CTI Products TSAM Transmitter Steering & Audio Matrix - Manual (Page 13)

TSAM Installation and Maintenance Rev. 2.10 Chapter 2
CTI Products, Inc. Main Channel Operation
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2. Main Channel Operation
The Main radio channel is the steered radio channel. The TSAM has inputs to monitor the receiver Vote
or Select lines from the radio system comparator. The Vote indications are processed to determine the start
and end of transmissions from field radios. The TSAM then determines the best site for the next
dispatcher or repeater transmission, based on the criteria outlined in subsequent sections. Upon site
selection, audio from the C1 (Console 1) input line is switched to the steered site line driver.
2.1 Steering Algorithms
Steering algorithms determine how transmitter selection or "steering" occurs. An algorithm processes the
receiver vote information to determine the best transmitter site available. Once determined, the TSAM
activates the steered site. When a site is activated is different from how the site is selected. The Steering
Algorithm determines which site to select, and the Update Mode determines when that site becomes active.
2.1.1 First Receiver Voted Selection Algorithm
One mode for making the steering decision is to select a site based upon the first voted site during a
particular mobile/portable transmission. This mode has the advantage of being able to make a steering
decision before the mobile/portable transmission is complete. However, since the mobile or portable can
change between receive sites during a transmission, the First Received algorithm does not necessarily
reflect the best site to answer the unit at the end its transmission.
2.1.2 Smart-Steer     Intelligent Selection Algorithm
The Smart-Steer Algorithm watches the voting activity and choses the site that was voted the longest at the
end of the mobile or portable transmission. This gives the benefit of selecting the site closest to the field
unit towards the end of its transmission.
It is not sufficient to make the decision based on the last site voted. On receivers with dual level squelch
circuits, this causes problems. Dual squelch receivers lengthen the squelch tail on weak signals. A
receiver with a slow closing squelch circuit could be voted momentarily at the end of a reception. Picking
the last site voted actually picks a site with poorer reception.
The Smart-Steer selection mode eliminates these problems by picking the site voted for the longest total
time over a programmable period. The TSAM unit offers the benefits of a last-voted steering mode
without the problems caused by slow squelching and dual-level squelch receivers.
2.2 Basic Transmit Site Update Modes & Controls
Update Modes determine when the TSAM selects the transmitter based upon the results of the steering
algorithm. Two basic Update Modes are available:
1. Instant Update Mode allows the new transmit site to be activated as soon as the steering algorithm is
complete.
2. End of Receive Update Mode delays the update till the completion of a portable or mobile
transmission.
The operation of these update modes can be changed by advanced options such as Home Site Revert and
Dynamic Update Mode.