SNV-12 Operations Manual
5-27
The TX Hangtime settings also apply to tone keying operation. When single-tone keying is
selected, the keying tone remains present for the set Hangtime after the repeat PTT input is no
longer active. When the EIA tone sequence is used, the low guard tone (also called the hold
tone) remains present for the set Hangtime following the de-activation of PTT.
5.21
Duplex and Simplex Modes
Duplex Mode should be used at all times unless the voting system has transmitters and
receivers operating on the same frequency or uses half-duplex transceivers. In Duplex Mode,
the voter continues the voting process while the console PTT is active. If automatic or manual
TX steering is activated while the console is keyed, the voter will not switch to the newly
selected TX sites until the console unkeys and keys again. The voter never switches transmit
sites in the middle of a transmission.
When set to Simplex, voting is inhibited and voted audio is muted whenever console PTT is
active. Since simplex systems transmit and receive on the same frequency, this voting inhibit
during console transmissions ensures that receivers do not vote the console audio. The SNV-12
will also hold off voting for an adjustable time period following the completion of a console
transmission. This guarantees the voter does not vote the squelch tail that follows that
transmission. When a console operator is letting the STARS algorithm select a site for
transmission, and sends several replies to the selected site; the voting hold off ensures the voter
does not vote the squelch tail of one of these replies, which could cause the next console reply
to be sent to the wrong site.
The voter can also be configured so that console transmissions are inhibited during Simplex
Mode operation whenever any site is voted. This ensures that the console operator does not
inadvertently cut off an important transmission from a remote site by transmitting at the same
time on the same frequency. (Set to
Field Priority
rather than the default
Console Priority
.
See Section 5.19.4 for more information and Section 3.12.2.4 for switch settings).
When in the Repeat Mode, the SNV-12 also behaves differently depending on whether the
SNV-12 is set to Duplex or to Simplex. When the unit is set to Duplex, voted audio is repeated
(retransmitted) to the sites determined by the voter‟s configuration settings;
this may include
the voted site
. When set to Simplex, Voted audio is
not retransmitted to the voted site
. This
exclusion can be overridden on a site-by-site basis by a dipswitch on each SVM module. See
Section 5.15 for more about the Repeat Mode and Section 3.12.6.4 for instructions to set the
Voted Site Simplex Repeat Enable dipswitch.
Summary of Contents for SNV-12
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