Instruction Manual
79
E04819 Issue 1.0
8.2 Compatible NMEA sentences
The following NMEA 0183 sentences are processed by the
RS86/RS87 in order to transmit the boat’s position if a Distress
Alert is initiated:
NMEA 0183 versions 2 and 3 – GGA, GLL, RMC, ZDA.
8.3 Transmission range
Because VHF signals travel in a straight line and are not reflect-
ed back off the ionosphere as lower frequency signals are, the
range of VHF signals is limited to ‘line of sight’, beyond which
the other vessel passes behind the curve of the Earth. Therefore,
the range will increase greatly, the higher above sea level the
antenna is positioned (Fig 8.1; note, the distances given assume
maximum transmission power is used).
Therefore, the typical ship-to-ship range of a fixed VHF radio
such as the RS86/RS87 with a masthead antenna will be approx-
imately 20 km (12 miles). This will increase as height above sea
level increases or if the other radio user’s antenna is at a greater
height. Note that the range between the yacht with the antenna
mounted on a 9 m (30 ft) mast and the shore station increases to
46–53 km (29–33 miles).
Fig 8.1 - VHF transmission ranges
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