| 摘要 |
PURPOSE:To perform line monitoring with a small number of measuring errors even in a line state with low C/N for generating one-bit error in several frames by providing a frame comparator in addition to error check by a parity bit, and utilizing the information of the comparator in a digital radio circuit. CONSTITUTION:A reception signal is synchronized at a frame synchronization circuit 1, and is separated to data, a frame bit and the parity bit by a separation circuit 2. Circuit monitoring by the comparator 3 is performed in an ordinary operation. In other words, the parity bit P7 inputted to one of eight frames of CH1 is separated, and for example, a result in which the number of '1' is counted is compared and decided. Thence, when a line goes to a low C/N and the monitoring in unit of one multiframe using the parity bit approaches limitation, the bit string of frame synchronous patterns F1-F8 is separated, and the error is detected by the comparator 4. Since the frame pattern is known, it is possible to decide, for example, eight frame bits in one multiframe by bit unit and to control the number of multiframes for the measuring time by a control circuit 5. |
