Prosecution refused disclosure for speeding charge.

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Decatur
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Re: Prosecution refused disclosure for speeding charge.

Unread post by Decatur on

"Any object, bridge, railway line, powerlines will cause interference and doubt the readings." Not true. Some of these MAY cause interference under some circumstances. However, interference is not additive to the reading it just cuts down on the range at which the officer may pick up the vehicle. I've never seen a stationary object like a bridge or a railway line cause any interference. A powerline may but I tend not to point the radar up in the air to read a powerline.

"Doppler effect of Radar will produce different readings for different kind of objects for example plastic car (Honda pilot) versus big all metal car (like Hummer) also different size like a difference between a small car like smart or a big truck or a bus." Not true. These examples will only affect the range at which the object can be picked up by the radar.

Most radar operators know that the beam covers all lanes of the highway. Thats why we tend to use our eyes to see which one is travelling faster.

btw.. There is no such thing as a "wrong reading" on radar just a wrong interpretation.


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Unread post by ejadoo on

Just reading DOT HS 809 811 document, this for Lidar. The document states that the unit should be checked and verified against electromagnetic interference for different bands of frequencies like FM, AM. Is is way more important for radar as they use radio waves not laser. Your radar unit should be recently certified against the electromagnetic interference. Now DOTs are US documents, canadian requirements could be different, but they must either prove it or disclose it. Another thought :)


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Unread post by ejadoo on

Decatur wrote:"Any object, bridge, railway line, powerlines will cause interference and doubt the readings." Not true. Some of these MAY cause interference under some circumstances. However, interference is not additive to the reading it just cuts down on the range at which the officer may pick up the vehicle. I've never seen a stationary object like a bridge or a railway line cause any interference. A powerline may but I tend not to point the radar up in the air to read a powerline.

"Doppler effect of Radar will produce different readings for different kind of objects for example plastic car (Honda pilot) versus big all metal car (like Hummer) also different size like a difference between a small car like smart or a big truck or a bus." Not true. These examples will only affect the range at which the object can be picked up by the radar.

Most radar operators know that the beam covers all lanes of the highway. Thats why we tend to use our eyes to see which one is travelling faster.
btw.. There is no such thing as a "wrong reading" on radar just a wrong interpretation.
Bridges are made of solid iron. when heavy traffic passes over a bridge they vibrate. Did you ever stand on top of a bridge and felt the vibration? this vibration can cause interference. Railway lines are the same examples. Powerlines too, they can be vibrating just because of wind, or different kind of power or power transferring with different frequencies and KVs will cause all different kind of interference. A radar reading must be fool proof to convict someone otherwise the advantage of doubt should go towards the accused.

Doppler works on the principle of phase shift. different hardness will produce different phase shift. Thats the principle used in ultrasound machines to differentiate between different tissues. You may be right on this. Have to read in depth that how is the phase shift being interpreted in a speed radar. but it will definitely produce different result. Range is more affected by the power (Watt or milliwatt) also somewhat the frequency used (indirectly related to power) or depending on the objects that can cause interference within the beam of the radar.

Sorry, this is a language issue. I still have to learn English, its not my first language. excuse my language please


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Unread post by Decatur on

Police speed measuring devices will not pick up the vibration of a bridge or railway line.

Some interference from electronic devices may occur if you point the speed measuring device directly at them. It's simply a matter of moving the device.

Modern police speed measuring devices internally eliminate electromagnetic interference (EMI) and are also equiped with radio frequency interference (RFI) detection circuits that will shut down the systemwhen an excessive level is reached.

Police speed measuring devices use the doppler shift to obtain their speeds. Phase shift is not even taught.

And again.... interference is not additive to a reading. It simply reduces the range at which you can pick up a target.


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Unread post by Pepsi on

Ejadoo, can I call you as an expert witness ;) I sent you a private message on the board and email. Please check both if you want to coordinate trial attendance.
The DOT documents may be US but Ontario police boards must comply with them as per AI-013. For Lidar some refer to DOT HS 809 239 but it looks like it has been replaced in 2012 by the 811 you're looking at. Key here is disclosure. We want to see the policies to link them to NHTSA, to DOT documents, to examine the discrepancies.


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Unread post by Pepsi on

Decatur, you mentioned several interesting topics.
1. Tuning forks. My argument is not regarding the usage of the forks, but the lack of mandatory equipment which is not supplied with Canadian units or even mentioned in the manual. If Ontario didn't require adherence to NHTSA standards that would be a different thing but I have evidence that it does.

2. "Most radar operators know that the beam covers all lanes of the highway. Thats why we tend to use our eyes to see which one is travelling faster." Most? tend to? I What about those officers who don't? Those who do know, how did they find out? Not from the Operating Manual. And yet, the manual is all they need to know in the eyes of the law. If they follow the manual and point the radar at 4 lanes and flag down the wrong car that is ok in the face of the law. I know speeding tickets maybe a trivial thing in the eyes of law enforcement and the courts especially considering all the ugliness they have to deal with on daily basis. But for those faced with fines and skyrocketing insurance rates it is no small matter, and if they were wrongly ticketed that is a double injustice. Yes, I am ranting;) I realize that is not your fault, I am just pointing out that a manual on its own is insufficient.

3. "Thats why we tend to use our eyes to see which one is travelling faster". Thanks for bringing that up.
a. So, how exactly do you know what you're aiming the radar at? Is there some kind of a scope on the device? With several cars in the line of sight can you tell which one the radar is picking up?
b. There is a brief mention of an antenna for GVPD in the manual but I don't see it on the device or instructions.
Thanks!


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Unread post by Decatur on

1. Haven't used tuning forks for years and I certainly don't miss them. Check case law on "tuning forks."
2. I say "most" because I don't know anyone elses practices or training programs. It would be rather arrogant of me to assume that we are all perfect. More than reading the manual is required in Ontario. Again.... caselaw.....
3.a There is no scope on the Decatur handhelds. Point it. With several vehicles in line of sight it's rather easy to tell which one is being displayed. It's based on reflective capability, position, and in some cases the speed of the target.
b. I can't seem to find what you mean in my manual.(They may be different editions) The antenna on the GVPD is actually in the housing and you can't see it.


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Unread post by Decatur on

I just had a quick look through the NHTSA standard and I couldn't find anything that indicates that tuning forks must be included and used in operator testing.
The only thing I saw was that when a manufacturer submits a device for testing it must be accompanied by them.


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Unread post by ejadoo on

I don't mind helping anyone who is working hard for an objective. As far as "Expert" I don't think court will except me as an expert. to be an expert on a system, you should have the specific theoretical and practical education, specific training and an advance level of experience. I will not be considered an expert just on the basis of education. But I can prepare for radar and raise a number of question and doubts. In my case, a lidar was used, I have been working on it and found very useful information and I am very confident about Lidar now. I didn't even know that radar uses doppler shift :), but can prepare for that too. PM you too.

As far as radar interference, yes any analog filters can be applied to filter out EMI. But any doppler shifted harmonics can not be filtered out. all the expected frequencies caused by a doppler shift that are needed to calculate the speed will never be filtered out. two moving objects side by side will cause two different doppler shifted harmonics. a doppler shifted frequency by one car will be further shift by other car moving behind the car. any moving object 10-20 feet above the road can also create a doppler harmonic that can be received by radar. a vibrating railway line, a vibrating HV power line will all act like a tuning fork and can generate doppler harmonics as long as they are within the radar beam. you don't have to point your radar towards the power line to receive that doppler shift frequency. the way radar beam gets bigger with the distance, there is very high probability that the radar can receive those frequency harmonics.

I have not read about the principles of the radar. I will have to read more and look at drawings as well to go in depth. All the required testing of radars and regulatory requirements and technical issues has to be reviewed.


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Unread post by ejadoo on

Hi pepsi, were you able to find AI-013 for toronto? i found for ottawa n brantfold, but cant find it for toronto. thanks


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Unread post by Decatur on

AI-013 is a Provincial Standard. It's the same for all agencies in Ontario. You just have to find the current one.


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Unread post by ejadoo on

Thanks Decatur for the quick reply.


Pepsi,
I found this interesting, thought i should post it here for any future reference. We Canadians learning from US experiments usually after 10 years. Thats why we are making a real estate bubble now after it was busted in USA in 2007. I think its time that we should learn something from this ruling too :)
http://www.lawenforcementservices.biz/L ... 202011.pdf


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Unread post by Pepsi on

lol ejadoo, only too true! unfortunately the courts rely on precedent to decide cases so in reality decisions are made by a few select judges and the rest follows or has to follow? I'm not sure if I judge can successfully rule against a precedent. thanks for the link


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Unread post by Pepsi on

ejadoo, re ai-013, decatur is right, there is only one. Unfortunately I wasn't able to find it, from an official source at least. I think there is enough reference to it from individual police boards that we will have a case for at least requesting to see it. This info should be available to public at large; we shouldn't have to waste hours surfing the web looking for it.


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Unread post by Decatur on

It probably is available to the public. You may have to do an FOI request from the originator of the document. The Ministry of Community and Correctional Services. When you do ask for documents, make sure you ask for the version that was vaild at the time of the alleged offence.






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