I experience the same symptom: the door lock remote decreases in range from 15 meters to 1 meter. My car is a Citroen CX with an aftermarket (which does *not* mean cheap and crappy here!) remote locking system which I installed myself. The car does not have an alarm system.

A few thoughts:

- the symptoms that I see are very, very similar to the symptoms others see, so I guess it's a valid conclusion that they have the same reason.

- as my car doesn't have any fancy electronics like an alarm system, and the remote locking system is connected to nothing else but the doors, ignition and 12V power, we can rule out interaction with alarms or other comfort electronics as a reason.

- the symptoms disappear as sonn as I pull out the empeg. Range is back to normal, even if I do not change the batteries in the remote. So we can rule out bad batteries as reason.

- my car's head unit (Kenwood TV/FM/Navigation system) draws its power from the same point as both the empeg and the remote lock system. However, leaving the Kenwood running does not have an impact on the range. The Kenwood uses a big backlit LCD, so I'm very sure it draws more power than the empeg, which would cause a much bigger drop in voltage on the power lines. Btw, the current an empeg draws in standby mode should cause only *minimal* voltage drops, if any. So we can rule out voltage drops as a reason.

- In Germany, the only radio frequency that is available for things like remote door locks is 433MHz. So, as my remote door locking system is EU certified, I strongly assume (couldn't verify, unfortunately) that is operates at that frequency. I just performed an interesting experiment to check if the empeg has any influence on 433MHz devices: cordless mice use the same frequency, so I placed the base station of my Logitech cordless optical mouse on top of the empeg (the empeg running on AC). The distance between the base station/empeg and the mouse was around 1 meter. And indeed: as soon as the empeg was running or in standby mode, the mouse behaved erratically! When I disconnected the empeg from AC power without moving the base station, the effect went away.

Moving the base station more than a few centimeters away from the empeg also cured the problem, so the empeg doesn't radiate much. However, as the remote door locking sender uses very tiny batteries, it sends a *very* low power signal, which means the receiver in the car has to be *very* sensitive.

In my car, the receiver's antenna is some 50 cm away from the empeg. If I remember correctly, the power of an electromagnetical signal drops with distance to the second power. So, if I use the remote from 10 meters distance to the car, which is 20 times the distance the empeg has to the antenna, then even if the empeg sends with only 1/400th of the already very low-power remote signal, the antenna would receive them both with the same strength. This (admittedly not very detailled) calculation leads me to the conclusion that despite the empeg being FCC certified, it it very possible that it still interferes with weak remote door locking signals.

So, the next steps would have to be:

- find out with which power a remote usually sends. Can anybody who experiences the problems try to ask their car manufacturers or even try to find that in your manuals?

- try to get access to a measuring receiver to actually measure the radiation (frequency and power) of the empeg. Empeg folks: do you have any data from your FCC tests that could be helpful here?

- based on that data, do a more thorough calculation to see if my theory can be proved or disproved.

Daniel

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"My software never has bugs. It just develops random features."

- In Germany, the only radio frequency that is available for things like remote door locks is 433MHz. So, as my remote door locking system is EU certified, I strongly assume (couldn't verify, unfortunately) that is operates at that frequency. .

It will be, 98% probability. This is the European standard low power license exempt frequency for telemetry systems

And indeed: as soon as the empeg was running or in standby mode, the mouse behaved erratically! When I disconnected the empeg from AC power without moving the base station, the effect went away.

This does seem to show that there is some interference from the empeg, I have to admit.

Moving the base station more than a few centimeters away from the empeg also cured the problem, so the empeg doesn't radiate much. However, as the remote door locking sender uses very tiny batteries, it sends a *very* low power signal, which means the receiver in the car has to be *very* sensitive.

It is. The receivers for the 433MHz band data transmission system often have quoted sensitivities of around -107dBm, witch is technical speak for absolutely sod all power. Bear in mind this is for receiving a good signal, as well. Much less power on the right frequency will cause interference, if the transmitter is close enough.

- find out with which power a remote usually sends. Can anybody who experiences the problems try to ask their car manufacturers or even try to find that in your manuals?

The output power varies slightly with application and country. However, in the UK this band is regulated under the MPT1340 exemption, covering both 418MHz and 433MHz, and limits the output power to less than 1mW effective radiated power. One TX module I have used had a power output with a 1/4 wave antenna of something like 500uW. This really isn't a lot.

- try to get access to a measuring receiver to actually measure the radiation (frequency and power) of the empeg. Empeg folks: do you have any data from your FCC tests that could be helpful here?

This has been done. Believe me, this has been done. Ad nauseum. It's a pain in the arse, the tests you have to go through to be able to sell any electronics nowadays. And, unless you have access to (1) an electromagnetically clean isolation chamber, and (2) a good RF spectrum analyser and probes (the one the RF test company kindly lent us for a few days cost them in excess of $30000, and that was the cheap spare), you won't even be able to find the emissions of the empeg over the RF hash produced by everything else around you, never mind measure it properly.

The MK1 was a bit of a bugger due to the USB controller. It radiated dozens of harmonics of the 16MHz fundamental oscillator, with peaks at multiples of 48MHz, all the way up to at least 2GHz. I had a hell of a time trying to kill off these parasitic oscillations during the original design phase, and even though we got it under the EEC and FCC limits, I couldn't stop it completely. The manufacturer of the chip finally admitted they had a problem with the thing, but couldn't really suggest any good complete fix.

However, the Mk2 uses a different USB chip, with a completely different oscillator, and doesn't suffer from the same problem.

That said, any complex computing device will produce spurious emissions. All you can do is try to keep the output level down to whatever standard the thing has to meet. Unless we went to something like Tempest classification shielding, a little RF will leak. In the case of most PC equipment, a lot will leak.

I suspect it's only because of the close proximity and extreme sensitivity of the receivers being affected that allow them to in fact BE affected. The frequency they use isn't one that the empeg intentionally produces, but is either a harmonic of one of the oscillators, the bus clock, or the core clock, or a mixing product of two or more of them.

I don't recall any peaks in the emission spectrum around that frequency, but it might be that a multiple of the 200MHz or so CPU core clock is to blame. It in fact probably isn't a signal on the same frequency, but a fairly broadband one near it, at extremely low power. The box is pretty well shielded, and unfortunately there isn't a lot you can easily do to make it any better at that part of it's job. Most of the RF leakage will be through the front panel, and covering that with a stainless steel sheet rather defeats the object, I'm afraid.

Look on the bright side. If your in-car entertainment system used, for instance, a 433MHz intel processor, you'd have no chance.

One thing does occur to me now that I think about it. Does this effect occur when the empeg is completely shut down, ie with the ignition off? Under these circumstances the only thing that should be active is a small part of the PSU, the PIC that controls it, and the RTC, none of which should produce harmonics anywhere near 433MHz at power levels above the nanowatt range.

When the empeg is running or in standby mode with the light flashing the CPU is active, and if it's that producing the putative interference it shouldn't occur when the unit is off.

This only applies to the MK2 of course. The MK1 is completely dead when the ignition is off, as it uses a different PSU circuit.

Patrick

Opinions expressed in this email may contain up to 42% water by weight, and are mine. All mine.

I believe it was reported that this only occurs while the empeg is in standby. If you configure the shutdown time to, say, 5 seconds that gives you time to switch it back on manually if you want to but also ensures that it is fully powered down by the time you exit the vehicle and use your remote.

if you do have this problem, given that the car player operates well within both FCC and (the much stricter) CE guidelines, chances are your vehicle would suffer from any high speed in-dash computer. Since the regulations also specify that a product must be immune to EMC radiation well beyond the levels that the car player produces, I have to wonder as to the design quality of the receivers in question. We certainly don't have a problem with any of our demo or staff owned vehicles.

Rob

Ok, as an update, I tried Damien's Rio Car last night in my sled. Whenever his player was playing or in standby, the door locks worked just fine. I probably unlocked and locked the doors about 25 times with his player, and only occasionaly it wouldn't work, and was probably a matter of not pushing the button all the way. Putting my player in his car did not show the problem there, possibly due to differences in the dash design between the LS and SL. (I'm still looking into where the system is in my car...)

After putting his player in my car, then putting my empeg back, mine seems to be causing the problem less and less, but is definitly still there. About 75% of the time, the locks won't respond now.

What differences were there in the Mark 2 and Mark 2a? Could the serial cable issue in the origional batch in any way be affecting this? The serial cable is tucked behind my dash in a place I can get to it easially, and happens to sit right next to an electrical fuse box in the car. Last night I remember moving the cable to show Damien, so thats the only thing I can think of that changed last night with my player install. I suppose another test I could do would be to try another Mark 2 in my car. I am heading to E3 this year, and will be bringing my car, so anyone in the LA area want to meet up with me to test this?

What differences were there in the Mark 2 and Mark 2a?

Very minor PSU tweaks, very minor audio input tweaks, and a change of RAM layout. It now has 2 x 64Mbit chips, rather than 6 x 16Mbit chips.

I'm getting the feeling that this problem, in the rare occasions it occurs, may be down to extremely low-level RF emitted by bus activity being picked up by insufficiently filtered receivers. The apparent fact that the 2A doesn't seem to cause it in a car where the 2 does might support this, as the smaller number of ram chips also requires less bus wiring length. This would have the effect of radiating somewhat less RF, since the effective antenna length would be completely different for bus signals. Also, if it's some sort of RF mixing process that's generating the offending frequency, different circuitry would be resonant at different frequencies. It seems feasible, anyway.

The serial cable is tucked behind my dash in a place I can get to it easially, and happens to sit right next to an electrical fuse box in the car.

That may be your main problem. The serial lead might act as a feeder, coupling any interference into the car wiring more inductively than any other way.

I have one suggestion that might be worth trying. Get a biggish ferrite toroid, about an inch and a half across, and wind a couple of turns of the serial lead through it near the back of the docking cage. Do the same thing with the main empeg wiring, ie disconnect the ISO connector, feed it through a toroid a couple of times, and reconnect it. See if this helps in any way. You should be able to get suitable toroids from Radio Shack or a similar electronics supplier.

Rob is right, though, the problem is most likely down to bad (cheap) RX design on the part of the car manufacturers.

Patrick.

Opinions expressed in this email may contain up to 42% water by weight, and are mine. All mine.

If my empeg (Mk2) is powered up (can be in standby, or playing) the FM reception on my JVC head unit becomes very weak. Sometimes it cannot pick up a signal at all.
Pulling the empeg from the sled fixes the problem.

Could be releated?

Jazz
(List 112, Mk2 12 gig #40. Mk1 4 gig #30. Mk3 1.6 16v)