AN IMAGING SYSTEM

摘要

An imaging system (1) comprises an antenna array (2), 24 GHz transceivers (3), and a digital receiver (4) including an ADC and circuits for filtering. The digital receives commands from the host PC (5) and passes data to the host PC (5) for display. The host PC 5 initiates volume scans, performs system diagnostics and error reporting, and collects scan data and displays it for the operator. The digital receiver (4) presents the scan requests to the antenna array (2) in a synchronised manner. All control signals in the antenna array are presented via a presentation clock (an individual presentation clock being generated for sub-sections of the array; of the order of five hundred presentation clocks are generated). The spectral content of each presentation clock is adjusted via a spreading circuit, thus adjusting the spectral interference radiated through the printed circuit board traces to the FET elements that each presentation clock feeds. The spreading clock generation circuit include taps (Tap 1, Tap 2 . . . Tap N) on a delay line, feeding a multiplexer. Delayed versions of the master clock are switched onto the presentation clock in a given sequence such that the presentation clock is composed of different phases of the master clock. This alters the spectral content of the presentation clocks with respect to the master clock, lowering the power at the fundamental frequency. This in turn lowers the power at the harmonics of the fundamental, reducing the electromagnetic radiation across the spectrum. The presentation clocks may be offset in their spreading pattern and hence in their presentation frequency such that the electromagnetic radiation is further reduced.