Wanting to test home built lidar jammer

[DrCoke]

Am I the only 1 who don't know that the h@ll they are talking about? Maybe this is the reason I failed engineering class.

[speed-dreams]

Am I the only 1 who don't know that the h@ll they are talking about? Maybe this is the reason I failed engineering class.

dont worry they got off topic a bit...

[Solion]

Yeah , sorry about that everyone.

Now that is cleared up...YA science,

Lets talk about the HMLJ ... actually decided today to call it the HMLT Spyder P2.

(home made lidar transponder spyder(8 heads 4 front 4 back) prototype 2)

Today I started in on the second set of heads for the headlights. these will be round and will fit into the turn signal lamp housing. turn lamps will work as per normal since it is a doughnut shaped assembly that surrounds the original lamp.

Tested for the ammount of loss through the amber lens using the 2 watt Led in the previous video. the answer is ... almost none, upon closer inspection with the IR camera I discovered that the polycarbonate of that lense looks nearly transparent in the Near Ir.

However , do to refraction the whole friggin headlight housing is one big glowy bright mass of IR now. I think my headlight shots are well and truly protected to be honest.. but wont know till testing day.

Photos to come soon. Or untill it freaking warms up.. went out this evening to put my headlight back on in the cold... at night .. gods that sucked.

[thx1138]

I'm looking forward to your testing results! Appreciate the work you're putting into this and sharing with the community.

[fulcrum]

Again, I think this a misunderstanding of the real power output of a lidar gun. its not 20 watts, its maybe 50mw I can assure you at no time are you getting that much energy. its a class1 device for a reason. the video pretty much proves how bright the reflected energy from a lidar gun is. But give an ahour or so . let me show you 4w.

You really don't get it. Do you???
You can buy a 75w Osram pulsed laser diode for less than 50$.
It will output 75w PULSED power in very short pulses of a few ns per pulse. If you make the pulses to long, the diode will be destroyed. If you pulse it with a too high frequency it will also burn out.

The average power output of this laser is extremely low, and (in general) not dangerous. But this little laser diode will be very visible/detectable close to a very dangerous cw laser with thousands of times higher average output power costing more than 2000$.

Why do you think you can see a xenon strobe light flashing next to a 500watt halogen floodlight? The average power of the halogen light is much higher than the average power of the strobe light.

Why do you think you can hear the sound of a firecracker going of close to a passing freight train? There is so much more (sound) energy from the freight train. Again the pulse power of the firecracker is much higher than the average power of the freight train.

Why do you think a laser gun works so good in bright daylight? (Read your own post about the amount of near IR in sunlight)

The other effect that works against passive blinding is the fact that light output is cumulative. The laser pulses will be added to the light level of the constant on source. These pulses can be separated from the background noise using specialized photodiode based receivers. (As used in any lasergun)

Read something about photodiode (pulse) receivers, especially about handling high ambient light levels and/or separating ns pulses. Whole books have been written about these subjects.

Forget passive jamming with LED's it simply doesn't work with modern laser guns. You need a pulsed source. The switch on speed to full power has to be within 1-50 ns, the switch off time is not critical. A pulse frequency of a few 1000 Hz will not work with most laser guns. (Of the 4 laser guns I own, only the European LaserPatrol can be jammed this way) If you want to jam other guns, you need pulse frequencies approaching 1MHz or even more)

Again, passive jamming normally doesn't work. I tried it with a few hundred 880nm HP infrared LEDs. I still have about 1000 of them here. Passive jamming only works a little bit on bad reflecting targets. The type of laser gun also matters.

By the way, if you want to measure and or compare brightness of different infrared sources (including laserguns, LED's etc) then a video camera is a very bad tool for it. Remove the IR filter of a digital photocamera, and make longer exposures (in the dark) without clipping the image. You can use photoshop etc. to get the bit values of the pixels. As light is cumulative, it will give you much better information.

[Solion]

Again, I think this a misunderstanding of the real power output of a lidar gun. its not 20 watts, its maybe 50mw I can assure you at no time are you getting that much energy. its a class1 device for a reason. the video pretty much proves how bright the reflected energy from a lidar gun is. But give an ahour or so . let me show you 4w.

You really don't get it. Do you???
You can buy a 75w Osram pulsed laser diode for less than 50$.
It will output 75w PULSED power in very short pulses of a few ns per pulse. If you make the pulses to long, the diode will be destroyed. If you pulse it with a too high frequency it will also burn out.

Okay well two things today, First the newest of the switching units I Just finished.

See photos below. this one is 12ns Tf/Tr and will be used to run the other sets of diodes.

Second is to address fulcrums statements here and set a couple thing straight about what I am doing.

If I was trying to build a clone of a Blinder or LI, Let me say emphatically That I could. would it take time, Yes .. would it be something anyone could build? Not a chance in hell. This was to see what could be built for under 50.00 and could such a device actually jam anything And the answer is yes. I managed with 40.00 to Jam a PLIII to 28 feet consistently CM and 128 feet on a headlight shot. Will these sorts of numbers hold up on other guns? Well at the end of the month we will all find out for sure. Would love to test again sooner. but I will take what I can get.

But lets take a look at the analogy's Fulcrum has stated here.

Quote : Why do you think you can hear the sound of a firecracker going of close to a passing freight train? There is so much more (sound) energy from the freight train. Again the pulse power of the firecracker is much higher than the average power of the freight train.

ME: Well, How much of the sound created by the freight train is in the same frequency range created by the firecracker? How about a train full of firecrackers! can you honestly tell me you will pick out the one you set off? this sort of thought experiment only works if your comparison is apples to apples and not apples to cucumbers..

Quote: Why do you think you can see a xenon strobe light flashing next to a 500watt halogen floodlight? The average power of the halogen light is much higher than the average power of the strobe light.

ME : Again with the apples and cumbers. lets take that and flip it on its head how about an massive strobe light putting out 90khz and you set the little one in front of it. You are going to be able to tell the difference?

Quote: Again, passive jamming normally doesn't work. I tried it with a few hundred 880nm HP infrared LEDs. I still have about 1000 of them here. Passive jamming only works a little bit on bad reflecting targets. The type of laser gun also matters.

ME: Well we can agree that 880nm Leds don't work for brute jamming. I tried them in my first test to a resounding utter fail. Then I went to the Varshay 890's and got 28foot jam on PLIII

QUOTE: Forget passive jamming with LED's it simply doesn't work with modern laser guns. You need a pulsed source. The switch on speed to full power has to be within 1-50 ns, the switch off time is not critical. A pulse frequency of a few 1000 Hz will not work with most laser guns. (Of the 4 laser guns I own, only the European LaserPatrol can be jammed this way)

ME: Did you even read through the whole build so far?...egads , let me help you .. here are the Vishay Leds I am using now with success 30ns Tr/Tf
http://www.vishay.com/docs/81313/tshf5210.pdf

Quote: The other effect that works against passive blinding is the fact that light output is cumulative. The laser pulses will be added to the light level of the constant on source. These pulses can be separated from the background noise using specialized photodiode based receivers. (As used in any lasergun)

ME: Okay this is just flat out wrong. I don't know where you got this information but lets look at the statement here, You are suggesting the light from 2 different emission points traveling in opposite directions are going to accumulate.. That the light traveling from your gun to the LED's is going to have an additive effect vs a light pollution effect. I suppose you can see the milky way in the middle of a city as well.

QUOTE :Why do you think a laser gun works so good in bright daylight? (Read your own post about the amount of near IR in sunlight)

ME: that statement was to put to bed the fear mongering idea that my IR leds were going to melt peoples eyeballs like raiders of the lost ark. But your statement was to use mine about power to prove your point?. NO, 500 watts per square meter from the sun will not cause problems because the frequency range the lidar gun SEES is a tiny slice of that. in like .023 watts... arrrgghhhhh!


ME: EGHH I have a headache in my spleen now , for the sake of science and our viewing audience let me explain why your statement has a few massive holes in it . some thought experiments for a moment. And why a passive jammer can work.

First lets talk about light, You cant actually see light untill it strikes something to illuminate it. or excites a material (like in your retina) to turn it into signals for your brain. So how we live most of our lives with light is seeing reflected light off of objects. Or exciting things like phosphorous.

If you take a laser and shine it at a car bumper, the reflected light is what you see. same for a lidar gun. the reflected light is how it determines distance. There is nothing magical about pulses. reflected energy is reflected energy. so at a set distance you will get X amount of MW to the receiver of the gun.

With me so far?, Okay. SO lets take a couple of handfuls of IR LEDs and throw it into the equasion. The amount of reflected light from the lidar gun remains the same (except in cases of emmitive saturation) from your bumper You don't get any more light to help you. My leds are not helping your laser. The best you can do is try and detect the DIFFERENCE between the levels. However , if you are throwing out enough IR what happens is that the signal gets lost in the noise. Pulsed or not. you have saturated to the highest level of the sensors ability to detect the tiny tiny changes. But you DO have to have enough to do it< And I do for the PLIII and I will have more.
what it depends on is the reflectivity (there is that word again ) of the item you are shooting.

Lidar sensors, gated or not have a maximum sensitivty and a maximum output. take a look at typical IR sensor PDF. http://catalog.osram-os.com/media/_e...00043391_0.pdf

There is no such thing as a sensor with infinite sensitivity.

At a distance light blooms into one big blob. you can look at cars comming down the road and see how the radiant cones comming from their headlights merge into one another untill they get close enough to be able to tell them apart. This effect at a distance works to cover a large portion of the car. where as the power continues to keep going up the closer I get to the gun.

Now then. I am going to continue with the build and test it against all of Cat4's guns. I will be testing with both Pulsed and NON pulsed sources to drive the leds. If it works in NON pulsed with the margin of error in comparison to other Jammers then I have changed jamming forever. If it works with the 2mhz driver unit again within the margins of normal units, Then I have built the cheapest effective jammer in the world.

WIN WIN , it already jams the PLIII. So the hall is rented, the orchestra engaged .. lets see if I can dance.

[ELVATO]

For what it's worth, the M20/40 line of Blinders used 880 nm LEDs and jammed the PLIII pretty well. They have since improved their LEDs (probably got something closer to 904).

[STiMULi]

Since I have the M40 any step forward is real progress. From what I understand the M40 (especially on my car with 4 heads in front on a Subaru Impreza WRX STi) will do the trick in my area but I would much rather have the HMLT Spyder P2 with some of the transmitters in the HLs.

I would bet from what I am learning from Solion I could move 2 heads to the rear and the have front and rear SNAGS (Speed Not Available at Gun) = Current JT/FG [Avoiding the use of the character "j" for obvious reasons]


Where can I get tickets to the Dance?

[fulcrum]

You will find my response in bold-blue....

Quote : Why do you think you can hear the sound of a firecracker going of close to a passing freight train? There is so much more (sound) energy from the freight train. Again the pulse power of the firecracker is much higher than the average power of the freight train.

YOU: Well, How much of the sound created by the freight train is in the same frequency range created by the firecracker? How about a train full of firecrackers! can you honestly tell me you will pick out the one you set off? this sort of thought experiment only works if your comparison is apples to apples and not apples to cucumbers..

The anology with light on average and peak power fully applies, except for the fact that sound is not really cumulative. Make a recording of this example and view it in a wave editor. You will see exactly what is happening.



Quote: Why do you think you can see a xenon strobe light flashing next to a 500watt halogen floodlight? The average power of the halogen light is much higher than the average power of the strobe light.

YOU: Again with the apples and cumbers. lets take that and flip it on its head how about an massive strobe light putting out 90khz and you set the little one in front of it. You are going to be able to tell the difference?

I don't know why you ask this, but yes you will be able to tell the difference:
a) If the pulse frequency of the small one is different than the massive one you can seperate the signals by first sampling the combined signals, and then look at the frequency/amplitude spectrum by using filtering techniques like bandpass or fourier analysis.

b) If the pulse frequencies are the same and 100&#37; in sync, you can detect the small one by looking at the amplitude of the combined signals. (Analog threshold filtering, yes light works cumulative)

Going back to your initial reply. Trying to hide a stobelight in a flood of 'normal' light is an almost perfect and understandable representation of what you are trying to do. The question in your reply only blurs the subject.


Quote: Again, passive jamming normally doesn't work. I tried it with a few hundred 880nm HP infrared LEDs. I still have about 1000 of them here. Passive jamming only works a little bit on bad reflecting targets. The type of laser gun also matters.

YOU: Well we can agree that 880nm Leds don't work. I tried them in my first test to a resounding utter fail. Then I went to the Varshay 890's and got 28foot jam on PLIII

Depends on the lasergun and more specifically on the filter installed between the lens and photodiode. If these are the simple low pass type (like the one you removed from your video camera) then 880nm might work just as good as 905nm or 950nm. If the gun has a sharp narrowband filter, then the wavelength of the jammer LED or laser becomes critical, and it should match that of the lasergun or it will be blocked by its filter. I personally have experience with 2 guns that can be jammed perfectly with a standard 880nm or 950nm LED. (LaserPatrol and PLIII)

Test again on a modern LTI or LaserAtlanta........... The PLIII is extremely easy to jam compared to many other guns. The good old days when you could even jam a gun with bright headlights are really over.



QUOTE: Forget passive jamming with LED's it simply doesn't work with modern laser guns. You need a pulsed source. The switch on speed to full power has to be within 1-50 ns, the switch off time is not critical. A pulse frequency of a few 1000 Hz will not work with most laser guns. (Of the 4 laser guns I own, only the European LaserPatrol can be jammed this way)

YOU: Did you even read through the whole build so far?...egads , let me help you .. here are the Varshay Leds I am using now with success 30ns Tr/Tf
http://www.vishay.com/docs/81313/tshf5210.pdf

Nice powerfull and fast LED, but you will never be able to switch them that fast with your current design. (Read some of the older posts) To reach that switching speed you also need a very well designed driver circuit.






Quote: The other effect that works against passive blinding is the fact that light output is cumulative. The laser pulses will be added to the light level of the constant on source. These pulses can be separated from the background noise using specialized photodiode based receivers. (As used in any lasergun)

YOU: Okay this is just flat out wrong. I don't know where you got this information but lets look at the statement here, You are suggesting the light from 2 different emission points traveling in opposite directions are going to accumulate.. That the light traveling from your gun to the LED's is going to have an additive effect vs a light pollution effect. I suppose you can see the milky way in the middle of a city as well.

Do you really think that???? Did you do any research on the behaviour of light? Light is cumulative. If you point a lasergun on a car with a jammer, then the light received by the lasergun is an addition of its reflected light and the direct light of the jammer.
Light is cumulative.... Why are you using multiple LEDs???? Yes, because the total output of your jammer is the addition of the output of the individual LEDs. If you point 2 flashlights or 2 LEDs or 2 lasers at the same spot on the wall, that spot will be brighter with 2 lightsources than with only one. It is as simple as that......

And to prove my point further; Yes indeed! you can take pretty nice pictures of faint astronomical objects in light polluted city skies. It is a standard technique used in astro photography using CCD camera's. For example you take 10 pictures of the same region of the sky, you make sure these pictures are not overexposed (clipped) by the lightpolution. The next step is aligning the images and then totalling the value of each pixel of the 10 aligned frames you have in to a new frame. What will happen is that the noise (light pollution) information which has a random character adds up differently in each picture, but the data of object your interested is (more or less) the same in each picture. You will end up with a resulting image that has a greatly enhance signal to noise ration. You then substract a fixed value from each pixel in the resulting image to remove the light pollution part, and then expand the contrast. Et voila a faint astronomical object photographed even in a light polluted night sky.
Astrophotography happens to be one of my hobbies, don't tell me light is not cumulative, you are so 100% totally wrong on this matter.

Maybe you don't believe me just read this http://www.astropix.com/HTML/J_DIGIT/COMPEXP1.HTM or many other articles on the same subject.



YOU: First lets talk about light, You cant actually see light untill it strikes something to illuminate it. or excites a material (like in your retina) to turn it into signals for your brain. So how we live most of our lives with light is seeing reflected light off of objects. Or exciting things like phosphorous.
If you take a laser and shine it at a car bumper, the reflected light is what you see. same for a lidar gun. the reflected light is how it determines distance. There is nothing magical about pulses. reflected energy is reflected energy. so at a set distance you will get X amount of MW to the receiver of the gun.

Just to get things clear: The amount of reflected light is not how a lasergun measures range and/or speed. The amount of reflected light is used by some laserguns to adjust the bias of its photodiode to make the noise filtering more effective. (In other words setting a threshold level to isolate the reflected laserpulses from ambiant noise or light from a passive jammer)



With me so far?, Okay. SO lets take a couple of handfuls of IR LEDs and throw it into the equasion. The amount of reflected light from the lidar gun remains the same (except in cases of emmitive saturation) from your bumper You don't get any more light to help you. My leds are not helping your laser. The best you can do is try and detect the DIFFERENCE between the levels. However , if you are throwing out enough IR what happens is that the signal gets lost in the noise. Pulsed or not. you have saturated to the highest level of the sensors ability to detect the tiny tiny changes. But you DO have to have enough to do it< And I do for the PLIII and I will have more.
what it depends on is the reflectivity (there is that word again ) of the item you are shooting.
Lidar sensors, gated or not have a maximum sensitivty and a maximum output. take a look at typical IR sensor PDF. http://catalog.osram-os.com/media/_e...00043391_0.pdf
There is no such thing as a sensor with infinite sensitivity.

I would love to have a discussion on photodiode based pulse detectors, but you should first research the subject before writing about it. If you don't understand or agree on even the most basic principles on light, then a discussion about the subject is a waste of time.


YOU: At a distance light blooms into one big blob. you can look at cars comming down the road and see how the radiant cones comming from their headlights merge into one another untill they get close enough to be able to tell them apart. This effect at a distance works to cover a large portion of the car. where as the power continues to keep going up the closer I get to the gun.

And your point is?



YOU: Now then. I am going to continue with the build and test it against all of Cat4's guns. I will be testing with both Pulsed and NON pulsed sources to drive the leds. If it works in NON pulsed with the margin of error in comparison to other Jammers then I have changed jamming forever. If it works with the 2mhz driver unit again within the margins of normal units, Then I have built the cheapest effective jammer in the world.
WIN WIN , it already jams the PLIII. So the hall is rented, the orchestra engaged .. lets see if I can dance.

You're right on this one. Try jamming other guns first before you start to dance..........

[BullyDawg19]

why does everything have to end up in a pissing contest. its not about who is smarter but about the journey. good luck - hope to see the results soon.