Abstract: A method and apparatus is described for preparing and assessing machine readable payment documents such as bank or postal checks to avoid fraud. The checks are prepared by enciphering the serial number and the amount for which the check is made out with secret code data to provide a crypto number which is printed on the check with the serial number and the amount. The check is assessed as valid by reading out the printed data and enciphering the amount and serial number with the same secret code data as used when preparing the check to provide a crypto number which is compared with the crypto number read from the check. If the two crypto numbers are the same the check is assessed as valid.The crypto number can be derived from additional data such as the credit card number of the person making out the check, the time and date and the number of the machine preparing the document.

Abstract: An apparatus for simultaneously viewing diapositives and front viewed pictures or images, especially transparent printed copies and prints produced therefrom under standardized illumination conditions, comprising a rear viewing device encompassing a support for supporting a diapositive or transparent positives or images and light source means arranged behind said support through which the light can be projected. There is also provided a front viewing device comprising a support for the front viewed image or picture and light source means arranged in front of said last-mentioned support. The rear viewing device and the front viewing device are hingedly interconnected with one another and can be selectively fixed in adjustable mutual angular positions relative to one another.

Abstract: A method of, and apparatus for, transmitting and receiving electrical speech signals transmitted in ciphered form, wherein at the transmitter end there are formed in sections or intervals from the speech signals to be transmitted, by frequency analysis, signal components or parameter signals containing frequency spectrum-, voiced/voiceless information- and fundamental sound pitch coefficients, these signal components are ciphered, the ciphered signal components or parameter signals are transformed into a transmission signal and this transmission signal is transmitted over a transmission channel, and at the receiver end there is reobtained from the transmission signal the ciphered signal components or parameter signals and deciphered, and from the thus-obtained deciphered signal components or parameter signals there is generated by synthesis a speech signal which is similar to the original speech signal.

Abstract: A light source of adjustable colour is provided, primarily for use in apparatus for printing coloured originals. The invention is primarily useful in printing photographs.According to one aspect of the invention there is provided a light source of adjustable colour, comprising three light emitters of seperately adjustable intensity, a light mixer adapted to mix light emitted by the emitters into one beam, and filtering means whereby the first emitter emits light containing one additive primary colour, the second emitter emits light containing the same colour and one other additive primary colour, and the third emitter emits light of all three additive primary colours.The colour emitted by all the emitters, and therefore most easily adjustable to be richest in the final light beam, is, when the light is used for printing photographs, that colour which takes longest to develop.