【発明の名称】デュアル枝路受信機 - Philips Electronics Nemrose Fennaught Shap

Title:

【発明の名称】デュアル枝路受信機

Document Type and Number:

Japanese Patent JP2603699

Kind Code:

B2

Abstract:

A dual branch receiver consists first and second branches (12, 14) respectively comprising first and third mixers (16, 20) and second and fourth mixers (17, 21). An input terminal (10) for a signal having a carrier frequency ( omega c) is connected to the first and second paths. A first local oscillator frequency ( omega o) is supplied in quadrature to the first and second mixers (16, 17), where omega c- omega o = DELTA and DELTA omega is of the order of 2 pi x 100 radians/sec. A second local oscillator (30) frequency is supplied in quadrature to the third and fourth mixers (20, 21). An output signal is derived by connecting a sum circuit (22) and a difference circuit (24) to the first and second branches. The outputs of the sum and difference circuits (22, 24) are also used to provide gain and phase correction signals. It has been found that if the correction signals are based on signals centred on 2 DELTA omega then they are substantially free of ripple. The gain correction is derived by mixing the 2 DELTA omega signals derived by multiplying difference by difference (or sum by sum) with the 2 DELTA omega signals derived by multiplying sum by difference and low pass filtering. The phase correction is derived by mixing a 90 DEG phase shifted difference signal with the sum signal (or vice versa) and deriving the 2 DELTA omega signals which are mixed with 2 DELTA omega signals derived by multiplying the difference by difference (or sum by sum) and low pass filtering.

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