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Overview - Equipment - Getting Started - Mapping - Crown - Heights - Other Data - Data Review

Sylvan Datalogger

Equipment

The equipment necessary to use the Sylvan datalogger program include:

Laptop, Netbook or Tablet Computer

A couple of considerations include that you have sufficient batteries to run the computer for a days field work. This can be done by having several replacement batteries charged for each day or have a 12 volt source and a 12 volt computer power supply. We have tried both of these and they both work with differing advantages and disadvantages.

If running in single user mode, only one computer is needed but the one computer will have to be moved around the plot to stay within 25 feet of the laser measuring device. This is because practical limit of the bluetooth wireless connections.

If running in the multi-tasking environment you will need a computer to function as a server for the plot. this computer will need a wireless connection which most laptop today have as standard equipment. We recommend a laptop as the larger screen can be helpful for this task. You will also need a simple computer to run datalogger-lite for each crew member that has a laser ranging device. The computers need to have both a wireless connection and a bluetooth connection. We have found touch screens very convenient for work in the forest.

Currently our software is available on Windows (XP and 7), MacOS and Linux (Ubuntu) we have the potential to produce a Windows mobile version but that has not been tested.

Laser Ranging device

We have tested a large number of device and they all seem to provide the basic functionality yet some are much more convenient that others. The device must have the ability to measure distance with a pulsed ranging laser in either English or metric units. It does not matter if the device can convert the unit as the software can convert unit on the fly. The laser ranging must also have a means of producing a azimuth (Compass or Angle device) and a clinometer build in as well. The device must produce NEMA surveying packet described in the section below. This is a very common output packet and an industry standard. The device must communicate with a computer through a serial port, Bluetooth devices use serial ports to communicate, We have test a could wire serial devices and they work as well as long as they have the required output packet.

Sturdy tripod

We have found that mapping work much better is the laser ranging device is mounted on a sturdy tripod during mapping. During the other measurements the laser can be hand-held. Be sure the tripod you get has the correct size bolt to match the laser ranging device we have both 1/4" mounts and 1/2" mount among the equipment we have.

Height pole

We have found a standard fiberglass height pole very helpful in mapping plots it is used to determine the height of the instrument during mapping and can be use to provide an offset if the base of the a tree is obstructed by vegetation or course woody debris. Very tall height poles are not necessary.

D-tape or Tree Caliper

The diameter of the tree will have to be measured using a tradition diameter measuring device of your preference

Datalogger Program Input Specifications

The Sylvan Stand Structure Model uses complex spatial data from stands to predict the growth of trees. To make it easier to collect this type of data, we have developed a data entry program called Datalogger. The purpose of the program is to directly collect from electronic measurement instruments the necessary information and store that data in a SQL database. The SQL database can be used in the Sylvan Stand Structure Model or the data can be export to a comma delimited file format.

As with all Sylvan software, it will run on Windows (XP, Vista, Windows 7), Linux (Ubuntu), and MacOS. We have the serial port communication working on Windows, MacOS and Linux.

If you have a ranging/compass device that emits a standard NEMA packet in the following format.

$PLTIT,HV,8.13,F,265.70,D,3.39,D,8.15,F*6E
Where
$
is the start of the string

PLTIT
is a source identification

HV
identifies this as a horizontal vector format

8.13
is the horizontal distance

F
means the measurement is in feet, M means the measurement is in meters

265.70
is the measured azimuth

D
means the measurement is in degrees (max. 360), G means the measurement is in Gradients (max. 400)

3.39
is the pitch or inclination up (positive) or Down(negative), where horizontal is 0

D
means the measurement is in degrees (max. 360), G means the measurement is in Gradients (max. 400)

8.15
is the slope distance or the distance along the pitch

F
means the measurement is in feet, M means the measurement is in meters

*
is the end of the packet string

6E
next two characters are a hexadecimal CRC value to confirm that the packet was sent correctly

If you have set the correct communication port, you will see the following screen on firing the device measurement button. This screen is very large to allow easy reading from some distance.

Graph of the function in Figure 1

Figure 1. Example the the approval screen produced each time the laser is fired.


Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 3.0 United States License.

Author: Dr. David R. Larsen
Created: January 31, 2013
Last Updated: February 19, 2013