A method of detecting and correcting errors that occurs while digital signals are transmitted in series. In this method, in a processing unit of a transmitter, n addresses (ad) are allocated to respective n digital signals. Using these addresses (ad), bits of the digital signals are picked out, a plurality of bit strings (g) are created by combining information bits and check bits of the selected bits, and the plurality of bit strings (g) thus created are subjected to parity checks to determine the value of the check bits of the digital signals. A transmission code (1) thus created are transmitted to a receiver.

In the processing unit of the receiver, the plurality of bit strings (g) are created from the signal received. The plurality of bit strings (g) thus created are subjected to parity checks to detect and correct errors in the transmission code (1).

Bit error rate (BER) measurement in a receiver in which digital codes are received and decoded which, at the transmitter end, are encoded into codewords which comprise information and check symbols. On decoding at the receiver end, correction of any erroneous codewords takes place. Since the correction is unsuccessful in only a negligible number of cases, the BER can be determined on the basis of the ratio of the number (c) of symbol corrections and the number (r) of received symbols, which may be equated to the symbol error ratio before decoding (SER_before). Said ratio (c/r) is derived from the decoder by an arithmetic unit (1). A conversion unit (2) converts the ratio (c/r) into a post-decoding symbol error rate (SER_after). A second arithmetic unit converts this into the required BER.

An information recording apparatus comprises a data converting means 10 for performing data conversion on record information consisting of a digital signal in accordance with a predetermined data conversion table, a data modulating means 6 for inverting an initial output signal when bit information of data after the data conversion is "1" given that the initial output signal is "0"; and a recording means 3 for recording the output signal on an optical recording medium.

An information reproducing apparatus comprises a reading means 7 for reading information from the optical recording medium to yield a reproduced signal; a level detecting means 11 for detecting a level of the reproduced signal and outputting digital data; an error connecting correcting means 12 for, upon detection of a sequence of "01110" in a bit pattern of the digital data, correcting the sequence to a sequence of "01010" and outputting corrected data, and, upon detection of no error, outputting the digital data; and a data reverse converting means 13 for performing reverse conversion on the output data of the error correcting means in accordance with the data conversion table, yielding reproduced information.