Trimble Business Center

Hi,

I was a heavy trimble user a couple of years ago, but now work in a metrology role with Leica gear and specialised software package. So I don't have the kit or TBC license to test this :-( I do have budget to hire gear for testing, but want to know if something is at least plausible before trying. I know this isn't necessarily strictly a TBC question, and could be an Access or Siteworks issue, but felt the data will end up in TBC one way or another so this is a good place to start :-)

I wish to track the realtime roll of a ship with 2 total stations tracking 2 prisms mounted equal distance from ship centreline port and starboard.  The total stations would be onshore 100-200m away. My idea is that, using the change in height between two prisms, the roll value can be computed.

One major problem however is, in order for the change in height values to be accurate, I need to time-align the observations exactly. Just pressing measure on two dataloggers at the "same time" isn't going to cut it. Ideally, I want to keep the total error budget for prism height values <5mm. And even on a calm day, the ship will be moving more than that every second or so. As part of this test, I wish to use RTK GPS as well (although my expectation is 15-40mm error in heights will make GPS alone unsuitable for the task).

So, my first thought. Run Access in Integrated survey mode. Setup total station to continuously measure the prism. Switch to GPS, enable continuous measurement. Repeat for 2nd pair of prism and GPS. When the two separate jobs are dragged back into TBC, the recorded epochs from the GPS datasets could be somehow used to align the data from two data loggers?

 Does anyone know if this might be possible? Or perhaps have another idea for a methodology? I

Other random thoughts:
- I have sent this question to Trimble as well and am awaiting an answer - I imagine they might be a while since it is a little strange
- It doesn't even necessarily need to be an integrated survey, I could just drag a raw T02 file from the GPS into the TBC job? But presumably, the total station observations are tagged with whatever the time happens to be set as on the total station or datalogger - not necessarily in sync with GPS time?
- A machine control software suite might be better suited, I see dozers driving around with dual GPS all the time, but not sure if I have seen multiple prisms mounted on the one machine before?  
- T4D can connect to multiple instruments, but it isnt really something that can be setup ad-hoc in the field easily (and not sure if it will get sub-second time alignment?)
- My metrology software (Spatial Analyser if anyone is interested) has a synchronised measurement option, and supports real time connection to multiple total stations. In theory it is perfect. In my workshop testing however, the "simultaneous" observations are significantly lagged and not fit for this purpose.

Thank you in advance for any comments, 
Damian

------------------------------
The Dude
------------------------------

Really interesting problem.  I work with laser screeds and the way those work is the machine monitors the height difference between one side of the screed and the other.  This is possibly similar to one side of a dozer blade vs the other.  One side is locked to the total station with a prism.  It knows where one side is from the total station, and it knows where the other side is from the onboard sensors detecting the difference between the two points.

If you can detect the difference between your two points with some type of on-ship processing, then you'd only need to track one of the prisms.  Recording both sets of data...  You could sync the two data sets by detecting some sort of "slate" (film industry term).  Basically a slate is an event that is detectable in both sets of data to by synced.  In film it's audio vs video sync.  The slate makes an audible slap that appears in the audio data, while the slap is clearly visible in the video track = easy sync during post production.  This of course was back in the day before they synced everything with wireless SMPTE time code.  There are many ways to sync two sets of data.  What you need is live, differential tracking of two points in space.  Then you only need to reference that data to your total station data.  It's all easier said than done, like most things in life.

------------------------------
Brian C
------------------------------

Original Message:
Sent: 06-09-2022 00:19
From: The Dude
Subject: Time-syncing data from two total stations - is it possible?

Hi,

I was a heavy trimble user a couple of years ago, but now work in a metrology role with Leica gear and specialised software package. So I don't have the kit or TBC license to test this :-( I do have budget to hire gear for testing, but want to know if something is at least plausible before trying. I know this isn't necessarily strictly a TBC question, and could be an Access or Siteworks issue, but felt the data will end up in TBC one way or another so this is a good place to start :-)

I wish to track the realtime roll of a ship with 2 total stations tracking 2 prisms mounted equal distance from ship centreline port and starboard.  The total stations would be onshore 100-200m away. My idea is that, using the change in height between two prisms, the roll value can be computed.

One major problem however is, in order for the change in height values to be accurate, I need to time-align the observations exactly. Just pressing measure on two dataloggers at the "same time" isn't going to cut it. Ideally, I want to keep the total error budget for prism height values <5mm. And even on a calm day, the ship will be moving more than that every second or so. As part of this test, I wish to use RTK GPS as well (although my expectation is 15-40mm error in heights will make GPS alone unsuitable for the task).

So, my first thought. Run Access in Integrated survey mode. Setup total station to continuously measure the prism. Switch to GPS, enable continuous measurement. Repeat for 2nd pair of prism and GPS. When the two separate jobs are dragged back into TBC, the recorded epochs from the GPS datasets could be somehow used to align the data from two data loggers?

 Does anyone know if this might be possible? Or perhaps have another idea for a methodology? I

Other random thoughts:
- I have sent this question to Trimble as well and am awaiting an answer - I imagine they might be a while since it is a little strange
- It doesn't even necessarily need to be an integrated survey, I could just drag a raw T02 file from the GPS into the TBC job? But presumably, the total station observations are tagged with whatever the time happens to be set as on the total station or datalogger - not necessarily in sync with GPS time?
- A machine control software suite might be better suited, I see dozers driving around with dual GPS all the time, but not sure if I have seen multiple prisms mounted on the one machine before?  
- T4D can connect to multiple instruments, but it isnt really something that can be setup ad-hoc in the field easily (and not sure if it will get sub-second time alignment?)
- My metrology software (Spatial Analyser if anyone is interested) has a synchronised measurement option, and supports real time connection to multiple total stations. In theory it is perfect. In my workshop testing however, the "simultaneous" observations are significantly lagged and not fit for this purpose.

Thank you in advance for any comments, 
Damian

------------------------------
The Dude
------------------------------

Access saves the time stamp in the job file, but only with seconds accuracy.
TBC also shows it in the properties pane.
You'd need to time synch both controllers, online timeserver synch should be accurate enough for that, and start a "Continuous Topo" measurement. Minimum interval is 1 sec and in the job file it will only show it with seconds accuracy as well. The recording seems to happen in synch with the controller clock seconds.

But Access can also output a configurable string via the COM-Port. 
See here https://help.trimblegeospatial.com/TrimbleAccess-PDFs/2022.00/en/TA_General_Survey.pdf, page 386 and following.

I'm rather surprised that you claim that data input into Spatial Analyzer is lagged. What kind of connection, protocol are you using there?

Quick example, SX10 in Tracking mode, data output set to continuous, no job file recording, TSC7 with Null-Modem cable, plus serial to USB adapter.



And that combining of multiple stations sounds more like an Excel Job then.

Don't you need to compute values in real time? To avoid excessive tilt?

I used the GDM output years ago with a single totalstation to stream measured coordinates directly into an Excel-Spreadsheet that listened to the Laptop COM-Port (back then TSC3 and laptop connected via Null-Modem, is possible with a TSC7 as well). Was used to track prisms on an incremental launch bridge, but also monitor the pillars. In stakeout mode I only had to tap the right prism, the instrument
turned to it, took the reading and the excel spreadsheet sorted it to the right point and showed live graphs. The trick in your case would be to make Excel listen to two COM-ports simultaneously.

I'll have to log a ticket with our Trimble dealer though. The GDM output doesn't seem to honor the job decimal settings anymore. I had a look at my 10 year old Excel spreadsheets and back then I had 4 decimals output. I used the same setup to check the curved formwork and leaning guide bearings of the bridge and a perpendicular to DTM macro.

------------------------------
Ronny Schneider
------------------------------

Original Message:
Sent: 06-09-2022 13:05
From: Brian C
Subject: Time-syncing data from two total stations - is it possible?

Really interesting problem.  I work with laser screeds and the way those work is the machine monitors the height difference between one side of the screed and the other.  This is possibly similar to one side of a dozer blade vs the other.  One side is locked to the total station with a prism.  It knows where one side is from the total station, and it knows where the other side is from the onboard sensors detecting the difference between the two points.

If you can detect the difference between your two points with some type of on-ship processing, then you'd only need to track one of the prisms.  Recording both sets of data...  You could sync the two data sets by detecting some sort of "slate" (film industry term).  Basically a slate is an event that is detectable in both sets of data to by synced.  In film it's audio vs video sync.  The slate makes an audible slap that appears in the audio data, while the slap is clearly visible in the video track = easy sync during post production.  This of course was back in the day before they synced everything with wireless SMPTE time code.  There are many ways to sync two sets of data.  What you need is live, differential tracking of two points in space.  Then you only need to reference that data to your total station data.  It's all easier said than done, like most things in life.

------------------------------
Brian C

Original Message:
Sent: 06-09-2022 00:19
From: The Dude
Subject: Time-syncing data from two total stations - is it possible?

Hi,

I was a heavy trimble user a couple of years ago, but now work in a metrology role with Leica gear and specialised software package. So I don't have the kit or TBC license to test this :-( I do have budget to hire gear for testing, but want to know if something is at least plausible before trying. I know this isn't necessarily strictly a TBC question, and could be an Access or Siteworks issue, but felt the data will end up in TBC one way or another so this is a good place to start :-)

I wish to track the realtime roll of a ship with 2 total stations tracking 2 prisms mounted equal distance from ship centreline port and starboard.  The total stations would be onshore 100-200m away. My idea is that, using the change in height between two prisms, the roll value can be computed.

One major problem however is, in order for the change in height values to be accurate, I need to time-align the observations exactly. Just pressing measure on two dataloggers at the "same time" isn't going to cut it. Ideally, I want to keep the total error budget for prism height values <5mm. And even on a calm day, the ship will be moving more than that every second or so. As part of this test, I wish to use RTK GPS as well (although my expectation is 15-40mm error in heights will make GPS alone unsuitable for the task).

So, my first thought. Run Access in Integrated survey mode. Setup total station to continuously measure the prism. Switch to GPS, enable continuous measurement. Repeat for 2nd pair of prism and GPS. When the two separate jobs are dragged back into TBC, the recorded epochs from the GPS datasets could be somehow used to align the data from two data loggers?

 Does anyone know if this might be possible? Or perhaps have another idea for a methodology? I

Other random thoughts:
- I have sent this question to Trimble as well and am awaiting an answer - I imagine they might be a while since it is a little strange
- It doesn't even necessarily need to be an integrated survey, I could just drag a raw T02 file from the GPS into the TBC job? But presumably, the total station observations are tagged with whatever the time happens to be set as on the total station or datalogger - not necessarily in sync with GPS time?
- A machine control software suite might be better suited, I see dozers driving around with dual GPS all the time, but not sure if I have seen multiple prisms mounted on the one machine before?  
- T4D can connect to multiple instruments, but it isnt really something that can be setup ad-hoc in the field easily (and not sure if it will get sub-second time alignment?)
- My metrology software (Spatial Analyser if anyone is interested) has a synchronised measurement option, and supports real time connection to multiple total stations. In theory it is perfect. In my workshop testing however, the "simultaneous" observations are significantly lagged and not fit for this purpose.

Thank you in advance for any comments, 
Damian

------------------------------
The Dude
------------------------------

Hi Ronny,

Thank you for the detailed reply, you have given me a lot to think about. 

RE: Spatial Analyser
This program only saves points to the nearest second, and the timestamp is taken from the moment each point is saved in the program, *not* when the observation was taken from the total station. Kinematics support replied to me, and say the communication is packet based and the recorded timestamp may be off anyway depending on comm's lag etc. Certainly my testing confirms this, although I would have thought with a serial cable the data would be streaming in consistently.

RE: Online time sync of controllers
I think this is worth testing, as you said, everything is rounded to the nearest second, but it might be close enough for purpose. I don't need millisecond resolution after all (heck, even 0.5 second might do the trick).

RE: GDM output
This could be interesting, perhaps in excel or even a python script? I have no idea on logging data simultaneously but presumably it must be possible. The data could even be timestamped from the computers clock if necessary. I believe there are system calls that work down to millisecond resolution.

Looking at the Trimble Access manual, psuedo NMEA seems limited to 2 decimal places, but 'GDM user defined' should match the Access job units.

Regards,
Damian

------------------------------
The Dude
------------------------------

Original Message:
Sent: 06-09-2022 20:59
From: Ronny Schneider
Subject: Time-syncing data from two total stations - is it possible?

Access saves the time stamp in the job file, but only with seconds accuracy.
TBC also shows it in the properties pane.
You'd need to time synch both controllers, online timeserver synch should be accurate enough for that, and start a "Continuous Topo" measurement. Minimum interval is 1 sec and in the job file it will only show it with seconds accuracy as well. The recording seems to happen in synch with the controller clock seconds.

But Access can also output a configurable string via the COM-Port. 
See here https://help.trimblegeospatial.com/TrimbleAccess-PDFs/2022.00/en/TA_General_Survey.pdf, page 386 and following.

I'm rather surprised that you claim that data input into Spatial Analyzer is lagged. What kind of connection, protocol are you using there?

Quick example, SX10 in Tracking mode, data output set to continuous, no job file recording, TSC7 with Null-Modem cable, plus serial to USB adapter.



And that combining of multiple stations sounds more like an Excel Job then.

Don't you need to compute values in real time? To avoid excessive tilt?

I used the GDM output years ago with a single totalstation to stream measured coordinates directly into an Excel-Spreadsheet that listened to the Laptop COM-Port (back then TSC3 and laptop connected via Null-Modem, is possible with a TSC7 as well). Was used to track prisms on an incremental launch bridge, but also monitor the pillars. In stakeout mode I only had to tap the right prism, the instrument
turned to it, took the reading and the excel spreadsheet sorted it to the right point and showed live graphs. The trick in your case would be to make Excel listen to two COM-ports simultaneously.

I'll have to log a ticket with our Trimble dealer though. The GDM output doesn't seem to honor the job decimal settings anymore. I had a look at my 10 year old Excel spreadsheets and back then I had 4 decimals output. I used the same setup to check the curved formwork and leaning guide bearings of the bridge and a perpendicular to DTM macro.

------------------------------
Ronny Schneider

Original Message:
Sent: 06-09-2022 13:05
From: Brian C
Subject: Time-syncing data from two total stations - is it possible?

Really interesting problem.  I work with laser screeds and the way those work is the machine monitors the height difference between one side of the screed and the other.  This is possibly similar to one side of a dozer blade vs the other.  One side is locked to the total station with a prism.  It knows where one side is from the total station, and it knows where the other side is from the onboard sensors detecting the difference between the two points.

If you can detect the difference between your two points with some type of on-ship processing, then you'd only need to track one of the prisms.  Recording both sets of data...  You could sync the two data sets by detecting some sort of "slate" (film industry term).  Basically a slate is an event that is detectable in both sets of data to by synced.  In film it's audio vs video sync.  The slate makes an audible slap that appears in the audio data, while the slap is clearly visible in the video track = easy sync during post production.  This of course was back in the day before they synced everything with wireless SMPTE time code.  There are many ways to sync two sets of data.  What you need is live, differential tracking of two points in space.  Then you only need to reference that data to your total station data.  It's all easier said than done, like most things in life.

------------------------------
Brian C

Original Message:
Sent: 06-09-2022 00:19
From: The Dude
Subject: Time-syncing data from two total stations - is it possible?

Hi,

I was a heavy trimble user a couple of years ago, but now work in a metrology role with Leica gear and specialised software package. So I don't have the kit or TBC license to test this :-( I do have budget to hire gear for testing, but want to know if something is at least plausible before trying. I know this isn't necessarily strictly a TBC question, and could be an Access or Siteworks issue, but felt the data will end up in TBC one way or another so this is a good place to start :-)

I wish to track the realtime roll of a ship with 2 total stations tracking 2 prisms mounted equal distance from ship centreline port and starboard.  The total stations would be onshore 100-200m away. My idea is that, using the change in height between two prisms, the roll value can be computed.

One major problem however is, in order for the change in height values to be accurate, I need to time-align the observations exactly. Just pressing measure on two dataloggers at the "same time" isn't going to cut it. Ideally, I want to keep the total error budget for prism height values <5mm. And even on a calm day, the ship will be moving more than that every second or so. As part of this test, I wish to use RTK GPS as well (although my expectation is 15-40mm error in heights will make GPS alone unsuitable for the task).

So, my first thought. Run Access in Integrated survey mode. Setup total station to continuously measure the prism. Switch to GPS, enable continuous measurement. Repeat for 2nd pair of prism and GPS. When the two separate jobs are dragged back into TBC, the recorded epochs from the GPS datasets could be somehow used to align the data from two data loggers?

 Does anyone know if this might be possible? Or perhaps have another idea for a methodology? I

Other random thoughts:
- I have sent this question to Trimble as well and am awaiting an answer - I imagine they might be a while since it is a little strange
- It doesn't even necessarily need to be an integrated survey, I could just drag a raw T02 file from the GPS into the TBC job? But presumably, the total station observations are tagged with whatever the time happens to be set as on the total station or datalogger - not necessarily in sync with GPS time?
- A machine control software suite might be better suited, I see dozers driving around with dual GPS all the time, but not sure if I have seen multiple prisms mounted on the one machine before?  
- T4D can connect to multiple instruments, but it isnt really something that can be setup ad-hoc in the field easily (and not sure if it will get sub-second time alignment?)
- My metrology software (Spatial Analyser if anyone is interested) has a synchronised measurement option, and supports real time connection to multiple total stations. In theory it is perfect. In my workshop testing however, the "simultaneous" observations are significantly lagged and not fit for this purpose.

Thank you in advance for any comments, 
Damian

------------------------------
The Dude
------------------------------

Hi Brian,

Thank you for your reply. For my purposes, computation of roll via high quality IMU's (like a laser screed) is actually one of the methods I wish to test (along with height differentials from total station and RTK GPS). It is possible IMU values, say from an R12 GPS, may be accurate enough, or even more accurate, then two total station measurements anyway.

I am thinking, to begin at least, to test this on shore, where at least initially I can work around lack of time sync. 

Regards,
Damian


------------------------------
The Dude
------------------------------

Original Message:
Sent: 06-09-2022 13:05
From: Brian C
Subject: Time-syncing data from two total stations - is it possible?

Really interesting problem.  I work with laser screeds and the way those work is the machine monitors the height difference between one side of the screed and the other.  This is possibly similar to one side of a dozer blade vs the other.  One side is locked to the total station with a prism.  It knows where one side is from the total station, and it knows where the other side is from the onboard sensors detecting the difference between the two points.

If you can detect the difference between your two points with some type of on-ship processing, then you'd only need to track one of the prisms.  Recording both sets of data...  You could sync the two data sets by detecting some sort of "slate" (film industry term).  Basically a slate is an event that is detectable in both sets of data to by synced.  In film it's audio vs video sync.  The slate makes an audible slap that appears in the audio data, while the slap is clearly visible in the video track = easy sync during post production.  This of course was back in the day before they synced everything with wireless SMPTE time code.  There are many ways to sync two sets of data.  What you need is live, differential tracking of two points in space.  Then you only need to reference that data to your total station data.  It's all easier said than done, like most things in life.

------------------------------
Brian C

Original Message:
Sent: 06-09-2022 00:19
From: The Dude
Subject: Time-syncing data from two total stations - is it possible?

Hi,

I was a heavy trimble user a couple of years ago, but now work in a metrology role with Leica gear and specialised software package. So I don't have the kit or TBC license to test this :-( I do have budget to hire gear for testing, but want to know if something is at least plausible before trying. I know this isn't necessarily strictly a TBC question, and could be an Access or Siteworks issue, but felt the data will end up in TBC one way or another so this is a good place to start :-)

I wish to track the realtime roll of a ship with 2 total stations tracking 2 prisms mounted equal distance from ship centreline port and starboard.  The total stations would be onshore 100-200m away. My idea is that, using the change in height between two prisms, the roll value can be computed.

One major problem however is, in order for the change in height values to be accurate, I need to time-align the observations exactly. Just pressing measure on two dataloggers at the "same time" isn't going to cut it. Ideally, I want to keep the total error budget for prism height values <5mm. And even on a calm day, the ship will be moving more than that every second or so. As part of this test, I wish to use RTK GPS as well (although my expectation is 15-40mm error in heights will make GPS alone unsuitable for the task).

So, my first thought. Run Access in Integrated survey mode. Setup total station to continuously measure the prism. Switch to GPS, enable continuous measurement. Repeat for 2nd pair of prism and GPS. When the two separate jobs are dragged back into TBC, the recorded epochs from the GPS datasets could be somehow used to align the data from two data loggers?

 Does anyone know if this might be possible? Or perhaps have another idea for a methodology? I

Other random thoughts:
- I have sent this question to Trimble as well and am awaiting an answer - I imagine they might be a while since it is a little strange
- It doesn't even necessarily need to be an integrated survey, I could just drag a raw T02 file from the GPS into the TBC job? But presumably, the total station observations are tagged with whatever the time happens to be set as on the total station or datalogger - not necessarily in sync with GPS time?
- A machine control software suite might be better suited, I see dozers driving around with dual GPS all the time, but not sure if I have seen multiple prisms mounted on the one machine before?  
- T4D can connect to multiple instruments, but it isnt really something that can be setup ad-hoc in the field easily (and not sure if it will get sub-second time alignment?)
- My metrology software (Spatial Analyser if anyone is interested) has a synchronised measurement option, and supports real time connection to multiple total stations. In theory it is perfect. In my workshop testing however, the "simultaneous" observations are significantly lagged and not fit for this purpose.

Thank you in advance for any comments, 
Damian

------------------------------
The Dude
------------------------------

Hi,

If you're just interested in the ROLL, then why not use real time tri-axial inclinometer?
Just install it square to the CentreLine of the boat. No need for GPS nor Total Station.

We're using SENCEIVE to monitor rail deformation. Those can be set to 1Hz frequency.

------------------------------
Marian
------------------------------

Original Message:
Sent: 06-12-2022 18:22
From: The Dude
Subject: Time-syncing data from two total stations - is it possible?

Hi Brian,

Thank you for your reply. For my purposes, computation of roll via high quality IMU's (like a laser screed) is actually one of the methods I wish to test (along with height differentials from total station and RTK GPS). It is possible IMU values, say from an R12 GPS, may be accurate enough, or even more accurate, then two total station measurements anyway.

I am thinking, to begin at least, to test this on shore, where at least initially I can work around lack of time sync. 

Regards,
Damian


------------------------------
The Dude

Original Message:
Sent: 06-09-2022 13:05
From: Brian C
Subject: Time-syncing data from two total stations - is it possible?

Really interesting problem.  I work with laser screeds and the way those work is the machine monitors the height difference between one side of the screed and the other.  This is possibly similar to one side of a dozer blade vs the other.  One side is locked to the total station with a prism.  It knows where one side is from the total station, and it knows where the other side is from the onboard sensors detecting the difference between the two points.

If you can detect the difference between your two points with some type of on-ship processing, then you'd only need to track one of the prisms.  Recording both sets of data...  You could sync the two data sets by detecting some sort of "slate" (film industry term).  Basically a slate is an event that is detectable in both sets of data to by synced.  In film it's audio vs video sync.  The slate makes an audible slap that appears in the audio data, while the slap is clearly visible in the video track = easy sync during post production.  This of course was back in the day before they synced everything with wireless SMPTE time code.  There are many ways to sync two sets of data.  What you need is live, differential tracking of two points in space.  Then you only need to reference that data to your total station data.  It's all easier said than done, like most things in life.

------------------------------
Brian C

Original Message:
Sent: 06-09-2022 00:19
From: The Dude
Subject: Time-syncing data from two total stations - is it possible?

Hi,

I was a heavy trimble user a couple of years ago, but now work in a metrology role with Leica gear and specialised software package. So I don't have the kit or TBC license to test this :-( I do have budget to hire gear for testing, but want to know if something is at least plausible before trying. I know this isn't necessarily strictly a TBC question, and could be an Access or Siteworks issue, but felt the data will end up in TBC one way or another so this is a good place to start :-)

I wish to track the realtime roll of a ship with 2 total stations tracking 2 prisms mounted equal distance from ship centreline port and starboard.  The total stations would be onshore 100-200m away. My idea is that, using the change in height between two prisms, the roll value can be computed.

One major problem however is, in order for the change in height values to be accurate, I need to time-align the observations exactly. Just pressing measure on two dataloggers at the "same time" isn't going to cut it. Ideally, I want to keep the total error budget for prism height values <5mm. And even on a calm day, the ship will be moving more than that every second or so. As part of this test, I wish to use RTK GPS as well (although my expectation is 15-40mm error in heights will make GPS alone unsuitable for the task).

So, my first thought. Run Access in Integrated survey mode. Setup total station to continuously measure the prism. Switch to GPS, enable continuous measurement. Repeat for 2nd pair of prism and GPS. When the two separate jobs are dragged back into TBC, the recorded epochs from the GPS datasets could be somehow used to align the data from two data loggers?

 Does anyone know if this might be possible? Or perhaps have another idea for a methodology? I

Other random thoughts:
- I have sent this question to Trimble as well and am awaiting an answer - I imagine they might be a while since it is a little strange
- It doesn't even necessarily need to be an integrated survey, I could just drag a raw T02 file from the GPS into the TBC job? But presumably, the total station observations are tagged with whatever the time happens to be set as on the total station or datalogger - not necessarily in sync with GPS time?
- A machine control software suite might be better suited, I see dozers driving around with dual GPS all the time, but not sure if I have seen multiple prisms mounted on the one machine before?  
- T4D can connect to multiple instruments, but it isnt really something that can be setup ad-hoc in the field easily (and not sure if it will get sub-second time alignment?)
- My metrology software (Spatial Analyser if anyone is interested) has a synchronised measurement option, and supports real time connection to multiple total stations. In theory it is perfect. In my workshop testing however, the "simultaneous" observations are significantly lagged and not fit for this purpose.

Thank you in advance for any comments, 
Damian

------------------------------
The Dude
------------------------------

Hi Marian,

Those look pretty good! If the specification sheet is to be believed, they would be accurate enough for sure.

One problem I see is mounting. An IMU sensor has a small footprint, and the structure of a ship is rarely square or flat. Multiple sensors will give different absolute values. I suppose, if they can be time aligned (back to this chestnut!!), then it would be trivial to "zero" out the different readings and still get the redundancy of multiple sensors...

We potentially need the GPS on the ship anyway for other aspects of the test, so I am planning on using the IMU in an R12 initially at least (plug and play, pitch/roll values already saved in the point metadata). As I mentioned above, the aim is to compare IMU, GPS and Total Station derived roll values. The total station is the most clunky solution, and only accurate if I can reasonably align the data. Fun to research and experiment though!

Regards,

Damian

------------------------------
The Dude
------------------------------

Original Message:
Sent: 06-12-2022 18:28
From: Marian Plucinski
Subject: Time-syncing data from two total stations - is it possible?

Hi,

If you're just interested in the ROLL, then why not use real time tri-axial inclinometer?
Just install it square to the CentreLine of the boat. No need for GPS nor Total Station.

We're using SENCEIVE to monitor rail deformation. Those can be set to 1Hz frequency.

------------------------------
Marian

Original Message:
Sent: 06-12-2022 18:22
From: The Dude
Subject: Time-syncing data from two total stations - is it possible?

Hi Brian,

Thank you for your reply. For my purposes, computation of roll via high quality IMU's (like a laser screed) is actually one of the methods I wish to test (along with height differentials from total station and RTK GPS). It is possible IMU values, say from an R12 GPS, may be accurate enough, or even more accurate, then two total station measurements anyway.

I am thinking, to begin at least, to test this on shore, where at least initially I can work around lack of time sync. 

Regards,
Damian


------------------------------
The Dude

Original Message:
Sent: 06-09-2022 13:05
From: Brian C
Subject: Time-syncing data from two total stations - is it possible?

Really interesting problem.  I work with laser screeds and the way those work is the machine monitors the height difference between one side of the screed and the other.  This is possibly similar to one side of a dozer blade vs the other.  One side is locked to the total station with a prism.  It knows where one side is from the total station, and it knows where the other side is from the onboard sensors detecting the difference between the two points.

If you can detect the difference between your two points with some type of on-ship processing, then you'd only need to track one of the prisms.  Recording both sets of data...  You could sync the two data sets by detecting some sort of "slate" (film industry term).  Basically a slate is an event that is detectable in both sets of data to by synced.  In film it's audio vs video sync.  The slate makes an audible slap that appears in the audio data, while the slap is clearly visible in the video track = easy sync during post production.  This of course was back in the day before they synced everything with wireless SMPTE time code.  There are many ways to sync two sets of data.  What you need is live, differential tracking of two points in space.  Then you only need to reference that data to your total station data.  It's all easier said than done, like most things in life.

------------------------------
Brian C

Original Message:
Sent: 06-09-2022 00:19
From: The Dude
Subject: Time-syncing data from two total stations - is it possible?

Hi,

I was a heavy trimble user a couple of years ago, but now work in a metrology role with Leica gear and specialised software package. So I don't have the kit or TBC license to test this :-( I do have budget to hire gear for testing, but want to know if something is at least plausible before trying. I know this isn't necessarily strictly a TBC question, and could be an Access or Siteworks issue, but felt the data will end up in TBC one way or another so this is a good place to start :-)

I wish to track the realtime roll of a ship with 2 total stations tracking 2 prisms mounted equal distance from ship centreline port and starboard.  The total stations would be onshore 100-200m away. My idea is that, using the change in height between two prisms, the roll value can be computed.

One major problem however is, in order for the change in height values to be accurate, I need to time-align the observations exactly. Just pressing measure on two dataloggers at the "same time" isn't going to cut it. Ideally, I want to keep the total error budget for prism height values <5mm. And even on a calm day, the ship will be moving more than that every second or so. As part of this test, I wish to use RTK GPS as well (although my expectation is 15-40mm error in heights will make GPS alone unsuitable for the task).

So, my first thought. Run Access in Integrated survey mode. Setup total station to continuously measure the prism. Switch to GPS, enable continuous measurement. Repeat for 2nd pair of prism and GPS. When the two separate jobs are dragged back into TBC, the recorded epochs from the GPS datasets could be somehow used to align the data from two data loggers?

 Does anyone know if this might be possible? Or perhaps have another idea for a methodology? I

Other random thoughts:
- I have sent this question to Trimble as well and am awaiting an answer - I imagine they might be a while since it is a little strange
- It doesn't even necessarily need to be an integrated survey, I could just drag a raw T02 file from the GPS into the TBC job? But presumably, the total station observations are tagged with whatever the time happens to be set as on the total station or datalogger - not necessarily in sync with GPS time?
- A machine control software suite might be better suited, I see dozers driving around with dual GPS all the time, but not sure if I have seen multiple prisms mounted on the one machine before?  
- T4D can connect to multiple instruments, but it isnt really something that can be setup ad-hoc in the field easily (and not sure if it will get sub-second time alignment?)
- My metrology software (Spatial Analyser if anyone is interested) has a synchronised measurement option, and supports real time connection to multiple total stations. In theory it is perfect. In my workshop testing however, the "simultaneous" observations are significantly lagged and not fit for this purpose.

Thank you in advance for any comments, 
Damian

------------------------------
The Dude
------------------------------

Hi Brian (again),

RE: the slate/clapper

I thought about this - lifting both prisms together could work as a 'sync' event. The moment both prisms record the highest point gives you a sync event. But then, I need to maintain prism lock and install them both onto the ship. Perhaps not feasible. Maybe my subconscious will come up with another idea :-)

Cheers,
Damian

------------------------------
The Dude
------------------------------

Original Message:
Sent: 06-09-2022 13:05
From: Brian C
Subject: Time-syncing data from two total stations - is it possible?

Really interesting problem.  I work with laser screeds and the way those work is the machine monitors the height difference between one side of the screed and the other.  This is possibly similar to one side of a dozer blade vs the other.  One side is locked to the total station with a prism.  It knows where one side is from the total station, and it knows where the other side is from the onboard sensors detecting the difference between the two points.

If you can detect the difference between your two points with some type of on-ship processing, then you'd only need to track one of the prisms.  Recording both sets of data...  You could sync the two data sets by detecting some sort of "slate" (film industry term).  Basically a slate is an event that is detectable in both sets of data to by synced.  In film it's audio vs video sync.  The slate makes an audible slap that appears in the audio data, while the slap is clearly visible in the video track = easy sync during post production.  This of course was back in the day before they synced everything with wireless SMPTE time code.  There are many ways to sync two sets of data.  What you need is live, differential tracking of two points in space.  Then you only need to reference that data to your total station data.  It's all easier said than done, like most things in life.

------------------------------
Brian C

Original Message:
Sent: 06-09-2022 00:19
From: The Dude
Subject: Time-syncing data from two total stations - is it possible?

Hi,

I was a heavy trimble user a couple of years ago, but now work in a metrology role with Leica gear and specialised software package. So I don't have the kit or TBC license to test this :-( I do have budget to hire gear for testing, but want to know if something is at least plausible before trying. I know this isn't necessarily strictly a TBC question, and could be an Access or Siteworks issue, but felt the data will end up in TBC one way or another so this is a good place to start :-)

I wish to track the realtime roll of a ship with 2 total stations tracking 2 prisms mounted equal distance from ship centreline port and starboard.  The total stations would be onshore 100-200m away. My idea is that, using the change in height between two prisms, the roll value can be computed.

One major problem however is, in order for the change in height values to be accurate, I need to time-align the observations exactly. Just pressing measure on two dataloggers at the "same time" isn't going to cut it. Ideally, I want to keep the total error budget for prism height values <5mm. And even on a calm day, the ship will be moving more than that every second or so. As part of this test, I wish to use RTK GPS as well (although my expectation is 15-40mm error in heights will make GPS alone unsuitable for the task).

So, my first thought. Run Access in Integrated survey mode. Setup total station to continuously measure the prism. Switch to GPS, enable continuous measurement. Repeat for 2nd pair of prism and GPS. When the two separate jobs are dragged back into TBC, the recorded epochs from the GPS datasets could be somehow used to align the data from two data loggers?

 Does anyone know if this might be possible? Or perhaps have another idea for a methodology? I

Other random thoughts:
- I have sent this question to Trimble as well and am awaiting an answer - I imagine they might be a while since it is a little strange
- It doesn't even necessarily need to be an integrated survey, I could just drag a raw T02 file from the GPS into the TBC job? But presumably, the total station observations are tagged with whatever the time happens to be set as on the total station or datalogger - not necessarily in sync with GPS time?
- A machine control software suite might be better suited, I see dozers driving around with dual GPS all the time, but not sure if I have seen multiple prisms mounted on the one machine before?  
- T4D can connect to multiple instruments, but it isnt really something that can be setup ad-hoc in the field easily (and not sure if it will get sub-second time alignment?)
- My metrology software (Spatial Analyser if anyone is interested) has a synchronised measurement option, and supports real time connection to multiple total stations. In theory it is perfect. In my workshop testing however, the "simultaneous" observations are significantly lagged and not fit for this purpose.

Thank you in advance for any comments, 
Damian

------------------------------
The Dude
------------------------------

Update, I successfully read data from two total stations at the same time via serial-USB cables. At the moment, I just captured the data using "Putty", but unfortunately the time stamps come from each total station not the common laptop internal clock. My next test is to use one of the many RS232 logger programs available to log both streams as they arrive, with a common timestamp.

Getting closer!

------------------------------
The Dude
------------------------------

Original Message:
Sent: 06-09-2022 00:19
From: The Dude
Subject: Time-syncing data from two total stations - is it possible?

Hi,

I was a heavy trimble user a couple of years ago, but now work in a metrology role with Leica gear and specialised software package. So I don't have the kit or TBC license to test this :-( I do have budget to hire gear for testing, but want to know if something is at least plausible before trying. I know this isn't necessarily strictly a TBC question, and could be an Access or Siteworks issue, but felt the data will end up in TBC one way or another so this is a good place to start :-)

I wish to track the realtime roll of a ship with 2 total stations tracking 2 prisms mounted equal distance from ship centreline port and starboard.  The total stations would be onshore 100-200m away. My idea is that, using the change in height between two prisms, the roll value can be computed.

One major problem however is, in order for the change in height values to be accurate, I need to time-align the observations exactly. Just pressing measure on two dataloggers at the "same time" isn't going to cut it. Ideally, I want to keep the total error budget for prism height values <5mm. And even on a calm day, the ship will be moving more than that every second or so. As part of this test, I wish to use RTK GPS as well (although my expectation is 15-40mm error in heights will make GPS alone unsuitable for the task).

So, my first thought. Run Access in Integrated survey mode. Setup total station to continuously measure the prism. Switch to GPS, enable continuous measurement. Repeat for 2nd pair of prism and GPS. When the two separate jobs are dragged back into TBC, the recorded epochs from the GPS datasets could be somehow used to align the data from two data loggers?

 Does anyone know if this might be possible? Or perhaps have another idea for a methodology? I

Other random thoughts:
- I have sent this question to Trimble as well and am awaiting an answer - I imagine they might be a while since it is a little strange
- It doesn't even necessarily need to be an integrated survey, I could just drag a raw T02 file from the GPS into the TBC job? But presumably, the total station observations are tagged with whatever the time happens to be set as on the total station or datalogger - not necessarily in sync with GPS time?
- A machine control software suite might be better suited, I see dozers driving around with dual GPS all the time, but not sure if I have seen multiple prisms mounted on the one machine before?  
- T4D can connect to multiple instruments, but it isnt really something that can be setup ad-hoc in the field easily (and not sure if it will get sub-second time alignment?)
- My metrology software (Spatial Analyser if anyone is interested) has a synchronised measurement option, and supports real time connection to multiple total stations. In theory it is perfect. In my workshop testing however, the "simultaneous" observations are significantly lagged and not fit for this purpose.

Thank you in advance for any comments, 
Damian

------------------------------
The Dude
------------------------------

Hi Damian,

I am a student, and I have a group project that is trying to track a UAV without GNSS. We have come across this post and was wondering how you were able to log the data through pUTTy. We have tried and we are not able to open the serial port, any suggestions would be appreciated. 

Thanks,

Anneliese

------------------------------
Anneliese Lassen
------------------------------

Original Message:
Sent: 06-14-2022 15:20
From: The Dude
Subject: Time-syncing data from two total stations - is it possible?

Update, I successfully read data from two total stations at the same time via serial-USB cables. At the moment, I just captured the data using "Putty", but unfortunately the time stamps come from each total station not the common laptop internal clock. My next test is to use one of the many RS232 logger programs available to log both streams as they arrive, with a common timestamp.

Getting closer!

------------------------------
The Dude

Original Message:
Sent: 06-09-2022 00:19
From: The Dude
Subject: Time-syncing data from two total stations - is it possible?

Hi,

I was a heavy trimble user a couple of years ago, but now work in a metrology role with Leica gear and specialised software package. So I don't have the kit or TBC license to test this :-( I do have budget to hire gear for testing, but want to know if something is at least plausible before trying. I know this isn't necessarily strictly a TBC question, and could be an Access or Siteworks issue, but felt the data will end up in TBC one way or another so this is a good place to start :-)

I wish to track the realtime roll of a ship with 2 total stations tracking 2 prisms mounted equal distance from ship centreline port and starboard.  The total stations would be onshore 100-200m away. My idea is that, using the change in height between two prisms, the roll value can be computed.

One major problem however is, in order for the change in height values to be accurate, I need to time-align the observations exactly. Just pressing measure on two dataloggers at the "same time" isn't going to cut it. Ideally, I want to keep the total error budget for prism height values <5mm. And even on a calm day, the ship will be moving more than that every second or so. As part of this test, I wish to use RTK GPS as well (although my expectation is 15-40mm error in heights will make GPS alone unsuitable for the task).

So, my first thought. Run Access in Integrated survey mode. Setup total station to continuously measure the prism. Switch to GPS, enable continuous measurement. Repeat for 2nd pair of prism and GPS. When the two separate jobs are dragged back into TBC, the recorded epochs from the GPS datasets could be somehow used to align the data from two data loggers?

 Does anyone know if this might be possible? Or perhaps have another idea for a methodology? I

Other random thoughts:
- I have sent this question to Trimble as well and am awaiting an answer - I imagine they might be a while since it is a little strange
- It doesn't even necessarily need to be an integrated survey, I could just drag a raw T02 file from the GPS into the TBC job? But presumably, the total station observations are tagged with whatever the time happens to be set as on the total station or datalogger - not necessarily in sync with GPS time?
- A machine control software suite might be better suited, I see dozers driving around with dual GPS all the time, but not sure if I have seen multiple prisms mounted on the one machine before?  
- T4D can connect to multiple instruments, but it isnt really something that can be setup ad-hoc in the field easily (and not sure if it will get sub-second time alignment?)
- My metrology software (Spatial Analyser if anyone is interested) has a synchronised measurement option, and supports real time connection to multiple total stations. In theory it is perfect. In my workshop testing however, the "simultaneous" observations are significantly lagged and not fit for this purpose.

Thank you in advance for any comments, 
Damian

------------------------------
The Dude
------------------------------