| 摘要 |
PURPOSE:To improve the performance of privacy call by not only dividing a signal sent in space into a prescribed time slot and applying time compression to the signal but also dividing the frequency band of the signal and allocating the signal to a sub slot different timewise at random or in a prescribed order. CONSTITUTION:After a signal on a time axis is subject to speed change in a speed conversion circuit 131, the signal is divided for plural frequency bands and the signal of each band is allocated to plural divided sub slots included in each of specific time slot assigned in advance in a prescribed order or at random according to, e.g. a random number table and the result is sent. Then time slots assigned in advance are selected by a signal selection circuit 111 at a receiver side and signals for different frequency bands allocated to sub slots according to the same order to that at the sender side are synthesized at a same time and the signal is subject to speed conversion to the original pitch by a speed decoding circuit 138. Thus, the performance of privacy call is improved. |
