Grand Rapids Business Daily

How do you trace or track down a radio signal?

If i am in contact with a radio, how can I trace the location of the radio? Is there a way to geolocate a radio signal. I dont have any of the radios information, and am and will be unable to get any information regarding the equipment. However, I am in communications with that radio. How would I go about being able to find where the radio is located? Is there any sort of special equipment that I can use to geolocate it?

Public Comments

1. This problem has exercised the minds of many government departments over the years. It's simplest if the station transmits it's own co-ordinates. This is the way it's done with cellphones which use GPS to locate themselves: <http://en.wikipedia.org/wiki/Automatic_Position_Reporting_System> Otherwise you will need to resort to radio- direction finding: <http://en.wikipedia.org/wiki/Radio_direction_finding>
2. Using a directional antenna such as a loop or a beam antenna (Yagi or log periodic) rotate the antenna and note in what direction the signal peaks. If this is done from two positions (triangulation) then the transmitter is at the intersection of the two bearings as drawn on a chart.
3. triagulation is the most common method but only with nearby transmissions (ie less than 1 mile). However if the radio signal is in the VHF or higher bands, there is a good chance that it is relayed by a booster or automated repeater, in which case triagulation will only locate the repeater and not the originating transmitter. This is always the case with cell phones. Also, propagation effects can be such that you are not receiving on a direct path, but rather a reflection off structures, mountains or even the ionisphere. HF radio that comes from distant transmitters cannot be triangulated with any reasonable precision because of propagation distortions. If there is a public need to locating the transmission, the FCC field engineer office has equipment and operators that could be enlisted. Even if they cannot be directly involved, the field engineers office can provide information on equipment and techniques.