Direction Finders
Locator Beacons
Emergency Receivers
Dual-Band Direction Finder System


Mobile Land

The RT-300 is an all-purpose direction finder system that is designed for operation on two different frequency bands depending on the application. The RT-300 sets new benchmarks in terms of precision and reception sensitivity. Special algorithms permit fast, stable display of information.


The RT-300 VS is the standard model and combines the functionality of a communication direction finder system for the VHF marine band with the functions of an MOB direction finder . The RT-300 VU VHF/UHF is an SAR direction finder for civilian and military applications.

The RT-300 direction finder system is designed for mobile use at sea or on land under extremely adverse conditions and is equally suitable for shore-based VTS facilities. The RT-300 not only sets new benchmarks in terms of performance but also features various functions that in the past could be obtained only by using various direction finder systems. The flexible system configuration makes it possible to support many different applications.

Special Features

  • Universal dual-band direction finder system for the VHF marine and aviation bands and the VHF/UHF aviation bands
  • SAR direction finder, communication direction finder and navigation aid
  • Automatic monitoring of emergency frequency 121.500 MHz during work on marine radio band
  • Unsurpassed reception sensitivity in this class to permit detection of extremely weak or distant signals
  • Selective squelch to avoid false alarms
  • Display of bearing with reference direction as true north, magnetic north or relative
  • Completely illuminated control unit
  • Optimized signal processing for fast, stable direction finding
  • Excellent localization precision
  • NMEA, RS-485 and RS-232 interfaces for system integration and remote control capability
  • Correction of lag error after changes in direction
  • Optimized for use at sea: robust, compact design, waterproof (IP67)


Method of bearing Doppler-principle (3 kHz rotational frequency, right / left rotation)
Bearing accuracy better ±5°
Displayed resolution Digital display: 1°; LED circle: 10°; 0.5° at serial NMEA output
Bearing reference Relative to antenna orientation, magnetic or geographic north
Internal resolution 0.5°
Sensitivity for system accuracy of 5° RF-voltage at receiver input (50 Ohms)
≤ 50 nV (VHF+UHF)
Electrical field (radiated sensitivity):
121.500 MHz: ≤ 0.5 µV/m
156.800 MHz: ≤ 1.5 µV/m
Frequency stability ±2.0 ppm (Δf/f = ±2·10-6) [at temperature range -30°C...+80°C]
Receiving bands 2
Receiving frequencies:
(or see type plate for special customer options)
RT-300 VS
VHF air band: 118.800 ... 121.500 ... 124.000 MHz
VHF marine band: 156.000 ... 156.800 ... 162.300 MHz (maritime, channel 01 - 88)
RT-300 VU
VHF air band:118.800 ... 121.500 ... 124.000 MHz
UHF air band: 241.000 ... 243.000 ... 245.000 MHz
Frequency steps 25 kHz
Bearable kinds of modulation A3E, F3E, A3X (ELT-modulation); bearing largely independent of modulation
Polarisation vertical
Error of polarisation ≤ 5° at 60° field vector rotation
Garbling cone app. 30° to the vertical
Time of response ≤ 100 ms (with sufficient receiving field strength)
User interface LC-graphic display 98x32 dots with backlight
13 buttons with legend illumination
36 LED circle for bearing display
Free adjustable dimming of LCD brightness, LCD backlight, legend illumination and LED circle illumination
Supply voltage range 12 V ... 28 V DC
Current consumption
supply voltage 12V 28V
stand by 350mA (4.2 W) 250mA (7.0 W)
typ. without ext. speaker 400mA (4.8 W) 300mA (8.4 W)
typ. with ext. speaker 600mA (7.2 W) 400mA (11.2 W)
max. without ext. speaker 450mA (5.4 W) 350mA (9.8 W)
max. with ext. speaker 800mA (9.6 W) 600 mA (16,8 W)
External audio max. 1.5 W at 4 Ohm (Upp-max = 10 V)
Interface RS232; NMEA (RS422 with galvanic isolated input); RS485
Relay contact (switching on if alarm is detected)
Input for self bearing suppression
Weight Display control unit (DCU): app. 700 g
Antenna unit (AU): app. 1400 g
Operating temperature range - 20°C ... + 60°C
Storage temperature range - 50°C ... + 70°C
Protective systems Display control unit (DCU): IP 67 Antenna unit: IP 67



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