Raytheon SNV-12, Инструкция по установке и эксплуатации

Страница: 59 / 206

SNV-12 Operations Manual
3-31
JP7 Voted Audio Mute Input Configuration
The external input that mutes the voted audio output can be set to either active low or active
high by JP7. Please note that there is a pull-up resistor on this input, so if the jumper is placed
in the Active High position and no connection is made to the input terminal, the pull-up will
hold the input active and the Voted Audio Output will remain muted.
JP8 PTT/UNSQ Output Configuration
This jumper provides a 10k pull-up to +12 VDC for proper operation of this output as the
RECEIVING input when used as the conventional voter in an EDACS system. Note: The
output must also be set as active high using the configuration dip-switches. The standard output
is pulled up to +5 VDC as are most other SNV-12 outputs.
JP9 Console PTT Input Configuration
The standard configuration is a logic level, active low input with a pull-up resistor to +5 VDC.
The alternate jumper setting provides an E&M input to the SNV-12 console PTT function.
Threshold is approximately -5 VDC. Specification is PTT active for voltages equal to or below
-10 VDC, PTT inactive for open-circuit or voltage 0 VDC or higher.
The Console PTT Input may also be configured as an active high input via CIM-2A dipswitch
SW4-4. See Section 3.12.2.5. When set to active high via this switch, the keyed/unkeyed
conditions for the E&M JP9 configuration are also reversed. That is, the standard specification
of “PTT active for input below -10 VDC, inactive for open circuit or above 0 VDC” changes to
“PTT inactive for input below -10 VDC, active for open circuit or above 0 VDC.”
3.12.2.2 CIM Switch SW1; Console TX Audio Delay
SW1 is a BCD rotary switch used to add delay to the Console TX Input Audio. The Console
TX Audio Delay feature allows communications system TX audio and PTT control paths to be
set and stable before console audio is passed through.
The delay is adjustable from 0 to 450 ms in 30 ms steps. Actual total delay is the listed delay
setting plus the inherent audio delay of under 10 ms. This inherent delay is the result of the A to
D, DSP computations, then D to A processes.
Up to 50 ms delay is required to interpret all inputs for correct PTT and audio routing in a full
12 site single chassis SNV-12. This control signal delay is a result of the need for the CPM
module, after it receives a request to key, to poll all of the SVMs to see if any TX Inhibit or
Manual TX Steering inputs are currently active. The CPM must then direct the proper
module(s) to transmit. The first two settings steps are below the typical TX control signal delay
of approx 50ms, so a setting of 60 ms is recommended. Additional delay is required when
expanding to a two or three chassis voting system.
The recommended delays ensure that the correct PTT output(s) and all required audio gates are
set before console audio is sent to the selected SVM(s). Additional delay may be added to
account for other delays in the rest of the system, or to hold up the console audio until EIA
High Guard and Function Tones are transmitted.
If the voter is set to add EIA keying tones to the TX output, the tone sequence begins as soon as
the voter invokes the TX mode, while the console audio input is delayed per the SW1 setting.