Inductive communication system with increased noise immunity using low-complexity transmitter
First Claim
Patent Images
1. A transmitter comprising:
- a pseudo noise generator which provides a pseudo noise signal;
a spread spectrum coder which receives an input signal and the pseudo noise signal and combines the input signal and the pseudo noise signal to generate a spread spectrum signal at a signal output port;
a pulse code modulator having a signal input port connected to the signal output port of the spread spectrum coder to pulse code modulate the spread spectrum coded signal, yielded by the spread spectrum coder, into a pulse-code modulated signal on a pulse code modulator output; and
an output stage connected to an output of the pulse code modulator output to output the pulse code modulated signal to a transducer for transmission.
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Abstract
A modulator for a communications system includes a spread spectrum coder and a pulse code modulator having a signal input port connectable to a signal output port of the spread spectrum coder. The modulator performs a robust and error free modulation and coding scheme by using a modified spread spectrum scheme combined with pulse code modulation. The communication system contains a low data rate, noise robust modulation and coding scheme using a very simple transmitter. This results in a very straightforward transmitter circuit, reducing size and costs of the transmitter.
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Citations
14 Claims
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1. A transmitter comprising:
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a pseudo noise generator which provides a pseudo noise signal; a spread spectrum coder which receives an input signal and the pseudo noise signal and combines the input signal and the pseudo noise signal to generate a spread spectrum signal at a signal output port; a pulse code modulator having a signal input port connected to the signal output port of the spread spectrum coder to pulse code modulate the spread spectrum coded signal, yielded by the spread spectrum coder, into a pulse-code modulated signal on a pulse code modulator output; and an output stage connected to an output of the pulse code modulator output to output the pulse code modulated signal to a transducer for transmission. - View Dependent Claims (2, 3, 4, 5)
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6. A demodulator for a communications system, the demodulator corresponding to a transmitter within said communications system and comprising:
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a correlator which performs a correlation of a received signal and a reference signal, the reference signal being representative of a system response of the transmitter when excited by a particular pulse-code modulated sequence, the particular pulse-code modulated sequence being representative of a selected pulse-code modulated value; a peak detector, an input port of the peak detector being connected to an output port of the correlator; and a spread spectrum decoder, an input port of the spread spectrum decoder being connected to an output port of the peak detector.
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7. A data transmission system for healthcare applications comprising:
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an on-body transmitter for mounting adjacent a body which absorbs E-field signals and propagates B-field signals, the transmitter including; a sent-site spread spectrum encoder which receives a data signal and encodes the data signal into a spread spectrum signal, a sent-site pulse-code modulator which receives the spread spectrum signal and encodes it into a pulse code modulated signal, an output stage which receives the pulse code modulated signal and applies the pulse code modulated signal to a transmit transducer to transmit a B-field signal; and a demodulator including; an input circuit connected with a receive transducer to receive the transmitted B-field signal, a pulse code demodulator which demodulates the B-field signal to generate a pulse code demodulated signal, and a spread spectrum decoder which decodes the pulse code demodulated signal to recover the data signal. - View Dependent Claims (8, 9)
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10. A method for transmitting data from a transmitter to a receiver comprising:
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performing a spread spectrum encoding on a signal representative of said data yielding a spread spectrum coded signal; performing a pulse code modulation on the spread spectrum coded signal yielding a pulse-code modulated signal; transmitting the pulse-code modulated signal; receiving the transmitted pulse-code modulated signal; performing a correlation of the pulse-code modulated signal and a reference signal to obtain a cross-correlation, the reference signal being representative of a system response of the transmitter when excited by a pulse-code modulated sequence, the pulse-code modulated sequence being representative of a selected value out of possible values of the spread spectrum coded signal; performing a peak detection on the cross-correlation. - View Dependent Claims (11, 12)
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13. A communications system for operating near a body that absorbs electrical field signals, the communications system comprising:
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a transmitter; and a demodulator including; an input circuit connected with a receive transducer to receive a transmitted pulse-coded signal, a pulse code demodulator which demodulates the transmitted pulse-coded signal to generate a pulse code demodulated signal, and a spread spectrum decoder which decodes the pulse code demodulated signal to recover a data signal. - View Dependent Claims (14)
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Specification