I have previously used similar, but more advanced Doppler radar devices in my previous job. These for testing small arms up to artillery rockets. The company makes more advanced systems too, both for external and internal (in-bore) velocity measurements. See their main website (www.infinition.com).

As to the triggering of the radar. Seeing as it can be used to measure non-firearms, this suggests a Doppler signal triggering in addition to the previous mentioned acoustic triggering system. In this mode the system monitors the input Doppler signal level and, when the signal rises above a certain (voltage) signal threshold, triggers the acquisition and processing of the Doppler signal (digitisation, FFT and the curve fitting or linear regression of a FFT spectra peaks). Seeing as the retardation on arrows and bolts is so low, this isn’t really a problem bows and crossbows. For small arms, this would require the weapon muzzle to be near the radar head, so minimising MV calculation errors, both due to timing and geometric (look angle) errors. Neither are optimal triggering systems in noisy conditions such as a busy firing range. A flash detector or a pressure sensor that requires a high pressure level (i.e. very near the muzzle) would be a better option.

The device most likely operates at (IEEE US) X-Band, so a nominal 10.525 GHz. Going by their other devices, their power outputs and range capabilities, the device would have an output in the low milliwatt (mW) range, say 100-200 mW. Use of the device in the UK may require a radio broadcast licence.

Tracking of projectiles is RCS (radar cross section) and keeping the projectile in the beam dependant. It can track, under optimal conditions, an undisclosed .308 projectile to 100 yards. So larger (diameter) projectiles will be seen for further, smaller for shorter distances. The projectile base shape and the use of tracer ammunition will reduce the projectile RCS and hence tracking range.

Neil Gibson
Weapons Technical Analyst,
IHS Jane’s

As to the triggering of the radar. Seeing as it can be used to measure non-firearms, this suggests a Doppler signal triggering in addition to the previous mentioned acoustic triggering system. In this mode the system monitors the input Doppler signal level and, when the signal rises above a certain (voltage) signal threshold, triggers the acquisition and processing of the Doppler signal (digitisation, FFT and the curve fitting or linear regression of a FFT spectra peaks). Seeing as the retardation on arrows and bolts is so low, this isn’t really a problem bows and crossbows. For small arms, this would require the weapon muzzle to be near the radar head, so minimising MV calculation errors, both due to timing and geometric (look angle) errors. Neither are optimal triggering systems in noisy conditions such as a busy firing range. A flash detector or a pressure sensor that requires a high pressure level (i.e. very near the muzzle) would be a better option.

The device most likely operates at (IEEE US) X-Band, so a nominal 10.525 GHz. Going by their other devices, their power outputs and range capabilities, the device would have an output in the low milliwatt (mW) range,say 100-200 mW. Use of the device in the UK may require a radio broadcast licence.

Tracking of projectiles is RCS (radar cross section) and keeping the projectile in the beam dependant. It can track, under optimal conditions, an undisclosed .308 projectile to 100 yards. So larger (diameter) projectiles will be seen for further, smaller for shorter distances. The projectile base shape and the use of tracer ammunition will reduce the projectile RCS and hence tracking range.

Editor: That is a good question. Keep in mind, this is not a sonic device registering the sound of ammo fired with microphone. The device is directional — you angle the orange “box” slightly downrange along the bullet’s flight path. But we honestly don’t know if the radar can pick up a shot fired from the next lane over. From the mfg’s website it looks like the radar is placed about 1m to the left of the shooter, with the head of the unit at about a 45-deg angle. See more here: http://vimeo.com/83448608

Range is 100 yards with a .308 projectile. The range for smaller and larger projectiles will vary with their radar cross section (RCS). The projectile base shape effects the RCS, as does the use of tracers.

No details on the transmitting frequency or the processing system. Most likely digitisation of the Doppler signal, fast Fourier transformation (FFT) of this and then curve-fitting or linear regressions or a series of spectra peaks.

It’s use in the UK may require a broadcasting licence, all depends on the transmitting frequency and power output.