Laser jammer leds?

TSi+WRX · #6 (**permalink**) 2009-06-28

Looks like the Intr4w3b ate my posting - I'll try to reconstruct it.

Hopefully, this time, it won't get eaten by the 3rrorNet!

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Streaker, as steagall said, the darkened lenses do just that: they serve as a initial filter for ambient light.

This is why, when you view the jammer heads under IR-videography or photography, the portions covered by this type of filter will suddenly appear transparent, as they are, despite being near-opaque to visible light, completely IR-transparent.

Ambient light - bright ambient light - is a big problem for jammers and detectors. This is true for *ALL* jammers/detectors, not just specific brands/models. Some will "warn" of such conditions, but nevertheless, none are exempt from such conditions' detriment to overall jammer effectiveness, which can actually be upwards of 30% or more (see raw-numbers data from the Osijk SpeedLabs [not to be confused with the Stateside based Speed Measurement Labs/SML - SpeedLabs is a group of European enthusiasts] test of various jammers).

Typically, we see such issues when driving directly into (front-facing heads) or directly away (rear-facing heads) a rising or setting sun. However, other conditions, such as *very* bright sunlight or sun glare (i.e. snow-fields, sand-dunes, "high noon") can also cause similar problems. Thus, a smart driver will use extra caution during such times, particularly as the altered lighting backdrop can further give an advantage to enforcers, if they carefully take that into account during their trap setup.

In terms of fitting constant-on IR-LEDs or laser-diodes to your vehicle, unfortunately, we currently have no independent data to suggest too much, either way. While we've seen *some* effect of various HID as well as halogen-incandescent lighting to confer some protective effects to the vehicles targeted - either with delayed lock or even the return of an error-code on the police LIDAR device, with no reported speed/distance readings - such effects are very inconsistent, and the hobbyist community has yet to be able to truly test various permutations of such an equation (i.e. wattage of incandescent lighting, traditional halogen-incandescent versus HIR, HID color-temperature, differences in optics, etc.), to see what really produces the various observed effects, or how to specifically achieve such desired effects.

With current-generation police LIDAR devices, the outgoing jamming output/light must be modulated, so as to achieve the desired effects.

In order to properly jam a police LIDAR, the outgoing light output from your jammer device has to sync within a specific time-window what the police LIDAR "expects" to be its own reflection - time-in-flight as well as the jamming "algorithm," thus, must be rather precise. This is especially important if you want to minimize/eliminate any "jam-code" alerts, remembering that it is possible to "flood" the LIDAR device with a high enough pulserate from your jammer that it literally forces the device into fault/error (i.e. "Brute Force" jammers, such as the now-defunct Lidatek LE-10).

Here's a good beginner's read:

Laser jammer question. Are pulses needed to jam? - Radar Detector Jammer Forum

Hope this helps!

Speed Trap Hunter · #7 (**permalink**) 2009-06-28

Allen,

Can you translate those first two lines into english?

STH

Veil Guy · #8 (**permalink**) 2009-06-28

Some years ago, when there was some extensive testing being done on Veil (G2) on a silver metallic C5 corvette repeatedly pitted with a Laser Atlanta R model (in either mode) at a particular time of the day, namely towards the sunset, the silver metallic hood of the vette began reflecting huge amounts of sunlight (which of course was chock-full of IR). During a brief time the targeting range of the mighty Laser Atlanta R dropped dramatically and I mean dramatically. We were not using laser jammers at the time, either, just Veil.

The following morning we spoke with a developer of the Laser Atlanta lidar gun and he explained what we had observed in very simple terms.
He suggested that if we think of police lasers as essentially photographic devices (in a sense) that they exhibit the same types of reaction to auto-exposure metering systems. When too much ambient light is present, the police lasers essentially dial-back their exposure sensitivity to compensate, much as a camera does.

These filtering mechanisms employed (in both countermeasures and detectors as well as the guns themselves) each work to strip out the "noise-floor" so to speak.

I hope this explanation describes simply what is essentially going on in these circumstances.

While the LTI was certainly the original and remains one the highest caliber companies, I really do appreciate the (over) engineering brilliance of the Laser Atlanta R model. Yes I know it is relatively heavy, but the darn thing is built like a tank and designed to survive in the field for a very long time, something that some of the newer LTI ultralytes have had some difficulty doing (according to a NJ State Trooper who returned to using on older Gen II LTI 20-20 Marksman).

Veil Guy

TSi+WRX · #9 (**permalink**) 2009-06-28

^ Very true - thank you for sharing that tale, and definitely, it was something that I should have better taken into account in my prior posting, which lacked "balance."

Indeed, this is a tactical consideration that, like many others, cuts both ways.

Both instruments rely on simple optical principles.

Given the right specifics, such conditions could favor the target vehicle, just as it may favor the enforcement device.

But it stands well for everyone to remember - we start off "behind the 8-ball," already. And in starting on the defensive, we must assume the worst.

Don't count on the conditions to favor you, even when you think it might!

Instead, take steps to insure that you will not compromised, should the specifics of the conditions actually either give you no favor, or, alternatively, puts you at a disadvantage!

Speed Trap Hunter · #10 (**permalink**) 2009-06-28

Allen,

Don't be so hard on yourself.

It's all good.

STH