CDL Datum Underwater Modem

CDL Datum Underwater Modem – Available for rental, hire and ex-rental purchase from Ashtead Technology.

DATUM is an acronym for Digital Acoustic Transponder & Underwater Modem. The CDL DATUM system uses state of the art spread spectrum and digital signal processing technology to offer a long range high speed device for use in ranging and data applications in deep water.

Purpose designed algorithms provide high reliability data communications with a bit error rate of 10 e-6 or better with very high immunity to noise, Doppler fading and multi-path effects.
Each unit is uniquely addressable and the system is networkable. Data can be sent or received from any DATUM in the network.

The DATUM is available in ship/ROV mount version or with integrated battery pack. DATUM is also available with a number of options which add facilities for pitch, roll, heading, temperature, and depth.

Sale Information
Ex-rental unit for sale - sold as seen. Contact us for information.

Key features

  • High Accuracy Ranging
  • High Speed Modem
  • High Reliability
  • Vessel/ROV/Seabed Mount
  • Networkable
  • Spread Spectrum Technology
  • Low Power
  • Small Size

Technical specifications

Depth Rating3,000m
Range3km approx (line of sight)
Data Rates100 or 480 bits per second
Bit Error Rate10(-6) bit error rate or better
Accoustic Doppler ToleranceHigh immunity to noise and to multi-path and Doppler fading.
Tolerance of =/- 5ms-1
BandwidthBroadband operation 16Khz to 30Khz
ModulationDirect sequence spread spectrum / OFDM
Error DetectionCRC16 error detection
Digital interfaceRS232
Output Rate1200, 2400, 4800, 9600 baud
Electrical ConnectionBurton 8 pin Connector
Operating Voltage18-30VDC
Power RatingListen Mode - 1 watts approx @ 18VDC Transmit Mode - 3.5 watts approx @ 18VDC


Housing diameter120mm4.7"
Transducer Head diameter80mm3.1"
Total Height193mm7.6"
Weights3kg (in air), 1kg (in water)6.6lbs (in air), 2.2lbs (in water)