fight spam for the same reason we fight crime: not because we
are naive enough to believe that we will ever stamp it out, but because
we do not want the kind of world that results when no one stands
against crime. Geoffrey Welsh
===========================
See the bottom of this issue for subscription and archive details
and the name of our lawyer, and other stuff of interest.
Date: Sat, 01 May 2010 22:10:20 -0700
From: Sam Spade <sam@coldmail.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: IEEE article on GSM interference affecting GPS landing systems
Message-ID: <VKednciJosGhlEDWnZ2dnUVZ_gednZ2d@giganews.com>
Steven wrote:
> Last year while a friend was driving with me, he got a call on his
> AT&T phone, right after he answered it my TomTom GPS went nuts. I'm
> not sure if it was the phone as there were major power transmission
> lines crosssing the highway, so it could have been those, but in the
> past I never noticed it. He was on the phone just a short time so
> the next time he is with me I'll have him make a call and see what
> happens, my phone is Sprint and I have never had problems like that
> at all.
His phone was very close to your antenna and receiver.
That proximity can't happen on an airliner.
Date: Sun, 2 May 2010 11:08:45 -0400
From: "Michael D. Sullivan" <mds@camsul.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: IEEE article on GSM interference affecting GPS landing systems
Message-ID: <i2wa76e5e941005020808q4c3a2a9erddb7d37693507df7@mail.gmail.com>
On Sat, 01 May 2010 15:18:04 -0700 Steven wrote:
[snip]
> Last year while a friend was driving with me, he got a call on his AT&T
> phone, right after he answered it my TomTom GPS went nuts. I'm not sure
> if it was the phone as there were major power transmission lines
> crosssing the highway, so it could have been those, but in the past I
> never noticed it. He was on the phone just a short time so the next
> time he is with me I'll have him make a call and see what happens, my
> phone is Sprint and I have never had problems like that at all.
AT&T uses GSM, which in turn employs TDMA transmissions. These switch
your phone's transmitter on and off about 1000 times per second when
the handset is communicating with a base station (yes, even when you
aren't using it, the handset periodically checks in). The result is
that a 1 kHz square wave is emitted. This can be induced into nearby
unshielded electronics and heard as an audio buzzing sound. This
often happens when a TDMA phone is next to a speakerphone, amplified
computer speaker, etc. This emission is very low level, so the phone
needs to be very close to the audio device.
Sprint and Verizon phones don't use TDMA transmissions, so they don't
cause this buzzing.
--
Michael D. Sullivan
Bethesda, MD
Date: Sun, 02 May 2010 12:06:51 -0700
From: Steven <diespammers@killspammers.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: IEEE article on GSM interference affecting GPS landing systems
Message-ID: <hrkigb$fhk$1@news.eternal-september.org>
Michael D. Sullivan wrote:
> On Sat, 01 May 2010 15:18:04 -0700 Steven wrote:
> [snip]
>> Last year while a friend was driving with me, he got a call on his AT&T
>> phone, right after he answered it my TomTom GPS went nuts. I'm not sure
>> if it was the phone as there were major power transmission lines
>> crosssing the highway, so it could have been those, but in the past I
>> never noticed it. He was on the phone just a short time so the next
>> time he is with me I'll have him make a call and see what happens, my
>> phone is Sprint and I have never had problems like that at all.
>
> AT&T uses GSM, which in turn employs TDMA transmissions. These switch
> your phone's transmitter on and off about 1000 times per second when
> the handset is communicating with a base station (yes, even when you
> aren't using it, the handset periodically checks in). The result is
> that a 1 kHz square wave is emitted. This can be induced into nearby
> unshielded electronics and heard as an audio buzzing sound. This
> often happens when a TDMA phone is next to a speakerphone, amplified
> computer speaker, etc. This emission is very low level, so the phone
> needs to be very close to the audio device.
>
> Sprint and Verizon phones don't use TDMA transmissions, so they don't
> cause this buzzing.
>
I know about the types of technology that the companies use, I'm a COEI
Installer and though I work mostly on wire line switches I have in the
past and sooner or later will again work on Cell switches.
Right after the problem happened I contacted TomTom support and they
told me about the same thing, but that the GPS is made so as not to get
interference from other devices. I have since updated to a newer unit
and have yet to have a problem, as I said next time I get a chance to
test it I will. I have been on the same highway with the transmission
lines and did not have a problem, the GPS I have now is set for real
time updates so it is getting updated from traffic and weather services
as well as other TomTom GPS units.
--
The only good spammer is a dead one!! Have you hunted one down today?
(c) 2010 I Kill Spammers, Inc., A Rot in Hell. Co.
TELECOM Digest is an electronic journal devoted mostly to telecom-
munications topics. It is circulated anywhere there is email, in
addition to Usenet, where it appears as the moderated newsgroup
'comp.dcom.telecom'.
TELECOM Digest is a not-for-profit, mostly non-commercial educational
service offered to the Internet by Bill Horne. All the contents
of the Digest are compilation-copyrighted. You may reprint articles in
some other media on an occasional basis, but please attribute my work
and that of the original author.
The Telecom Digest is moderated by Bill Horne.
Contact information: Bill Horne
Telecom Digest
43 Deerfield Road
Sharon MA 02067-2301
781-784-7287
bill at horne dot net
Subscribe: telecom-request@telecom-digest.org?body=subscribe telecom
Unsubscribe: telecom-request@telecom-digest.org?body=unsubscribe telecom
This Digest is the oldest continuing e-journal about telecomm-
unications on the Internet, having been founded in August, 1981 and
published continuously since then. Our archives are available for
your review/research. We believe we are the oldest e-zine/mailing list
on the internet in any category!
URL information: http://telecom-digest.org
Copyright (C) 2009 TELECOM Digest. All rights reserved.
Our attorney is Bill Levant, of Blue Bell, PA.
---------------------------------------------------------------
Finally, the Digest is funded by gifts from generous readers such as
yourself who provide funding in amounts deemed appropriate. Your help
is important and appreciated. A suggested donation of fifty dollars
per year per reader is considered appropriate. See our address above.
Please make at least a single donation to cover the cost of processing
your name to the mailing list.
All opinions expressed herein are deemed to be those of the
author. Any organizations listed are for identification purposes only
and messages should not be considered any official expression by the
organization.
End of The Telecom Digest (3 messages)
|
or 