Consultants say interference in vehicle electronics is possible
in [Technical]
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From: clare on 26 Mar 2010 16:12 On Fri, 26 Mar 2010 08:36:04 -0500, "E. Meyer" <e.p.meyer(a)verizon.net> wrote: >On 3/26/10 8:06 AM, in article EZ-dnRV2qrn7LDHWnZ2dnUVZ_oGdnZ2d(a)posted.visi, >"Mark Olson" <olsonm(a)tiny.invalid> wrote: > >> E. Meyer wrote: >>> On 3/25/10 8:52 PM, in article >>> 4-idndohTq_BjjHWnZ2dnUVZ_qWdnZ2d(a)giganews.com, "dr_jeff" <utz(a)msu.edu> >>> wrote: >> >>>> 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. >> >>> Every car I have owned, starting with the 1960 Chrysler Imperial, has been >>> equiped with cruise control. They are/were all designed to regulate vehicle >>> speed, not engine speed. I can't remember any instance of a system that >>> attempted to regulate engine speed, though I do remember some aftermarket >>> kits in the 60's & 70's that were simple mechanical throttle controls. >> >> No one was claiming any factory cruise control worked by keeping engine >> speed fixed. Aftermarket cruise controls had that option though, and for >> cars with standard transmission it was a reasonable choice to tap off the >> coil signal rather than affix magnets to the driveshaft. The only down- >> side was if you set the cruise to 60 in 5th gear, and resumed in 4th you'd >> be doing 70 or so, depending on gear ratios. >> >All the aftermarket kits (as well as factory add-on kits) I encountered for >manual shift cars all passed the speedometer cable through the unit for >speed sensing and added a second cut off to the clutch pedal (along with the >brake pedal cut off present on automatic trans units). All in your experience mabee - but there were a whole LOT that used magnets on the driveshaft instead of tapping into the speedo - and quite a few that used the engine tachometer signal. I've installed hundreds of them. Likely 50 or more with the engine tach input - and those from at least 3 manufacturers. Compu-Cruise was one, ARA and Dayna I THINK were two others - I know we installed a fair number of each of them.
From: clare on 26 Mar 2010 18:04 On Fri, 26 Mar 2010 15:43:02 -0500, "E. Meyer" <e.p.meyer(a)verizon.net> 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. Actually on a standard transmission it worked just great.. On an automatic it wasn't any worse than a lot of today's OEM systems which also "fall out" on a downshift. Only drawback was the "resume" was no good after a shift. > >> 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: dr_jeff on 26 Mar 2010 18:14 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. > --scott MY bad. The 12 W limit is for SSB transmissions.
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." |