GPS camera detectors - time til active?

How long does it take you your GPS base camera detector to aquire satalites and start doing its job?

 

Im mainly looking for a warm start time when the unit has been off under 12 hours.

 

My snooper S4 neo takes between 5 and 7 mins on average, which to me seems excessive but this is the second one ive had so im assuming its not the unit itself.

 

Also while im on the subject, how accurate is you GPS detector, mine seems to be upto 100m out, depending on the camera. Im putting this down to snoopers database being out as they seem to use co-ordinates uploaded by users.

 

As a comparison, my royaltek sapphire GPS mouse (for tomtom navigator) sits not more than 6 inches from the snooper and aquires satalites within 30 secs and seems to be accurate to within >10m.

 

Please list make and model and if you have had any other issues with it.

hi john

 

ive got a road angel,

 

 

seems pretty accurate to me distance wise,

 

aquire sats pretty quick unless the weather is bad,but the most it ever takes is about a mile or 2 up the road from start up

 

cheers baldy

My Road Angel is normally ready for use within 20-30 seconds after a warm start.

 

I find its very accurate as to where the speed cameras are, mostly less than 10 metres. Occasionly it may stop bleeping before the camera but never more than 15 metres and thats pretty rare, normally its spot on.

 

I must admit if it took up to 7 minutes to start and then was sometimes only accurate to 100 metres it would have been confined to the bin (eBay) a long time ago

 

I've had no problems with the Road Angel in 10 months of everyday use. What sold it to me was the ability to easily swap it from one car to the next, I certainly wouldn't want to drive far without it

I have an S4 Neo also

It only takes maybe 10-15 secs to pick up the satellites and in terms of accuracy, when the warning text starts flashing it is just before the start of the markings on the road for the Gatso's.

Maybe your unit is faulty

This is my second unit, I sent the first back due to the accuracy problems, So chance are the replacment is ok. Which is why im trying to find out what others are like.

 

I should say that maybe 1 time in 10, especially if its only been switched off for an hour or so it does pick up the sat's in about 30 secs.

Originally posted by JohnK

This is my second unit, I sent the first back due to the accuracy problems, So chance are the replacment is ok. Which is why im trying to find out what others are like.

 

I should say that maybe 1 time in 10, especially if its only been switched off for an hour or so it does pick up the sat's in about 30 secs.

 

It should pick up the satalites almost instantly, but depends how long the computer takes to process all the signals. Cheap GPS systems will only be about 100m accurate, if the ones fitted to planes are only to the nearest 100mtr, then ones fitted to cars wont be any better.

My Origin B2 takes about 30 seconds - I'm in the middle of nowhere and surrounded by hills too, I generally only pick up 3 or 4 satellites.

I was surprised how accurate my Angle is it always seems to be accurate to with in a few metres. Not let me down yet.

John, call me tomorrow, and I'll phone Snooper to find out what happened with yours.

The shouldn't take that long to access satelites, and their accuracy is pretty damn close.

 

The only thing that is a possibility, we've had problems in the past with GPS aerials being too close to each other, when we've installed GPS detectors near GPS satelite aerials. Maybe the Tom Tom thing is interfering with it?

Matt Ill try to give you a call tomorrow about it.

 

As for interference, its just the same in both cars, I dont bother with gps in the corsa

Originally posted by mcanny

My Origin B2 takes about 30 seconds - I'm in the middle of nowhere

Being in the middle of nowhere wouldn't make any difference Michael.

Originally posted by Timwildman

It should pick up the satalites almost instantly

I'm sure that's not right Tim. I've seen a chart somewhere listing different models and how long they take on average for a Cold First Fix etc

Cheap GPS systems will only be about 100m accurate, if the ones fitted to planes are only to the nearest 100mtr, then ones fitted to cars wont be any better.

Hmmm, My £170 Emtac Bluetooth GPSR is accurate to 10mtr or better. When it shows I'm going over a bridge or whatever I really am, when I set it to find an address it takes me to the exact house number and tells me when I'm there.

Obviously I'm talking about SatNav here not Speed Camera stuff but it's the same technology, right?

As Jake says, most GPS recievers have 3 different times listed in there specs, Cold, warm and hot start, depending how long they have been unpowered.

 

Also my satnav is spot on too, re bridges, house numbers ect.

Originally posted by Jake

Being in the middle of nowhere wouldn't make any difference Michael.

I'm sure that's not right Tim. I've seen a chart somewhere listing different models and how long they take on average for a Cold First Fix etc Hmmm, My £170 Emtac Bluetooth GPSR is accurate to 10mtr or better. When it shows I'm going over a bridge or whatever I really am, when I set it to find an address it takes me to the exact house number and tells me when I'm there.

Obviously I'm talking about SatNav here not Speed Camera stuff but it's the same technology, right?

 

ok, if a £50,000 plane gps system, is not more than 100mtr accurate (sp?) then i'm sure a £130 car version is not that good. but with a car they know with in reason it'll be on a road so with the data base, they can pin point the location quite well. If they claim it's only 10mtr out thats a good claim..

 

For a gps first fix, there is a lot a of data that they transmit to the receiver, cant remember how long it takes to get all the info but it's along time. emorpheous data, almamnac data, and something else:innocent: Basically if the unit has all the data already then it can determin a position almost instantly. Processing power dependant.

 

Err cant remember anything else Bud sapping mental power:D not that i had alot in the first place:).

I really find it varies from day to day. Not sure if its ever weather related but I thought GPS didn't suffer that....

 

My Road Angel sometimes works by the end of my road, other times take 10 mins or so

 

My PDA navigation stuff seems to click in pretty quick all the time.

 

Blackspot (makers of RA) told me to take it inside overnight and leave it powered on all night, this will make it flush all the old GPS data, then power on again in the morning back outside in your car, and not through the windscreen, eg nothing blocking sight and it will come up 15mins later after re-aquiring from scratch new satelites. Did this a few months back and it worked quite well, think I might need to do it again!

Civillian access to GPS used to only be accurate to around 100M because the time signal would 'randomly' drift. The military could remove the drift and get much higher accuracy.

 

They have since updated their systems and the public system is down to a few meters - the military system is rather more accurate.......

 

Note that the military can turn the system off, as they did in the last Gulf war.

 

BTW, general aviation navigation does not need to be that accurate anyway, a n airliner will cover 100M in about 1/2 second.

 

Originally posted by Timwildman ok, if a £50,000 plane gps system, is not more than 100mtr accurate (sp?) then i'm sure a £130 car version is not that good. but with a car they know with in reason it'll be on a road so with the data base, they can pin point the location quite well. If they claim it's only 10mtr out thats a good claim..

Originally posted by Timwildman

ok, if a £50,000 plane gps system, is not more than 100mtr accurate (sp?) then i'm sure a £130 car version is not that good.

Well I'm sure you're wrong Tim, as others have said : car Sat Nav is spot on.

Is it trickier to give an exact location for planes because they aren't at ground level maybe? [/guess]

Originally posted by Matt Harwood

The only thing that is a possibility, we've had problems in the past with GPS aerials being too close to each other, when we've installed GPS detectors near GPS satelite aerials. Maybe the Tom Tom thing is interfering with it?

 

My Snooper S6 takes a lot longer now I got an iPaq GPS right next to it. Hmm

Something that makes car sat nav systems seem more accurate, is map matching. The manufacturers assume that you're going to be sticking to the roads on the mapping system, and adjust themselves accordingly. Fixed car systems also use speed pulse inputs, so that they can gain even more accuracy with map matching, and even more again, with a built in gyroscope. They need these backups for occasions when satelites cannot be read. Big built up cities, tunnels etc.

All this combined should give a fixed car sat nav an accuracy of a couple of metres or less.

I believe military satelites are generally within 10 metres to the public.

GPS systems (i have 2) have an internal almanac of satellites and their orbit. They know how long they've been switched off for and they know where they were last time they were on, so they know which satellites to look for if they've only been off for 15 minutes.

 

If you've moved a long distance (approx. 600miles) since the unit was last switched on, then the satellites it last was talking to probably won't be the ones in the visible sky now so it does a "general search" and this takes longer.

 

Most GPS' need 3 satellites for a "2D" fix and 4 satellites for a "3D" fix. (i.e. knows altitude too).

There's no reason why a plane's GPS will be any more accurate than a ground-based GPS that you can buy cheaply, other than because it has an unobstructed view of the sky it will lock onto many more satellites (& prob. a bit quicker cos no obstructions) and this will mean it'll have a fix of about +/- 13feet. Best i've ever got was receiving 11 satellites at once on a boat on Pacific Ocean off North-Eastern Coast of Australia, which gave a fix of +/- 13feet. Normally i'll have a fix of +/- 23 - 30feet once it's got 4 or more satellites.

 

"Warm start" (unit has been off a max. of 15minutes) takes about 15 seconds, and "cold start" takes about 1 minute, but this depends a lot on how many solid objects are obscuring view of the sky.

 

"Initial start" for a GPS is the very 1st time it's powered up from new and takes about 5 minutes.

 

One more thing is that the time on your GPS is VERY accurate (atomic clock accurate) as it gets the time of day from the satellites themselves and the satellites get the time from an atomic clock.

 

A GPS works simply because it actually knows the time down to a zillionth of a second that the satellite sent it a signal and it simply times how long the signal took to get to it. Once it's got 3 or 4 it knows it's position down to a few metres via triangulation of the signal. Each satellite is approx. 11,000miles away.

 

The USA govt. used to have "SA" (=Selective Availability) switched on all the time which degrades the accuracy for civvies, but a few years ago they (nicely) switched it off so civvy GPS receivers are more accurate now. They can switch it back on at any time etc.

 

Faster speed i got on my GPS is 468mph on board a 747 ! (it works holding it up against the window...) Though the air stewardess said that the pilot already had a GPS and so asked me to switch it off ! it doesn't transmit any signal to the satellite (contrary to what the stewardess thought it's NOT like a mobile fone in that it just receives.)

 

sorry for rambling.

 

cheers all

Yes, SA was turned off by the US government a few years ago allowing GPS civvy GPS to be horizontally accurate to within a few meters. In car navigation, as Matt says, relies heavily on the stored road network to improve the relative accuracy of your position. I havent tried yet, but I'm not sure how well an incar nav system would perform if you took it off road (significantly off road, not just through a park!!!).

 

Incar nav systems also dont really have to worry about the vertical measurements (altitude). The z measurement has historically been harder to get as accurate on standard GPS. Differential GPS (used in surveying) is extremely accurate on all three axes.

The wife's S6 neo takes an age

Originally posted by Doughie

it doesn't transmit any signal to the satellite (contrary to what the stewardess thought it's NOT like a mobile fone in that it just receives.)

 

sorry for rambling.

 

cheers all

 

 

Which would dispel the popular myth that the "governments" can track you by using your GPS device.

Originally posted by Patrick_Devlin

but I'm not sure how well an incar nav system would perform if you took it off road (significantly off road, not just through a park!!!).

 

 

It does seem accurate in my experience. When I travel along the Selby by-pass, Tom Tom doesn't have this road in its latest version, so it just shows me traversing "space", but it accurately displays railway lines and the Selby Canal when I drive over them on the new bypass.

Some figures for comparson......

 

Startup times....

 

19th May 6am, - 2 mins to come online then another 4 for the speedo to work correctly (sticking on zero, 12mph ect.)

 

19th May 4pm - 7 mins

 

20th May 6am - 1.5 mins

 

20th May 4pm - 4 mins

mine aint worked for nearly 2months now and waiting for possibly the third replacement to arrive:(