Active timing offers higher precision than UHF as they use a completely different technology for activating the transponder and calculating the time, as such they cannot be used together. Active Transponders contain a battery and internal processor creating a powerful transponder with additional features that would not be possible with UHF transponders. 

Active systems do not use a series of antennas but instead a loop cable that emits an electromagnetic signal. Most of the time the transponder is sleeping, but when in close proximity to a RACE RESULT loop, the 125kHz signal from the loop will wake up the transponder.

The transponder analyzes the 125kHz signal and if it stems from a RACE RESULT loop, it will turn on its microcontroller which analyzes the signal strength from the loop, calculates the time when it crossed the center of the loop, and transmits this information on a 2.4GHz channel to the decoder. When the decoder acknowledges that the data has been received, the transponder goes back to sleep.

Active timing is possible with Ubidium,  RACE RESULT Decoder with an Active Extension or using the standalone USB Timing Box.

The Loop Box provides additional flexibility to the setup, it can be run as a standalone timing point, but must be used with one of the main Active systems to receive the data either wirelessly via 2.4 GHz or from Store Mode on the transponder. 

The Track Box Active uses 2.4 GHz to receive trackpings from transponders (when activated), and does not rely on any additional loop cable. Track Boxes contain a different algorithm for calculating times and so offer lower precision and should not be used in areas where participants may be stationary for prolonged periods of time (such as Triathlon transition zones).