CTI Products TSAM Transmitter Steering & Audio Matrix - Manual (Page 18)

TSAM Installation and Maintenance Rev. 2.10 Chapter 2
CTI Products, Inc. Main Channel Operation
10
2.4 Simplex Operation
In simplex systems, the voting receivers will hear the base station transmitters. If the comparator is active
during this time, the TSAM must be instructed to ignore any voting activity. This is done by programming
the ‘ Sense RX activity during Console 1 PTT’ option is set to ‘ N’ This is found under the TX
Steering menu.
The receivers (and comparator Voted output) will still be active for a short time after the console PTT is
released. TSAM units with version 1.62 firmware and later include a Simplex PTT Release Mask Timer.
This tells the TSAM unit to ignore any Voted activity for a period after C1PTT is released.
The Simplex PTT Release Mask Timer is only enabled when the ‘ Sense RX activity during Console 1
PTT’ option is set to ‘ N’ . If this option is set to ‘Y’, this timer has no effect, since the TSAM assumes
that it a repeater or split-frequency system.
The ‘ Sense RX activity during Console 1 PTT’ option and the Simplex PTT Release Mask Timer
are programmed under the TX Steering menu.
2.5 Repeater Operation
TSAM firmware versions 1.50 and later provide repeater operation for the TSAM unit. In a simplex
system, the TSAM only keys the steered transmitter when a console PTT is activated. In a repeater
system, the TSAM must also key the steered transmitter whenever a received signal is present and repeat
operation is enabled. The TSAM unit will generate its own internal Repeater PTT based upon activity on
the Voted inputs. Repeater transmitters normally remain keyed for a fixed amount of time after the
received signal drops. This time is the Repeater Hang Time.
Hang Time has several purposes, the main purpose is to minimize system access time. When using tone
keying and CTCSS or DCS, various system delays add up. This forces a repeater user to key for a
significant period of time before audio is repeated to receiving stations. By keeping the repeater
transmitter keyed after an initial transmission several of these access delays are eliminated. Hang time also
provides other benefits, such as eliminating some of the squelch bursts on carrier squelch systems and
providing an audible indication that a user accessed the system and keyed the repeater transmitter.
In a repeater system with transmitter steering, access time and hang time are far more complex than in a
single site repeater system. There are some access time tradeoffs to be considered in a steered system.
These are issues that must be addressed in the system design. The TSAM employs several steering
algorithms and is fully programmable which provides maximum flexibility when designing the steering
system.