The GST-1 is powered from the computer or TNC serial port,
and housed in a DB-9 male-to-female feed-thru adaptor.
By using RS-232 levels for I/O, the GST-1 will interface with both desktop and laptop
Note: If you are using a Palm device you will need an external power cable
for the Earthmate which will also power the GST-1.
The GST-1 automatically establishes initial communication with the GPS,
then communicates with the GPS at 9600 baud while sending
NMEA sentences to the TNC/Computer at 4800 baud.
It will accurately convert the binary positional information from the GPS into
$GPRMC, $GPGGA, and $GPGSA NMEA-0183 version 2.0 sentences every second.
How can I initialize an Earthmate's location??
Download and use freeware program InitEartha.zip
Will the GST-1 work with the DeLorme Tripmate?
No. The GST-1 converts the Rockwell Binary output from certain GPS receivers
into NMEA-0183 format. Since the DeLorme Tripmate outputs
in the NMEA-0183 format, no conversion is necessary.
Will the GST-1 work with the SONY SkyMapGPS?
Yes. The SONY SkyMap serial GPS, as sold by ETAK outputs data
in the supported Rockwell binary format.
Can I use the GST-1 with my Kenwood TH-D7A or
PacComm Hardware Single Port switch and my TNC?
Yes. there are two approaches to using the GST-1 with these devices.
In both of these approaches the GST-1 computer connector pins 2 (Output data)
and pin 5 (Ground) are used for the data signal to the THD-7A or KPC-3.
Further details can be found here
- Connect a 9V battery between pins 5 (-) and pin 6 (+) on the GST-1
computer connector. The GST-1 draws an average 8.5 ma.
Do not ever apply 9 volts to pin 9 of the GST-1 or any pin of the
Earthmate. To do so will likely destroy your Earthmate.
- All current GST-1's being shipped will accept power from the external cable,
if present. Early GST-1's required modification but this is no longer the case.
Can data be sent to a GPS through the GST-1?
No. The GST-1 is a one-way device, sending data from the GST-1 to the computer/TNC only.
At GPS receiver startup, however, some data may be sent from the GST-1 to the GPS to
Are the NMEA-0183 GSV ($GPGSV) sentences supported?
In the current version, No.
In order to add support for GSV, which would give more information on satellites in view,
the GST-1 output update rate would likely have to drop from 1Hz to 1/2 Hz. We are still
debating the tradeoffs of this feature.
How is the GST-1 powered?
The GST-1 requires that at least one of the following handshake signals
present on the TNC or computer serial port to provide power.
If more than one signal is present the GST-1 will share the load between them.
The handshake lines and DB-9 pin numbers are DTR (4), DSR (6), & RTS (7).
Can I use my Delorme external power adapter with the GST-1
Yes. Simply connect your external power adapter between the
computer and the GST-1.
Will I harm the GST-1 if I connect the external power cable to it by
No. If you should inadvertently connect your adapter between the GST-1
and your TNC or computer, no harm will be done however the power will
not reach the Earthmate. (Also see the question above)
Return to the main GST-1 page.
* Earthmate and Tripmate are trademarks of DeLorme.,
SkyMap is a trademark of the Sony Corporation.