Campbell Scientific TX320/312

Campbell Scientific’s TX320 is a high data rate (HDR) transmitter that provides communications, via GOES satellites, from a Data Collection Platform (DCP) to a receiving station. It is compatible with most Campbell Scientific dataloggers and offers a convenient telemetry option for remote DCPs in the Western Hemisphere.

Benefits and Features

  • Transmission rates of 300 and 1200 bps
  • Transmitter certified as High Data Rate version 2 compliant
  • NESDIS-certified transmitter
  • Automatic GPS correction of clock and oscillator drift
  • Very stable clock that provides up to 28 days of operation between GPS fixes for more reliable operation in areas with poor GPS reception
  • Diagnostics and status information can be sampled by the datalogger and transmitted as part of the data stream
  • Readily added or retrofitted to existing Campbell Scientific systems
  • Non-volatile setups configured with Windows-based software
  • USB port for connecting PCs to setup and perform diagnostics
  • Independent self-timed and random data buffers

Technical Description

The TX320 supports data transmission rates of 300 and 1200 bps. Because clock accuracy is critically important for GOES satellite telemetry, the TX320 includes a robust, temperature-compensated-oscillator (TCXO) based clock and a GPS receiver. The real-time clock's precision allows independent operation for up to 28 days without GPS correction.

GOES System
GOES satellites have orbits that coincide with the Earth’s rotation, allowing each satellite to remain above a specific region. GOES satellites cover the western hemisphere.

The GOES system is administered by the National Environmental Satellite Data Information Service (NESDIS). NESDIS assigns addresses, uplink channels, and self-timed/random transmit time windows. Self-timed windows allow data transmission only during a predetermined time frame. Random windows are for applications of a critical nature (e.g., flood reporting) and allow transmission immediately after a threshold has been exceeded.


Data Collection Platform (DCP) Equipment

  • TX320 GOES satellite transmitter (includes an SC12 cable)
  • 17992 GPS antenna and the 18017-L cable. The GPS antenna mounts to the end of a crossarm via the 7623 ¾-in. threaded pipe and a 1049 NU-RAIL fitting or CM220 Mount.
  • Datalogger
  • 25316 11-dBi Right-Hand Circular Polarized (RHCP) Yagi antenna with mounting hardware.
  • COAXNTN-L RG8 antenna cable
  • ENC16/18 or larger enclosure
  • Power supply consisting of Campbell Scientific’s BP12 12-Ahr, BP24 24-Ahr, or BP84 84-Ahr battery pack, CH200 or CH100 regulator, and SP10 10-W or SP20 20-W solar panel
  • 16981 Surge Suppressor Kit (optional)


Retrieving Data from the Ground Receiving Station

  • Choose one of the following methods:
  • Internet (see NESDIS for requirements)
  • Domsat
  • LRGS
  • DRGS (Direct Readout Ground Station)

TX320 Specifications

  • Operating Voltage Range: 10.8 to 16 Vdc
  • Transmission Data Rates: 300 and 1200 bps
  • Frequency Range: 401.7 MHz to 402.1 MHz
  • Height: 15.8 cm (6.2 in.)
  • Length: 24.9 cm (9.8 in.)
  • Width: 5.3 cm (2.1 in.)
  • Weight: 1.02 kg (2.25 lb)

Supply Current @ 12 Vdc

  • Idle or Sleep: 5 mA
  • During GPS Fix: 80 mA for 15 minutes per day
  • Transmission: 2.6 A


Channel Bandwidth

  • 300 bps Transmission Rate: 750 Hz
  • 1200 bps Transmission Rate: 2250 Hz

USB Port

  • Connector: USB type B
  • Command Protocols: ASCII Command Protocol

CS I/O Port

  • Signal Levels: TTL
  • Interface Protocol: Campbell Scientific Synchronous Device Communication (SDC)
  • Command Protocol: ASCII Command Protocol1 or Binary Command Protocol2


RS-232 Port

  • Signal Levels: RS232C
  • Connector: DB9F
  • Command Protocol: ASCII Command Protocol1 or Binary Command Protocol2

Output Power

  • Complies with NOAA/NESDIS, GOES DCPRS Certification Standards
  • at 300 bps and 1200 bps, version 2.0
  • For a 1200 bps link: DCPRS shall operate with an EIRP of 43 to 47 dBmi, assuming appropriate antenna
  • For a 300 bps link: When transmitting to the GOES-13 or later satellites, the DCPRS shall operate with an effective EIRP of 37 to 41 dBmi, assuming appropriate antenna
  • Example output power: 11.2 W @ 1200 bps transmission rate


  • Setting Accuracy: ±100 µs synchronised to GPS
  • Drift: ±10 ms/day over -40° to 60°C
  • GPS Schedule: 1 fix at power up, 1 fix per day afterwards
  • Transmission Continuation w/o GPS Fix: 28 days

Frequency Stability

  • Initial Accuracy: ±20 Hz disciplined to GPS
  • Short-Term Drift: ±0.04 Hz/seconds
  • Aging: ±0.1 PPM/year
  • Vcc + Temperature: ±0.1 PPM

Temperature Range

  • Operating: -40° to 60°C
  • Storage: -55° to 70°C


1 - ASCII command protocol is described in “G5 ASCII Command Protocol (Document number 700-G5-CMND-ASCII)."

2 - Binary packet protocol is described in “G5 Binary Command Protocol (Document number 700-G5-CMND-BIN)."

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