G-858BP Backpack Mag Operators Manual
it may effect the data from the EM-61. Also, if a substantial part of the G859's battery current finds its
return path through the COM1 cable, a magnetic field will be produced. This magnetic field could effect
the data when the G859 is working as a magnetometer.
We have found that building a 100 ohm resistor into the return wire of the COM1 RS-232 cable
prevents such problems. Simply omitting the return connection in the COM1 cable will also work, but this
can cause confusion when the system is being tested, because two cables must be connected before the
COM1 RS-232 connections are complete.
Field Notes
You may extract the field notes into a file in much the same manner as extracting GPS data (se
Chapter 9). This is done by using the BINTOASC program with options to tell it to only extract the field
notes.
Type the following line at the command prompt:
BINTOASC input.bin output.txt -R0 -M0 -D0 -P0 -U0 -S0
where
input is the name of the file containing the binary downloaded data (you must type the
.BIN extension
output is the filename you wish for the GPS data (you must give it an extension. The
TXT extension is a suggestion, however, you may use what you wish.)
-R0 ... The options tell the program not to extract everything except the field notes.
They are a dash, a letter, and the numeral zero.
You will now have created a file of the field notes, along with some G-858BP formatting
information. Lines will be as shown below:
33 Fell into a hole 10:59:14.80 06/01/95
33 Ran into a tree 11:16:25.40 06/01/95
33 Fell into a hole 12:01:36.80 06/01/95
Please contact Geometrics for information regarding availability of programs which automate
usage of these features.
EM-61 Data
The data from the Geonics EM-61 consists of two numbers and a gain code. The new G859
software allows this data to be taken from the COM1 serial port and used in place of the magnetometer
readings.
Since the numbers from the EM-61 can be both positive and negative, but the G859 software was
designed for magnetic fields, which can never be negative, the EM-61 values are adjusted to make them
appear in the normal range of magnetic readings. To do this, the numbers are corrected for the gain code,
multiplied by 4/125 and then added to 50000.
The readings will span:
50000 - 15.000 * 32768 * 4/125 = 34271.36
50000 + 15.000 * 32767 * 4/125 = 65728.16
97
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