Over the years, we’ve been asked multiple times whether it’s necessary to short the end of the Coaxial Cable for Velocity of Detonation (VoD) testing using the ShotTrack VoD units. The answer is no.
Our VoD unit functions as a Time Domain Reflectometer (TDR) system. It sends a pulse down the cable, and this pulse is reflected back to the unit from either an open or closed circuit at the cable’s end. By calculating the length over time, we can determine the continuous VoD as the cable is consumed during the blast.
This method’s advantage is that it captures nearly every data point transmitted down the cable, yielding clean data for processing.
However, many VoD users might be more accustomed to using a resistive type VoD system. This system requires shorting the cable ends as it relies on a fully closed circuit to record the resistance change when the circuit or cable becomes shorter. These systems depend on the cable ends fusing together as the cable is consumed in the blast hole.
Although the resistive type system can yield similar results, it often encounters “open-circuit” occurrences during the blast, causing numerous data drop-outs.
Using the ShotTrack VoD for testing saves time and money by utilising a standard coaxial cable as the consumable, while delivering clean and reliable data results.
For more info get in touch with the ShotTrack team: info@shottrack.com.au
