Abstract: A method for upgrading a wavelength division multiplex (WDM) optical communication system includes replacing an installed transmitter operable to transmit a data stream at a defined bit rate with a return-to-zero M-ary phased shift keying (RZ-mPSK) transmitter operable to transmit the data stream at the defined bit rate and at least one other data stream at the defined bit rate together in an RZ-mPSK signal having a combined bit rate at least double the defined bit rate and a symbol rate equal to the defined bit rate. An installed receiver operable to receive the data stream at the defined bit rate is replaced with an RZ-mPSK receiver operable to recover the data stream at the defined bit rate and the at least one other data stream at the defined bit rate from the RZ-mPSK signal.

Abstract: Correction of coordinates input by a user through an input device is effected using coordinate correction parameters. To calculate the coordinate correction parameters, a plurality of reference points are displayed on the input device. Coordinate input is designated by a user, and if the coordinate is determined to correspond to a reference point, then the coordinate input is retained. The process is repeated until a coordinate is kept for each reference point, wherein only remaining reference point(s) for which a corresponding coordinate has not yet been retained are displayed. Once coordinates have been input for the reference points, a correspondence between coordinate input and a reference point is determined, and corresponding coordinates are kept for each reference point. Using correction parameters calculated based on the kept coordinates, it is possible to correct device characteristics of the input device such as position aberration, even if such characteristics are non-linear.

Abstract: An image positional relation apparatus is provided, in which coordinate data of a real targed photographed by a CCD camera and coordinate data of a virtual target logically calculated from the predetermined position of the real target are transmitted to a superimpose circuit, and the real target and the virtual target are superimposed to be displayed on a monitor screen. A user operates a controller so that the real target coincides with the virtual target. An amount of such operation is transmitted to the superimpose circuit as a correction amount, and the positional relation between the real target and the virtual target, i.e., the positional relation between the real image and the virtual image can be properly corrected.