Abstract: In one aspect of this invention, a receiver sequentially demodulates sequentially received burst signals into original digital data signals. A data extraction unit extracts base station information from the digital data signals sequentially demodulated by the receiver. A level detector detects the signal levels of received signals containing the burst signals sequentially received by the receiver. A control unit causes a display unit to display the signal levels detected by the level detector in accordance with elapse of the reception time, and display the base station information extracted by the data extraction unit. In another aspect of this invention, a determination unit quantitatively determines errors of the burst signals from the digital data signals sequentially demodulated by the receiver, and outputs the determination results concerning the validity of the digital data contained in the burst signals.

Abstract: An electrooptic effect element of this invention has first, second, and third electrodes. The first and second electrodes are formed on a substrate having an electrooptic effect, in order to form a high-frequency electric field for polarizing a light beam, thus constituting a microstrip line, as in the conventional element. The third electrode is spaced apart from the second electrode on the substrate in order to form another electric field for canceling the polarized light by the high-frequency electric field. In an electrical signal waveform measuring apparatus of this invention, an electrical signal obtained from an optical detection system coupled to the electrooptic effect element is fed back to form a closed loop in the third electrode.