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Sokkia Data Recorders - procedure

Uploading/Downloading using a Sokkia SDR33

Communications Settings on the Computer

The following parameters are set using the Data Recorders Configuration function described previously.

I/O Port : user selectable
Baud Rate : 1200
Parity : none
Data Bits : 8
Stop Bits : 1
Flow Control : software
Timeout : 5

Communications Settings on the Instrument

The required communications settings for the SDR33 are as follows:

Port : Top
Modem : No
Baud Rate : 1200
Parity : Not set
Data Bits : 8
Stop Bits : 1
Output delay : 0
File : No

The following instructions describe how to set these parameters on the instrument.

To set or check the communications section on the instrument
1. Select Communications from the main menu and press OK.
2. Press the F2/F7 button to activate the COM screen.
3. Scroll through the communication option screen using the up/down arrows and select values using the left/right arrows. When you have selected the appropriate values as described above
4. press the OK button when all options are set to return to the communications mode.

Downloading Data from the Instrument

1. Ready the software to receive the data as described in Data Recorders Down Load To File
2. Select Communications from the main menu and press OK
3. Select SDR as the data format using the left/right arrow key
4. Press the F4/F9 key to enter SEND mode
5. Select 'select jobs' and press the OK key
6. You are now presented with a screen which lists all jobs in the instrument. Using the arrow cursor key select YES to the job that you want to down load.
7. Press the OK key to begin the data transfer

Uploading Setout Points to the Instrument

GEOVIA assumes that you will be using SDR33 format with 14 character alpha numeric point ID's as opposed to the 4 character numeric point ID's used in the SDR2x formats. If you are using SDR2x format point ID's you cannot upload point data using the SDR33 option.

Before uploading setout points to the SDR33 you may have to create a job to store the data in. Use the Job Manager menu option to create a new job. Please remember to select 14 character alpha numeric point id when you create the job.

The following steps will enable you to upload data into the SDR33.

1. Process your point data ready for uploading as described in Data Recorders Upload Coordinates
2. Select Communications from the main menu and press the OK key
3. Select SDR as the data format using the left/right arrow keys
4. Press the F5/F10 key to enter SEND mode
5. Press APPLY in the software to begin the transfer

Data Format Notes

The Sokkia SDR2, SDR20, and SDR22 are identical data formats. The SDR33 format is slightly different. The primary difference between the SDR33 and the SDR2x formats is that the SDR33 permits 16 character alpha-numeric names for point, and station identifiers as compared to the 4 digit numeric identifiers of the SDR2x data recorders. Similarly, the co-ordinate fields of the SDR33 are also longer than the co-ordinate fields of the SDR2x.

The Sokkia SET4C2 is very different from the other two formats and it must be noted that for upload a baud rate of 9600 must apply.

The Sokkia data recorders have special records for instrument station details, backsight station details, target height, observation record start of job and recorded co-ordinates. Each of these record types are used to access the information required for the survey. Alphanumeric capabilities are present so point descriptions, if required, are accessed from the point description field in the observation record.

There is no proper backsight data retrieval with the sokkia SET4C2 and therefore it is calculated as the first record in the data file.

String numbers are also accessed from the description field of the observation record. The first part in the description may contain the string number. If a string number is not present in these positions then the string number for the current point is the last string number defined. If the string number is not defined at all then all points will be assigned to string 1.

The point description if required must immediately follow the string number.

An example of an SDR2/SDR22 data file follows.

00NMSDR2     V02-07C117622-JAN-86 21:00 111111
10NMSDR2JOB1
12NMPROROSED BASALT QUARRY INVESTIGATION
06NM1.00000000
01NM2                 000000               00000031                      0.000
02IR0091100.000 100.000         20.000          1.530
08KI00922.000   100.000         20.000   
03NM1.470
07IR009100920.00000             359.99833
09F100910103358.111             91.74417        162.29833 2PTDESC
09F100910104336.114             91.21139        166.24000PTDESC 
00000

• '10' - Job record.

The job record contains a short description that pertains to the following survey.

• '00' - Header record

The date and time are obtained from this record.

• '02' - Instrument Station.

The number of the instrument station and the height of the instrument axis are extracted from this field. The instrument station number is in columns 5-8 and is always numeric. This number without leading zeroes, must be defined in the control database, i.e. the database must contain a station called '91' in the above sample file.

• '03' - Target Height.

The height of the target/reflector that is being measured is extracted from this field.

• '05' - Environmental record

The temperature and pressure are obtained from this record.

• '07' - Backsight Station.

The number of the backsight station and the reference angle to the backsight station is extracted from this record. The backsight station number is in columns 9-12. For the example file above, the control database must contain a station called '92'.

• '08' - Co-ordinate record

Co-ordinate data are extracted from this record. Values obtained from this field are:

1) Point Number - columns 5-8

2) Calculated northing of the point

3) Calculated easting of the point

4) Calculated elevation of the point

5) String number. The characters immediately following the elevation field may contain either a string number, a point description, or both. The string number is taken from the first part of the field if it is numeric and the description comes from the remainder of the field.

• '09' - Observation data.

Data extracted from this field are:

1) Point Number - columns 9-12

2) Slope distance

3) Vertical angle

4) Horizontal Angle

5) String number. The characters immediately following the H.A. field may contain either a string number, a point description, or both. The string number is taken from the first part of the field if it is numeric and the description comes from the remainder of the field.

Single Face Pointings To New Stations

Surveyed points may be stored as new stations in the survey database. To identify a surveyed point as a new station use the following code. The point description field in the SDR data recorder must contain something like 'STNABC'. If this exists then the characters which immediately follow 'STN' are used as the name of the station for saving in the database. In this case the stations name would be 'ABC'.

If you are surveying a new station underground and want to store the height from the floor to the target, you must enter the height in millimetres separated by a comma immediately after the station identifier. For example,

`STNABC,2357'

In this example, the height from the floor to the target at station `ABC' is 2.357.

You are given some options regarding the creation of the new station. This is done via the Options for New Station form, see here for more details.

Use of station errors table: If a station errors table exists in the survey database, information regarding the order of the new station may be displayed. See here for more details.

RESECTION

Resection is a method for determining the unknown 3D position of an occupied station by measuring angles and distances to stations whose 3D coordinates are known. Surpac allows you to enter observations to multiple known stations, and uses a least squares solver to find the best coords for the unknown station based on all the data. The least squares solver uses several parameters related to the instrument accuracy of the particular data recorder (measured angle standard deviations etc). These parameters are set using the Data Recorders Configuration function described previously.

The Sokkia SDR33 data recorder supports resection in Surpac.

Note on the use of Resection: Resection is a form of triangulation. Therefore for optimum results, points for observation (i.e. the resected point and the known stations to be used for the resection observations) should be selected to give strong geometric figures. That is, for the resection observations you should avoid features such as very acute turned angles between known stations, and having the new resection point and two or more of the known stations being used for the resection being in (approximately) a straight line. Another well documented limitation of the Resection method is that if you are performing a resection without recording any slope distances (i.e. you only record horizontal and vertical angles), then the resection point itself and the first three known stations used in the resection observations must not all lie on the same circle.

The implementation of resection for the Sokkia SDR33 data recorder is best illustrated by an example from a raw data file:

00NMSDR33  V04-04.10000010-Jan-97 11:13 111121
10NMSURVEYA ST      121111
06NM1.00000000      
01NM:                000000                00000031                                0.00000000      
02TP            NEW157360.92400000  45609.11400000  23.34000000     0.00000000                <- resection station and instrument height   
07TP            9001            STN1149.77486283    309.30861111                              <- backsight station info
03NM0.000                                                                                     <- target height
09F1            9001            900039.02800000     87.78555555     309.30861111    RESSTN1   <- resection observation           
09F1            9001            100016.23400000     88.60416666     351.54888888    RESSTN2   <- resection observation            
09F1            9001            10015.67800000      89.70833333     5.02666666      RESSTN3   <- resection observation          
09F1            9001            10029.65000000      90.25222222     92.61138888     RESSTN4   <- resection observation          
09F1            9001            100338.96700000     92.85083333     238.29388888              <- normal observation     
09F1            9001            100410.67700000     87.94527777     195.25888888              <- normal observation 

In the example above we have set up our instrument at an unknown station called NEW1 (which currently does not exist in the database). The nominated known backsight station is STN1. We then take observations (horizontal angle, vertical angle and slope distance) to 4 known stations STN1, STN2, STN3 and STN4 (these four stations must currently be in the database). These MUST be in clockwise order and the first station MUST be the nominated backsight station. The observations are identified as resection observations using the point description field. If the first three characters of the point description field are 'RES' then the observations are taken as 'resection observations'. The characters after 'RES' are taken as the known station to which the observations are made. These observations are then taken to be 'resection observations'. Once an observation has been identified as a resection observation all following observations will be taken as resection observations until an observation is encountered that does not have 'RES' as the first three characters of the point description field.

When the resection observations cease all the resection observations are put into a least squares solver and the coordinates of the unknown station are calculated. At this point you are given the option of putting the new resected station into the database as a permanent record, or just using the calculated coordinates temporarily. Now you can continue taking readings as though the resected station is a KNOWN instrument station, and the backsight station used is the one that you nominated for the resection observations. So in the example above, by the time we get to the first normal observation, the station NEW1 is now a known station and it is used as the instrument station for this observation, and STN1 is used as the backsight station. The normal observation is now surveyed as usual and its point coordinates are calculated and put in the string file. You can enter a new target height before each resection observation line.

Surpac also supports double face resection (for face left and face right observation pairs). Here the face left observation must come first (and the face left observation must have a vertical angle between 0 and 180 degrees), and the face right observation to the same station second. The readings pairs are meaned before being used in the least squares solver. Note: You cannot mix single face and double face observations in the same resection calculation. Below is an example of a double face resection:

00NMSDR33  V04-04.10000010-Jan-97 11:13 111121
10NMSURVEYA ST      121111
06NM1.00000000      
01NM:                000000                00000031                                0.00000000      
02TP            NEW157360.92400000  45609.11400000  23.34000000     0.00000000                   
07TP            9001            STN1149.77486283    309.30861111    
03NM0.000                
09F1            9001            900039.02800000     87.78555555     309.30861111    RESSTN1             
09F1            9001            900039.02800000     272.21444444    129.30861111    RESSTN1             
09F1            9001            100016.23400000     88.60416666     351.54888888    RESSTN2              
09F1            9001            100016.23400000     271.39583333    171.54888888    RESSTN2              
09F1            9001            10015.67800000      89.70833333     5.02666666      RESSTN3            
09F1            9001            10015.67800000      270.29166666    185.02666666    RESSTN3            
09F1            9001            10029.65000000      90.25222222     92.61138888     RESSTN4            
09F1            9001            10029.65000000      269.74777777    272.61138888    RESSTN4            
09F1            9001            100338.96700000     92.85083333     238.29388888                  
09F1            9001            100410.67700000     87.94527777     195.25888888              

You are given some options regarding the creation of the resected station. This is done via the Options for Resected Station form, see here for more details.

Use of station errors table: If a station errors table exists in the survey database, information regarding the order of the new resected station may be displayed. See here for more details.

Summary of important points for resection:

• The first resection observation must be to the nominated backsight station;
• The resection observations must be to stations taken in clockwise order;
• You are allowed a maximum of 20 resection observations to calculate the coords of a resection station, or 20 pairs of readings for double face observations;
• You must have horizontal angle and vertical angle readings for resection observations, but the slope distances are optional. If the slope distances do not appear or are set to 0.0 in the raw data file then only the angles will be used in the least squares solver for the resection station coordinates. You can have some resection observations with and some without slope distances in the same resection calculation. For double face resection you can also have face left with a slope distance and face right without a slope distance (or vice versa). Note that slope distances are still required for all conventional point surveys.
• If angles and slope distances are present then resection observations to a minimum of two known stations are required. If only angles are present then resection observations to a minimum of three known stations are required;
• If an underground database is used and the new resected station is stored in the database, then the nominated backsight station is stored as the 'station from' and the reverse bearing from the new station to the nominated backsight station is stored as the 'reverse bearing'.

Below is an example of the report created when resections are encountered.

RESECTION REPORT

Purpose : Testing purpose

UNADJUSTED OBSERVATIONS

INSTRUMENT ACCURACIES

Results

Station NEW1 has been inserted into the database.

OBSERVATION ADJUSTMENTS

Note: The Observation Adjustments are tabulated above to help highlight any erroneous observations.

Note: In the Resection Report file, all horizontal and vertical angles are displayed in Degrees, Minutes, Seconds format.

Note on "Standard deviations" in the RESULTS section of the RESECTION REPORT file: In general the more stations that you take readings to for the resection, the better these values become as a measure of the accuracy of the coordinates of the unknown station. This is because the more readings that exist the more "redundant" information there is. Redundant information is important in a least squares adjustment as it helps to show the consistency of the observations used to calculate the coordinates. However, even if you only take resection observations to the minimum of two fixed stations there is still some redundant information, that is one slope distance and one vertical angle, so the standard deviations are still meaningful even in this most simple case.