TRANSMISSION OF ADDITIONAL DATA WHEN CONVEYING DIGITAL SOUND SIGNALS IN THE FTURE ISDN.

In order to convey the bit-streams of two stereophonic or four monophonic digital sound signals of high quality in a single H 12 channel of the future integrated services digital network (ISDN), functioning at 1920 kbit/s, it has been suggested that the scale-factor words relating to the physical records of 2-ms sound periods may be transmitted using signaling-in-parity (SIP). The article shows the interrelationship between the bit-error ratio which mutilates a signal and the resulting error ratio for the additional data and the scale factors carried using SIP. It has been demonstrated experimentally that five-fold repetition of a bit of the additional data or the scale factor gives satisfactory results. A data-error ratio of approximately 5. 10** minus **6 can be expected with a bit-error ratio of 10** minus **3, corresponding to an improvement of approximately 2. 10**2. The computed synchronization time of 130 ms for scale-factor blocks of 2-ms duration, during transparent transmission in the H 12 channel, is relatively long compared to the 11 ms (approximately) in blocks synchronized to the frame. However, through the use of intermediate storage there will be no additional delay, and it is possible to combine data from separate signal sources for transmission in an H 12 channel without the need for synchronization with multiframes.