# Thread: LI beam divergence; only one sensor needed?

1. ## LI beam divergence; only one sensor needed?

The LI has divergence of 5.5degrees up and down (11 total), and 12.5degrees left to right (25 total). Lets assume there is one head on the front of the car, and it gets hit with a laser shot from 2000 feet out.

At that range, and with the stated bean divergence, using simple geometry and trig the sensor is going create a "null zone" where jamming will take place that is 385' tall, by 886' wide. Obviously, the LI isn't working at full power for the full range of operation listed. So, lets assume that it is effective for half of the listed range. This makes a "null zone" of 192' tall by 443' wide. Even if we halve that, we get 96' tall by 221.5' wide. Yes, half of the 96 (or most of it) will be directed towards the ground), so half of 96 will be effective. This is 48', which is still plenty to reach the top of an overpass.

Surely, this is a large enough area to jam a gun that is in the median, on the berm, or on an overpass, right??

Obviously, two sensors will pick up a laser shot better than one, but it seems as if only one transmitter is needed for either the front, or rear. Does this make sense, or am I on crack?

Here is the simple math and geometery I used.

2. ## Re: LI beam divergence; only one sensor needed?

^ That's assuming all other factors are in our favor.

I don't want to belabor the point, so I'll simply ask you to kindly surf over to the LI Forums, look for the thread titled:

"LI's sensor alignment (Roll, Pitch and Yaw)"

In the bottom half (general threads) of the "Installs" sub-Forum.

What's presented there by the other hobbyists would be an alternative view of what you've cited above.

If you're on the optimistic side of the scale, they're on the pessimistic.

3. ## Re: LI beam divergence; only one sensor needed?

Originally Posted by TSi+WRX
^ That's assuming all other factors are in our favor.

I don't want to belabor the point, so I'll simply ask you to kindly surf over to the LI Forums, look for the thread titled:

"LI's sensor alignment (Roll, Pitch and Yaw)"

In the bottom half (general threads) of the "Installs" sub-Forum.

What's presented there by the other hobbyists would be an alternative view of what you've cited above.

If you're on the optimistic side of the scale, they're on the pessimistic.
Could you supply a link, I can't find this. thanks

4. ## Re: LI beam divergence; only one sensor needed?

Hey bro,

I'll have to do PM - I don't know if linking over to the LI Forums is Kosher, by RD.net's standards and practices.

5. ## Re: LI beam divergence; only one sensor needed?

This does make sense... hmmmm.

6. ## Re: LI beam divergence; only one sensor needed?

... and if you get hit off-center at half that distance?

7. ## Re: LI beam divergence; only one sensor needed?

Originally Posted by 9500ier
... and if you get hit off-center at half that distance?
That is why I said you would probably need two receivers and one transmitter.

And again, I could be out in left field. But using the data provided and basic math, it seems that the LI heads are quite powerful and cover a wide area.

That being said, am I still going to but two more heads for the rear? yup! better safe than sorry.

8. ## Re: LI beam divergence; only one sensor needed?

It seems that one diode head should protect most cars. To me, the problem would be detecting the actual laser signal, especially with the Tru Speed, a gun even the ZR4 has trouble detecting.

9. ## Re: LI beam divergence; only one sensor needed?

^ +1.

Well-said, ELVATO.

When even Ivan - who is literally the brains behind pretty much all of the top laser-diode based jammers available today - outright says that even with the LI, placement/setup is CRITICAL to properly defeating the TruSpeed, it can only be said that this concern is very real.

10. ## Re: LI beam divergence; only one sensor needed?

Originally Posted by ELVATO
It seems that one diode head should protect most cars. To me, the problem would be detecting the actual laser signal, especially with the Tru Speed, a gun even the ZR4 has trouble detecting.
Is the CI/ZR4 good at jamming Tru Speed? I haven't seen any conclusive tests.

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