Technical Manual

8-2 GUARDIAN VHF MOBILE
Priority 2 Scan: Priority-2 channel is sampled in a similar fashion to the priority-1 channel. Activity on the
priority-2 channel overrides all other modes except emergency and priority 1.
Receive Only Channel: A feature that does not allow outgoing transmissions on the channel. It is used for channels
in which transmission is prohibited (i.e., weather channels). If PTT is pressed on a receive-only channel, RX ONLY
appears on the display.
Receiver/Exciter/Control Module (RECM): Transceiver module containing all radio functions except RF/audio
amplifiers and display/keypad circuitry.
Repeater Delay: A delay timer used to prevent a radio from receiving its own transmission from a tactical repeater.
Scan Delay: The amount of time the scanner dwells on an active receive channel after the carrier is dropped. This
prevents another message from being received before a response can be made.
Scan Reply: If a PTT press interrupts the scan delay timer, this is the amount of time allowed to ensure a reply to a
received message.
Scan List: A group of channels in a zone that are designated as active scan list channels. Channels are added or
deleted from the scan list using the PC programmer or the radio keypad.
Scan Revert Channel: The transmit channel that the radio reverts to when PTT is pressed during or following a
scanned message.
Search Mode: The radio scans for and opens on carrier only regardless of CTCSS, DCS, or the digital ID.
Selective Receive Squelch: The radio receives any transmission having the correct NAC and TGID.
Shadow Channel: The radio of primary channels, each of which can have up to 7 shadow channels. A shadow
channel has the same transmit and receive frequencies, options, and transmit power levels as its primary channel.
Individual shadow channels can be configured for different channel types (analog or digital), BW (12.5 or
25 kHz for analog channels), squelch modes, P25 NACs (digital channel only), and encryption key (only one primary
or shadow channel can have CVSD DES enabled). When properly configured, shadow channels can be created to
allow a user to hear all transmissions on a receive/transmit frequency regardless of channel type, BW, squelch mode,
or encryption. Shadow channels are created and their settings edited using the PC programmer.
Talk Group Identifier (TGID): Selective squelch for the digital mode, used to group users into functional teams.
Transmit Inhibit and Override: A feature that stops users from talking over other radio conversations. There are
three options: CARRIER prevents transmission if any activity is detected on the channel, TONE prevents
transmission on an active channel with a squelch code other than your own, and NAC prevents transmission on an
active channel with the same NAC. There is a quick-key override feature available that allows a user to override the
transmit inhibit state by quick-keying the radio (i.e., 2 PTT presses within a short time frame).
Transmit Timeout: Prevents inadvertent or prolonged transmit operations.
User Interface: The same as a man-machine interface.
Zone: A group of channels. There is a maximum of 16 zones per radio and each zone can contain up to 16 channels.
Three zones can be selected using the toggle switch or 16 zones selected by the radio keypad.
Zone Scan List: A group of zones in a bank designated as active scan list zones. Zones are added or deleted from
the scan list using the PC programmer or the radio’s keypad.