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Technical Articles

As the demand for quality and playability on sports fields continues to grow, so does the demand for laser grading. Laser grading is establishing surface elevations within a given area using an automated blade control system.

To understand a little more laser grading, you first have to understand a few terms and principles. A basic understanding of the types of lasers also helps.

Laser transmitters come in a number of configurations from simple to more complex. The basic principles are all the same. As a laser transmitter rotates, it sends out a beam of light over an area that is picked up by a receiver. In the process of laser grading, the receiver is mounted on the grading equipment, attached to a mast or pole. The receiver picks up the signal from the transmitter and in turn sends the signal to a control box that simultaneously raises or lowers the grading blade to keep the cutting edge of the blade at a consistent elevation relative to the transmitter beam. Ultimately the established grade will mirror the laser transmitter beam.

The four main types of lasers are the level laser, single plane laser, dual plane laser and cone laser. The area of the laser beam emitted from the laser transmitter is called a plane. The plane is a two dimensional area. Picture a flat sheet of paper. Now picture that sheet of paper as being large enough to hover over the area to be graded. Maybe that’s why it’s called a plane? A plane has a Y axis and an X axis. The Y axis could be considered one edge of the paper and the X axis could be considered the edge perpendicular to the first.

The most basic laser is the level laser. This laser is typically used to document existing relative elevations within an area. This laser is designed to send out a flat “level” beam of light. That is, the X axis and the Y axis are both level creating a level plane above the area being documented.

Example: The laser transmitter is set up in a location within view of the area to be documented. The laser has to be set up in “plane” sight, pun intended. Anyway, the operator uses a grade rod marked off in feet and inches or other measurement such as tenths, meters etc. The grade rod is equipped with a laser receiver. The operator can document the relative elevation at any location within the proposed area. First, he or she positions the grade rod perfectly vertical on that location. Then, by maneuvering the receiver up or down on the grade rod to intersect with the beam sent by the laser transmitter, the operator can read the corresponding measurement on the grade rod; the higher the corresponding measurement, the lower the actual elevation. By documenting the relative elevations over a grid work of locations the operator can chart the surface contours or topography of a given area. Once the operator has done this, he or she can develop a better understanding of water movement and use this information to develop an effective grading plan.


It is important to note that when documenting relative elevations, these elevation readings are only relative to the height or elevation of the laser transmitter at that time. If the transmitter is repositioned, the operator will come up with totally different readings on the grade pole. To allow for this, a benchmark is established at the time the elevations are documented. A benchmark is a location within plane site of the transmitter that is a permanent elevation such as a concrete pad, footing, or possibly the base of a fencepost. By establishing a benchmark, the operator can reposition the transmitter on a day to day or even year to year basis as long as the elevation of the benchmark doesn’t change. By documenting the new reading for the benchmark, the operator can translate the new readings to correlate with those documented in the past.

The benchmark is used as the reference elevation when positioning the receiver on the mast above the laser grading equipment. First the laser transmitter is positioned, turned on and programmed to the desired slop. The cutting edge of the grading blade directly below the receiver is positioned on the benchmark elevation. The receiver is raised or lowered on the mast to intersect with the laser bean. The receiver will remain in this position as long as the transmitter is not repositioned. Whenever the laser transmitter is repositioned, the laser receiver must also be repositioned to correlate with the elevation of the new transmitter location. The same process is carried out to position the receiver correctly when a grade rod is used.

A single plane laser has the ability to slope the Y axis while the X axis always remains level. This creates a flat plane but not a level plane. It is important to note that the terms “flat” and
“level” are many times used interchangeably. In reality they can

Lasers are commonly used for alignment, levelling, control and survey tasks for construction work. The Work Health and Safety (WHS) Regulations impose certain requirements in relation to the safe use of laser equipment at the workplace.

The WHS Regulations prohibit the use of laser classes 3B and 4 in construction work. Laser classes that can be used for construction work are classes 1, 2, 3A, and 3B(Restricted). Although class 3B(Restricted) lasers can be used for construction work they should not be used in dimly lit work areas.

The table below sets out the system of classification of laser devices and the potential hazards of the laser classes from Australian Standard 2397:1993 – Safe use of lasers in the building and construction industry. Further information on the safe use of lasers for construction work is available in this standard.

Laser Class


For use in building and construction industry

Class 1

Safe for use under all conditions of exposure.


Class 2

Low-powered lasers that may require some administrative controls but present little hazard (for example, eye protection is usually provided by normal blink and aversion responses).

Yes, with Administrative Controls

Class 3A

These lasers emit higher levels of light and their use requires more stringent engineering and administrative precautions in order to ensure they are not used with optical instruments (for example, a builder’s level or theodolite) which would concentrate the beam so that it would all enter the eye.

Yes, with Administrative Precautions

Class 3B(Restricted)

These lasers operate at the same power levels as Class 3A but have higher levels of irradiance (power density).

These lasers can be used for building or construction applications but should not be used in dimly lit building or construction applications (that is less than approximately 100 lux).

Yes, with Administrative Precautions and not in a <100 lux environment

Class 3B

These lasers emit either invisible or visible radiation potentially hazardous to the eye and skin.

These lasers must not be used for building or construction tasks.


Class 4

These lasers are high-power devices capable of producing diffuse reflections hazardous to the eye. Skin exposure to the direct beam of a Class 4 laser is also hazardous.

These lasers must not be used for building or construction tasks.


Content based on AS 2397-1993, Section 2.2

The Schonstedt Instrument Company provides solutions for the detection and location of ferrous objects and utilities below the surface of the ground or water. Founded in 1953, the Schonstedt Instrument Company designs and manufactures instruments for location of underground objects. Schonstedt offers both pipe and cable locators and magnetic locators.

The purpose of this article is to briefly explain the differences in each Schonstedt Underground Locator model, and the features they offer.

First, we'll mention that they're all called "Underground Locators". Some people call them Utility Locators, Yellow Sticks, or sometimes Metal Detectors. Schonstedt Instrument Company basically makes two different types of Underground Locators. The first is a "Magnetic Locator", and the other is a "Pipe and Cable Locator". We will explain the basic differences and how they work in this article. This will allow you to hopefully learn more about the differences in the various models and figure out which model best suits the tasks that you'll use your Underground Locator for.

Magnetic Locators

You'll need to understand that Magnetic Locators will ONLY locate metal objects that are made of ferrous material. Basically speaking, if a magnet will stick to it, a Magnetic Locator will detect it. Please understand that how deep in the ground you can detect something depends on it's mass. A surveying nail you can find up to about 2, maybe 3 feet. An underground storage tank you can find up to about 15 to 17 feet deep. Magnetic Locators will not detect objects such as electrical power cable made of aluminum or copper, since these materials are not considered ferrous. Items that are found using Magnetic Locators are usually cast iron pipes, property corner markers, steel enclosures or hardware, hazmat drums, mag and pk nails, manhole covers, marker magnets, septic tanks, unexploded ordnance, valve boxes, weapons, and well casings.

Pipe and Cable Locators

With Pipe/Cable Locators, they do NOT detect metal objects like a magnetic locator does. A Pipe/Cable Locator will ONLY locate objects that have some type of charge or signal placed on them. Many utilities give off or transmit a signal of their own that is sometimes detected by a Pipe/Cable Locator such a 60Hz for live for power lines. But, sometimes the person doing the locating must induce a signal onto the line in order to be able to locate it. Most Pipe/Cable Locators have the ability to induce a signal onto an object (like a waterline) using a Transmitter, and the object must be metallic in order to conduct the signal. Pipe/Cable Locators typically come with a receiver and a transmitter but not always. It depends on the model you purchase. Some models come with a portable pocket-sized transmitter with limited features, and some come with standard transmitters that are built into a hard case and offer more features for varied situations.

To simply describe how a Pipe/Cable Locator works, the transmitter is just like a radio station that's putting out a signal, and to pick up the radio station you want to listen to (for example your favorite rock music station) you need a receiver. Just like radio stations, the transmitters transmit signals in certain frequencies. Some Pipe/Cable Locators come from the factory with multiple signals to choose from, and some come from the factory with a single frequency that you decide and select before the purchase. To induce a signal onto a pipe or cable, the Transmitter along with Signal Clamps or Alligator Clips that you place or fasten around on onto pipe, fire hydrants, cables, and other utilities or lines that you're wanting to locate. When accessibility to the utility’s end-points (above ground) are not known, the transmitter can also induce a signal from above, through the ground to reach the utility. This allows the Transmitter to send it's signal onto the pipe or cable you're wanting to locate.

Some Pipe/Cable Locator models come with the accessories like Signal Clamps and Alligator Clamps or Inductive Antennaes, and sometimes you have to purchase the accessories separately. Items that are found using Pipe/Cable Locators are usually cable TV lines, fiber optic lines with a metallic conductor along side, irrigation lines, plastic pipe or conduit (plastic pipe can be located by inserting a sonde or mini-transmitter and locating the sonde), plastic pipe tracer wire, power lines, street light power, and water lines.

Jim Bach from Schonstedt covers the basics of underground locating with three Schonstedt magnetic locators

Now hopefully you have a better understanding of how a Magnetic Locator, and a Pipe-Cable Locator works.

Underground Locator Model Suggestion
Hopefully this will help you quickly figure out which model is suggested for the job. It basically depends on what you want to accomplish with your new Underground Locator, so start out by asking yourself and your co-workers, exactly what do you want to accomplish with an Underground Locator.

Magnetic Locators

Schonstedt Magnetic Locator GA-52Cx
This is the work-horse model. It has audio only, as it does not have a visual display. It's the most popular selling model.

Schonstedt Maggie
Ergonomic, pistol grip handle. Battery compartment is located on the handle for ease of battery changes in the field. Display has sensitivity and volume adjustments. Comes with a soft case and strap.

Schonstedt Magnetic Locator GA-72Cd
This model is the same as the GA-52Cx only it has a handle, audio, sensitivity adjustment, as well as an LCD visual display, which displays polarity and signal strength. The display helps define the outer edges of the target.

Schonstedt Magnetic Locator GA-92XTd
This model has an expanding and retractable body. Makes it easier to carry in the field, and easier to store in small places (behind your truck seat for example). This model has an LCD visual display which displays polarity, sensitivity, and signal strength. The display helps define the outer edges of the target.

Schonstedt Magnetic Locator GA-92XTi
This model has an expanding and retractable body. Makes it easier to carry in the field, and easier to store in small places (behind your truck seat for example). It has audio with sensitivity and volume controls.

Schonstedt Magnetic Locator MAC-51Bx
This model has been discontinued and is no longer available.

Pipe & Cable Locators

Schonstedt XTpc Pipe and Cable Locator
This is the most portable Pipe & Cable Locator as it has an expanding and retractable body. It comes with a pocket-sized Trasmitter. It is made in two frequencies. You select a single frequency before purchase (either 33Khz or 82 Khz). Great for rural and less congested areas.

Schonstedt XTpc+ Pipe and Cable Locator
The newest model of Pipe and Cable Locators that offers 3 frequencies (512Hz, 33Khz and 82Khz). Has adjustable watts (from .5 to 5) for pushing the signal further distances. Great for use in very congested areas. The XTpc+ is the replacement for the Schonstedt TraceMaster. The Schonstedt TraceMaster is no longer available.

Schonstedt XT 512
Can only be used to find sondes and inspection cameras. The operating frequency of this unit is 512HZ.

Survey Pro v5.7.1 is a maintenance update to version 5.7. See the General Updates section below of a description of what was fixed. The 5.7 release notes are included here for completeness. The 5.7 version will be disabled on the website so it will no longer be available. Spectra Precision Survey Pro version 5.7 is an incremental update and is available to all customers with a current software maintenance plan (software warranty). Version 5.7 has an updated .survey file version.

New features and changes

  • Refreshed Traverse / Sideshot screen that includes all of the following new features: o Measure only o Store a previous measurement o Measure and store at the same time (Sideshot) o Angle-Only measurement o Offset measurements o Repetitions o Robotic control from the Traverse / Sideshot screen It is important to note that the separate routines for repetitions, offsets, and robotic control are still in place and available as alternative methods.
  • Max+ mode for features and options to perform combined GNSS/Robotic measurements and setups o Switch back and forth between GNSS and Robotic seamlessly o Switch to GNSS Data Collection and other measurement screens using the Quick Pick menu o Use GNSS to set points for resections and other station setups and then measure with the robot
  • Added a GNSS Distance-Distance offset option to the offset feature
  • Configured many of the preview maps and map views to support background maps
  • Added a map view for the GNSS and Robotic staking screen
  • Open Street Maps (OSM) maps are now supported as background maps
  • Added support for the Spectra Precision FOCUS 35RX robotic total station
  • Added support for the Spectra Precision SPDL2.4 Bluetooth to 2.4GHz radio
  • Added support for the Trimble S5 and S9 total stations
  • Added CCC base support for the Spectra Precision ProFlex 800

Read more: Release Notes - Survey Pro 5.7.1

I'm surprised how many surveyors i've spoken to over the years that aren't aware of nodal prisms and the accuracy that can be gained by using them. 

The principle behind a nodal prism is relatively simple: the optical and mechanical centre of the return wavelength of light coincide with each other. In other words -  regardless of the prisms orientation in the holder ( tilted  vertically or rotated horizontally)  there are no offsets induced at the target.

Two of the most common offsets for nodal prisms are -17.5 (for 25-mm prisms) or -40 mm offset (for 62-mm prisms). They have aligned the mechanical and optical axis over the pivot point. The offset is derived from the diameter, thickness of the glass, position within the housing, the housing on the axis and the speed of light as it travels through the glass. Once these calculations are computed the offset is the result.

If you are using a zero offset target your are more than likely using the worst choice in offsets that will result in an induced error for any off-axis shots.

Read more: Nodal prism targets explained

Cody Corporation Pty Ltd supplies a range of self leveling lazer levels for the surveying, construction, civil and building industries and trades such as concreting, plumbing, electricians, kitchen and bathroom installation, suspended ceilings, interior fitout, building and construction, farmers, builders, tilers & earthmoving.

Cody Corporation have a range of automatic levelling lasers and Optical Dumpy / auto levels as well as internal fit out lasers with cross lines and dot laser level. Cody's brands include Bear Scientific, Proshot and Spectra Precision and are sold Australia wide in all major citys including, Adelaide, Sydney, Melbourne, Perth, Brisbane, Hobart, Newcastle, Geelong, Darwin, Gold Coast, Central Coast, Bendigo, Wagga, Moorabbin, Braeside, Brooklyn, Granville, Toowoomba, Wollongong, Hoppers Crossing, Wingfield, Townsville, Horsham, Hamilton, Launceston, Fyshwick, Albury, Nerang and Cairns. Call us for closest location. Each laser level is checked for calibration before dispatch here in Australia.

Cody Corporation has been importing and distributing quality laser levels and survey equipment for over 30 years from Germany, America and Japan.

Cody Corporation supplies lasers for sale through its extensive dealer network through out Australia, New Zealand and Papua New Guinea.  If you are thinking about buying Red Back, CST, spot on, tanley, lufkin, bosch, topcon, sokkia, pls, imex, proshot, stabila, pentax, or any other brand check our lasers first for our quality, support, knowledge, back up, service and price, we believe we can provide you with the best levellig solution for your business.

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