System and method for phase modulation over a pulse width modulated/amplitude modulated signal for use in a radio controlled clock receiver
First Claim
1. A radio receiver method, said method comprising:
- receiving broadcast signal data frames comprising phase modulation (PM) over a legacy amplitude modulated (AM) signal, said broadcast signal transmitted as ‘
0’ and
‘
1’
bits encoded with time information separate from timing information, said timing information based on a known synchronization sequence spanning multiple seconds beginning at a known point within each data frame;
extracting said time and timing information from the phase of said received signal;
wherein said phase modulation comprises discontinuous binary phase shift keying (BPSK) modulation, wherein carrier amplitude transmitted during low portions of a bit is zero;
wherein information represented by said phase modulation is independent of information represented by said legacy amplitude modulation;
wherein said ‘
0’
bit is represented by said legacy amplitude modulated signal transmitted without a phase inversion; and
wherein said ‘
1’
bit is represented by said legacy amplitude modulated signal transmitted with a 180 degree phase inversion.
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Accused Products
Abstract
A system and method for a radio controlled clock receiver adapted to extract timing and time information from a phase modulated signal. The official time signal is broadcast from a central location using a modified modulation scheme, which adds phase modulation over the legacy amplitude modulation, such as the legacy WWVB pulse width modulated (PWM)/amplitude shift keying (ASK) modulation, thereby allowing for improved performance. The information modulated onto the phase contains a known synchronization sequence having good autocorrelation properties, error-correcting coding for the time information and notifications of daylight-saving-time (DST) transitions that are provided months in advance. The modulation scheme is based on a form of phase modulation, such as binary-phase-shift-keying (BPSK) or phase reversal keying (PRK). The reception of multiple frames with repeated or sequential information allows for the accumulation of received energy over multiple frames to provide for a corresponding gain in the receiver.
59 Citations
21 Claims
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1. A radio receiver method, said method comprising:
-
receiving broadcast signal data frames comprising phase modulation (PM) over a legacy amplitude modulated (AM) signal, said broadcast signal transmitted as ‘
0’ and
‘
1’
bits encoded with time information separate from timing information, said timing information based on a known synchronization sequence spanning multiple seconds beginning at a known point within each data frame;extracting said time and timing information from the phase of said received signal; wherein said phase modulation comprises discontinuous binary phase shift keying (BPSK) modulation, wherein carrier amplitude transmitted during low portions of a bit is zero; wherein information represented by said phase modulation is independent of information represented by said legacy amplitude modulation; wherein said ‘
0’
bit is represented by said legacy amplitude modulated signal transmitted without a phase inversion; andwherein said ‘
1’
bit is represented by said legacy amplitude modulated signal transmitted with a 180 degree phase inversion. - View Dependent Claims (2, 3, 4, 5)
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-
6. A radio receiver, comprising:
-
a receiver circuit operative to receive broadcast signal data frames comprising phase modulation (PM) over a legacy amplitude modulated (AM) signal, said broadcast signal transmitted as ‘
0’ and
‘
1’
bits encoded with time information separate from timing information, said timing information based on a known synchronization sequence spanning multiple seconds beginning at a known point within each data frame;a circuit operative to extract said time and timing information from the phase modulated portion of said received signal; wherein said phase modulation comprises discontinuous binary phase shift keying (BPSK) modulation, wherein carrier amplitude transmitted during low portions of a bit is zero; wherein information represented by said phase modulation is independent of information represented by said legacy amplitude modulation; wherein said ‘
0’
bit is represented by said legacy amplitude modulated signal transmitted without a phase inversion; andwherein said ‘
1’
bit is represented by said legacy amplitude modulated signal transmitted with a 180 degree phase inversion. - View Dependent Claims (7, 8, 9, 10)
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11. A radio receiver method, said method comprising:
-
receiving phase modulated (PM) broadcast signal data frames encoded with time information separate from timing information, wherein said phase modulation is applied over a legacy pulse-width modulated (PWM)/amplitude modulation (AM) signal and transmitted as ‘
0’ and
‘
1’
bits, said timing information based on a known barker code transmitted at a predictable point in each data frame;extracting said time and timing information from the phase modulation of said received signal; accumulating received energy over multiple broadcast signal data frames thereby providing a corresponding gain in reception; wherein information represented by said phase modulation is independent of information represented by said legacy pulse-width modulated (PWM)/amplitude modulation (AM); and wherein said ‘
0’
bit is represented by said legacy amplitude modulated signal transmitted without a phase inversion and wherein said ‘
1’
bit is represented by said legacy amplitude modulated signal transmitted with a 180 degree phase inversion, whereby the Euclidean distance between the ‘
0’ and
‘
1’
phase modulated waveforms is increased over that of the ‘
0’ and
‘
1’
legacy amplitude modulated waveforms thereby improving the performance of said radio receiver. - View Dependent Claims (12, 13, 14, 15)
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16. A radio receiver, comprising:
-
a receiver circuit operative to receive phase modulated (PM) broadcast signal data frames encoded with time information separate from timing information, wherein said phase modulation is applied over a legacy pulse-width modulated (PWM)/amplitude modulation (AM) signal and transmitted as ‘
0’ and
‘
1’
bits, said timing information based on a known barker code transmitted at a predictable point in each data frame;said receiver circuit further operative to accumulate received energy over multiple broadcast signal data frames thereby providing a corresponding gain in reception; a circuit operative to extract said time and timing information from the phase modulated portion of said received signal; wherein information represented by said phase modulation is independent of information represented by said legacy pulse-width modulated (PWM/amplitude modulation (AM); and wherein said ‘
0’
bit is represented by said legacy amplitude modulated signal transmitted without a phase inversion and wherein said ‘
1’
bit is represented by said legacy amplitude modulated signal transmitted with a 180 degree phase inversion, whereby the Euclidean distance between the ‘
0’ and
‘
1’
phase modulated waveforms is increased over that of the ‘
0’ and
‘
1’
legacy amplitude modulated waveforms thereby improving the performance of said radio receiver. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification