Manual
HOW THE HARDWARE WORKS:
The purpose of PinPoints 3D-iDs hardware system is to determine the distance
between tags and antennas. There are three elements involved in this process.
The first two are the tags and the antennas. The third is the cell controller,
which coordinates the actions of the tags and antennas and interprets their
signals.
Each tag is on (and detectable) for a very short period of time. Because this
on time is so brief - relative to the off times - the chances of two tags being
on at once are very remote. With this in mind, we can examine the Cell
Controllers operation. The Cell Controllers basic job is to record the amount of
time a radio signal takes to go between each antenna and the tag which is cur-
rently on and back. The Cell Controller can calculate the distance between a
single Antenna and a Tag from the transmission time and the speed of light.
The following is the procedure it follows for deriving the time needed for a radio
signal to travel between the Tag and the Antenna:
1. The Cell Controller sends an antenna a spread spectrum radio signal to
broadcast to the tags at 2.442GHz.
2. Whichever tag is on at that moment (assuming one is on and in range of
the antenna):
2.1. Receives the signal
2.2. Converts it to 5.770GHz
2.3. Modulates its unique serial number on the return signal
2.4. Retransmits the signal
3. The current antenna receives the signal and sends it back to the Cell
Controller.
4. The Cell Controller receives the signal and runs filters to remove multi-
path and then demodulates the signal.
5. The Cell Controller determines the delay between the sent and the
received message and then uses that to calculate the distance between
the tag and the antenna.
6. The newly created Tag Antenna Distance (TAD) data is then forwarded to
the Cell Controllers subscribers in the software system.
7. The Cell Controller then returns to step one, cycling the next antenna.
The Cell Controller cycle time is fast enough for every antenna on a Cell
Controller to detect a tag during that single tags on time.