The RT-800 is a radio direction finder for stationary coast surveillance and identification of ships that are transmitting on the VHF radio band. The bearing information from transmitters can be correlated with the corresponding radar target and AIS-position information at a VTS centre. Two or more RT-800 Systems on different locations can be used to locate a ship’s exact position by triangulation. The RT-800 can easily be integrated in a VTS environment.

Special Features

• A-Class System according to IALA recommendations (IALA Guideline No. 1111)
• Best relation of performance and price
• Decoding of transmissions on all 19 Cospas-Sarsat channels
• Bearing (finding the direction) of the Cospas-Sarsat
• Full manual operational functionality at installation site for calibration and service
• Fast frequency monitoring by scanning of up to 8 frequencies
• Low costs due to no moving parts
• Easy and reasonable priced installation as no patched HF antenna cable has to be used
• Effective remote operation via RS-232, Ethernet and LAN
• Extreme compact, rugged and light-weight DF antenna for easy installation and use in maritime weather conditions
• Maintenance-free due to no moving parts
• External lightning protection available

Technical Data

Method of bearing

Doppler-principle (3kHz rotational frequency)

Bearing accuracy

≤ 2° (RMS)

Internal resolution

Stability of frequency

±2.0 ppm

Frequency range

VHF air band: 118.000 to 124.000 MHz
VHF marine band: 154.000 to 163.000 MHz (Channel 0 to 88, Sea & Coast)
UHF air band: 240.000 to 246.000 MHz
Cospas/Sarsat: 400.000 to 406.092 MHz
UHF-FM Band: 406.100 to 410.000MHz

Frequency extensions possible see below in Accessories

Channel pattern

VHF Air Band: 8.33 kHz
VHF Marine Band: 5 kHz
UHF Air Band: 25 kHz
UHF FM-Band: 5 kHz

Monitoring/Scanning modes:

Four additional frequencies (emergency frequency 121.500 MHz and three free selectable frequencies) are monitored during normal operation.
The Cospas-Sarsat and 121.500 MHz emergency frequency are monitored at all times in standby mode.
Fast Marine Ship Band Scan (within approx. 3sec):
Fast scan (without gap) within the range of ship channels [01..88] = [156,050 .. 157,425 MHz]. Detection of each signal (also between the channel grid).
Fast Channel Scan (within max. 2sec):
Fast scan of up to eight freely selectable frequencies/channels.

Signal filtering

Optional: all emergency frequencies can be filtered for Distresssignal-modulation (false alarms disabled).

Cospas-Sarsat analysis

Reception and analysis of Cospas-Sarsat data signal (112 or 144bit, 400baud, biphase L-phase modulated, with Bose-Chaudhuri-Hocquenghem error test, specified according Cospas-Sarsat C/S T.001 October 1999)
Indication of data content (mode, country, GPS-coordinates)

Bearable modulation types

A3E, F3E, A2X (PLB-modulation); bearing largely independent of modulation.



Polarisation error

≤ 5° at 60° field vector rotation

Garbling cone

approx. 30° to vertical

Response time

≤ 50 ms typ. (with sufficient reception field strength)


Foil on the front with integrated keyboard matrix and EL background illumination

TFT Graphic Display

320 x 240 pixel with max. brightness of approx. 450cd/m2, continuously adjustable or automatic control.

Power supply

115 V to 230 V ± 10 % AC,
50 to 60 Hz

Rated Current

0,5 to 1 A

Audio out

Internal speaker 4W Line out (adjustable from 100mV pp to 2000mV pp)

Data Interfaces

Remote Control Channel 1 Audio: Ethernet LAN (RJ45)
Remote Control Channel 1 NMEA: Ethernet LAN (RJ45)
GPS: RS-422 / 9 pin D-Sub
Remote Control Channel 2 Audio: Ethernet LAN (RJ45) (Optional)
Remote Control Channel 2 NMEA:
Ethernet LAN (RJ45) (Optional)


AU: approx. 5200 g
DCU: approx. 5900 g

Operating temperature

DCU: -20 °C to +60 °C
AU: -40 °C to +60 °C

Bearing senitivity VHF Air Band

≤ 4 µV/m / 2,5 µV/m typical at ±5° bearing fluctuation

Bearing sensitivity VHF Marine Band,

≤ 3 µV/m / 2 µV/m typical at ±5° bearing fluctuation

Bearing sensitivity UHF Air Band

≤ 6 µV/m / 4 µV/m typical at ±5° bearing fluctuation

Bearing sensitivity COSPAS-SARSAT

≤ 6 µV/m / 4 µV/m typical at ±5° bearing fluctuation

Bearing sensitivity UHF FM-Band

≤ 6 µV/m / 4 µV/m typical

Power Consumption

30 W at 230 V


Lightning protection rod

Full width lightning protection

The Lightning Protection Rod for precision direction finders is designed to protect direction finders from RHOTHETA against the effects of direct lightning strokes into a direction finder system.

Optional Frequency extensions

Full width rt 800 frequenz option

F1 VHF-Airband: 118,000 – 136,992 MHz
F2 VHF-Marineband: 137,000 – 224,995 MHz
F3 UHF-Airband: 225,000 – 399,975 MHz
F4 UHF-FM Band: 406,100 – 470,000 MHz

The Optional Frequency extensions can be ordered seperatly to extend the frequency range of each system individually.

DF Commander Software

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The main purpose of the “DF Commander" Software is to provide the remote control and monitoring of multiple DF-Channels and DF-Systems from a standard PC. This software allows the visualizing of the bearing data, such as bearing angle, signal level and frequency of an appropriate channel. The simple and convenient design of the “Bearing Page” and the possibility to adjust the orientation of the compass rose towards the tower window view makes the controller’s work very comfortable.

Furthermore the software provides the possibility to simultaneously monitor the status of all channels connected, which is also a helpful feature for the technical monitoring and maintaining of the DF-System.

DF Commander MK2 Software

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The DF Commander MK2 software enables remote control and monitoring of radio direction finding systems. Besides displaying the direction finding results on different electronic charts, the software is able to calculate cross bearings on different frequencies. Soundings, cross bearing results and status information of radio direction finding systems are made available via an integrated server. Radio direction finding systems can also be set and controlled via the same server. Thus the software is to be understood as a DF service.

DF-Emmulator Software

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The "DF Emulator" is a software that emulates a bearing system on a Windows PC by playing a pre-recorded log file. In the simplest case, the DF emulator uses the serial COM port of the PC to transfer the data via RS232 to another PC or system that displays the bearing data.
This software is designed for projects like bearing data integration in radar displays or other map- and control displays and is intended to facilitate the work of integrators.

GPS UTC Timebase

Full width gps mouse frei hp ready

By connecting the RT-800 with a GPS-mouse, it is possible to provide a peak data packet transmitted via LAN with a UTC time stamp. This ensures that it is possible to display the pitch data of different direction finding systems in a synchronized manner and triangulation for position determination on a map software becomes possible.


Vessel Traffic Service (VTS)

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Coast Surveillance

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