Data Acquisition & Telemetry Systems
Multi-Channel Acoustic Telemetry Systems

C&M designed and developed real time array systems for the Naval Research Laboratory and ARPA. The major components of the system are:

  • Surface Telemetry Buoy (STB)
  • Tether Cable
  • Subsurface Data Acquisition Package (DAP)
  • Array(s) (32 to 64 channels)

The STB rides on the ocean surface and is tethered to the subsurface DAU by means of a electromechanical tether cable. The tether cable contains two twisted-pair electrical cables. One pair transmits unregulated DC power to the DAU and the other transmits uplink PCM data from the DAU to the STB. The STB contains the transmitter, antenna and battery pack for the array subsystem. The information from the telemetry system to the processing station is achieved by either radio or satellite transmission.

View Typical Configuration

 

 

 Features

  • Real time RF data transmission
  • Remote configuration and control via RF command link
  • Configuration data embedded in telemetry stream
  • Hydrophone channels are individually configurable
  • Flexible channel/bandwidth combinations
  • Outputs standard IRIG PCM stream
  • Uses dual-sensitivity, current mode hydrophones
  • Real Time Clock

 

Options

  • Embedded recording systems
  • Shipboard data logging systems (DAT, Iomega Jaz,  etc)
  • Remote control of sample rate and number of  channels
  • Acoustic modem command link
  • Diesel genset power source
  • Acoustic sound sources and waveform generators                         

 

Specifications

General  
Acoustic channels: 1 to 128
Acoustic Bandwidth: 5Hz-256Hz to 5Hz-20KHz (switch selectable)
Channel-to-Channel Gain Match: +/-0.5dB
Channel-to-Channel Phase Match: +/-5 degrees
Digitizer: 16-bit delta-sigma
Word size: 12 or 16 bit (switch selectable)
Non-acoustic channels: 256
Non-acoustic bandwidth: 1/256 x selected acoustic bandwidth
Non-Acoustic data: hyd. config., status, engineering sensor data, time code
Output Bit Rate (bits/sec): (number of hyd + 4) x bandwidth x 2 x bits/word
System Output: serial: NRZ-L, bit clock....parallel: data, word clock
 
Data Link  
Frequency band: 1710-1850 MHz (L-band)
Transmit frequency select: 10 switch-selectable channels
Transmit power: 10 watts
Transmit range: 3-5 NM (depends on bit rate and sea state
Transmit and receive antenna: Omni-directional, 3dBi gain
Polarization: vertical
Receiver IFBs: 2,4,6,10 MHz (switch selectable)
Baseband filters: 0.375, 0.750, 1.25, 2.5MHz (switch selectable)
 
Command Link  
Method: RF modem (Motorola RNET)
Frequency: 425 MHz
Baud Rate: 300, 600, 1200, 2400, 9600 (jumper selectable)
Downlink commands:
  • power ON/OFF
  • channel gain
  • global gain
  • pre-emphasis (ON/OFF)
  • sensitivity (HI/LO)
  • analog CAL (ON/OFF, signal select)
  • digital simulation (ON/OFF, signal select)
  • set real time clock
 
Surface Telemetry Buoy & Spar  
Battery capacity: 15KW-hrs
Battery life: 3 days (64 channel, continuous operation)
Operating voltage: 250 Vdc
STB size: 58"dia x 71" high
STB weight: 2000 lb. (with battery pack)
 
Umbilical Cable  
Length: up to 5000ft
Diameter: 0.6"
Breaking Strength: 8000 lb
Working load: 3000 lb
Construction: Electrical core, kevlar overbraid, Dacron jacket

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