Abstract: A direct sequence spread spectrum receiver includes correlators for handling prompt, late and early signals. An estimator is used to provide an estimate of the prompt signal and this used in a multiplication process with the late and early signals. The resultant signals are further processed to generate control signals.

Abstract: The apparatus receives an input signal via an antenna or cable 2, and the signal is applied to a frequency converter 4. Frequency converter generates complex I Q baseband signals which are applied to a respective correlator comprising a multiplier 6 and an accumulator 12 in respect of the inphase signal and the multiplier 8 and an accumulator 14 in respect of the quadrature phase signal. The output of the correlators are subjected to a modulus squaring function which comprises multipliers 16, 18 and an adder 20. The output of the adder 20 is applied to a store 22, and the inputs and outputs to the store are arranged to be added together in an adder 24, the output of which is compared in a comparator 26. The correlators and store are controlled by a controller 28 which is arranged to control the setting and resetting of the accumulators 12 and 14.

Abstract: Conventional Rake receivers for spread spectrum signals are typically restricted in the number of multipath components they can usefully combine. The present apparatus for combines all the useful multipatlh components in a received signal with modest complexity. Digital correlators are provided over the multipath delay spread of the signal at predetermined intervals and their outputs are maximal ratio combined. With close to rectangular transmission received filters, almost all the entire signal energy can be recovered at the output of the combiner even though no attempt is made to accurately to align any of the correlators onto a specific multipath component.

Abstract: The apparatus includes circuitry for determining which base station a mobile unit should be affiliated to for best reception, and circuitry for maintaining affiliation with the base station to which the mobile is currently connected. Cancellation circuitry is provided for cancelling the interference caused as a result of the mobile unit being affiliated to the base station giving non-optimum reception.