Channel switching system

Abstract

A channel switching system in a digital radio transmission circuit with at least one regular channel and a standby channel has a received signal supply circuit, signal frequency divider circuits, signal order change circuits, a comparator, a hitless signal switching circuit and a frequency multiplier. Each channel transmits a digital multiplexed signal including a data signal of N (N is an integer of 1 or more) strings. The received signal supply circuit supplies a data signal to a receiving-side regular channel through a standby channel when a corresponding transmitting-side regular channel has a circuit failure. The signal frequency divider circuits N frequency-divide a data signal received through a regular channel and the data signal received through the received signal supply circuit. The signal order change circuits change orders of the N signal strings in response to different signal order change signals. The comparator supplies the regular or standby N signal string to the signal order change circuit when a noncoincidence is established, but generates a coincidence signal when a coincidence is established. The hitless signal switching circuit receives the signal string from the signal order change circuit and generates the regular or standby channel signal string in accordance with the coincidence signal from the comparator. The frequency multiplier multiplies an output from the hitless signal switching circuit with N.