Two-wires stadia survey

This function is used to reduce two-wire stadia observations to co-ordinates. Observations are entered in rounds from a given survey station. The reduced observations are saved to a string file.

To run this function: Choose Survey > Surface surveys > Stadia two-wires, or...

• In the Function Chooser, type TWO-WIRES STADIA SURVEY, and press ENTER.

Define the .DAT and .STR file to create.

Enter the Location name and ID number of the file to be created.

The `.dat' file is used to record entered observations for later correction if necessary. The `.str' file will contain the co-ordinates of the entered points.

Purpose

Enter a brief description to help identify the file, this will be written to the header record of the created `.str' file.

Process existing file

Enter `N' for Keyboard entry. After the completion of data entry all set-up and observations are saved to a file (Loc)(Id).dat for future reference.

Enter `Y' to reprocess an existing `.dat' file.

Vertical circle zero

Enter the zero position of the vertical circle, if vertically above `zenith', vertically below `nadir'.

Vertical circle face

Enter if the observations are taken with `face left' or `face right' angles.

Complete the ENTER TWO-WIRE STADIA SURVEY OBSERVATIONS form and choose Apply to display the DEFINE THE BACKSIGHT AND SET-UP STATIONS form.

Backsight

Enter the name of the backsight station that was used for this set-up.

Reference angle

Enter the reference angle used for this setup. This allows entry of field observations with a non zero backsight. The angle must be in the format described below:

• If you have selected DEGREES as your Angle units, the angle must be entered in DDD.MMSS format.
• If you have selected GRADS as your Angle units, the angle must be entered in GRADS to four decimal places.

Setup

Enter the name of the instrument station that was used for this set-up.

Instrument height

Enter the height from the station to the instrument axis.

Note:If the instrument axis is above the station the height must be `+', if the instrument axis is below the station it must be `-'.

Surveyor

Enter the name of the person who completed the survey. This value will only be used if you choose to nominate one of the surveyed points as a new station, in which case it will be stored in the survey database where it can be used for audit purposes.

Survey Date

Enter the date of the survey. The date must be entered in the form YYYY-MM-DD HH:MM:SS, although the HH:MM:SS part is optional, eg 2003-10-23 10:20:33 and 2003-10-23 are both acceptable values. This value will only be used if you choose to nominate one of the surveyed points as a new station, in which case it will be stored in the survey database where it can be used for audit purposes.

Complete the DEFINE THE BACKSIGHT AND SET-UP STATIONS form and choose Apply to display the ENTER OBSERVATIONS FOR TWO-WIRE STADIA SURVEY form.

Backsight

The name of the backsight station display only.

Setup

The name of the set-up station display only.

Reference angle

The reference angle display only.

Instrument height

The instrument height display only.

String

Enter the string number of the observed point. If you wish to introduce a break into the string enter `0', otherwise use a positive integer no greater than 32000.

Bot Wire

Enter the bottom wire observation.

Top Wire

Enter the top wire observation.

V.angle

Enter the vertical angle observation. The angle must be in the format described below:

• If you have selected DEGREES as your Angle units, the angle must be entered in DDD.MMSS format.
• If you have selected GRADS as your Angle units, the angle must be entered in GRADS to four decimal places.

H.angle

Enter the horizontal angle observation. The angle must be in the format described below:

• If you have selected DEGREES as your Angle units, the angle must be entered in DDD.MMSS format.
• If you have selected GRADS as your Angle units, the angle must be entered in GRADS to four decimal places.

Description

Enter a relevant description for the surveyed point.

OFFSETTING POINTS FROM THEIR SURVEYED POSITION

If necessary, it is possible to offset a point from its surveyed position. This is often necessary when a point is either in a position which is too dangerous, or in a position which is inaccessible.

In situations such as these it is possible to enter a code as part of the point description which will offset the surveyed point to its desired location.

The point offset information is entered into the description field in the form
D-/+n.nn O-/+n.nn V-/+n.nn
where D indicates a distance offset along the line from the set-up station to the surveyed point with `+' indicating an increase in the horizontal distance and `-' indicating a decrease in the horizontal distance.

Note:This will not alter the elevation.

O indicates a perpendicular offset from the line between the set-up station and the surveyed point with `+' indicating an offset to the right of the line when looking from the set-up station to the surveyed point, and, `-' indicating an offset to the left of the line.

V indicates a vertical offset from the surveyed point. `+' indicates an increase in elevation and `-' indicates a decrease in elevation.

n.nn is the distance which is to be used as the offset value.

The letters which are used to indicate the offset direction MUST be uppercase, a point description can be added after the codes.

For example,

Using underground type stations

See here for notes on the differences between using underground and surface type stations.

Nominating surveyed points as Stations

A survey of an area may be carried out more efficiently if you nominate surveyed points as temporary or low grade survey stations for subsequent setups during the course of a survey. This is possible by including a station identification code in the point description field of the point which is to be used as a survey station.

To identify a point as a survey station enter something like `STNABC' in the point description. The `STN' indicates that the point is to be used as a survey station and saved to the survey database. The characters after `STN', in this case `ABC', are used as the identifier for the new station.

Note:When the calculations for the new station are performed you are given some options regarding the creation of the new station. This is done via the Store New Station As Surface or Underground 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.

Complete the ENTER OBSERVATIONS FOR TWO-WIRE STADIA SURVEY form and choose Apply to display the DEFINE THE BACKSIGHT AND SET-UP STATIONS form. If you do not have another Two-wire Stadia Survey set-up choose Cancel and return to the SURVEYING menu.

Result

The observations are saved to a '.DAT' file for later editing if necessary and the co-ordinates of the observed points are calculated and saved to a '.STR' file.