FIG. 14A is a block diagram of an illustrative localization system 1400 comprising multiple synchronized (e.g., phase coherent) interrogators including master interrogator 1402 and three receive-only interrogators 1404, 1406, 1408. Although there are three receive-only interrogators shown in the illustrative embodiment of FIG. 14A, in other embodiments, a localization system may include any suitable number (e.g., one, two, four, five, six, seven, eight, nine, ten, etc.) of receive-only interrogators synchronized with master interrogator 1402. In addition, although in the illustrated embodiment of FIG. 14A each of the interrogators 1404, 1406, and 1408 is a receive-only interrogator, in other embodiments, any of the interrogators 1404, 1406, and 1408 may be capable of transmitting and receiving RF signals, but may be configured to operate in a receive-only mode.
The system 1400 further includes synchronization circuitry comprising fixed-frequency reference oscillator 1410 and lines 1412 configured to provide output of oscillator 1410 to each of the interrogators 1402, 1404, 1406, and 1408. The master interrogator 1402 may be of any suitable type including any of the types interrogators described herein. Each of interrogators 1404, 1406, and 1408, may be of any suitable type including the type described below with reference to FIG. 14C.
