Abstract: A recording system such as a magnetic tape data recording and reproducing system is arranged to record data management information to three different storage devices. The recording system records management information on a record medium such as a tape, a cassette memory built in a tape cassette and a recorder memory of the recording system. A control section of the recording system first reads the management information from the cassette memory, further reads the management information from the recorder memory if the management information of the cassette memory is insufficient, and finally reads the management information from the record medium if the management information of the recorder memory is still insufficient.

Abstract: Disclosed is a signal processor for an ultrasonic fish detector, in which the signal processing circuit is arranged separately from the display unit, whereas conventionally both are configured integrally, within a case with the provision of a composite converting circuit and RGB converting circuit with associated video output terminal and RGB output terminal, thereby allowing the user to configure a fish detection system by merely purchasing the fish detection signal processor made up of the signal processing circuit and a transducer and utilizing a home television set or an RGB graphics monitor oriented to personal computers.