User's Manual

April ’00 Chapter 3. Synchronization

3.2.2 Wireless Synchronization

Wireless synchronization can be used to control the coordination of readers, with

standard antennas, provided the electrical noise in the environment is low for the

type of antenna in use and the noise levels are constant.

Wireless synchronization is only valid for charge-only reading of transponders.

During operation, when the reader detects noise above the adjusted background lev-

el it assumes that it is another reader and “backs-off” for a set period before com-

mencing its own cycle. Wireless synchronized readers can read together or

alternately.

Advantages:

1. There are no wires to run.

2. All readers are autonomous (no Master unit).

3. Enables Hand held readers to co-exist with fixed units (using wireless syn-

chronization).

Disadvantages:

1. In noisy environments, there is too much sensitivity with larger antennas

(G04 and larger custom antennas) to allow accurate setting of the back-

ground levels.

2. It is not suitable for operations other than Charge-only read.

3. It cannot be used when other readers are writing information to transpond-

ers.

4. Where the environmental conditions change, for example: a ground loop

antenna’s characteristics are changed by a vehicle over it, the synchroni-

zation adjustment could be wrong.

3.2.3 Wired Synchronization

Wired Synchronization works in the same way as wireless synchronization with the

exception that the reader obtains its information about the presence of another read-

er through a hard wired connection and not via the antenna.

Advantages:

1. It is a Peer-to-Peer network and does not need a Master unit.

2. It use a single twisted pair cable.

Disadvantages:

1. It is only suitable for charge-only reading of transponders.

2. It cannot be used when other readers are writing information to transpond-

ers.

3. If the power fails at any of the readers the bus fails.

3.2.4 Combined Wireless/Wired Synchronization

When this option is selected, groups of reader connected by the wired synchroniza-

tion cabling can synchronize with other groups of wired synchronization readers, or

with individual readers, by using wireless synchronization.

The advantages and disadvantages of both wireless and wired synchronization as

given above still apply.