Post by K5ARN on Jan 5, 2013 9:45:58 GMT -6
Time Difference of Arrival antenna is an interesting concept.
Two dipoles side by side are switched to the receiver very fast by a 555 timer.
If the antennas are not perpendicular to the fox transmitter there will be a slight difference in time of arrival between the two signals. They will then be out of phase and the switching between them will generate a tone in the receiver.
When the antenna is perpendicular to fox transmitter there is no tone. The only thing then is to figure out, is it in front of you or behind you.
More info here:
webhome.idirect.com/~griffith/tdoa.htm#TDOA Fig1
It does not seem to be that difficult to build and the parts are pretty cheap. I will use a Radio Shack "Experimenter Printed Circuit Board" SKU# 276-170 as the PCB.
Important is that both antennas and their leads are the identical, if not it can cause enough TDOA to indicate the wrong direction.
Two dipoles side by side are switched to the receiver very fast by a 555 timer.
If the antennas are not perpendicular to the fox transmitter there will be a slight difference in time of arrival between the two signals. They will then be out of phase and the switching between them will generate a tone in the receiver.
When the antenna is perpendicular to fox transmitter there is no tone. The only thing then is to figure out, is it in front of you or behind you.
More info here:
webhome.idirect.com/~griffith/tdoa.htm#TDOA Fig1
It does not seem to be that difficult to build and the parts are pretty cheap. I will use a Radio Shack "Experimenter Printed Circuit Board" SKU# 276-170 as the PCB.
Important is that both antennas and their leads are the identical, if not it can cause enough TDOA to indicate the wrong direction.