Cell phone interference w/ car computer? - diyAudio
Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 5th November 2012, 02:53 AM   #1
diyAudio Member
 
Join Date: Mar 2007
Location: Canandaigua, NY USA
Default Cell phone interference w/ car computer?

Understand I'm not a cell phone person! Can't stand the annoying things. I happened to bring one on a trip today in my POS 2004 Mazda3. When I got in the car the door locks all clattered at the same time, twice for several seconds. Later I made a call and the dome light wouldn't respond to the switches and turn off anymore. Shutting off and restarting the car put everything right again. I know they affect computer audio systems and sometimes video, but has anybody ever seen anything like this? Random chance problem or was it really the cell phone getting involved with the alarm or computer system?
__________________
May the root sum of the squares of the Forces be with you.
  Reply With Quote
Old 5th November 2012, 03:01 AM   #2
diyAudio Member
 
theAnonymous1's Avatar
 
Join Date: Feb 2004
Location: Anonymityville
Never heard of such a thing myself. What type of phone is it, CDMA or GSM?

I guess to be certain, try and duplicate the incident?
  Reply With Quote
Old 5th November 2012, 09:23 AM   #3
marce is offline marce  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Location: Blackburn, Lancs
There have been similar problems in the past:
EMCIA - EMC Industry Association, Products and Members
Have a look at past "Bannana skins" section of the EMC club siteif yoiu get chance, some of the problems caused by EMI are worrying and in some cases humourous. But it is an increasing problem and one which in general is often overlooked on DIY sites.
Thisiswhy mobiles have to be switched off when near sensitive medical equipement and during take of and landing on planes.
imaginewhat problems an EMCevent could causewhen your coming in to land..
  Reply With Quote
Old 5th November 2012, 02:04 PM   #4
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
I have about 5 years of experience designing cell phones, about 10 years ago. I have always been concerned with cell phones and electronics for reasons other than my job. I build loud guitar amps!

Cell phones operate on several different non compatible standards called "MA's". MA stands for multiple access, a means for several simultaneous conversations on a single radio channel. Most 3G and 4G (3rd and 4th generation technology) MA's use continuous transmission, the radio transmitter runs continuously all the time the phone is sending data.

Some 2G and 3G MA's use TDMA (Time Division Multiple Access) to allow multiple access. The voice is digitized and the data is packetized. The base station will allow the phone to use one or more time slots on a given radio channel, which is divided up into small parcels of time that are dynamically assigned to each concurrent user. The radio transmitter is switched on during its time slot and off during the transmit time for other users at a rate from 16 to 66 mS depending on the MA.

Phones using this pulsed transmission mode are the ones most likely to cause interference with electronic devices, and the fast rising RF edges are what you hear in your cheap PC speakers. The usual offenders are GSM, iDEN, EDGE, and variants of these, since they all use TDMA. GSM is the most popular MA in the world, but all of these MA are slowly being replaced with 3G and 4G systems.

I admit to having fun in some of the big box electronics and music stores by taking a phone, cranking its RF power up to max and going into the home theater room or the hands on guitar amp room. Some electronics are succeptable to RF from cell phones, and some isn't. The low priced stuff like cheap PC speakers are usually bad, but there are some surprises. A $7000 Yamaha digital grand piano went absolutely bonkers whenever I got within a few feet of it.

When cars started getting "drive by wire" throttle control I was skeptical, but I have been unable to cause any anomalies in several cars even when a "worse case" phone was placed on the "brain box" or ran all over the sensors and actuators under the hood.

It is possible that the phone caused the anomalies that you observed, but there would likely be a secondary cause. Usually it is caused by a repair tech not reinstalling all the shielding, and grounding features originally installed in the car.

I built a hot rod Dodge back in the 80's, installing a turbo charged engine using early (1984) digital engine control into a car that was originally carbureted. I left out a lot of stuff I didn't absolutely need and made my own wiring harness from scratch. Yes, it was possible to stall that car with an iDEN phone next to the unshielded brain box board.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 5th November 2012, 03:17 PM   #5
diyAudio Member
 
Join Date: Mar 2007
Location: Canandaigua, NY USA
Very interesting. Drive-by-wire scares the $hit out of me. I want my critical controls mechanically connected to the things they operate!
__________________
May the root sum of the squares of the Forces be with you.
  Reply With Quote
Old 5th November 2012, 03:55 PM   #6
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Were any of the car electrics made in China? If so, some of the EMC compliance components may have been omitted in the factory; I can't believe that it is only SMPS which get this treatment.
  Reply With Quote
Old 5th November 2012, 04:05 PM   #7
marce is offline marce  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Location: Blackburn, Lancs
Nope, and sometimesimported products dont measure up very well, even withthe CE mark on them...
  Reply With Quote
Old 5th November 2012, 04:30 PM   #8
diyAudio Member
 
Join Date: Mar 2007
Location: Canandaigua, NY USA
Well, false alarm. The Mazda3 is still a POS and it did it again this morning with no cell phone present. Just failing electronics I guess, or maybe something related to the cold.

I should qualify my comments in that the intro year of the Mazda3 was a POS, but the later ones seem better. Most unreliable and expensive to own car I've ever had in 38 years of driving.
__________________
May the root sum of the squares of the Forces be with you.
  Reply With Quote
Old 5th November 2012, 05:15 PM   #9
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
In the UK we always found it difficult to take Mazda cars seriously, because to most people Mazda is a brand of light bulb. Older folk may remember Mazda radio valves too.
  Reply With Quote
Old 5th November 2012, 05:28 PM   #10
marce is offline marce  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Location: Blackburn, Lancs
Try a Citroen C3, gearbox disintegrated, ECU gone duff, clutch, heater, brake calipers , two springs and a few other things in the last 8 months...spent more time in the garage than on the road recently. As to the elctronics, got a load of controls on the steering wheel, great fun, we have a lottery now on what will happen when a button is pressed, my favorite is volume up, it operates the rear wiper
P>S> it is for sale if anyone interested (well when I get a new ECU)
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
mobile phone interference Witti Analogue Source 2 15th May 2012 01:19 PM
What cell phone do you have? blackwillam01 The Lounge 35 28th October 2009 03:27 AM
Mobile Phone Interference gingertube Tubes / Valves 14 6th October 2009 10:20 PM
Horn for Cell phone alexmoose Multi-Way 1 9th August 2008 10:20 PM
Cell Phone mini speakers Ranjit Multi-Way 0 15th July 2005 04:16 PM


New To Site? Need Help?

All times are GMT. The time now is 04:50 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2