Mapping and GIS Solutions Community

Hi,

I have set up my Trimble Base on a Control Mark at a construction site. There is another surveyor who is using Topcon Rover and is connected to my Trimble Base Station. 

We have done the accuracy checks on both our Rover's using the already established Control Marks on site. We are using the same coordinate system and Geoid in both Rovers. My Trimble Rover is giving/showing acceptable accuracy. But the other surveyor's Topcon Rover is showing about 0.046mm error in height. . We have checked all the settings in both controllers, check the Rover heights, checked the base station height and also restarted the base. But still getting the same height error in Topcon Rover.

wondering if anyone else had experienced a similar issue when connecting Topcon Rover to Trimble base and could share their advice on this. Would anyone know if Topcon geoid models would be slightly different to Trimble Geoid Models?

any help would be much appreciated.

Cheers

------------------------------
Ravi Prasad
------------------------------

4.6cm sounds suspiciously like the height of antenna phase center (APC) above antenna mount.  I think all GNSS receivers internally work with APC so I suspect one of the rovers (the one giving 4.6cm higher elevation) doesn't have the right antenna type selected or doesn't know what offset to use to get to the base / mounting point of receiver or isn't using the base-to-APC offset correctly.

------------------------------
Norman Smart
------------------------------

Original Message:
Sent: 11-04-2021 23:49
From: Ravi Prasad
Subject: Trimble base connected to Topcon Rover

Hi,

I have set up my Trimble Base on a Control Mark at a construction site. There is another surveyor who is using Topcon Rover and is connected to my Trimble Base Station. 

We have done the accuracy checks on both our Rover's using the already established Control Marks on site. We are using the same coordinate system and Geoid in both Rovers. My Trimble Rover is giving/showing acceptable accuracy. But the other surveyor's Topcon Rover is showing about 0.046mm error in height. . We have checked all the settings in both controllers, check the Rover heights, checked the base station height and also restarted the base. But still getting the same height error in Topcon Rover.

wondering if anyone else had experienced a similar issue when connecting Topcon Rover to Trimble base and could share their advice on this. Would anyone know if Topcon geoid models would be slightly different to Trimble Geoid Models?

any help would be much appreciated.

Cheers

------------------------------
Ravi Prasad
------------------------------

Thanks, Norman.

we have done all the checks again today. Seems like for some reason the Topcon Reciever is not able to do the base-APC offset correctly when connected to the Trimble base. As the site is running on a Trimble base, we have subtracted 4.6cm from the Topcon pole height.

Cheers

------------------------------
Ravi Prasad
------------------------------

Original Message:
Sent: 11-07-2021 12:47
From: Norman Smart
Subject: Trimble base connected to Topcon Rover

4.6cm sounds suspiciously like the height of antenna phase center (APC) above antenna mount.  I think all GNSS receivers internally work with APC so I suspect one of the rovers (the one giving 4.6cm higher elevation) doesn't have the right antenna type selected or doesn't know what offset to use to get to the base / mounting point of receiver or isn't using the base-to-APC offset correctly.

------------------------------
Norman Smart

Original Message:
Sent: 11-04-2021 23:49
From: Ravi Prasad
Subject: Trimble base connected to Topcon Rover

Hi,

I have set up my Trimble Base on a Control Mark at a construction site. There is another surveyor who is using Topcon Rover and is connected to my Trimble Base Station. 

We have done the accuracy checks on both our Rover's using the already established Control Marks on site. We are using the same coordinate system and Geoid in both Rovers. My Trimble Rover is giving/showing acceptable accuracy. But the other surveyor's Topcon Rover is showing about 0.046mm error in height. . We have checked all the settings in both controllers, check the Rover heights, checked the base station height and also restarted the base. But still getting the same height error in Topcon Rover.

wondering if anyone else had experienced a similar issue when connecting Topcon Rover to Trimble base and could share their advice on this. Would anyone know if Topcon geoid models would be slightly different to Trimble Geoid Models?

any help would be much appreciated.

Cheers

------------------------------
Ravi Prasad
------------------------------

It's not an ideal solution but it should do the job.  Just remember that you have done this tweak - the receiver may start taking base-APC offset into account when you do a software update, then all your heights will be 4.6cm too low. . .

------------------------------
Norman Smart
------------------------------

Original Message:
Sent: 11-09-2021 23:08
From: Ravi Prasad
Subject: Trimble base connected to Topcon Rover

Thanks, Norman.

we have done all the checks again today. Seems like for some reason the Topcon Reciever is not able to do the base-APC offset correctly when connected to the Trimble base. As the site is running on a Trimble base, we have subtracted 4.6cm from the Topcon pole height.

Cheers

------------------------------
Ravi Prasad

Original Message:
Sent: 11-07-2021 12:47
From: Norman Smart
Subject: Trimble base connected to Topcon Rover

4.6cm sounds suspiciously like the height of antenna phase center (APC) above antenna mount.  I think all GNSS receivers internally work with APC so I suspect one of the rovers (the one giving 4.6cm higher elevation) doesn't have the right antenna type selected or doesn't know what offset to use to get to the base / mounting point of receiver or isn't using the base-to-APC offset correctly.

------------------------------
Norman Smart

Original Message:
Sent: 11-04-2021 23:49
From: Ravi Prasad
Subject: Trimble base connected to Topcon Rover

Hi,

I have set up my Trimble Base on a Control Mark at a construction site. There is another surveyor who is using Topcon Rover and is connected to my Trimble Base Station. 

We have done the accuracy checks on both our Rover's using the already established Control Marks on site. We are using the same coordinate system and Geoid in both Rovers. My Trimble Rover is giving/showing acceptable accuracy. But the other surveyor's Topcon Rover is showing about 0.046mm error in height. . We have checked all the settings in both controllers, check the Rover heights, checked the base station height and also restarted the base. But still getting the same height error in Topcon Rover.

wondering if anyone else had experienced a similar issue when connecting Topcon Rover to Trimble base and could share their advice on this. Would anyone know if Topcon geoid models would be slightly different to Trimble Geoid Models?

any help would be much appreciated.

Cheers

------------------------------
Ravi Prasad
------------------------------