September 28th, 2020

ShotMarker SNAFU — What’s Wrong with this Picture?

Adam McDonald Shotmarker sensor wires

Canadian F-Class shooter Michael Traynor was surprised when he saw this “flat-line” target displayed from a ShotMarker system. That’s 30 shots with almost no vertical at all. So what gives? The ShotMarker uses acoustic sensors to plot shot location. It is normally accurate to within a few millimeters. Traynor posted: “I’ve never had this happen before with a waterline. This is myself and another shooter, 30 rounds total, including four sighters at 900 meters in super strong winds that twitched back and forth every minute.”

So what happened? It turns our that the system’s wires were not connected correctly. AccurateShooter IT expert (and top F-Class Shooter) Jay Christopherson posted: “The wires are connected incorrectly… you’ve got the sensors crossed”. This ShotMarker system error can be diagnosed by doing a “tap test” as explained by Cal Waldner: “Thats a crossed sensor wire! That’s why a tap test needs to be done every time you rig the equipment. If a wire is crossed then you will catch it on the tap test.”

Other folks who viewed Traynor’s target photo on Facebook said that they have seen a similar problem, so this is NOT an uncommon fault:

“Yup, my club had the same issue (and results) in an early outing with one of our ShotMarker units. The system reads the target area as a horizontal rectangle not as a square.” — Laurie Holland.

“I have seen this exact same result with the sensors plugged incorrectly.” — Dino Christopoulos

“This happened to several people at one match early on. Sensors crossed.” — Jen Bondurant

“I thought I was shooting a great waterline once [but the] wires were crossed — [a mistake from] setting up in the dark.”– Jerry Stephenson

Adam McDonald Shotmarker sensor wires

The ShotMarker System — Technology and Performance

The ShotMarker was invented by Adam McDonald, a brilliant young Canadian who also created the AutoTrickler. The ShotMarker is an advanced system for plotting shot impacts on targets using acoustic sensors placed in the four corners of the target frame. The central Sensor Hub at each target transmits to the Access Point at the firing line using LoRa, a low frequency RF protocol. Unlike Wifi, this power-efficient design works at over 2 miles and provides hassle-free connectivity even without direct line of sight.

Adam McDonald Shotmarker sensor wires

Adam McDonald Shotmarker sensor wires

The sensor unit in each corner of your frame contains two precision MEMS ultrasonic microphones which are capable of measuring a supersonic bullet within 1mm – when the frame is perfectly still.

Adam McDonald Shotmarker sensor wires

Real-world accuracy will be limited by motion of the sensors and the air while shots are being detected. Typically, every shot will be reported within a few millimeters, with ideal performance being realized on a stable frame in calm conditions.

CLICK HERE for more ShotMarker Technical Information »

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