Microwave Receiver


LRX-310B is a small, lightweight, microwave receiver module with integral antenna. It outputs trigger pulses as it passes through the beam of an LTX-310 Lap Trigger transmitter. The interval between pulses is determined by the transmitter settings and thus by making an appropriate choice of settings and transmitter locations around the circuit, it is possible to identify which particular transmitter the receiver is passing.

The LRX-310B itself cannot distinguish between different transmitter settings. This task must be performed by software in the ECU to which LRX-310B is connected.


  • Lap timing when used with compatible ECU and track-side transmitter.


Characteristics assume use with an LTX-310 or similar Lap Trigger Transmitter.

  • Supply Voltage 5.0±0.25V DC
  • Operating frequency 10.6±0.5GHz
  • Beamwidth (Between -3dB points) :
    • ±13° horizontal
    • 40° above horizon, 27° below horizon
  • Range approximately 25m (when properly aligned)
  • Range approximately 82' (when properly aligned)
  • Supply current 130mA max with 5.0V supply
  • Output characteristics :
    • Impedance <60Ohm (<10mA sink/source)
    • Max voltage outside LTX beam 150mV
    • Max voltage inside LTX beam 4.75 to 5.25V (depending on unit supply voltage)
  • Output voltage increases with signal strength as antenna passes through LTX beam
  • Output voltage pulses low to <0.15V for 100±10us with interval between pulses determined by LTX setting
  • Valid pulse intervals are in the range 456-1576us (36 unique intervals in 32us steps)
  • Response time <2ms (Time to first pulse after entering LTX beam)

Electro Magnetic Compatibility

  • Complies with the essential protection requirements of 2004/108/EEC

Connector Definition

  • EHS 0F 303 XLC case-mounted Lemo socket with male pins
  • Pin 1Supply
    Pin 2Ground
    Pin 3Output


  • Case material: aluminium alloy, hard black anodised
  • Antenna covered by 75um thick PTFE/fibreglass tape
  • Weight approx 80g
  • Mounted using two M3 tapped holes on rear of case


  • Splash resistant to standard motorsport fluids
  • Operating temperature 0°C to +60°C
  • Storage temperature -25 to +85°C
  • Bump tested to ±50g ½ sine 11ms five times per axis
  • Random vibration with spectrum below, three axes, 24hrs
  • 100Hz0.00797 g2/Hz
    200Hz0.17157 g2/Hz
    300Hz0.54279 g2/Hz
    650Hz0.00965 g2/Hz
    1000Hz0.02080 g2/Hz
LRX-310 Mechanical Drawing
LRX-310O 030 040 003 000

Application Note

Lap Triggers


Technical Support