Digital technique for FM modulation of infrared headphone interface signals
First Claim
1. A method for modulating an infrared headphone interface signal, comprising the steps of:
- providing a first audio signal having an analog audio value;
providing a memory having a plurality of locations and containing digital phase offset values;
providing a dock signal having a dock frequency;
providing a second audio signal having a center carrier frequency that deviates with the analog audio value of the first audio signal;
determining an instantaneous value of the center carrier frequency;
dividing the dock frequency by the instantaneous carrier frequency value to thereby calculate a number of samples per cycle;
dividing a number of location addresses in the memory by the number of samples per cycle to thereby calculate a memory access interval;
accessing the memory at location addresses separated by the calculated memory access interval; and
using the digital phase offset values at the accessed memory location addresses to reproduce the first audio signal by use of headphones.
1 Assignment
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Accused Products
Abstract
A method of modulating an infrared headphone interface signal includes providing a first audio signal having an analog audio value. A memory is provided having a plurality of locations and containing digital phase offset values. A clock signal having a clock frequency is provided. A second audio signal having a center carrier frequency that deviates with the analog audio value of the first audio signal is provided. An instantaneous value of the center carrier frequency is determined. The clock frequency is divided by the instantaneous carrier frequency value to calculate a number of samples per cycle. A number of location addresses in the memory is divided by the number of samples per cycle to calculate a memory access interval. The memory is accessed at addresses separated by the memory access interval. The digital phase offset values at the accessed memory addresses are used to reproduce the first audio signal.
6 Citations
20 Claims
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1. A method for modulating an infrared headphone interface signal, comprising the steps of:
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providing a first audio signal having an analog audio value; providing a memory having a plurality of locations and containing digital phase offset values; providing a dock signal having a dock frequency; providing a second audio signal having a center carrier frequency that deviates with the analog audio value of the first audio signal; determining an instantaneous value of the center carrier frequency; dividing the dock frequency by the instantaneous carrier frequency value to thereby calculate a number of samples per cycle; dividing a number of location addresses in the memory by the number of samples per cycle to thereby calculate a memory access interval; accessing the memory at location addresses separated by the calculated memory access interval; and using the digital phase offset values at the accessed memory location addresses to reproduce the first audio signal by use of headphones. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An audio headphone arrangement, comprising:
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a source of a first audio signal having an analog audio value; a pair of audio headphones including a memory device having a plurality of locations containing corresponding digital phase offset values; and an infrared transmitter apparatus including; a clock generator configured to produce a dock signal having a dock frequency; a receiver in communication with the source of the first audio signal; a phase offset generator in communication with the dock generator and with the receiver, the phase offset generator being configured to; sample a second audio signal that is dependent on the first audio signal, a frequency of the sampling being dependent upon the dock signal; and generate a phase offset signal dependent upon the sampling step; and a phase accumulator in communication with the phase offset generator and configured to; calculate a net phase value dependent upon the phase offset signal; and transmit an infrared signal to the headphones, the infrared signal being indicative of location addresses in the memory device to be accessed in order for the headphones to reproduce the first audio signal. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method of operating headphones, comprising the steps of:
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providing a memory having a plurality of locations and containing digital phase offset values; providing a second audio signal having a center carrier frequency that deviates with an analog audio value of a first audio signal; determining an instantaneous value of the center carrier frequency; dividing a frequency of a dock signal by the instantaneous carrier frequency value to thereby calculate a number of samples per cycle; dividing a number of location addresses in the memory by the number of samples per cycle to thereby calculate a memory access interval; transmitting an infrared signal indicating location addresses in the memory, the location addresses being separated by the calculated memory access interval; and using the digital phase offset values at the accessed memory location addresses to reproduce the first audio signal by use of the headphones. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification