possible cure for x50 false laser alerts

[TSi+WRX]

GHott

It's definitely *not* our knock sensor or anything of the like - the "noise" is electrical, not physical.

In most cases, isolating the ground loop, using another circuit for your taps, or cleaning up the particular taps you already are using will, with our Scoobys, permanently cure the issue.

Our Scoobys are electrically rather noisy, unfortunately. ops: A fellow LGT owner, also using the TXS Knock-Light, actually got enough ground-loop feedback to cause his ECU to see enough -KC that it pulled down his IAM to, get this, ZERO! And on my wife's WRX, when the weather's just right, if we engage the windshield wipers, we get noticeable feedback noise on her XM. This noise is purely electrical, and as such, in the vast majority of cases, such electrical fixes will eliminate it.

[yeswork]

This seems to me like low voltage (and compensatory high) spikes on the +12V supply line.

Has anyone tried adding a stiffening capacitor on the +12V line near the radar detector?

1 Farad would probably smooth out low voltage dips caused by brake lights and other electrical loads.

Just a suggestion; I don't have similar problems so I have not tried it.

[TSi+WRX]

^ Very interesting............ thanks for the suggestion!

[GHott]

Thanks for all the awesome info guys.

[jim1969]

I'm getting this with my brand new 9500i. I never had this with my recently sold 8500 X50. I'm not happy.

[jimbonzzz]

From what I understand, most of these laser falsing problems are NOT caused by noisy power going to the detector, but by RFI generated by the vehicle.

It's easy for people to assume that power supply noise that causes these problems, and that additional power supply filtering such as a choke or capacitor would be the solution. For some reason, a lot of people find it very difficult to wrap their head around the fact that strong RF pulses can cause laser false alerts, since RF and laser are different. But that is indeed what happens: high-powered RF pulses overpower the shielding and leak into the laser detection circuit via tiny gaps.

For example, this is the reason for laser false alerts around airports: it's a high-powered pulsed RF souce causing the laser false alerts, not any kind of laser system. Of course, in this situation it should be obvious that these false alerts are not caused by a noisy power supply: you can filter the detector's power supply all you want, and it isn't going to do anything for you.

The airport example above is actually similar to what happens when RFI is generated by the vehicle: some vehicle subsystem is acting as a pulsed RF transmitter, and the detector receives the RF interference transmitted through the air, not the vehicle power or wiring. Since the detector is close to the source, the RF need not be high-powered. Sure, people can try capacitors, chokes, etc to provide additional filtering to the power going to the detector, since additional filtering isnt going to hurt anything. But if people are expecting such measures to cure their laser falsing issues, I expect that a lot of them are going to end up disappointed.

The best thing to do is send it in for service (as MEM-TEK suggested), and let them know what is going on so they can tweak it or improve the shielding.

[TSi+WRX]

^ Very enlightening.

That does make sense - there's definitely those vehicles out there in which the in-line filters have not worked, and that would stand to-reason.

jimbonzzz - I haven't been following that V1/M6 thread in the Valentine sub-Forum. Is that what's happening there, albeit on K-band?

Thanks yet again for the lesson!

[jim1969]

I'm sending it in on Thursday. 10-12 day turnaround. They will increase the shielding around the laser. According to the person I spoke with, there will be a decrease in laser sensitivity but "since by the time the laser alerts you, you're already hit" it doesn't matter about the reduced sensitivity.

[TSi+WRX]

^ Thanks for the update, bro!

You know, for as much as I do subscribe to the "laser alert = toast" belief, I also know, from first-hand experience, that we can get lucky, and can catch good scatter (enough to get a good slow-to-PSL/reasonable effort) from a high-mount.

I don't like it that this will reduce the laser sensitivity, but I also don't see any good way around this.

Just out of curiosity, have you tried the in-line filter solutions?

I actually broke-down just 5 minutes ago, and called Escort to order the 9500i Red ops: . On my way home from work, I reasoned that even if I did run into this issue, I would give the in-line solutions a try and/or try the "laser off" setting on the detector itself, to see how things might play out. (And to send it back in for an adjustment, if-necessary.) This way, I can also further corroborate your own datapoint, and help out not only us LGTers, but also others here with inherently "noisier" cars, too.

[jim1969]

supposedly none of the in-line solutions work well. According to the tech at Escort I spoke with, I can expect about a 30% reduction in sensitivity. Great.