Consultants say interference in vehicle electronics is possible
in [Toyota]
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From: dr_jeff on 26 Mar 2010 18:19 E. Meyer wrote: > On 3/26/10 2:51 PM, in article tm3qq5p3ms5rs8tfhl74auqb5hbekl3in6(a)4ax.com, > "clare(a)snyder.on.ca" <clare(a)snyder.on.ca> wrote: > >> On Thu, 25 Mar 2010 21:52:28 -0400, dr_jeff <utz(a)msu.edu> wrote: >> >>> clare(a)snyder.on.ca wrote: >>>> On Thu, 25 Mar 2010 17:28:15 -0500, dbu'' <nospam(a)nobama.com.invalid> >>>> wrote: >>>> >>>>> In article <4babdcf1$1_2(a)news.tm.net.my>, "TE Cheah" <4ws(a)gmail.com> >>>>> wrote: >>>>> >>>>>> 15 yr ago I read of 1 car in USA using auto cruise control drtve >>>>>> past a truck using CB radio, this car @ once got unintended >>>>>> acceleration, this driver switched off his auto cruise & ended this >>>>>> problem. He told medias to warn users of auto cruise control >>>>>> against CB radios. >>>>> Maybe fifteen years ago, but EMI suppression has advanced since then in >>>>> the automotive industry and many other industries too. >>>> There was ONE model of cruise control I heard about that was >>>> extra-fussy about CB Radio interference and IIRC it was OK with a 4 >>>> watt unit installed in the vehicle, but a 100 watt Linear amp in a >>>> vehicle within a couple hundred feet could "jam" it. >>>> >>>> Those cruise control units were VERY primitive compared to anything on >>>> the market today. The affected unit was made by ARA if I remember >>>> correctly and the problem only occurred if using the engine speed >>>> sensor option instead of the magnets on the driveshaft - and that was >>>> closer to 20 or 25 years ago (very early 1980s - early Chevy Citation >>>> comes to mind. >>> Cruise control usually used vehicle speed rather than engine speed. If >>> the car kicks in a lower gear (e.g., when going up hill), then the car >>> would slow down to keep the engine speed constant. >>> >>> I am not saying that there weren't any cars that used engine speed >>> rather than vehicle speed, but I would think that there are few. >>> >>> Jeff >> >> I've installed likely hundreds of aftermarket cruise controls - and on >> front drive vehicles - and particularly with automatic transmissions, >> there were a LOT that used engine RPM to sense speed.. >> Compucruise had that option for sure, as did ARA if I remember >> correctly, and at least one other major manufacturer that I cannot >> remember right now.. If the transmission downshifted the cruise >> control immediately shut down, the same as on a standard shift car. >> ANYTHING that allowed the engine speed to climb quickly disengages the >> cruise on these units - without requiring a clutch switch if installed >> on a standard. >> > > Boy, that's one sucky setup. Useless from any practical standpoint. It would work just as well as the setup on my car (a standard), at least until the clutch starts to go. But the cool thing is that my car will maintain the same speed if I upshift and reengage the cruise control (although I why I would want to be in 3rd gear at 65 mph is another question). Jeff >> I do remember at least one GM X-Car installation that didn't like a >> HAM radio installation - and another - can't remember what right off >> hand - that didn't like the old mobile telephone system installation. >
From: Scott Dorsey on 26 Mar 2010 19:40 dr_jeff <utz(a)msu.edu> wrote: >Scott Dorsey wrote: >> dr_jeff <utz(a)msu.edu> wrote: >>> Wow! People are using CB radios with 12,000 W of power. That would >>> require a 1000 AMP alternator just for the radio (12 V x 1000 A = 12,000 >>> W). Note: the FCC limit is 12 W and 3 orders of magnitude is 1000 (10 x >>> 10 x 10). >> >> Nope, FCC limit is FOUR watts. >> >> And I have sadly seen Alabama Pillboxes in the 6KW range. Really nasty >> output waveform too. And yes, they require a seperate alternator and >> aren't normally run off a 12V system. > >MY bad. The 12 W limit is for SSB transmissions. The AM limit is measured as carrier power, so if you're doing a nice 100% modulation then the peak envelope power is actually eight watts because the positive signal peaks are twice the carrier level and the negative peaks are zero. The SSB limit is actually calculated as peak envelope power directly since there's no carrier with SSB. So comparing the two is really sort of comparing apples and oranges anyway. But most of the big illegal CB users are on AM... this may change in a couple years when the sunspot peak hits and the skip on 11M gets up to the level where it was in 1978... the CB DX craze may start up again. I hope not... --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis."
From: Scott Dorsey on 26 Mar 2010 19:53 dbu'' <nospam(a)nobama.com.invalid> wrote: >To sum, p.15 deals with cable, power lines, motors, switching supplies, >TV's, wireless products, computers, industrial devices and related >interferences to licensed services. > >I never mentioned legal or illegal CB operations of which I am not >involved with. I did, as did the person whom I was replying to in the message that you flamed. That was the whole point of the message you were replying to. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis."
From: Scott Dorsey on 27 Mar 2010 10:08 dbu'' <nospam(a)nobama.com.invalid> wrote: >> The SSB limit is actually calculated as peak envelope power directly since >> there's no carrier with SSB. > >That's not true, SSB is suppressed carrier. Carrier wave is present, >but suppressed. It may or may not internally generated, but it's not being transmitted. if it _were_ transmitted, it would create an annoying beat note on playback unless the receiver BFO was right on the mark. But, more importantly, it counts against your total output power... any residual carrier leakage is wasted power. That's bad, especially when the legal limit is so low you want as much as possible of your signal to actually be carrying information. Type acceptance requirements for aircraft, marine, and commercial SSB gear have limits for how much residual carrier leakage is allowed, and it's very little. Amateur radio operators don't have any such requirements but they are expected to know what they are doing. I don't know what the CB type acceptance requirements are like. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis."
From: C. E. White on 28 Mar 2010 16:45
"Tegger" <invalid(a)invalid.inv> wrote in message news:Xns9D455E8CFBB15tegger(a)208.90.168.18... > dbu'' <nospam(a)nobama.com.invalid> wrote in > news:VoCdnaFE4_R_kjfWnZ2dnUVZ_hc6AAAA(a)giganews.com: > > >> >> I run high power two way radio equipment in my Toyota and have NEVER >> in almost seven years had one glitch of any kind. Nor has any of my >> cell phone equipment ever caused any glitches. EMI can easily be >> suppressed and I believe Toyota has done an extremely good job of >> suppressing it. > > > > I find it difficult to imagine how stray EMI could interfere with the > throttle over a period of time and distance sufficiently long enough to > cause a vehicle to accelerate to a high speed. > > I also find it difficult to imagine how EMI could override many systems > all > at once, such that the car would be impossible to control or shut down. Unfortunatley, it only matters what a jury of untrained people can be convinced of... Ed |