Campbell Scientific TX320 Transmitter - Manual (Page 26)

TX320 Transmitter
1, 3, 5 are not used
2 = Ground
4 = RXD (output)
6 = SDE (input)
7 = CLK (input)
8 = 12V (input)
9 = TXD (input)
7.2.2.2 RS-232 Port
The RS-232 port is a DB9 female connector configured as DCE. Only three
pins are used, transmit on pin two, receive on pin three, and ground on pin five.
Transmit is an output and receive is an input to the TX320.
The RS-232 port allows the transmitter to be connected to a PC’s 9-pin serial
port or to a datalogger’s RS-232 port. Connection to a PC is required to
configure the transmitter via Device Configuration Utility.
7.2.2.3 USB Port
The transmitter also has a type B USB port for connecting to a PC. Many
newer computers only have USB ports. Configuration of the transmitter via
Device Configuration Utility requires that the transmitter is connected to a PC.
7.2.3 RF Connectors
7.2.3.1 RF Transmission Connector
The TX320 uses the type N female connector for RF power out. This
connector must have a proper antenna connection before transmission occurs.
Failure to use a properly matched antenna cable and antenna may cause
permanent damage to the RF amplifiers. The nominal impedance is 50 ohms,
the frequency range is approximately 400 to 403 MHz. At 300 bps
transmission rates, the nominal EIRP is 48 dBm with an 11 dBi gain antenna.
At 1200 bps, the nominal EIRP is 52 dBm. CS-2 standards use lower transmit
power.
7.2.3.2 GPS Connector
The GPS connector is an input to the TX320. Operation without an antenna
connected will not cause damage, but the transmitter will not transmit without
a valid GPS fix. The GPS connector is an SMA female. The GPS receiver
uses an active 3.3 V antenna.
The TX320 transmitter uses the GPS receiver for two functions. The precise
GPS time is used to ensure scheduled transmissions occur at the proper time.
The one-second GPS synchronization pulse is used to ensure a precise, drift-
free carrier frequency. See Section 7.4, GPS Antenna, for more information
regarding GPS and GPS antenna placement.
7.2.4 Power Connector
The TX320 power connector has two pins: ground and 12 V. The input power
requirement is 10.8 to 16 Vdc at 3 amps. Because the TX320 can use up to 3
A, the power should be connected directly to the battery. An in-line 7 A fast
blow fuse can be used to help protect the transmitter. The TX320 is shipped
16