User's Manual

Hi-G-Tek Ltd. Microelectronics & Asset Tracking Technology
50
System
5
5.1.System description
T
Complete Reader Session
Reader
H
Ine
at
e
d
r
e
rorgation
Random
Access
Window
Alert
Window
T
cw
T
aw
T
rw
T
hw
T
iw
Readers
Interlace
Window
5.1.1. General.
Hi-G-Tek DataSeals operate in sleep mode to conserve power. A
pre-determined periodically awakens them from sleep mode. This
allows them to monitor the surrounding airwaves for a Reader's
wake up signal.
Tw is the notation used throughout this manual for the wakeup cycle
time of the seal.
When the Reader initiates a session, it transmits a stream of data bits
of programmable length. The notation of the data stream length is Thw.
The seals use the SLOTTED ALOHA concept to communicate back to
a Reader. The length of an ALOHA time slot is notated as Ts. (Ts is
also notated as a window). This time slot is usually of fixed duration.
For the Verify, Addressed Verify and Tamper commands, Ts should
be defined externally in the command (see paragraph 5.6.3.2.).
Fig. 5.1 - RF Communication Channels