SN-ALT-300 ALTIMETER Hoytek SN-ALT-300 is a compact, lightweight, and industrial altimeter sensor designed for use in Observation Class ROVs, AUVs, and all platforms that require altitude measurement.

SN-ALT-300 implements CHIRP modulation, which sends a varying frequency ultrasonic pulse. The advantages of CHIRP include better signal to noise ratio, and much higher range resolution than non-CHIRP devices.

SN-ALT-300 uses a high frequency 500kHz transducer giving about 5° beam width for ROV and AUV altimeter and bathymetry applications. It has a measurement range of over 100m. A bottom-tracking algorithm runs on the device to determine the distance to the seafloor.

Technical Specifications

  • Dimensions: 65 (diameter) x 135mm (connector excluded)
  • Weight in Air: 840g
  • Weight in Water: 400g
  • Depth Rating: 300m
  • Communication: RS232, 9600 - 115200
  • Voltage Input: 9 - 24VDC


  • Minimum Range Resolution: 3mm @ <17m, 9mm @ <50m, 24mm @ >50m
  • Minimum Range: 0.3m
  • Maximum Range: 100m
  • Acoustic Frequency: 500kHz
  • Beam Width: 5° 2-way Conical
  • Modulation: CHIRP 20kHz Bandwidth, Monotone ping also supported


  • Data Mode: Continuous or Pooling 
  • Data Output: HEX, String and NMEA
  • Customizable Speed of Sound (for different values of salinity)
  • Customizable Range