April 19, 2014

FCC Technician Exam Question Of The Day (T8C01)

Q) Which of the following methods is used to locate sources of noise interference or jamming?

A) Radio direction finding

 NJ2X Notes:
Radio direction finding involves using antennas and receivers to determine the location of an RF source.  The are many different techniques:
  • Directional antennas - Using highly directional antennas such as yagi's, loops, etc. you can determine the direction of the signal.
  • Pseudo-doppler  - antennas are arranged in a circular array and then sequentially sampled to simulate the effect of a rotating antenna.  This modulates the received signal and the phase of this modulation can be used to determine the direction of the signal.
  • Phase interferometer - the phase difference between two spacially separated antennas is used to determine the direction of the signal.
Using triangulation in conjunction with the above techniques can help pinpoint a transmitter's location.
Written by: NJ2X, Michael Maher