[ Software ][ LTGs ]
The LTG38 includes Polycorder program GPS38 designed for the Polycorder 600 field data logger. The GPS38 code is embedded in the LTG38 and can be uploaded to the Polycorder. The Polycorder program GPS38 allows for the display of data. While displaying, the GPS38 converts each reading to an ASCII string and outputs data to an external logging device (e.g. GPS field computer). The GPS38 can co-exist in the Polycorder together with the Geonics standard data acquisition program EM38DM. Uploading GPS38 to the Polycorder will not affect the performance of the EM38DM 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 LTG38 and GPS38 were tested with Trimble ProXRS. However, it 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 EM38 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 LTG38. However they can only collect a maximum of 1.5 readings per second which is still an adequate speed for the EM38.
The GPS38 program converts the raw EM38 data to readings of the conductivity [mS/m] and Inphase [ppt]. The converted data are formed in 10 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 EM38 in the specific instrument mode of operation: AUTO, or Manual mode. The EM38 component (conductivity or Inphase) and dipole mode tag is sent to the GPS logger as well. This approach allows for collecting conductivity or Inphase components in either Vertical or Horizontal dipole mode readings at any time. The filtering option of the LTG38 program will distinguish conductivity and Inphase, and Vertical and Horizontal data in the GPS file and will place these readings in to separate data files.