| 摘要 |
A radio direction finding apparatus comprising an omnidirectional receiving element (21), an array of directional receiving elements (1.1-1.2N), two log video detectors (15, 16) suited for separate connection to two contiguous elements of said array and a subtraction circuit (27) for generating a signal containing the azimuth data of an r.f. transmitter. In order to select echoes received through the main lobes of the two connected receiving elements from those received through the main lobe of the one element and a side lobe of the other element, the radio direction finding apparatus is provided with a threshold circuit (18) and two gate circuits (19, 20) separately inserted between the log video detectors (15, 16) and the subtraction circuit (27). The threshold circuit (18) passes the applied signals through the gate circuits (19, 20) if the strength of the latter signals exceeds that of the echo signal obtained from the omnidirectional receiving element (21) via a third log video detector (22). |
