Garmin Signal™ VHF 400 Radio Marine VHF Radio with Built-in AIS Transponder

Garmin Signal™ VHF 400

The Garmin Signal VHF 400 is an advanced marine VHF radio that combines a built-in Class B AIS SOTDMA transponder, Class D Digital Selective Calling (DSC), and an integrated multi-constellation GNSS receiver into a compact, modern head unit designed to take up minimal space at the helm. A 3.5-inch color IPS LCD capacitive touchscreen with edge-to-edge glass and 1,000-nit backlight ensures clear visibility in all lighting conditions, while the intuitive interface makes operation straightforward even in demanding on-water situations.

With 25-watt transmit power, the radio covers all U.S., Canadian, and international marine VHF channels as well as NOAA weather channels and alerts. The built-in AIS transponder both transmits and receives, displaying the range, course, speed, and crossing situation of nearby AIS-equipped vessels directly on the unit's plotter view. Initiating a DSC call to any visible AIS vessel is as simple as selecting it on screen and tapping a button. The integrated GNSS receiver supports GPS, GLONASS, BeiDou, and Galileo constellations at a 10 Hz navigation rate, and an SMA connector is provided for an optional external GNSS antenna.

Audio clarity is enhanced through machine-learning-based adaptive noise cancellation that filters out wind, wave, and engine noise. Automated squelch continuously monitors radio activity to eliminate static, while VHF audio playback lets mariners replay missed messages for up to three minutes on any channel. Advanced watch modes simultaneously scan all VHF channels in the background while maintaining watch on channel 16 and user-defined preset channels.

The included fist mic delivers 5 watts RMS of built-in speaker output and can be mounted separately from the head unit. An external speaker output (15 W RMS, 4 Ω) and a hailer loudspeaker output (25 W RMS, 4 Ω) with listen-back functionality provide flexible audio configurations. Intercom support and night vision and stealth modes round out the feature set for tactical use.

Built-in Wi-Fi (802.11b/g/n, WPA2 Personal) acts as an access point for mobile phones, enabling configuration, MMSI programming, and over-the-air software updates through the ActiveCaptain smartphone app. The unit integrates seamlessly with compatible chartplotters via NMEA 2000 and the Garmin BlueNet Network, and supports up to five Garmin Signal RM 100 remote stations. Operating voltage spans 9.6–32 VDC, and the unit is rated IPX7 for water resistance.