[aprssig] Hybrids & HF-in-motion

Sun Feb 24 21:35:18 EST 2019

 Allow me to re-frame the issue that I raise.
An entire class of mobile vehicle cannot be used for HF Emergency Communications (see Part 97.1(a)) while in motion or otherwise regenerating.

Though the interference is "contained" to the operation originating inside of the car itself, the level of that interference is akin to that presented by BPL however without the ability to drive out of town to get away from it.

The very advantage of having a phenomenal mobile power plant is fully contradicted by the HF interference created by its' very operation.
It is disingenuous to suggest that there is no solution.  Manufacturers have simply exploited the Part 15 exemption given to them as an early-stage development incentive.
Dear ARRL: We need you.  Can you help?
Ev, W2EV

    On Sunday, February 24, 2019, 6:08:38 PM EST, Greg D <ko6th.greg at gmail.com> wrote:  

  I think any approach that aims antennas at an unsuspecting public is going to run afoul of any number of laws, if not the unwanted interest of some 3-letter agencies.  We should also remember that doing an RF scan from 160m through a few GHz is unlikely to happen in real-time as a car zips past at freeway speeds.  Nor do I think that it would be of much benefit if we could.

 The issue here, I believe, is not one of raising the planetary noise floor due to the fleet of cars moving from ICE to EV.  This is not a BPL type of issue.  Cars are still, for the most part, substantially enclosed metal boxes (i.e. Faraday cages), containing whatever RF generated within.  Rather, the question being asked is related to conducted and short-distance radiated interference within the car to the on-board systems.  This includes radios used for entertainment or vehicle communication and monitoring (cellular voice and data, radar, etc.), and the cameras and proximity sensors.  The on-board systems need to have a clean signal from all those devices in order to function properly.  As a result, while generating some RF across a variety of wavelengths is inherent in any electronic system, designers are required to have those fields limited in strength and contained in scope, regardless of regulations, just to make everything and everybody happy.

 My car, for what it's worth, does include an AM radio, but its antenna was improperly installed (it was left buried within the dash, and out of reach for fixing).  This means that the radio's AGC is cranked all the way up, so it's overly sensitive to any interference.   It kind of works when sitting in the garage, picking up the strong local stations without any interference.  Out on the road however, the lack of external reception, and the proximity to internal systems, combine to make the AM band relatively useless.  Often all I hear on AM is the power system, especially during either strong acceleration or regenerative braking.  Other owners who have a properly installed antenna fare a lot better, but there's not enough exclusively-AM content to make me want to take the dash apart to get to the antenna lead.  

 VHF / UHF communication seems fine, by the way, both Ham and FM broadcast.  The FT-817 radio that I have installed is working fine with the repeater network, with no apparent interference in either direction (car to radio or radio to car).  The radio does cover the HF bands, but I haven't tried going there for lack of a suitable antenna.  I may try rigging something up, just for the experimental data.  But trying to work HF when QRP mobile is not much fun without sunspots, so I'm not going to try for anything permanent.

 Also, a note that interference from ham transmitters to the car is not an EV-specific thing.  A club member recently mounted a mobile rig in his ICE truck, and whenever he transmits on 2 meters, even on low power, the car's dash display goes nuts.  He's added ferrites, but has yet to find a solution.

 Greg  KO6TH

 Robert Bruninga wrote:

   How about this!  Wrap a wire loop around an overpass and hang some dipoles along the side an just listen to all the cars going by.  write down the noisey ones. It wount be as good, but will bea fast sample...

  bob

  On Sun, Feb 24, 2019 at 3:18 AM Greg D <ko6th.greg at gmail.com> wrote:

  It would certainly be an interesting project, but a static "put it the Device Under Test on the test stand and aim an antenna at it" wouldn't give an  accurate picture of a car's behavior.  Just as an ICE's spark-gap transmitters, as well as alternators and the various other electronic systems change their characteristics with RPM and engine / accessory load, so do EVs, and with an added dimension when they go into regen.  You can't measure this stuff with a parking lot test.  

 More accurate, I think, would be to put the antenna and test equipment in/on the car, and drive it on a prescribed course, including acceleration and deceleration events.  This could be done on an actual track or a dynamometer.

 Greg

 Robert Bruninga wrote:

    We really do need to get a handle on this.

  Set up a standardized test coil in the Parking lot of ARRL and have every visitor park on it for a test.  Tehn publish the stats.  Good project!

  Bob

  On Sat, Feb 23, 2019 at 2:42 PM Ev Tupis via aprssig <aprssig at lists.tapr.org> wrote:

   I guess that I can assume that QRM is as prevalent as it always has been.  I was hoping that the state of the art would have progressed by now...but with an FCC waiver to Part 15 applied there is little incentive.

      On Friday, February 22, 2019, 10:19:21 AM EST, Ev Tupis via aprssig <aprssig at lists.tapr.org> wrote:  

     A number of years have passed since I asked this, and I find myself in the market for another  car, so I'll ask again. 
  Is there a recommendation (from personal experience) in regard to a hybrid car that presents minimal QRM  to HF operation while in-motion? 
  Ev, W2EV 
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