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How can electronic devices be protected from radio interference?
Deleted member 52902
Are you experiencing a problem? I am betting you are not, unless it is some vintage CB linear amplifier that were not engineered, and EMI/RFI tested.
I spent much time at GM where the company I worked for, installed a computer in a control room adjacent to a larger room where cars and light trucks were brought in, and chained down in place with drive wheels set on top of a 40 inch roll equipped, (instead of the typical 8.5 inch) dynamometer. Along with a custom, hydraulic driven fan, speed controlled to match air flow at any typical driving speed. The computer cabling was pulled through welded conduit, connected to the electric motors of the dyne, located underground and all RFI shielding between the vehicle room and the dyno motors and rather large SCR motor controller, also all RFI shielded. The vehicle room walls and vehicle entrance/exit and man doors were all completely sealed from any RFI leakage between that room and the control room.
To these walls, anechoic cones covered all wall, door and ceiling surfaces. When the car or light truck vehicle was rolled into this vehicle room and chained down onto the dyno, the exhaust pipe(s) had stainless steel tubes much like fire trucks use inside their buildings, to vent the exhaust to the outside.
The only electronics located in the vehicle room were a number of antenna arrays for frequencies between Low, Medium, High (HF), VHF and UHF. again the feed lines for these were located inside welded conduit with the transmitters to these antennas, located in the control room.
To run the vehicles through radiated signal testing, the vehicle had a special, adjustable-length arm our company created to be placed between the firewall inside the car, and the driver seat. Attached to this arm was a hydraulic ram, with air pumped to extend or retract the ram, with the ram-extension clamped to the vehicles accelerator pedal. room was completely sealed. That took some time to get the computer and ram to move the accelerator pedal smoothly; one of the engineers ( I forget if it was ours, bro GM's) introduced a way to "dither" the air flow to overcome resistance to undesired movement. Bearing in mind the accuracy off pedal movement was still better than a human's leg and foot action.
In the control room, the computer could be utilize the EPA City and Highway driving cycle used for gaining miles per gallon information. Now this same cycle would "drive" the vehicle through stops, starts, acceleration, etc that would be experienced in the city and highway driving. I recall we had manual; override with a vernier panel dial. And I imagine over time, other range of driving speeds and "distances" are programmed into the computer by the GM folks. So why all of this?
This lab was a joint design by GM and our company to be able to operate a vehicle as if it were outdoors and on the road on flat, uphill, downhill, speeding, etc to see what effect external RF signals would have on any and all of the vehicles electronics. An environment that exceeded the RF levels that we humans should never experience in the real world of radio waves, high power transmission lines, etc from any frequency from the AM broadcast band up into microwave beamed signals. This was back in the late 1980's when this project would put in place.
Other than two issues that occurred during my time with the company, I imagine this setup was used for years. Possible still Lin place today, except I am certain the custom built computer and software was eventually tossed and replaced with an off the shelf DELL or similar high-end PC in the control room. I do know of two issues with the system; one was our fault. The other, GM's fault;
One day while a vehicle was chained down and idling, I suppose before a test tun, inside this sound and RF proof room, our computer had thermal runaway in a chip that controlled the accelerator position. And of course, it shorted in such a manner that caused the accelerator to go to the floor. Nobody could hear the engine screaming away from the control room. Video recording later showed the vehicle smoking/steaming as it raced in its chain down position with the dyne free-wheeling. And shortly after all the smoke and steam, the engine blew. This was a very special "Mule" car where all of the tolerances in the powertrain are built to higher tolerances than product line cars. A very, very expensive Mule, blown engine. Ouch. Flying out from California pronto, to Michigan into a meeting room with a bunch of higher ups, I thought we were really going to, well, you can imagine. In any case, it went well; our engineers developed a fail-safe upgrade; swapped out the. board and did a lot of testing. Phew. Back to California. and never had another issue from our side. But...
GM one day, decided they needed to test to see what electronics in a as told to me, a dump truck might be affected by RF. So they set it up on the dyne in the vehicle room and began their testing. What I remember is the dump truck's anti-lock braking system locked up during a certain RF signal barrage. The truck was running on the dyne at a high speed when this occurred. The dyne that was designed and spec'd for car and light truck vehicle weight and engine torque, etc. When the dump truck brakes locked up, the giant flywheels that are clutch in on the dyne roll shaft and other mechanical components, were destroyed. A truck that was overweight for the dyne, really did a number on the dyne mechanicals. Two guys form our company were flown out pronto, to access the damage and order parts, besides the known parts already told to us, and shipped out to GM ahead of our guys. I left the company eventually to enter another job in mainframe computers but as far as I know; our setup there at GM may have had a lot of test vehicles run on it. And the point of all this was to insure the safety of any car and light duty truck, would not experience issues with external RF signals.
One would hope that todays cars and trucks et al, still undergo rigorist testing one individual electronics assemblies as well as complete vehicles to never have issue from any form of radiated source. That is, from any source that must conform to stringent FCC EMI/RFI testing.
An example that might cause issues; Today we have a litany of Chines made GMRS and FRS radios. And some amateur radio operators have found a way to alter a FCC certified VHF and/or UHF radio, to also operate in the GMRS/FRS frequencies. Could the modifications inside the ham radios to transmit in the 467.xxx frequencies, mess with the RF radiation output adversely? I doubt it. But only an expensive array of testing in an EMI/RFI lab or elsewhere with some level of test equipment could confirm any issue. Again, I seriously doubt it. All that can be said is these radios were not tested and FCC certified to operate on GMRS/FRS frequencies with the transmitter circuitry, optimized for 420-450 Megacycle range, now transmitting 16 Mc above the ham radio UHF band.
What I think personally about your question? I would not burn a person that has tinkered with their radios to operate outside of their FCC/CE certification. Without proof, six ways from Sunday that it does. I really doubt that you would find a problem with any electronics near or connected into a vehicles electronics. Honestly, I wish I never sold my old J10 truck. Other than the worst brakes on the planet and a harsh ride even on pavement, it had zero electronics except an AM radio. No LED's. No other electronics. Drivable after an EMP although we certainly hope that never happens.
I spent much time at GM where the company I worked for, installed a computer in a control room adjacent to a larger room where cars and light trucks were brought in, and chained down in place with drive wheels set on top of a 40 inch roll equipped, (instead of the typical 8.5 inch) dynamometer. Along with a custom, hydraulic driven fan, speed controlled to match air flow at any typical driving speed. The computer cabling was pulled through welded conduit, connected to the electric motors of the dyne, located underground and all RFI shielding between the vehicle room and the dyno motors and rather large SCR motor controller, also all RFI shielded. The vehicle room walls and vehicle entrance/exit and man doors were all completely sealed from any RFI leakage between that room and the control room.
To these walls, anechoic cones covered all wall, door and ceiling surfaces. When the car or light truck vehicle was rolled into this vehicle room and chained down onto the dyno, the exhaust pipe(s) had stainless steel tubes much like fire trucks use inside their buildings, to vent the exhaust to the outside.
The only electronics located in the vehicle room were a number of antenna arrays for frequencies between Low, Medium, High (HF), VHF and UHF. again the feed lines for these were located inside welded conduit with the transmitters to these antennas, located in the control room.
To run the vehicles through radiated signal testing, the vehicle had a special, adjustable-length arm our company created to be placed between the firewall inside the car, and the driver seat. Attached to this arm was a hydraulic ram, with air pumped to extend or retract the ram, with the ram-extension clamped to the vehicles accelerator pedal. room was completely sealed. That took some time to get the computer and ram to move the accelerator pedal smoothly; one of the engineers ( I forget if it was ours, bro GM's) introduced a way to "dither" the air flow to overcome resistance to undesired movement. Bearing in mind the accuracy off pedal movement was still better than a human's leg and foot action.
In the control room, the computer could be utilize the EPA City and Highway driving cycle used for gaining miles per gallon information. Now this same cycle would "drive" the vehicle through stops, starts, acceleration, etc that would be experienced in the city and highway driving. I recall we had manual; override with a vernier panel dial. And I imagine over time, other range of driving speeds and "distances" are programmed into the computer by the GM folks. So why all of this?
This lab was a joint design by GM and our company to be able to operate a vehicle as if it were outdoors and on the road on flat, uphill, downhill, speeding, etc to see what effect external RF signals would have on any and all of the vehicles electronics. An environment that exceeded the RF levels that we humans should never experience in the real world of radio waves, high power transmission lines, etc from any frequency from the AM broadcast band up into microwave beamed signals. This was back in the late 1980's when this project would put in place.
Other than two issues that occurred during my time with the company, I imagine this setup was used for years. Possible still Lin place today, except I am certain the custom built computer and software was eventually tossed and replaced with an off the shelf DELL or similar high-end PC in the control room. I do know of two issues with the system; one was our fault. The other, GM's fault;
One day while a vehicle was chained down and idling, I suppose before a test tun, inside this sound and RF proof room, our computer had thermal runaway in a chip that controlled the accelerator position. And of course, it shorted in such a manner that caused the accelerator to go to the floor. Nobody could hear the engine screaming away from the control room. Video recording later showed the vehicle smoking/steaming as it raced in its chain down position with the dyne free-wheeling. And shortly after all the smoke and steam, the engine blew. This was a very special "Mule" car where all of the tolerances in the powertrain are built to higher tolerances than product line cars. A very, very expensive Mule, blown engine. Ouch. Flying out from California pronto, to Michigan into a meeting room with a bunch of higher ups, I thought we were really going to, well, you can imagine. In any case, it went well; our engineers developed a fail-safe upgrade; swapped out the. board and did a lot of testing. Phew. Back to California. and never had another issue from our side. But...
GM one day, decided they needed to test to see what electronics in a as told to me, a dump truck might be affected by RF. So they set it up on the dyne in the vehicle room and began their testing. What I remember is the dump truck's anti-lock braking system locked up during a certain RF signal barrage. The truck was running on the dyne at a high speed when this occurred. The dyne that was designed and spec'd for car and light truck vehicle weight and engine torque, etc. When the dump truck brakes locked up, the giant flywheels that are clutch in on the dyne roll shaft and other mechanical components, were destroyed. A truck that was overweight for the dyne, really did a number on the dyne mechanicals. Two guys form our company were flown out pronto, to access the damage and order parts, besides the known parts already told to us, and shipped out to GM ahead of our guys. I left the company eventually to enter another job in mainframe computers but as far as I know; our setup there at GM may have had a lot of test vehicles run on it. And the point of all this was to insure the safety of any car and light duty truck, would not experience issues with external RF signals.
One would hope that todays cars and trucks et al, still undergo rigorist testing one individual electronics assemblies as well as complete vehicles to never have issue from any form of radiated source. That is, from any source that must conform to stringent FCC EMI/RFI testing.
An example that might cause issues; Today we have a litany of Chines made GMRS and FRS radios. And some amateur radio operators have found a way to alter a FCC certified VHF and/or UHF radio, to also operate in the GMRS/FRS frequencies. Could the modifications inside the ham radios to transmit in the 467.xxx frequencies, mess with the RF radiation output adversely? I doubt it. But only an expensive array of testing in an EMI/RFI lab or elsewhere with some level of test equipment could confirm any issue. Again, I seriously doubt it. All that can be said is these radios were not tested and FCC certified to operate on GMRS/FRS frequencies with the transmitter circuitry, optimized for 420-450 Megacycle range, now transmitting 16 Mc above the ham radio UHF band.
What I think personally about your question? I would not burn a person that has tinkered with their radios to operate outside of their FCC/CE certification. Without proof, six ways from Sunday that it does. I really doubt that you would find a problem with any electronics near or connected into a vehicles electronics. Honestly, I wish I never sold my old J10 truck. Other than the worst brakes on the planet and a harsh ride even on pavement, it had zero electronics except an AM radio. No LED's. No other electronics. Drivable after an EMP although we certainly hope that never happens.
