New England Instrument Co
GPS speed senders for marine applications

GPS Speed Senders

High quality GPS speed sender for marine applications

New England Instrument offers a GPS Speed Sender (GSS) that provides a reliable calibration free replacement for mechanical speed senders. Using data received from the Global Positioning Satellite network, the GPS Speed Sender calculates horizontal ground speed and provides a pulsed output compatible with most speedometers. This high technology solution will work with all hull configurations and eradicates the need for pitot tubes or other mechanical measurement devices.

Powerful Performance

The ability to track 12 satellites simultaneously, enhanced receiver sensitivity and active antenna result in fast time-to-first-velocity-calculation as well as the ability to operate in the harshest RF environments such as harbours and canyons.

Last known position and satellite information critical to fast start-up are battery backed in case of power failure.

Only North-South and West-East velocity measurements are used to calculate final speed; with vertical effects due to swell being eliminated. Final speed measurements are accurate to 0.2km/h and pulse output rates are updated 4 times per second.

Dead-reckoning is an optional feature that allows tracking to continue even when satelite coverage is limited. Where vehicles are likely to spend a large amount of time in tunnels, or where very high accuracy is required, this feature should be considered.

The number of pulses that are produced per kilometer travelled (ppk) can, with certain models, be set by the user between 1000ppk and 10 000ppk. The ppk value can be factory set for volume applications.

The GPS Speed Sender can be supplied with an external antenna (GSS - active) for challenging installations, or with an integrated antenna (GSS - passive) for cost sensitive applications.

GSS works equally well with speedometers calibrated in kilometers per hour, miles per hour or knots.

speed sender, active

Active GPS speed sender for use with external antenna


Rugged Hardware

GSS is supplied in a rugged ABS plastic enclosure with provision for screw mounting when required. Antenna connection for the active antenna is provided through a gold-plated threaded SMA connector. The active antenna is available in two options:

  • magnetic mount, suitable for mounting in the interior of the boat, for example under a fibreglass sill or instrument panel.
  • bulkhead mount, suitable for exterior mount, for example on the roof of the cabin.

GSS – passive is supplied in a rugged ABS plastic enclosure with provision for screw mounting when required. No antenna connector is provided as the antenna is integrated into the enclosure.

Power to the unit and pulse outputs are provided through four colour coded wires.

For optimum performance, the antenna or GSS – passive should be mounted horizontally and upright; and should have a clear view of the sky.

Red and a green LED's are provided to give the user status information. At power on, the red LED will begin to flash at 2Hz, indicating that the unit has power and is searching for satellites. When satellites have been acquired, the red LED will remain on. The green LED flashes in sympathy with the pulse output, and so will flash faster as the vehicle speed increases.

installation is quick and simple

Typical installation of GSS-active


Download Documentation

Download pdf brochure       download

Download setup instructions       download


Download Free Software

Convert between km/h, mi/h, knots etc.       download

This software converts between popular units of speed

Convert pulse rate to frequency       convert ppk to frequency

This software calculates the output frequency of a speed sender given pulse rate and speed


Performance Specifications

  • Pulse rate: variable (1000ppk to 10 000ppk)
  • General : 12 channel tracking receiver
  • Update rate: 4Hz
  • Accuracy, horizontal: < 5m (50%), < 8 (90%)
  • Accuracy, altitude: < 10m (50%), < 16 m (90%)
  • Accuracy, velocity: < 0.06m/sec = 0.22km/h
  • Acquisitions, after loss of lock: < 2s (90%)
  • Acquisitions, first time power applied: < 38s (50%), < 42s (90%)
  • Acquisitions, temporary loss of power: < 10s (50%), < 13s (90%)
  • Operational limits, altitude: 18000m
  • Operational limits, Velocity: 300km/h

Electrical Characteristics

  • Input voltage: 6V to 36V
  • Power consumption: GSS Active, 480mW (12V, 40mA)
  • Power consumption: GSS Passive, 240mW (12V, 20mA)
  • Battery backup: > 20 days
  • Output pulse: peak to peak voltage: 9.1V
  • Output pulse: on time voltage: 9.1V
  • Output pulse: off time voltage: less than 250mV
  • Output pulse: maximum current drain: 25mA
typical output waveform
Output pulses at 60km/h with 4000ppk setting


Physical Characteristics

  • GSS – active 50mm (L), 67mm (W), 21mm (H)
  • Antenna: 51mm (L), 42mm (W), 14mm (H)
  • Antenna cable length: 3-5m
  • GSS – passive 50mm (L), 67mm (W), 21mm (H)

magnetic mount antenna

Magnetic mount antenna

bulkhead mount antenna

Bulkhead mount antenna

passive speed sender

Passive speed sender with integrated antenna


Environmental Specifications

  • Operating temperature: -40oC to +85oC
  • Storage temperature: -55oC to +105oC
  • Humidity: 5% to 95% R.H. non condensing at 60oC

Interface Specifications

Power and pulse output:

  • Red input voltage (6V to 35V)
  • Black ground (0V)
  • Green pulse output
  • Blue inverted pulse output
RF interface (where applicable):
  • SMA (compatible connector supplied with antenna)
  • Magnetic mount or bulkhead mount antenna options available

Ordering Information

Part Number Description Price Buy Now
NEGS1A10MP Marine GPS speed sender, variable ppk value, passive antenna $192.00
NEGS4000MP Marine GPS speed sender, 4000 ppk value, passive antenna $192.00
NEGS8000MP Marine GPS speed sender, 8000 ppk value, passive antenna $192.00
NEGS1A10MM Marine GPS speed sender, variable ppk value, mag mount antenna $232.00
NEGS4000MM Marine GPS speed sender, 4000 ppk value, mag mount antenna $232.00
NEGS8000MM Marine GPS speed sender, 8000 ppk value, mag mount antenna $232.00
NEGS1A10MB Marine GPS speed sender, variable ppk value, bulkhead mount antenna $248.00
NEGS4000MB Marine GPS speed sender, 4000 ppk value, bulkhead mount antenna $248.00
NEGS8000MB Marine GPS speed sender, 8000 ppk value, bulkhead mount antenna $248.00


Contact us

Phone: 02 67658333

Fax: 02 67621181

International Phone: +61 0267658333

International Fax: +61 0267621181

E-Mail: neic@newenglandinstrument.com