Broadcast wave synchronization signal converting device
A broadcast wave synchronization signal converting device that synchronizes broadcast waves with GNSS signals on a reception side and corrects the broadcast waves to global standard times by use of correction values, thereby performing periodic calibrations of frequencies. The broadcast wave synchronization signal converting device includes: a PLL circuit reproduces system clocks on the basis of time information acquired from received broadcast waves; a subtractor (C 1 ) subtracts, from a counter value corresponding to the periodic signal intervals of GNSS signals, a counter value of the system clocks counted at the signal intervals and outputs the difference value; a control amount adjustor calculates a control amount of synchronization as a correction value on the basis of the difference value; and a subtractor (B) subtracts the correction value from the acquired time information and sets the corrected time information to a PCR counter as the internal time information thereof.
1. A broadcast wave synchronization signal converting device configured to synchronize time information, acquired from received broadcast waves, with a Global Navigation Satellite System (GNSS) signal and set the synchronized time information to internal time information, comprising:
a phase synchronization unit configured to reproduce a system clock based on the acquired time information; and
a synchronization correction unit configured to correct the acquired time information to be synchronized with the GNSS signal,
wherein the synchronization correction unit has:
a subtractor which subtracts, from a counter value corresponding to a periodic signal interval of the GNSS signal, a counter value of the system clock counted in the signal interval and outputs a difference value;
a control amount adjustor which calculates, as a correction value, a control amount of synchronization based on the difference value;
a setting unit which subtracts the correction value from the acquired time information and sets corrected time information to the internal time information in the phase synchronization unit;
an edge detector which detects a 1PPS edge of a Global Positioning System (GPS) signal;
a first frequency divider which frequency-divides a reproduction clock of the GPS signal;
a second frequency divider which frequency-divides the system clock;
a first counter which counts a clock from the first frequency divider and outputs, to the subtractor, a counter value by using an edge detection signal from the edge detector; and
a second counter which counts a clock from the second frequency divider and outputs, to the subtractor, a counter value by using the edge detection signal from the edge detector, and
wherein the clock output from the first frequency divider is the same in frequency as the clock output from the second frequency divider.
2. The broadcast wave synchronization signal converting device according to claim 1 , wherein the control amount adjustor calculates correction values for a plurality of channels, creates a list in which information on the channels is associated with the correction values, and selects a channel small in correction value from the list.
3. The broadcast wave synchronization signal converting device according to claim 1 , wherein when a difference value between the acquired time information and the internal time information falls out of a specific range, the phase synchronization unit invalidates and masks the difference value.
4. A broadcast wave synchronization signal converting device configured to synchronize time information, acquired from received broadcast waves, with a Global Navigation Satellite System (GNSS) signal and set the synchronized time information to internal time information, comprising:
a phase synchronization unit configured to reproduce a system clock based on the acquired time information; and
a synchronization correction unit configured to correct the acquired time information to be synchronized with the GNSS signal,
wherein the synchronization correction unit has:
a subtractor which subtracts, from a counter value corresponding to a periodic signal interval of the GNSS signal, a counter value of the system clock counted in the signal interval and outputs a difference value;
a control amount adjustor which calculates, as a correction value, a control amount of synchronization based on the difference value;
a setting unit which subtracts the correction value from the acquired time information and sets corrected time information to the internal time information in the phase synchronization unit;
an edge detector which detects a 1PPS edge of a Global Positioning System (GPS) signal; and
a counter which counts the system clock and outputs, to the subtractor, a counter value by using an edge detection signal from the edge detector, and
wherein the subtractor receives input of the edge detection signal from the edge detector and holds a counter value in an interval of 1PPS of the GPS signal, and subtracts the counter value of the counter from the held counter value and outputs a difference value by using the edge detection signal.
5. The broadcast wave synchronization signal converting device according to claim 4 , wherein the control amount adjustor calculates correction values for a plurality of channels, creates a list in which information on the channels is associated with the correction values, and selects a channel small in correction value from the list.
6. The broadcast wave synchronization signal converting device according to claim 4 , wherein when a difference value between the acquired time information and the internal time information falls out of a specific range, the phase synchronization unit invalidates and masks the difference value.