Radio transmitter frequency synchronisation unit - has frequency divider to provide signal for telephone line transmission, and controlled local oscillator

摘要

A radio transmission network has a frequency synchronisation unit to ensure synchronous transmission of the various transmitters. It avoids the use of a special cable and may use existing telephone lines for linking the transmitters. The synchronisation unit has a local oscillator (10) and a frequency divider (16) at a first transmitter. An adaptor (18) connects the divider (16) to telephone lines (20). The lines (20) transmit the low frequency signal to another adaptor (22) at another transmitter which also has a phase comparator (24), a filter (25), an amplifier (27) and a local oscillator (26). The phase comparator is fedback with a signal from the oscillator (30). The transmitter unit (30) is driven by the local oscillator (26) which is controlled by the previous units (24, 25, 27).