Filtering...

[sethy]

I was curous to know what the term Filtering really means... Is it basically just cutting sensetivity? or is there a way to really establish threats from non-threats

[jimbonzzz]

I was curous to know what the term Filtering really means... Is it basically just cutting sensetivity? or is there a way to really establish threats from non-threats

Basically, there is no way to tell 100% threats from non-threats.
In general, radar is radar, and it must be reported as an alert.
But, there are a few methods detectors use to attempt to minimize them:

1. Cut sensitivity

2. Don't report alerts shorter than a certain duration
I read a post where Radar Roy talks about the PNI doing this, maybe other detectors do this as well in city mode.

3. DSP:

I believe the Escort splits the radar carrier into 32 "levels", then ignores the strongest three, and determines if a signal is above the threshold of an alert based on the rest of the "levels". They use signal averaging here. i.e. If a signal is detected on one sweep over the threshold, but not in a specified number of subsequent sweeps, then they might suppress the alert. Most if not all detectors nowdays use DSP, and there are some different approaches and algorithms that they use to determine whether to report the alert or not, and to pick out radar from the noise.

They have to be careful not to go too far, without possibly suppressing actual police radar alerts. Some detectors might suppress alerts they aren't sure of, some report them to be cautious.

4. To prevent Ka falsing from other detectors, they can detect harmonics:

The problem was that the old detectors had a local oscillator of 11.55 GHz, and the third harmonic of this is in the Ka band (11.55 GHz x 3=34.65 GHz). This caused Ka false alerts. So, in order to suppress alerts from this, detectors look for the leaked LO frequency of 11.55 GHz, or the second harmonic at ~23.1 GHz (11.55x2), which would also normally be present with an interfering detector, but not police radar. But, because of X and K bandpass filtering in some of these detectors, the harmonics might be too weak to detect, so in some cases detectors must err on the side of caution and report an alert anyway. Detector makers have various ways to approach this, and some simply compare the harmonic relationship between different carriers deteced in these ranges, and if there IS a relationship then the alert is suppressed. The interfering signals don't always have to be present at the same time as the harmonic for the alerts to be suppressed, if these signals appear within a specified timeframe then the alert is suppressed.

5. I believe I read somewhere that they can determine if a Ka signal is false by watching to see if it changes freq i.e. if the other detector is changing the LO when sweeping to mix with the received signals.

Some detectors suppress false alerts naturally by not having a rear antenna. It would make sense that a detector with only a front antenna likely has 1/2 the falsing as one with both front and rear.

I also suspect that some detectors might be more directional than others i.e. so they are less likely to detect motion sensors that are well off to the side of the road you are driving on, but I'm not sure about this.

Well, those are the only methods I know of, if anyone else knows some methods please chime in...


Jim

[Iknox]

Thanks for the GREAT INFO :)

[compu44]

Tons of info there. Much appriciated jimbonzzz

[jimbonzzz]

I also forgot about the Cobra "Intellimute", which senses engine RPMs and can tell if you are stopped or going slow, and then mutes the alerts (since you probably aren't speeding)

Jim

[happya$$]

Jim,

What do you do for a living? You seem to know a lot about radar

[jimbonzzz]

Jim,

What do you do for a living? You seem to know a lot about radar

Well my job has nothing to do with Radar...

I'm no radar expert by any means, my interest in radar is really just a hobby like a lot of the other people who post here, so take anything I say with a grain of salt :D

Radar and detectors fascinate me, and so does the technology. I'm a ham and a scanner enthusiast, so I like messing around with radio and gadjets in general. I also like fast cars :D

But since you asked, I am an EE, I currently work with Engine/Transmission Control Modules at the GM Proving Ground in Michigan.


Jim

[compu44]

I also forgot about the Cobra "Intellimute", which senses engine RPMs and can tell if you are stopped or going slow, and then mutes the alerts (since you probably aren't speeding)

Jim

Good thing I don't have one, wouldn't want to have trouble on those 200km/h in neutral times.... :lol:

It's a feature that's selectable on/off. Never used it myself as I have no tachomoter.

[joop1987]

It's a feature that's selectable on/off. Never used it myself as I have no tachomoter.

It uses the frequency of your alternator; so no need to hook it up to a tach.

[SETITOFF]

On this Cobra INTELLIMUTE, it actually picks up the RPM directly from the engine. You're right, it doesn't need to be hooked to a tach due to the electronics built in. The engine RPM is sensed directly thru the power cord connected to the lighter. I have the Cobra 9400 and it has this feature.

I've had it set and it does work, eliminating any alerts while you are sitting still. Once you begin in motion again it goes into active scanning.

Let's say you're stopped near a WalMart with an auto-door opener: it will not alert on that door until you begin moving. It's an okay feature.

The way it is set is you activate it when the engine is in idle so it picks up the lowest RPM after the engine is at nromal operating temp of course, say 700RPM. Anything over that the unit is in active scanning.

[Veil Guy]

jimbonzzz,

Sounds nice. Have you worked with the new Z06, 7+ Litre small-block?

My understanding is that we can expect ~500hp at the crank.

Does your work involve the CAGs circuitry incorporated into the previous gens of C4 amd C5?

The Veil Guy 8)

[compu44]

It's a feature that's selectable on/off. Never used it myself as I have no tachomoter.

It uses the frequency of your alternator; so no need to hook it up to a tach.

Yeah, I understand that, it's just a might difficult to set up without a tach. I guess it's easy to do if you only want it to mute at idle, but i'd want a couple MPH going before it'd alert.

[jimbonzzz]

jimbonzzz,
Sounds nice. Have you worked with the new Z06, 7+ Litre small-block?

They're around of course, but right now my focus is on a V6 program....



Does your work involve the CAGs circuitry incorporated into the previous gens of C4 amd C5?

Why, you lookin' to change/disable it? :D
HPTuners (best way IMHO)

Jim

[abdrury]

I also forgot about the Cobra "Intellimute", which senses engine RPMs and can tell if you are stopped or going slow, and then mutes the alerts (since you probably aren't speeding)

Jim

BEAUTIFUL feature...that's the only thing i'll miss about my Cobra :cry:

[sethy]

I think cobras had some of the nicest features, but they lack in range.

I loved the Power off automatically when your car was off, and I like how it turned on when you turned on your car. I loved the intelimute, I think that was one of the best features the cobra had to offer...

The POP detection was a joke though...

[compu44]

No question about it- cobra has some of the best featuers and nicest looking detectors out there. If they could get that POP issue fixed and crank the K band range up a little, they'd be a seroius competitor.

[SmaartAasSaabr]

How come nobody makes detectors that really look good (to my eyes at least)...

I almost think the V1 comes closest, the original PASSPORT was pretty nice, How about a Passport 9500 that looks like a flat black pack of cigarettes? Well, I'd rather performance than aesthetics anyway (or else I would have a PNI RX7500...)

[compu44]

How come nobody makes detectors that really look good (to my eyes at least)...

I almost think the V1 comes closest, the original PASSPORT was pretty nice, How about a Passport 9500 that looks like a flat black pack of cigarettes? Well, I'd rather performance than aesthetics anyway (or else I would have a PNI RX7500...)

Well, I guess at least part of it is trying to make it blend in to reduce theft. That and keeping the glare minimal for all you low-mounters :)

[happya$$]

I have mounted low and high and from personal experience, mounting it high is BY FAR best for ME

[V1 Dave]

Radiation of radar detectors and POP detection are very similar as it increases the false alarm characteristics.

Cobra most specifically needs to get their radiation under control, although it is a little to late with hundreds of thousands or millions already on the road.

It seems they have been branded the worst at radiating X and K band radar frequencies that are similar to the characteristics of POP K band.

According to some sources this is their biggest stumbling block with making POP user friendly.

[sethy]

define user friendly...

[V1 Dave]

Not continuously getting false POP radiation passing certain radar detectors.

[Veil Guy]

I own a '91 6-Speed and have been following, with interest, the continuing development of the subsequent C5, and C6 vette family and the new HP caddy line, especially when it comes to electronics in ECM.

The Veil Guy 8)

[jimbonzzz]

I own a '91 6-Speed and have been following, with interest, the continuing development of the subsequent C5, and C6 vette family and the new HP caddy line, especially when it comes to electronics in ECM.

The Veil Guy 8)

I've worked a lot with Caddys. Yeah, there's definitely some cool stuff, Wish I could talk more about some of it, but of course I signed some major NDAs...

I'm an f-body guy myself. I keep telling them to bring them back, but they just won't listen to me for some reason :D


Jim

[SmaartAasSaabr]

YES F-Body's! :D

I want my, I want my, I want a new Firebird...

It really was pretty sad, they let the car wither on the vine for so long, then made it ugly, and still kept horrible interior, so the sales were poor and then they said "oh nobody wants sports cars anymore, so let's kill it and the plant"... :evil:

Mind you, those LS1/T56 F-bodies sure were a hell of a bargain in performance, but damn the interior was crappy....

[Veil Guy]

Kudus to GM for the great showing of V6 sedans with the CTS topping the list!

I still believe that the original Camaros were the sexiest bodies of the entire family line.

If only Chevy would take a cue from Ford [with their Mustang] and design a retro Camaro/Firebird/TransAm. That would be a hot ticket for sure.

Who knows, maybe with Lutz onboard, that's exactly what can happen. :idea:

The Veil Guy 8)

[fallen8511]

If only GM would make a decent sports sedan. Until then I think I will stick to German cars.

Also whoever thought up making the Pontiac GTO is an idiot. The reason it doesn't sell is because it looks like a normal car, it needs retro styling like the Mustang.

[SmaartAasSaabr]

Decent sports sedan?

Well, there are the 9-3 SS and the CTS....

The CTS-V is just amazing, If I only had 70K CND I would be having a mind splitting dilemma - CTS-V or Corvette... what a horrible decision to make, eh? :lol:

The 9-3SS fixes all the problems of the older 9-3 (loopy chassis), and throws a few more horses and an extra gear into the mix...

The CTS is light-years ahead of the old Catera, and with the 3.6L 255hp HFV6 (plus the manual transmission that comes with) who cares about the lame 330i? Of course, there is always 390hp 5.7 LS6 motor waiting... for twice the price however :?

The GTO is also a very good car, and I don't mind the styling. Unfortunately the earliest I can legally own a 2004 GTO in Canada is 2019!

Why oh why!!

[SETITOFF]

Geez, if you have to wait that long you may as well start building your own form the ground up. Buy the engine then piece mill the chassis, body, interior...

[Veil Guy]

SmaartAasSaabr,

You're right - the CTS V is a real Bahn-stormer. I still have a little adjustment [to make] to warm to the sharp edges but with the latest "Bangle'd" 5/7 series cars from München it they sure look like a viable alternative to their Teutonic cousins.

I nearly died when I heard the chief C5 designer, John Cafaro - who had penned many a beautiful C5 bodies - was being replaced by Tom Peters to develop the C6. This was the guy responsible for the Aztek look.

Personally I think the C5 - with all of its design flaws - is still easier to look at than the new vette.

Hopefully, the aftermarket can come to the rescue like it did with the new Chrysler 300.

The Veil Guy 8)

[SmaartAasSaabr]

Honestly, I preferred the C4 to the C5 and the C6 aesthetically... I don't like the C6 headlamp arrangement, nor the steering wheel, but aside from that, I really like the new C6. Now obviously this is not to say that I wouldn't mind having a C5 :wink:

Note I found it odd to see the same door handle on a Z06 as on my father's old Pontiac, plus a steering wheel out of a Grand AM :lol: but you got to save somewhere. The C5 and C6 are definately the best bang-for-buck you can buy today. For less $$$ than a Boxster, you get the closest thing to a 575M!

Eugh I really can't stand Bangle's reign of disgust over BMW. Previously BMW's were OK on the exterior, and the interiors were just beautiful, then they started getting the exteriors really beautiful as well, around the time of the 8-series. Then they rounded off the 3er in 1999, which was alright, but then the Bangle Bungle of the 7er, Z4, 5er, 1er and now the 3er again just crossed the propeller roundel off my radar screen...

[Veil Guy]

Yeah. I love what you can do with the vette as a platform.

There is an organization called www.cartek.net based out of NJ that has done some really impressive work on the c4, c5 platforms.

They currently have normally aspirated c5's doing under 10sec ETs.

Really incredible stuff - when you consider you can get a base c5 used and for another ~$20K have a sub 10sec car - simply amazing! :shock:

I don't understand BMW, either. For years the German's have rightly resisted the temptation to incorporate cup-holders and other "conveniences" within their interiors because they [rightly] feel they serve as distractions from the business of driving.

And yet with their latest offerings they go way overboard with I-drive.

I test drove a 760Li and couldn't find a away to simply select a radio station without having to take my eyes off the road to navigate a menu system to perform the task. Ditto for climate controls. Ergonomically, BMWs are suffering from disengenuous engineering.

This is blasphemous, pure and simple and I sincerely hope the MB, BMW, and Audi minimize their over-engineering of the electronics.

I think I read somewhere that Bangle was being "promoted."

I can only hope they get their act together and return to producing "pure" automobiles. Until that time, the CPO program is looking pretty darn good.

I make an exception for one automobile, though. My wife and I recently rented a Z4 to perform a radar detector comparison test (soon to be published on our veil site) in the West and found this particular car to be absent this electronic nonsense. It was an awesome ride. I humbly believe this has been Bangle's best work to date.

The Veil Guy 8)

[SmaartAasSaabr]

Cartek is nuts. I really felt bad when Ligenfelter died though... :cry:

I agree. For years BMW interiors were very well laid out, devoid of anything that was illogical or a distraction. The dash curved around the driver, the seat was comfortable and everything worked in harmony to produce "the Ultimate Driving Machine" (which btw. was the tagline for the Pontiac GTO in 1965...)

Now you got I-Drive, might as well have put CP/m on there with a keyboard, at least it would be easier to use when driving :)

What happened to climate and radio controls? On my 900's, I have three simple big knobs for heating, easy to use in the cold when you have gloves on, and the radio vol/on switch I can reach without even taking my hands off the wheel. Now everything has this huge computerized "thing" for the HVAC and radio, and many cases it's combined :shock:

Also, I have always been very unhappy about the importation policy practised by the European carmakers. Only the most costly models ever make it here....

For example, I was in some MB C-classes, but damn, the only one I'd consider was the "C230" with the 1.8 supercharged and the 6-speed, the mass of electronic BS on the C240, C320 etc was a little much for me... How come we don't get cars like the C180 CDI?

But, the Saab 9-3 Linear 1.8t, for some reason N. America gets the Saab 9-3 Linear with the 2.0t, but the rest is "normal" - this isn't such a bad deal

And then there's the problem about automatic transmissions, I can't stand a slushbox, but how many good cars can I get with a good manual shift? I can get a Chevy Aveo or a Corvette, not too much in-between :roll:

[Veil Guy]

Terrible tragedy with JL and a great loss for us all. I sincerely LPE continues to thrive in his absence.

The Veil Guy