ST-21 Argos Satellite Transmitter
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2.5 ArgosError (Error as string)
Public ErrorCodes as string * 20
ArgosError(ErrorCodes)
2.5.1 ErrorCodes
ErrorCodes is a string variable. ArgosError sends the command &h09, and then
waits for the returned string plus the ACK or NAK character. The returned string
is stored in the string variable ErrorCodes. If NAK (&h15) is returned, then
ArgosError() did not receive a proper response from the ST-21.
3. ST-21
Installation
3.1 BNC Antenna Connector and Antenna
The ST-21’s BNC connector is for attaching the antenna (see Figure 3-1).
Figure 3-1. The ST-21’s BNC connector attaches to the antenna via the
antenna cable
The connector’s RF output is 50 ohm impedance at a nominal 1 watt output at
about 401.6 MHz. Frequency is dependent on setup. For the ST-21, Campbell
Scientific offers the #12022 omnidirectional, unity gain antenna (see Figure 3-2).
An antenna with gain will perform significantly worse than an antenna with unity
gain. The #12022 antenna includes a 17 ft cable and a mounting bracket for
fastening the antenna to a mast. The antenna should be mounted vertically and the
connections kept dry.
