Patent ID: 6021137
Filing Date: 2000-02-01
Classification: H04B

Abstract:
A data collection system comprising:a plurality of terminal units each having a memory for storing therein data to be collected by the data collection system;a data collector; anda power line connecting each of said plurality of terminal units to said data collector with data communication being executed between each of said plurality of terminal units and said data collector via said power line,each terminal unit includinga modulating circuit configured to read out data from the memory of the respective terminal unit according to a common request signal transmitted from said data collector and subject said data to spread spectrum modulation, anda data transmitting circuit configured to transmit via said power line data modulated by said modulating circuit to said data collector, andsaid data collector includinga request signal transmitting circuit configured to transmit said common request signal via said power line to each of said plurality of terminal units,a demodulating circuit configured to subject data from each of said plurality of terminal units received via said power line, after transmission from said request signal transmitting circuit, to spread spectrum demodulation, anda data collecting circuit configured to collect data according to the data demodulated by said demodulating circuit, whereinsaid plurality of terminal units execute spread spectrum modulation using a common specified spread code in said modulating circuit and said demodulating circuit is a shared reversely spreading circuit for subjecting data modulated by each of said plurality of terminal units to reverse spread spectrum demodulation using said specified spread code.