Overview
ShotTrack’s VoD (Velocity of Detonation) units use digital Time Domain Reflectometry (TDR) to measure detonation velocity in blast holes. This provides high-resolution, accurate data to help improve blast efficiency, fragmentation, and safety.
What is TDR?
ShotTrack’s VoD units use Time Domain Reflectometry (TDR) to measure detonation velocity by sending fast electrical pulses down a coaxial cable placed in the blast hole.
These pulses reflect off both open and closed circuits, allowing the unit to maintain a clean, high-resolution signal. The system continuously measures the cable length in real time. When a 2 metre reduction is detected, the unit begins recording. As the blast consumes the cable, the return time shortens — enabling precise calculation of the velocity of detonation.
Stable, no-drift timing: The timing is captured using a digital clock, which does not require regular calibration. This is a major advantage over analogue resistive-wire systems, which can drift and often need yearly recalibration. With ShotTrack, the only setup required is selecting the correct cable type in the ShockAi App, or calibrating to a new cable with just the press of a button.
What Does the VoD Unit Capture?
Continuous velocity of detonation along the explosive column
High-resolution waveform of the detonation signal
Cable continuity check before firing
Optional metadata such as hole ID, charge type, and comments via the ShockAi App
Why It Matters
Accurate VoD measurement helps engineers and blasting professionals:
Identify cut-offs, misfires, or interruptions
Optimise explosive placement and column length
Validate and refine timing models
Improve fragmentation results and reduce overbreak
How to Use It in the Field
Insert the cable into the blast hole, ensuring it runs taut along the length of the explosive column.
Connect the RG59-Mini coaxial cable to the VoD unit via the BNC connector.
In the ShockAi App, select the correct cable type and check continuity.
Arm the VoD unit — it will begin recording automatically once detonation occurs.
After the blast, download the data via Bluetooth (BLE) for analysis and reporting.
📦 Note: Basic setup instructions are printed directly on the ShotTrack RG59-Mini cable box.
🎥 Watch the Video
Learn how ShotTrack VoD works in under 5 minutes:
What is TDR?
How to set up your VoD unit
How to get fast, accurate VoD measurements