User's Manual

Hi-G-Tek Ltd. Microelectronics & Asset Tracking Technology
51
5
System
Ts can have one of the following values: 21, 41, 63, 81 msec.
The System has four communication channels
Reader Interrogation Header with time duration of Thw. Within
this time frame the Reader sends a data stream to the seals.
Readers Interlace Window with time duration of Tiw. This
window is to allow other Readers to transmit and to share one
Random Access Window.
Random Access Window with time duration of Tcw. During this
period seals responds in random access mode. Because the
access is random, collisions between seal messages are to be
expected.
Alert Window with time duration of Taw. The last channel is an
emergency channel allowing seals with high priority alert messages
to transmit the message to the Reader.
Trw is the notation used for the seals transmitting (Reader is receiving)
time frame.
A complete communication Reader Session is Thw + Trw.
To overcome collisions, the seals should retransmit their message
several times within the Random Access Window. The number of
retransmissions should be defined externally in the command and is
called Rr.
The seal may also retransmit in the Alert Window. This is notated as Rt.
Both Thw and Tw can be programmed.
The relationship between Thw and Tw should be kept constant.
Thw=Tw+ 135 msec
See paragraph 5.2.3. for information on how to calculate Thw
and Tw