How do I do a tracklog if I am in a tunnel?

[ARMOR1]

As I send my wife to work in Beach Road from AYE, I might be going through the Marina Coastal Expressway to take a look before the new year and intend to tracklog my drive. What do I do if I go into the 3.6 km tunnel in MCE and lose the satellite connection? Anyway out of this?

[OngCC]

As I send my wife to work in Beach Road from AYE, I might be going through the Marina Coastal Expressway to take a look before the new year and intend to tracklog my drive. What do I do if I go into the 3.6 km tunnel in MCE and lose the satellite connection? Anyway out of this?

There is no way to track in the tunnel, but please help to track the external part & all the exists.

[JasonLee]

There is no way to track in the tunnel, but please help to track the external part & all the exists.

Bro OngCC is right, there is no way to receive satellite signals while in a tunnel and it may not be so easy for you to record the tracklog of the exit if you have lost satellite lock while in the tunnel and only re-established lock say 500m after the exit.

There is a way to prevent the loss of satellite signals while in the tunnel but I am not sure if that is coded into the MFM maps.

[ARMOR1]

There is no way to track in the tunnel, but please help to track the external part & all the exists.

Bro OngCC is right, there is no way to receive satellite signals while in a tunnel and it may not be so easy for you to record the tracklog of the exit if you have lost satellite lock while in the tunnel and only re-established lock say 500m after the exit.

There is a way to prevent the loss of satellite signals while in the tunnel but I am not sure if that is coded into the MFM maps.

Or on "dead reckoning" where the GPS device tries to extrapolate car movement based upon a previously determined position and advancing that position based upon known or estimated speeds over elapsed time?

[JasonLee]

Or on "dead reckoning" where the GPS device tries to extrapolate car movement based upon a previously determined position and advancing that position based upon known or estimated speeds over elapsed time?

Dear Bro ARMOR1,

You are much more knowledgeable than most.

Dead reckoning is only reliable if the tunnel is straight but what if the tunnel is a curve or worse - an S shape?

[user66]

need to use old skool methods with bearing and distance

[ARMOR1]

Or on "dead reckoning" where the GPS device tries to extrapolate car movement based upon a previously determined position and advancing that position based upon known or estimated speeds over elapsed time?

Dear Bro ARMOR1,

You are much more knowledgeable than most.

Dead reckoning is only reliable if the tunnel is straight but what if the tunnel is a curve or worse - an S shape?

No lah, just try to read up when I have doubt. Thought there was a workaround because from my experience in Brisbane and Perth, the GPS worked in the tunnels...or was that also dead reckoning because the GPS was not cut off and no lost of satellite message from the device when I drove for some distance in the tunnels??.

[ace]

Being able to use the GPS in the tunnel of KPE & CTE has been around for a couple of years already if you used the City Navigator or Garmin generated maps (unless I'm blabbering here.. ).

To do a fresh track of a newly opened tunnel like the MCE...hmm...first, you have to accept OngCC statement. That is, you can't track in a tunnel. No satellite signals, no logs, no track. And therefore no talk.

I guess the mapper will either have to mask the tunnel layout from LTA onto our map or find a way to draw it in without available tracks.

Once the MCE is drawn into the map, and you are travelling into the MCE, the Garmin software will then probably be able to extrapolate where your are going base on your routing, which is a simulated satellite log. In other words, for this so called dead reckoning to work, the road must be drawn already in the map.

Maybe this article can help...

http://www.boston.com/news/local/articl ... 57/?page=1

[JasonLee]

Being able to use the GPS in the tunnel of KPE & CTE has been around for a couple of years already if you used the City Navigator or Garmin generated maps (unless I'm blabbering here.. ).

To do a fresh track of a newly opened tunnel like the MCE...hmm...first, you have to accept OngCC statement. That is, you can't track in a tunnel. No satellite signals, no logs, no track. And therefore no talk.

I guess the mapper will either have to mask the tunnel layout from LTA onto our map or find a way to draw it in without available tracks.

Once the MCE is drawn into the map, and you are travelling into the MCE, the Garmin software will then probably be able to extrapolate where your are going base on your routing, which is a simulated satellite log. In other words, for this so called dead reckoning to work, the road must be drawn already in the map.

Maybe this article can help...

http://www.boston.com/news/local/articl ... 57/?page=1

Bro Ace is quite right in that the tunnel must first be drawn into the map and then coded so that you do not lose your signal. I know Garmin's compiler can do that but not sure if cgpsMapper can do likewise.

One way to try is to enter the tunnel in both directions and use a very sensitive handheld to record the track. Hopefully the satellite signal can be held long enough for the 2 tracks to join. At least you will have both entrances correctly recorded.

[ARMOR1]

Okay, I have uploaded 5 .gpx files tracking my drive along the MCE. Hope they will be of some help in mapping the MCE. As I do not know what to do with the .gpx files, I have uploaded the raw tracklogs.

Done! 306 - OngCC