Antennas
To optimize performance in a small form factor the Track Box Passive contains 2 antennas internally, TX (transmit) and RX (receive). The TX antenna is located in the lower half of the box and the RX is in the upper half, each antenna needs a clear line of sight to transponders in order to receive passings.
The below diagrams show the shape of the antenna field, the inner line represents expected 99% read rate at 4m from the front of the antenna, the outer line shows the 8m line with 90% expected read rate (with a single box).
Side View
Top View
Algorithms
Passive Transponders
Reaction Time & Dead Time
Similar to the RACE RESULT Decoder the Track Box (Passive) uses a detection algorithm to maximise the accuracy of recorded times.
The 2 key settings are the Reaction Time and Dead Time, which by default are set differently on Track Boxes due to their design.
The default Reaction Time is 10 seconds, the reason for this is that with antennas mounted to the side there is much greater chance of early detections, particularly if the Track Box is facing participants. A low reaction time may result in a less accurate time being recorded, by increasing this to 10 seconds it provides greater chance to record an accurate time. This does result in data being sent to the servers after a minimum of 10 seconds, so if speed of data is more critical than accuracy then this could be reduced.
Dead Time is set by default to 20 seconds, meaning that after a time is recorded then another passing will not be captured for 20 seconds, beware if using this on short laps or turnarounds. If multiple passings are expected within a shorter time then this can be reduced as necessary.
Both reaction time and dead time can be configured using Track Box Configuration Rules.
Hits & RSSI
When using the Track Box (Passive) you should also expect less hits compared to a RACE RESULT Decoder with standard antenna, this is due to the communication protocol used between Track Box and Transponder.
The reader will only communicate with each transponder in one of every 5 cycles, this maximises the opportunity for other transponders to communicate with the reader and thus maximising overall read rates.
Guidelines for RSSI values remain the same as Decoder detection data.
Modes
The Track Box Passive has 3 detection modes which impact the read rates of antennas, data transmission and thus also have an impact on battery performance.
Fast
In fast mode, the network modem stays connected permanently. The status of the box is updated every 15s and upload of passings is as fast as possible. This does not increase the read rate of the antennas but speeds up data communication.
This mode will drain the battery faster and use more data, so should only be used if battery and data consumption are not a concern.
A typical application for this would be a timing point for an announcer who requires the fastest data.
Normal
Normal mode is the best compromise for general timing and recommended for most applications. In this mode, the GPS module is shut down if the box does not move and the device status will be updated every 4 minutes.
In normal mode the antennas are reading 50 times per second, and passings will be uploaded in small chunks with smart processing to minimise delay and data consumption accordingly. If there is no data transmission pending then the modem will disconnect from the network.
Slow
Slow mode maximizes battery life of the Track Box Passive whilst still reading transponders. In slow mode the read rate of antennas is reduced to 10 times per second, this is suitable for slow-moving, low density splits (only reading a few transponders simultaneously), and will also produce less accurate times.
The data transmission and GPS module behaviour remains the same as normal mode for upload of passings and status.
In slow mode, you can expect battery life of over 24 hours from a full charge.
Track Box Synchronization
As with all UHF timing systems a transponder should only be in the field of one reader at any one time, furthermore, the strong output of one reader may inhibit the receive antenna of another box when directly facing each other.
To avoid interference between devices, Track Boxes are able to synchronize using the on-board 2.4Ghz which prevents the collision of the UHF readers. There are 2 modes of synchronization - pairing (2 boxes) and multi (more than 2 boxes).
Two or more boxes will automatically synchronize their UHF Readers to optimize read performance when:
- The boxes are within close range to each other (approx. 20m)
- The same 2.4GHz channel is set
- The reader is turned on (not in standby or laying flat)
- The reader is in NORMAL or FAST mode (not SLOW)
When synchronization is active the green LED (to indicate GPS & Network OK) will switch to a quick double blink.
Dual box synchronization is always enabled automatically regardless of the orientation of antennas, as even 2 boxes with their back to each other may experience some interference.
Synchronization is automatically disabled if the above criteria are no longer met, for example if the boxes are moved apart or the channels of the boxes are changed. It is also possible to disable dual box synchronization using Custom Track Box Configuration Rules.
As Track Box synchronization and Active Track Ping Detection both rely on the 2.4GHz antenna it is not advised to use the Track Box synchronization whilst also expecting Active Track Pings, since this will reduce possibility for the Track Boxes to receive Active Track Pings. Additionally, Track Boxes can only operate on a single channel, so changing the channel for pairing devices will change the channel on which the device is expecting to receive Track Pings.
Track Box Pairing
Using two Track Boxes together allows to cover a greater width of timing point and also maximises the chance for a clear line of sight between the antennas and transponders. When in pairing mode the Track Boxes will report SYNC in the RACE RESULT 14 Timing tab.
When in pairing mode the read rate of each box will be reduced by just over half to around 20x per second (down from approx 50x a second for a single unpaired box), this will result in reduced hits per box, for each transponder. When comparing a pair of boxes to single box performance you can expect roughly similar hits however the sum of the pair is still likely to be slightly lower due to having just under half the available read time per box.
If you have multiple boxes in close range, then you can create pairs of devices by setting the channel accordingly for each device. In this case, you should take care that any 2 boxes which are not synchronized do not have overlapping fields which may cause interference.
Multi Track Box
When more than 2 Track Boxes are in close range and meet the synchronization criteria they will enter Multi mode, this is also indicated in the RACE RESULT 14 Timing tab (MULT)
In Multi mode each box will drastically reduce its read rate to a much slower random mode. This mode is intended for use with indoor applications with many boxes in close proximity and is not intended for sports timing.