Digital Electronics

From reading some on-line articles, you might be led to believe that installing amateur radio gear into a vehicle will void the warranty. Nothing could be further from the truth! If you believed some of the palaver, you wouldn't even use your cellphone!

From the onset, it's important to point out that RFI egress (interference from the on-board electronics) is much more sever than RFI ingress (to those same electronic devices). Based on this fact, it behooves all of us to keep abreast of what's happening with respect to on-board electronics. The reason will become apparent as you read on.

Digital electronics have become so pervasive in modern vehicles, it is impossible to buy one without four or more factory installed digital processors. Known as ECUs (Electronic Control Units), they control every facet of a vehicle. Be that engine operation; standard and satellite radios; climate control systems; anti-lock brakes; vehicle stability systems; hybrid vehicle controllers; navigation systems; and supplemental restraints (so called air bags). More and more, these devices are being networked together. A good example of this is the integrated, voice commanded, Navi-Satellite-Climate control system made by Alpine Electronics available in Acura and Honda vehicles.

Anti-lock braking and vehicle stability systems is another example. In fact, in the not to distant future, integrated anti-lock-stability devices will become mandated on every vehicle sold in the United States. The rational is based on crash studies made by the NHTSA (Nation Highway Traffic Safety Administration), and the NTSB (National Transportation Safety Board), which prove their worth in saving lives. Independent studies by the ARC Network also bare out the results of the studies.

What all of this means is, there is going to be an ever-increasing number of on-board digital electronic devices in our vehicles. Every one of these devices egress some level of RFI. And perhaps a few might be susceptible to RFI ingress, but as pointed out above, that's much less of a problem than it would first appear.

Known as EDRs (and facetiously as black boxes), these devices record specific data which can be retrieved later. A good example is the OBD II (On-Board Diagnostic, level two), which has been mandated on every vehicle sold in the United States since 1996. The latest iterations record all manner of data collected by the various devices. In fact, starting this year and next (2009 & 2010), the number of federally mandated recorded parameters goes up drastically. In addition, manufacturers have their own set of parameters. These include, but aren't limited to, over revving, top speed, cornering Gs, braking force, and in one case, how much you use the radio!

Heretofore, the OBD II recorded mostly engine functions, such as misfires, inoperative devices, or sensor failures. The various codes are stored, which may or may not turn on the check engine light, and are retrieved using a code reader. Code readers come in plain Jane and fancy versions, and range in cost from $29 to as much as $200. They're available from most auto parts stores. Mobile operators would be wise to carry one with them, as RFI ingress is becoming more profound as the number of ECUs and sensors abound.

Every mobile operator has, or has had, instances of both RFI ingress and egress. For example, ignition noise is a pervasive egressed RFI we all have to deal with. However, some forms of ingress may not be pervasive enough to be noticed. For example, modern speedometers use solid state electronics to store the mileage in a form which cannot be "rolled-back" by unscrupulous mechanics. However, the trip data is typically stored by volatile memory. If you disconnect the battery, the data goes away. RFI ingress can also corrupt this data.

On several occasions, I have corrupted my Honda Ridgeline's trip data. In all cases, the leading digit changed. This has only happened while I was operating on 15 meters, which brings up an important point. To wit; RFI ingress and egress have different effects (or lack there of) at different frequencies. You might not have any RFI problems on 20 meters, but that doesn't mean you won't have them on some other band.

Automobile manufacturers do a very creditable job of bullet proofing their electronics against RFI ingress. Ford Motor Company is a prime example. They thoroughly test their electronics, and they even support a web site for what they call Electromagnetic Compatibility (EMC). Although aimed at OEM suppliers, the data presented can certainly be of interest to any amateur radio operator with an RFI ingress problem.

The one thing we'd all like to see, is an equal effect directed toward reducing RFI egress. Of particular importance are those associated with the control electronics in hybrid vehicles, as owners of Toyota's Prius can attest to. Some are so RFI noisy, their AM radios are nearly useless in low signal areas. Adding some insult, are COP ignition systems. While later model units have lower RFI levels than earlier models exhibited, they're far from ideal. As a whole, automobile electronics are a major contributor to the overall background hash we all have to endure.

Fuel injection systems are yet another bothersome source of RFI egress. The latest iterations spray the fuel directly into the chamber (rather than in the intake manifold airstream), and use very high pressure to do so. This requires the injector solenoids to be somewhat more powerful than earlier systems, so the resulting EMI (electromagnetic impulse) is much greater.

One unfortunate fact; automobile manufacturers are exempt from the FCC's Part 15 (Section 15.103, Exempted devices). While there are suggestions that the exempted devices should meet certain radiation levels, the fact remains they are exempt. Until the rules change (not in the foreseeable future), we're all going to continue to suffer ever-increasing levels of RFI egress.

RFI ingress can be annoying, but thankfully it's usually easy to cure. Sometimes a single bead will suffice, perhaps a bonding strap, and sometimes low-current wiring (i.e.: antenna motor control leads) will have to be shielded. One very important thing to keep in mind; for any given RFI problem, what worked on your last install, might not work on this one.

Regardless whether the RFI problem is egress or ingress, the first step is to identify the source. If it's egress, this article should help. If it's ingress, you already have the source, but perhaps not the cure. Just remember, proper wiring and bonding are important.

Hondas and OBD II

If you own a Honda product (including Acura, as well as Toyotas, Isuzus, Kias, and about a dozen others) you need to be aware of the following. They all use the EEC (Electronic Engine Control) to monitor the alternator's voltage and current. It uses these readings (in part) to control the fuel injector timing. This fact causes the fuel injection system to richen up the mixture if heavy loads (amplifier use) are imposed on the alternator. At slow speeds this will cause the engine to hunt (stumble and misfire), and in some cases cause an error code to be sent to the OBD II which turns on the Check Engine light.

Digressing; RFI ingress can also cause this problem, if the level is high enough to interfere with any of the various sensors feeding the EEC, or the EEC itself. If this is your problem, you might want to visit my Split Beads article.

If your Check Engine light turns on, don't panic! Auto Zone, Checkers, and others sell OBD II readers ($29 to $200+ depending on capabilities). They come with a book or CD-ROM listing all of the various error codes. They can also turn off the light and clear the memory as well. Most dealers charge between $50 and $100 to reset the light, so an OBD II reader is a bargain in the long run.

In some cases, the codes can tell you where to install RFI suppression beads. One of the codes I was seeing related to the throttle position sensor. I installed a bead on its wiring harness, and that particular code hasn't reappeared. By the way, just because the Check Engine light isn't on, there may very well be stored codes. Some of these may not be amateur radio related, and could indicate an actual problem.

One last comment with respect to Honda alternators. Most of the newer models use a double wound field coil replete with 12 diodes. For example, the new Ridgeline comes equipped with an 130 amp alternator that is physically smaller than Honda's 6 diode 105 amp unit. I've been told that all Honda vehicles now come with this type of alternator (except the hybrids of course). At least that is one good attribute for us mobile operators.

Data Buss Systems

The OBD II, along with the various on-board ECUs, use ISO-defined networking to transfer data between them. This eliminates redundant signal paths, and allows sharing of the various sensors. More and more new vehicles are being equipped with data buss systems.

Honda calls theirs MICS (Multiplex Integrated Control System). These systems are used to communicate data between the various on-board CPUs. From seat belt reminders, to door ajar warnings, and a myriad of others, their digital voice is easily heard.

For example, the Honda system uses three different frequencies (10.4 kbps, 33.33 kbps, and 500 kbps). These signals mix and produce birdies up and down the amateur spectrum. My Ridgeline has birdies every 5 kHz that are audible from 80 through 15 meters. They are there higher up, but are slightly less bothersome.

The worst offender is the Toyota Prius. The control birdies, along with its digital control circuitry, virtually wipe out the HF and low VHF spectrum. If you own one, or are think about buying one, and intend to operate HF mobile, you're in for a very rude awakening. It should be noted, that other manufacturers use Toyota's SynergyDrive® system, and in most cases, just as RFI noisy. Oddly enough, Honda's hybrid is just slightly noisier than a standard drive train, so there is hope!

The really bad news is, manufacturers will not address any concern whatsoever, with respect to these spurious signals. Remember, they are exempt under FCC rules.

First, we need to remain cognizant of the happenings within the NHTSA, the NTSB, and the automobile industry with respect to EDRs and their possible ramifications. This includes, but is not limited to, what might happen if you have crash, the EDR is corrupted because of RFI ingress, and you're held responsible.

Two, we all should keep the RFI problems we encounter in front of the respective automobile dealers. While most echo the manufacturers sentiments (our vehicles weren't designed for amateur radio), the squeaking wheel will eventually filter up the chain.

Lastly, do yourself a favor by keeping informed. Reading the auto section of your local newspaper, and by subscribing to a good automobile related magazine like AutoWeek are a good start.

Addendum

There is so much misinformation floating on the Internet these days, with respect to warranty coverage when amateur radio gear is installed in vehicles. The vast majority of the information is based on anecdotal and quasi-technical, dare I say, palaver. Most of the information is aimed at the various on-board computerized control equipment in modern vehicles. The common thread seems to be the damage which can (usually the wording is will) be caused to these computers when subjected to high level of RF generated by amateur radio. This is a blatant misrepresentation of the real facts!

Manufacturers go to great length to test all of their electronics, whether they make them, or purchase them. The included charts are from Ford Motor Company (click for enlarged views). The complete documentation can be read here Electromagnetic Compatibility. They represent the minimum testing level. In other words, the various on-board devices must pass muster when subjected to the RF level so listed.

Note the frequency range; .15 MHz, to 2,500 MHz! The Level 1 Requirements chart is dated 2003, but has been updated several times. The latest version extends this to 3,100 MHz to cover the new cellular bands. The revised chart is at right. Take note of the RF levels shown in the chart.

This chart (left) is the Level 2 Requirements, and includes variations based on the country in question. The real truth behind the data, you'd almost have to connect your coax directly to the devices in order to damage them! The chances of damaging them from radiated energy from amateur equipment is virtually nil. You can, however, interfere with their operation by causing false signals to be presented to them. Here are a few examples.

Probably the worse offender in improper wiring. Ford among others published specific wiring recommendations covering any type of installed radio gear, amateur or otherwise. Note their general outlines below. These are the exact recommendations stressed throughout this web site.

1). Power connections should be made directly to the battery and fused as close to the battery as possible. Avoid using cigar lighter or “Power Point” receptacles as power sources for radio communication equipment.

2). Antennas for two-way radios should be mounted on the roof or the rear area of the vehicle. Care should be used in mounting antennas with magnet bases, since magnets may affect the accuracy or operation of the compass on vehicles, if so equipped.

3). The antenna cable should be high quality, fully shielded coaxial cable, and kept as short as practical. Avoid routing the antenna cable in parallel with vehicle wiring over long distances.

4). Carefully match the antenna and cable to the radio to achieve a low Standing Wave Ratio (SWR) and to avoid RF currents on the antenna cable shield.

Note in 1). the comment about power point receptacles is very poignant. I'll add this; even if you're using the MFJ device that is supposed to allow such use! If you are using one of these, you're running a very great risk of an electrical fire, which is without doubt, the costliest of vehicle repairs.

Note in 2). the comment about mag mounts is also poignant. They can, and do, cause erratic operation of Navi equipment as well.

Note in 3). about keeping coax runs short and away from internal wiring. The latter is for those who don't properly install their antennas and end up with excessive common mode currents.

Note in 4). about properly matched antennas.

There is one more common problem which should be noted, and that is ground loops. Mag mount antennas, and using the chassis for DC ground returns is a sure-fire way to create a ground loop. Ground loops are the hardest of maladies to find and cure because they mask themselves as RFI ingress. It is simple to avoid them with proper wiring and mounting.

The next time you read a piece on warranty vs. amateur radio, you'll know the real score!

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