Time Difference of Arrival (TDOA) is a time based method for the localization of emitters. The procedure is centered on determining the time difference between the arrival of a transmitted signal at different receiving locations.
A TDOA network consists of three or more receiving stations that surround an area under observation. To obtain an unambiguous result, there must be at least three receivers and the location must be within the area covered.
The receiving stations simultaneously sample the transmitted signal over a defined time period in the form of an IQ data set. These samples are marked with a high precision timestamp and transmitted to a central computer, e.g. through a modem. Using the positions of the measuring receivers and the time differences within the samples, the computer can calculate the position of the emitter.
Since radio signals are propagated at the speed of light, the receivers must meet very exacting requirements with regard to their delay, timebase, and time resolution. In this instance, the precision and resolution of a localization are decided by nanoseconds.
The products in the SignalShark range are predestined for applications in a TDOA network, due to their high precision timebase and delay compensation for the RF cable to the antenna.
When combined with the automatic antennas in the ADFA range, they have the additional huge advantage of not only acting as an exceptional sensor in a TDOA network. The SignalShark and ADFA together can also perform an Angle of Arrival (AOA) measurement. When the results of an AOA and a TDOA are put together, this is known as a hybrid direction finding measurement, and the accuracy of the localization is further increased considerably.
