Abstract:
In an automatic telephone exchange certain subscribers can use short numbers instead of the directory numbers for calls to optionally selected extensions which often are called from the subscriber. The invention has for a purpose to indicate at the called subscriber''s instrument who is calling or has called with the use of a short number. A registering means for short numbers is arranged at the subscriber''s instrument. In the exchange identifying means and analyzer are arranged so that on one hand the identity of the called extension corresponding to a short number is indicated for connecting a telephone communication, on the other hand the short number of the calling subscriber valid at the called part is indicated for setting the registering means of the called subscriber''s instrument.
Abstract:
The invention relates to a method and a device for reducing the effect of a loss of information during transmission at compressed band width, particularly during transmission at compressed band width of a PCM-signal. Each of the serially generated PCM-words indicates the light intensity in picture elements that are serially scanned in a TV-frame, the number of transmitted PCMwords in each TV-frame being less than the number of generated PCM-words. According to the invention the effect of the loss of picture information is reduced in such a manner that when band width comprsssion is made TV-line by TV-line the loss will alternately occur on the left and right edges of the TV-lines on the screen viewed downwards in consecutive order and when band width compression is made TV-field by TV-field the loss will alternately occur on the upper and lower edges of the screen, the loss of picture information only appearing as a lesser degree of resolution along the respective edges of the screen.