[ Software ][ LTGs ]
The LTG31 includes Polycorder program GPS31 which is designed for the Polycorder 600 field data logger. The GPS31 code is embedded in the LTG31 and can be uploaded to the Polycorder. The Polycorder program GPS31 allows for the display of data. While displaying, the GPS31 converts each reading to an ASCII string and outputs data to an external logging device (e.g. GPS field computer). The GPS31 can co-exist in the Polycorder together with the Geonics standard data acquisition program EM31. Uploading GPS31 to the Polycorder will not affect the performance of the EM31 program, nor will it damage the stored data file. This allows the user to have both programs in one Polycorder and to use the standard Geonics data acquisition program in areas where the GPS signal is not available without the necessity of reloading the data logger.
The LTG31 and GPS31 were tested with Trimble ProXRS. However, the software may be used with other GPS systems that have the capability of logging external sensor data. The consideration here is the processor speed of the logger employed by the particular GPS receiver. For example, Trimble logger TSC1 allows you to log EM31 data with a frequency up to 3 readings per second. Other loggers that are used with the Trimble ProXRS (e.g. TDC2, TDC1, or MCV) will work with LTG31. However they can only collect a maximum of 1.5 readings per second which is still an adequate speed for the EM31-MK2.
The GPS31 program converts the raw EM31-MK2 or modified EM31 data to readings of the conductivity [mS/m] and Inphase [ppt]. The converted data are formed in 17 byte long strings and are sent to an external logging device at a rate specified by the operator. The program allows the user to set the EM31 in the specific instrument mode of operation: AUTO, or Manual mode. The EM31 dipole mode tag is sent to the GPS logger as well. This approach allows for collecting either Vertical or Horizontal dipole mode readings at any time. The filtering option of the LTG31 program will distinguish Vertical and Horizontal data in the GPS file and will place these readings in to separate data files.
Cable interfacing the EM31, Polycorder and GPS system
Polycorder 600 series data logger