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RDF TELEFUNKEN "TELEGON"
German built, as most German built RDF sets, very good.
type PE1026
gyro coupled, fully automatic
frequency bands
224 kHz - 538 kHz the white outer scale,
blue sub-scale is bandspread for the ranges
285-325, 405-415, 490-510 kHz
1600-4299 kHz
the art of Radio direction finding.
the very first system of radio navigation was the Radio Direction Finder, or RDF.
In use by the military, (counter)espionage, navigators in ships and aircraft.
By tuning in a radio station and then using a directional antenna, one could determine the direction to the broadcasting antennae.
A second (or 3rd) measurement using another station(s) was then taken.
Using triangulation, the two (or three) directions can be plotted on a map where their intersection reveals the location of the navigator.
Commercial AM radio-stations can be used for this task due to their long range and high power.
Strings of low-power radio beacons were also set up specifically for this task, especially along coasts, near harbours and airports.
Early RDF systems normally used a loop antenna, a smal loop of metal wire that is mounted so it can be rotated around a vertical axis.
At most angles the loop has a fairly flat reception pattern, but when it is aligned perpendicular to the station the signal received on one side of the loop cancels the signal in the other, thus producing a sharp drop in reception.
This is known as the "null"
By rotating the loop and listening for the "null" , the relative bearing of the station can be determined.
Loop antennas could be seen on most pre-1950s aircraft and pre-1990s ships.
RDF TELEFUNKEN "TELEGON"
German built, as most German built RDF sets, very good.
type PE1026
gyro coupled, fully automatic
frequency bands
224 kHz - 538 kHz the white outer scale,
blue sub-scale is bandspread for the ranges
285-325, 405-415, 490-510 kHz
1600-4299 kHz
the art of Radio direction finding.
the very first system of radio navigation was the Radio Direction Finder, or RDF.
In use by the military, (counter)espionage, navigators in ships and aircraft.
By tuning in a radio station and then using a directional antenna, one could determine the direction to the broadcasting antennae.
A second (or 3rd) measurement using another station(s) was then taken.
Using triangulation, the two (or three) directions can be plotted on a map where their intersection reveals the location of the navigator.
Commercial AM radio-stations can be used for this task due to their long range and high power.
Strings of low-power radio beacons were also set up specifically for this task, especially along coasts, near harbours and airports.
Early RDF systems normally used a loop antenna, a smal loop of metal wire that is mounted so it can be rotated around a vertical axis.
At most angles the loop has a fairly flat reception pattern, but when it is aligned perpendicular to the station the signal received on one side of the loop cancels the signal in the other, thus producing a sharp drop in reception.
This is known as the "null"
By rotating the loop and listening for the "null" , the relative bearing of the station can be determined.
Loop antennas could be seen on most pre-1950s aircraft and pre-1990s ships.