Symeo LPR
®
-System
LPR
®
-2DB
Product Documentation
System
Description
Copyright © Symeo 2012
Page 20 of 132
signal with precisely known delay and an individual frequency offset corresponding to the
fixed mounted unit measurement ID. The mobile unit computes the round-trip time-of-flight
and therefore the 1D distance to each transponder. Finally, the mobile unit calculates of all
single 1D distances a 2D position.
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Figure 2 - System setup for mode 1
1: Mobile unit
2: Wall-mounted unit
3: Communication channel (commands)
4: Broadband measurement signals
3.2.2
Operation Mode 2: Managed Cell
Mode 2 is used when several mobile units are present at the same time within the cell. In this
case the measurement intervals between the mobile units are synchronized. This is done by
using the setup of mode 1 and an additional master transponder for coordination. The master
transponder assigns the measurement slots for different mobile units. The mobile unit no
longer initializes the measurement and simply acts as base-station. The measurement of
mode 2 is based on the measurement principle RTOF (Round Trip Of Flight). The detailed
measurement procedure is as follows:
The master transponder repeatedly broadcasts his group-ID. Base-stations in range reply to
this broadcast with their ID. The master transponder keeps a list of active base-stations in
range, assigns measurement slots to the stations and broadcasts them to the individual
stations in range. The base-station then transmits the broadband measurement signal and
computes its position as described in mode 1.
Measurement rate for the stations present can be set to equal distribution for all mobile units
or to a preferred channel with maximum measurement rate for one base-station and slower
measurement rate for the remaining stations.
