TDT RZ2 Manual page 629

System 3
Using the miniBIRD® Set to FOB
The miniBIRD® tracker must be set to Normal Addressing Mode and the DIP settings
should be configured as below:
Boresight
A boresight command can be issued from an external 3V digital source via the
Boresight BNC input. This signal needs to be a logical high ('1') pulse of at least
200 ns in length. The signal then needs to be set logic low ('0') for at least 200
ns before another boresight command can be issued.
Activity Lights
Data
The Data LED indicates if the HTI3 is receiving data from the motion tracker unit.
This LED will also flash slowly (~1 Hz) if the tracker is not properly connected to
the HTI3.
CH1 Stat/Ch2 Stat
The Ch1 Stat and Ch2 Stat LEDs indicate if the interface is receiving data from
receiver 1, receiver 2 or both.
HTI3 properly connected to a base station and a motion tracker while acquiring data
from receiver 1.
HTI3 Circuit Design
The HTI3 parses incoming signals from a motion tracker into 16 channels of data
and sends it to a base station (such as RZ5, RX6, or RA16BA) at rates up to 25
kHz. Most motion trackers send data at a slow rate (~120 Hz). This means that
there is a large amount of redundancy in the data acquired by the base station. The
circuit designs described below will reduce the resulting redundancy and convert the
raw HTI3 output signals into useful information such as error codes, distance
measures and relative positional information such as Azimuth, Elevation, and Roll.
Acquiring and Scaling Motion Tracker Signals
Motion tracker signals are acquired via a fiber optic cable connecting the HTI3 to a
base station. The most common signals input via the fiber optic port are biological
signals amplified using one of the TDT preamplifiers; so all signals input through one
1 2 3 4
ON ON ON OFF
Active
The Active LED indicates if the HTI3 is connected to a base
station via a fiber optic cable. This LED will flash slowly
(~1 Hz) if this connection is not properly made.
The figure below shows the LED pattern for the
5 6 7 8
OFF OFF ON OFF
HTI3 Head Tracker Interface
17-11