| 摘要 |
<p>A distance measuring receiver system and method (101) for determining the distance of a receiving station from a transmitting station, which provides the distance information by the reception and processing of a pair of signals (preferably continuous wave carrier) transmitted by the transmitting station. The present invention receives the pair of signals (upper signal (F1) and lower signal (F2)) using an antenna (102) connected to a front end subsystem (104) for amplifying and frequency translating to baseband the received pair of signals (F1, F2). The pairs of signals (F1, F2) at baseband are supplied to the upper channel (401) and to the lower channel (402) of a filter subsystem (106). The upper channel (401) exctracts the upper signal and the lower channel (402) extracts the lower signal. The filter subsystem (106) supplies the upper signal to the first channel (501) and the lower signal to the second channel (502) of a lane expansion subsystem (108), which produces a plurality of difference frequency signals (113, 115, 117, 119) (of preselected multiples) in accordance with the upper and lower signals. An oscillator subsystem (110) generates an oscillator signal (210) (of preselected phase and frequency) as a function of a clock signal (123) generated by a precise source (125) (such as an atomic clock). A reference subsystem (112) in accordance with the oscillator signal (121) supplies a plurality of reference signals (127, 129, 131, 133) (having frequencies equal to the frequencies corresponding to difference frequency signals). By comparing the phase of corresponding difference frequency and reference signals, phase comparator subsystem (114) produces a plurality of measurement lanes of different lengths, which allow the present invention to zero in on the position of the receiving station. Substantial elimination of phase error to each signal caused by signal processing is achieved by the present invention. An upper channel automatic gain stage in accordance with the level of the signal pair controls the Vcc voltage provided to the amplifying stages of the front end subsystem and to the active devices of the upper channel, while a lower channel AGC controls the Vcc voltage provided to the active devices of the lower channel. This results in the power output of the amplifying stages and the devices being maintained at a preselected value irrespective of the level of the signal pair. In addition, the varactor diodes cancel out minute capacitance changes exhibited by the crystal tuned circuits in the upper channel and in the lower channel due to the change in Vcc, the output signal power and the movement of the operating point of the active devices.</p> |
