GMRS Radio Basic Functions

Overview

This lecture explains every basic menu option on a typical GMRS radio, focusing on functions, settings, and practical use for new users.

SQL (Squelch): Controls signal filtering; lower numbers allow weaker signals, higher numbers allow only clear transmissions.
STEP: Sets frequency increment for manual or scan tuning, mainly useful in frequency mode.
Scanning: Scans saved GMRS channels in channel mode; in frequency mode, scans all bands with selected step size.
TXP (Transmit Power): Adjusts transmission power; higher settings reach further but use more battery.
SAVE: Battery save mode cycles radio into sleep to conserve power; higher values save more battery but may miss initial transmissions.
VOX (Voice-Activated Transmission): Enables hands-free operation; sensitivity ranges from 1 (very sensitive) to 10 (less sensitive).
WN (Wide/Narrow Band): Sets bandwidth; channels 1–14 are narrow band by FCC rules, channels 15+ (including repeater) are wide band.

AB (Backlight Time): Sets how long the screen stays illuminated after use.
TDR (Dual Watch): Monitors two channels simultaneously and switches audio to the active one.
BE (Key Beep): Enables or disables button press sounds.
TOT (Timeout Timer): Limits how long you can transmit in one burst to prevent overheating (up to 60 seconds).

R-DCS/R-CTCSS/T-DCS/T-CTCSS: Privacy tones (digital/analog); receiving/transmitting with matching tones limits interference and enables repeater use.
BCL (Busy Channel Lockout): Prevents transmitting if the channel is already in use.

MDFA/MDFB: Selects what is displayed on the channel line (name, frequency, or channel number).
RC-ADD: Adds a new channel with custom parameters.
DCH: Deletes a channel.
RX LED/TX LED/WT LED: Sets screen color for receive, transmit, and standby modes.

AMO (Alarm Mode): Sets alarm behavior (local sound, transmit tone, or transmit coded alarm).
CODE: Sets personalized DTMF alarm code via CHIRP software.
RESET: Factory resets radio, erasing all settings and channels.

DTMF Tones: Keypad sends numeric codes during transmission for identification or signaling.
DTST, ANIS, DT+ANI: Control which DTMF tones you hear on your device.
ANID: Sets your radio’s DTMF ID.
PTTI/SCODE: Control when DTMF codes are sent (start, end, both) and which codes are sent per channel.
Squelch Tail Elimination (ST, RP ST, RPTR RL): Slightly reduce noise at end of transmission; rarely used in GMRS.

GMRS — General Mobile Radio Service, a licensed radio service in the US.
Squelch — A filter that blocks weak or unwanted signals.
Privacy Tones (CTCSS/DCS) — Sub-audible tones for limiting interference or activating repeaters.
DTMF (Dual-Tone Multi-Frequency) — Keypad tones used for signaling over the radio.
CHIRP — Software used for programming radio channels and settings.