CTI Products TSAM Transmitter Steering & Audio Matrix - Manual (Page 24)

TSAM Installation and Maintenance Rev. 2.10 Chapter 3
CTI Products, Inc. Secondary Channel Operation
16
3.1 Secondary Site Selection
The TSAM automatically completes the following steps when a dispatcher selects a secondary site.
Secondary Operation is initiated when the TSAM detects a non-zero secondary site on the binary active
low Site Select inputs. If the site is currently voted, the receiver is immediately disabled, forcing the
receive comparator to re-vote. If the site is currently keyed or steered, the transmitter is disabled and the
TSAM steers to the HOME A or the HOME B site. (If the HOME A site was selected for secondary
operation the TSAM steers to HOME B). Any interlocking required to prevent the TSAM from disabling
active sites is done externally.
The Secondary Site Select Sequence
1. TSAM C2 RX audio is normally muted and remains so. This prevents the secondary dispatcher from
hearing F1 comparator status tone.
2. The TSAM disables the secondary base RX at the receive comparator by forcing its Disable line low
and marking the transmitter as being unavailable for transmitter steering in internal memory.
3. The TSAM sends the currently selected secondary frequency select tones. The secondary frequency is
determined by 4 binary Secondary Frequency Inputs (SF1-SF8). These control lines are set by
dispatcher using the console Frequency Select control. The TSAM uses a programmable debounce
time to allow the inputs to settle before reading the final frequency value. The debounce time allows
the operator to scroll the frequency list without sending frequency select control tones for every
frequency. This time is programmable in 1 ms increments from 0 to 65.535 seconds (due to the 20 ms
scanning latency, the exact debounce is
± 20 ms).
4. If C2 PTT is detected before the debounce time expires, the transmitter is keyed immediately using the
most current frequency select input values. To allow for adequate debounce of the secondary site
select inputs, the inputs are scanned 20ms after the detection of C2 PTT.
5. Secondary Base RX audio outputs and TX audio inputs are routed to the secondary channel control
card in the dispatch console, and the audio paths are unmuted.
6. TSAM monitors Secondary PTT to initiate a secondary transmission.
7. Operator is free to use the Secondary channel or to change the frequency if required.
8. If interlocking of secondary site or frequency control is required, it must be done in the console.