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Thread: Jamming codes

  1. #1
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    Default Jamming codes

    Not sure if this point has been raised before but having gotten out my old trusty PLII today, I got thinking...

    We know there is a conflict issue at 100pps between the Ultralyte 100pps version and the Jenoptik LaserPatrol.

    Does this mean there is a similar issue at 238pps with Laser Atlanta and PLII?

    Would this explain the LPP's odd behaviour towards the Laser Atlanta (i.e. irregular jamming)?

    Any thoughts?

  2. #2
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    Considering the PLII doesn't throw jam codes, I would think they would focus more of their attention towards the LA. In other words, fine tune it towards the LA? That's just a thought.

  3. #3
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    yes.. but dont forget 2 versions of Stalker on same pulse rate, and pro lite and Kp3...

  4. #4
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    Quote Originally Posted by interceptor
    yes.. but dont forget 2 versions of Stalker on same pulse rate, and pro lite and Kp3...
    Of course, forgot about those too!

    So why would 2 guns sharing the same pps throw jam codes on another?

    I dont expect an exact answer Ivan as that's kind of trade secrets etc, but it just made me curious.

  5. #5
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    this is only isue with jenoptic..

    also on some old stalker, but here is why..

    jenoptic is having realy sensitive "jamming" trigger, something like good old 9mm... :-)

    so, algorythm that will jamm ultralyte is just to much for jenoptic and will trigger e-14 jamming on it, and algorythm that will jamm jenoptic is just not good enugh for Ultralyte as showed on GOL test..

    LI have no problems jamming both with same software version, tont ask me how... :-)

    on LA JA3 is triggered anyway... also when paning on road or snow...

    so isue (from other products) from bad PL2 jamming and bad LA jamming is not in avoiding to trigger jam codes, but simple same pulse rate and diferent speed aquisition algorythms in both guns..

    LI have no isue here... again dont ask me how.. :-)

  6. #6
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    I ask difficult things all the time. So, here is my question, or proposal, if you like.

    Can you, or anyone else, give us an example of how a lidar gun works, not in the physical layer (I use computer networks terminology), but in the application layer. I would like to see the algorithm used to acquire speed and how it detects jamming, if possible for the 2nd one.

    I would like to have the whole picture in more details and the time to search magazines (ex. IEEE) for methods etc it's just out of the question as my time is limited.

    I believe they just don't use contiguous pulses = many measures, so they create a D = D(t) diagram = speed. One manufacturer uses groups of 3 or 4 pulses, others uses 2 etc. After they receive the reflections = data, how they process them ? What stages they follow to give speed + jam code ? How they distinguish jamming pulses from real pulses ? A simple and easy example (let's say from an older lidar gun) would be perfect.

    Difficult and technical questions, but it's a good time to review my DSP knowledge. If there is a book or pdf or site or magazine easily accessible from university libraries (IEEE, Springer etc) I can easily read it, even give a short abstract to all other users. I just don't have the time to search on my own.

    Thnx for your time and sorry for being difficult sometimes.

    Today, it's the day the Italian forces invaded Greece back in 1940 and it's a national feast. So, I would like to wish, not even a single person in this planet would have to experience the consequences of a war ever again.

  7. #7
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    Quote Originally Posted by interceptor
    this is only isue with jenoptic..

    also on some old stalker, but here is why..

    jenoptic is having realy sensitive "jamming" trigger, something like good old 9mm... :-)

    so, algorythm that will jamm ultralyte is just to much for jenoptic and will trigger e-14 jamming on it, and algorythm that will jamm jenoptic is just not good enugh for Ultralyte as showed on GOL test..

    LI have no problems jamming both with same software version, tont ask me how... :-)

    on LA JA3 is triggered anyway... also when paning on road or snow...

    so isue (from other products) from bad PL2 jamming and bad LA jamming is not in avoiding to trigger jam codes, but simple same pulse rate and diferent speed aquisition algorythms in both guns..

    LI have no isue here... again dont ask me how.. :-)
    Thanks again Ivan for the info.

    I was curious as the LI gives a warning of "PLII or Laser Atlanta" so if both are at 238pps, then it doesnt differentiate between the two? Does it even matter in this particular case?

    Always more questions!!

    No need to respond Ivan, as I'm very aware that we are in secret territory here!

  8. #8

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    one thing i noticed is the diffrence in sound the pl3 makes when its getting jammed it makes a grunting sound.

  9. #9
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    Quote Originally Posted by pipinos1976
    I ask difficult things all the time. So, here is my question, or proposal, if you like.

    Can you, or anyone else, give us an example of how a lidar gun works, not in the physical layer (I use computer networks terminology), but in the application layer. I would like to see the algorithm used to acquire speed and how it detects jamming, if possible for the 2nd one.

    I would like to have the whole picture in more details and the time to search magazines (ex. IEEE) for methods etc it's just out of the question as my time is limited.

    I believe they just don't use contiguous pulses = many measures, so they create a D = D(t) diagram = speed. One manufacturer uses groups of 3 or 4 pulses, others uses 2 etc. After they receive the reflections = data, how they process them ? What stages they follow to give speed + jam code ? How they distinguish jamming pulses from real pulses ? A simple and easy example (let's say from an older lidar gun) would be perfect.

    Difficult and technical questions, but it's a good time to review my DSP knowledge. If there is a book or pdf or site or magazine easily accessible from university libraries (IEEE, Springer etc) I can easily read it, even give a short abstract to all other users. I just don't have the time to search on my own.

    Thnx for your time and sorry for being difficult sometimes.

    Today, it's the day the Italian forces invaded Greece back in 1940 and it's a national feast. So, I would like to wish, not even a single person in this planet would have to experience the consequences of a war ever again.
    Take a look at the US patents. Although there are several, here's one that applies to your question:

    Countermeasure detecting circuit, and associated method, for a laser speed detecting apparatus

    http://patft.uspto.gov/netacgi/nph-P...number=5715045

    Just because the company holds a patent, doesn't necessarily mean they're using the technology in the same way in their products. But regardless, it can still give good clues.

    Heres a high-level presentation which describes some of the factors involved such as the least squares algorithms:
    http://www.lasertech.com/ftp/reports/marksman.zip

  10. #10
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    Thnx a lot Jim. I'll look into it. I can't open the presentation though. It's from PowerPoint 4.0, which is old. I don't know why neither MS PowerPoint 2007, nor Open Office Impress can open this file. I tried everything and I always get the message that it's not a supported file.

    Thnx again.

 

 

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