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Use Of A Speed Gun
StuartBu
post Fri, 31 Aug 2018 - 16:30
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Reading an item in a Scottish Tabloid Rag about the trial of a well known Scottish footballer it mentioned questions being asked of the speed gun operator . The defence lawyer questioned the possibilty of the operators mobile 'phone affecting the reading...that he had pointed the gun at the cars grille and it should have been at the Number Plate and also that there were insufficient speed signs on the stretch of road ( it was a 50 limit dual carriageway)

The term"grasping at straws" comes to mind .Ive never heard it mentioned before about a 'phone affecting the speed gun

As for what he asked about the gun being pointed at the grille does that matter ...it's not as if the grille and the number plate are travelling at different speeds...the number plate must have been included at some point else they wouldn't know who to send the S172 to.

Are there regulations about how many signs should be placed on roads ..it doesnt mention if it was an unlit or lit road .

The bench was generous to a fault allowing the court case to end ( for now) early to allow the player to get in time to play yesterday and one of the JPs said to the accused that he hoped the game went the way he wanted it to .....
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post Fri, 31 Aug 2018 - 16:30
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The Rookie
post Fri, 31 Aug 2018 - 17:08
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The defence lawyer seems to think the laser produces a pencil beam, it’s a cone, for every 300m range the main impact area is 1m across, so if the grill is in the crosshairs (which may or may not be aligned with the laser) something more reflective like the plate or headlight almost certainly are.


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notmeatloaf
post Fri, 31 Aug 2018 - 17:36
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Add to that the method of lining the laser up isn't exact, the cross hairs will/should be approximately in the right place but not to the nearest centimetre.

With the mobile phone I imagine the argument will be that it interfered with the electronics within the gun rather than the laser beam itself. This is not as fanciful as it sounds - any clinical staff in hospitals can or at least should be able to tell you phones interfere with sensitive electronics like ECG machines. Much more of an issue would be the police radio if they have one.

I'm not sure if by this stage the guns have been tested but it could, if someone is prepared to throw money at it, be fairly timely. In the past mobile phones would communicate just when phone calls and messages are being received. Because of that one extraneous result is more likely to be noticed. Now, of course, if they are say listening to Spotify then their phone will be transmitting the entire time, and so if it raised all speeds by x% then it would be less obvious.

I think it is very unlikely, but of course laser guns do rely on making very precise measurements based on tiny differences in time. The laser beam and the image sensor work at very high speed and have to be totally synchronised. If they are out by even a couple of dozen picoseconds the measurements will be noticeably wrong. And that's in tech that is bounced around in a van and probably dropped enough times.

Signs have been covered here to death and I don't think you can accurately comment with only the facts from a tabloid.
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glasgow_bhoy
post Fri, 31 Aug 2018 - 18:16
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I felt like the lawyer was very scattergun- just throwing any argument that might get a tiny bit of traction out there.

Although 7 hours of questioning the speed camera guy. Thats less time than most relationships nowadays.
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666
post Fri, 31 Aug 2018 - 18:59
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QUOTE (notmeatloaf @ Fri, 31 Aug 2018 - 18:36) *
Add to that the method of lining the laser up isn't exact, the cross hairs will/should be approximately in the right place but not to the nearest centimetre.

With the mobile phone I imagine the argument will be that it interfered with the electronics within the gun rather than the laser beam itself. This is not as fanciful as it sounds - any clinical staff in hospitals can or at least should be able to tell you phones interfere with sensitive electronics like ECG machines. Much more of an issue would be the police radio if they have one.


Any electronic equipment made in the last 30 years or so must comply with strict regulations regarding both transmission of, and susceptability to, spurious electromagnetic radiation. The old signs warning you to turn off phones in hospital have long been redundant: patients are free to use mobiles even while connected to ECGs. The defence lawyer is grasping for a non-existent straw.
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notmeatloaf
post Fri, 31 Aug 2018 - 19:41
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You have no clue what you are talking about. As someone who has carried out countless ECGs I can tell you they are effected by mobile phone signals. It isn't uncommon for me to repeat ECGs because some idiot standing by the patients side has interfered with the reading.

Certainly lots of devices probably say no mobile phones because they couldn't be bothered to test them, but ECGs aren't in that category.

That doesn't mean laser guns would be effected, just that any incredibly precise machine typically only works accurately within certain parameters.
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Fredd
post Fri, 31 Aug 2018 - 19:49
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QUOTE (notmeatloaf @ Fri, 31 Aug 2018 - 20:41) *
You have no clue what you are talking about. As someone who has carried out countless ECGs I can tell you they are effected by mobile phone signals. It isn't uncommon for me to repeat ECGs because some idiot standing by the patients side has interfered with the reading.

Interesting. I've had three ECGs in recent years, in each case with my mobile switched on and in my pocket, with no apparent effect on the traces produced. I wonder how much different models differ in their susceptibility to EM interference, and to what degree it's actually tested for?


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peterguk
post Fri, 31 Aug 2018 - 20:28
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QUOTE (notmeatloaf @ Fri, 31 Aug 2018 - 20:41) *
As someone who has carried out countless ECGs I can tell you they are effected affected by mobile phone signals.

That doesn't mean laser guns would be effected affected, just that any incredibly precise machine typically only works accurately within certain parameters.


FTFY


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notmeatloaf
post Fri, 31 Aug 2018 - 21:16
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QUOTE (Fredd @ Fri, 31 Aug 2018 - 20:49) *
QUOTE (notmeatloaf @ Fri, 31 Aug 2018 - 20:41) *
You have no clue what you are talking about. As someone who has carried out countless ECGs I can tell you they are effected by mobile phone signals. It isn't uncommon for me to repeat ECGs because some idiot standing by the patients side has interfered with the reading.

Interesting. I've had three ECGs in recent years, in each case with my mobile switched on and in my pocket, with no apparent effect on the traces produced. I wonder how much different models differ in their susceptibility to EM interference, and to what degree it's actually tested for?

There is only interference if the mobile is transmitting at that time. Quite possibly your phone at the time wasn't transmitting - most ECGs are only measured over ten seconds.

Hence why in general you don't tell everyone to switch off their mobile, although I leave mine on my desk. Nothing more embarrassing than interfering with your own ECG.

EMG interference should be something that is picked up, anyone analysing an ECG should be trained to spot any internal and external artifacts. But, the interference still happens - it can either introduce minor "blips" where there shouldn't be, or just make the baseline wander entirely.
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666
post Fri, 31 Aug 2018 - 22:42
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QUOTE (notmeatloaf @ Fri, 31 Aug 2018 - 20:41) *
You have no clue what you are talking about. As someone who has carried out countless ECGs I can tell you they are effected by mobile phone signals. It isn't uncommon for me to repeat ECGs because some idiot standing by the patients side has interfered with the reading.

Certainly lots of devices probably say no mobile phones because they couldn't be bothered to test them, but ECGs aren't in that category.

That doesn't mean laser guns would be effected, just that any incredibly precise machine typically only works accurately within certain parameters.


My experience is in procuring custom-made electronic equipment, and having to go through many hoops to ensure compliance with the regulations (current version is The Electromagnetic Compatibility Regulations 2016, which brings EU Directive 2014/30/EU into UK law).

Is medical equipment somehow exempt from this? Any mobile phone currently in use should comply.
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The Rookie
post Sat, 1 Sep 2018 - 02:33
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The device is probably fine, it’s probably that it has sensors that are, after all, designed to pick up electromagnetic waves, just doing their job.
https://patient.info/health/electrocardiogram-ecg

I very much doubt a laser device would be affected.


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There is no such thing as a law abiding motorist, just those who have been scammed and those yet to be scammed!

S172's
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Council PCN's
Rookies 1-0 Warwick
Rookies 1-0 Birmingham

PPC PCN's
Rookies 8-0 PPC's
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Fredd
post Sat, 1 Sep 2018 - 09:44
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QUOTE (666 @ Fri, 31 Aug 2018 - 23:42) *
My experience is in procuring custom-made electronic equipment, and having to go through many hoops to ensure compliance with the regulations (current version is The Electromagnetic Compatibility Regulations 2016, which brings EU Directive 2014/30/EU into UK law).

Takes me back a few years to when I was working on large air defence radar systems. One of the company's more intransigent customers insisted that an EMP-hardened system specifically designed to blat out several killowatts of RF still had to go through EMC evaluation and be CE marked before they'd accept it!


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DancingDad
post Sat, 1 Sep 2018 - 10:45
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QUOTE (Fredd @ Sat, 1 Sep 2018 - 10:44) *
QUOTE (666 @ Fri, 31 Aug 2018 - 23:42) *
My experience is in procuring custom-made electronic equipment, and having to go through many hoops to ensure compliance with the regulations (current version is The Electromagnetic Compatibility Regulations 2016, which brings EU Directive 2014/30/EU into UK law).

Takes me back a few years to when I was working on large air defence radar systems. One of the company's more intransigent customers insisted that an EMP-hardened system specifically designed to blat out several killowatts of RF still had to go through EMC evaluation and be CE marked before they'd accept it!



Similar when I was working for a company that made resistance welding kit.
When you power up a welding transformer that is rated at 100s (even thousands) KVA there is one hell of a magnetic pulse.
Would wipe credit cards and magnetic storage devices with ease.
As more then one customer found, not a good idea to have cards or floppy discs in top pocket or rest a laptop by the throat of the machine.
The "blessing" was that it was a very localised pulse, decaying quite rapidly with distance.
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