Speedcam values

This unit is the MyWay system, also referred to as RNEG, made by Harman Becker.
Main Features: Also referred to as RNEG, the MyWay colour satellite navigation system, has SD card, integrated European mapping, live trafic information, voice guidance and graphics in 2D or aerial perspective & it features a Bluetooth® system (Bluetooth phone compatibility only - no Bluetooth Audio Streaming).

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bobins
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Re: Speedcam values

Post by bobins »

The speedcam speed warnings innacurracy (using SCDB) on RNEG is normal. I always put it down to the fact that they had to convert UK mph values into km/h with a small safety margin and then have to convert km/h back into mph with another small saftey margin.
ADY-ULTRAS
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Re: Speedcam values

Post by ADY-ULTRAS »

So, no way to sort it out?
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bobins
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Re: Speedcam values

Post by bobins »

Not that I've ever found.
ADY-ULTRAS
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Re: Speedcam values

Post by ADY-ULTRAS »

Ok, thanks for your help and support! 😉
lorddevereux
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Re: Speedcam values

Post by lorddevereux »

I can confirm this issue as of recent speedcams from SCDB, still happening. What I've done is turn off the visual alert, and just use audio as hopefully you always know what the speed limit is lol.
Mira308SW of mirascripts fame made a program that could partially decompile the LWD files used to store the speed limits. I can't find the 2017-2 maps radar file, but if you could upload it somewhere then I could have a look at the two sets and see if I can see what the difference is to help SCDB fix it.
Last edited by lorddevereux on 17 Apr 2019, 13:28, edited 1 time in total.
Homer
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Re: Speedcam values

Post by Homer »

Ah, was that supposed to show the correct speed limit? I always thought it just thew up some random figure since it never seemed to match. :rofl2:
lorddevereux
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Re: Speedcam values

Post by lorddevereux »

Thanks to ADY-ULTRAS for sending me some working and broken files, I've found out the following. I've used a speed camera I know well (set to 30mph) so I know the speed/location etc precisely.

Code: Select all

Latitude	Longitude	Direction	Limit flag	Speed	Limit mode	(Section)
Working:
50.969862	-1.337513889	96		1		30		10	28

Broken:
50.969862	-1.337513889	96		1		40		13	20
It appears to be that if you set the "Limit mode" flag to 10, then you can store the speed in mph (30), whereas SCDB stores all values as Limit mode 13 (which I assume is kmh). In fact the working file uses 15, 7, 13, 9, 10 and other types of limit mode whereas every camera in scdb is set to 13. This I assume is the problem, although I'll have to conduct a bit more analysis to work out what the different types all mean (maybe mph, kmh, average speed etc?).

The file format LWD only lets you store speed limits in units of tens (30, 40, 50 etc) so I think what is happening is their tool is converting the UK speed limits to their nearest kmh equivalent (30 -> 45) and then when it's built into the LWD file it stores the nearest round number which is 40kph, which is 37mph, which the unit then shows. This doesn't happen with 50mph sections because 50 -> 80kph almost exactly.

I have no idea what tool SCDB use to build their database and what configuration options it might have, but if someone has an active SCDB subscription (mine came with car from prev. owner) its probably worth feeding this back to see if they can fix it (or get me an email address and I can explain it to them directly). I don't know if the tool I'm using can successfully re-build the hazardareas.lwd to a working file but I'll give it a try with this camera when I get some time in case they can't fix it themselves.
ADY-ULTRAS
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Re: Speedcam values

Post by ADY-ULTRAS »

Hi! I have a subscription on SCDB but I think it's better if you send an email to support@scdb.info and let them know about your discovery. Maybe it will be sorted! Good luck!
ADY-ULTRAS
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Re: Speedcam values

Post by ADY-ULTRAS »

Hi guys! Any update in the values of the speedcams?
lorddevereux
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Re: Speedcam values

Post by lorddevereux »

Sorry I've been super busy with work lately. On further investigation, the limit mode flag is actually used to set the warning distance (one at 600yd out, next at 200yd out). The determination of km/mph I think is set elsewhere inside the header of the LWD file and is done on a section-by-section basis. The file format is a bit strange and basically groups speedcams into geographic boxes. So I think somewhere in the header for each "box" is a flag for KM/mph. Mira and some others did a reasonable job documenting the LWD format, but the km/mph flag is not one of those found (since they were all european based I guess they had no reason to worry about mph!).

I tried manually analysing the undocumented sections of the header to try and spot a pattern, without success so far. I think this one may need to be filed under "impossible" unless someone can get hold of the tool that is used by PSA to generate the official maps.
ADY-ULTRAS
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Re: Speedcam values

Post by ADY-ULTRAS »

Hi! Did you tried to get in contact with scdb ? They might be able to do something and if you help them they will give you free subscription.
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GiveMeABreak
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Re: Speedcam values

Post by GiveMeABreak »

I've also looked into the LWD format with those tools and gave up as the files have checksums so any alteration and they won't compile. Some uf us were trying ti amend the radar zones and add personalised speed traps - but the failed to work so we resigned ourselves that without the appropriate software we can't amend them.