Yozan Corporation

Sharp Kabushiki Kaisha Corporation

Chanming Zhou

Guoliang Shou

Sunao Takatori

Jie Chen

A compact and easily-assembled circuit for a complex despreading system, arranged such that the circuit does not contain pairs of adders at the output area. The configuration of the circuit enables the addition and subtraction of different signal components to occur before the multiplication stage and not at a pair of adders located at the output area The complex despreader system employs a complex matched filter at a receiver for despreading received signals with a QPSK system in the primary modulation and a BPSK system in the secondary modulation modulated at a transmitter. The input area of each matched filter of I and Q channels includes a pair of adders. One adder generates a first signal having a positive in-phase and a positive quadrature component. The other adder generates a second signal having a negative in-phase component and a positive quadrature component. Next, an I-channel multiplication circuit multiplies both components of the first signal by a spread code then adds the multiplication results together. Likewise, a Q-channel multiplication and addition circuit multiplies the components of the second signal by a spread code and then adds the multiplication results together.

Complex despreading system

A high-speed discrete cosine transformation circuit includes the one-dimensional input signals x(0) to x(7) being input in parallel to the positive input terminals '+' or the negative input terminals '-' of eight neural operation units (NOU) 11 to 18 through capacitors d0 to d6. In each NOU 11 to 18, input signals x(0) to x(7) are added and subtracted. Input signals x(0) to x(7) are multiplied beforehand by the coefficient in proportion to the capacities of capacitors d0 to d6 which are connected to NOU 11 to 18. Thereafter, discrete cosine transforming coefficients y(0) to y(7) are output. A two-dimensional discrete cosine transformation circuit is realized by using the one-dimensional discrete cosine transforming circuit.

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Tokyo, Japan

Chanming Zhou