Digital radio transmission and reception system applying a direct modulation and demodulation method
First Claim
1. A digital radio transmission and reception system applying a direct modulation and demodulation method, comprising:
- a receiving part for selectively receiving a signal of a desired channel band, amplifying the received signal, mixing the amplified signal with a carrier frequency, subtracting a modulated signal to eliminate a carrier frequency, and then comparing the resulting signal with a reference level signal, thereby outputting demodulated digital data;
a transmitting part for power amplifying a modulated transmitting signal, filtering spurious components and then outputting the filtered transmitting signal;
a transmission and reception control switch for connecting an antenna to said transmitting part or said receiving part according to an input of a transmission and reception mode signal;
a phase locked loop modulator for oscillating the carrier frequency corresponding to an oscillation control signal, outputting the oscillated carrier frequency and generating said modulated transmitting signal by frequency shift keying modulating transmitting data to a frequency band of said oscillated carrier frequency;
a selection switch for switching an output of said phase locked loop modulator to said transmitting part or receiving part according to the transmission and reception mode signal; and
a control part for detecting the amount of frequency offset of receiving data demodulated in said receiving part or monitoring a state of the carrier frequency oscillated from said phase locked loop modulator, thereby generating the oscillation control signal to regularly maintain said oscillated carrier frequency as well as the transmission and reception mode signal according to an operational state.
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Accused Products
Abstract
A digital radio transmission and reception system capable of preventing shift of carrier by fading through receiving a modulated signal radio-transmitted, and then directly demodulating the signal. The digital radio transmission and reception system applying a direct modulation and demodulation method, including: a receiving part for selectively receiving a signal of a desired channel band, amplifying the received signal, mixing the selectively amplified signal with carrier frequency, subtracting a modulated signal in which eliminates the carrier frequency, and then comparing the signal with a reference level signal, thereby outputting demodulated digital; a transmitting part for power amplifying a demodulated transmitting signal, filtering spurious components and then outputting the filtered; a transmission and reception control switch for connecting the antenna to the transmitting part or the receiving part according to an input of a transmission and reception mode signal; a phase locked loop modulator for oscillating the carrier frequency corresponding to an oscillation control signal, outputting the oscillated carrier frequency, frequency shift keying modulating transmitting data as frequency of the carrier frequency band, thereby outputting the data; a second transmitting selection switch for switching an output of the phase locked loop modulator to the transmitting part or receiving part according to the transmitting mode control signal; and, a control part for detecting the amount of frequency offset of receiving data demodulated in the receiving part or monitoring a state of the carrier frequency oscillated from the phase locked loop modulator, thereby generating an oscillation control signal to constantly maintain the oscillated carrier frequency as well as a transmission and reception mode signal according to an operational state.
38 Citations
19 Claims
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1. A digital radio transmission and reception system applying a direct modulation and demodulation method, comprising:
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a receiving part for selectively receiving a signal of a desired channel band, amplifying the received signal, mixing the amplified signal with a carrier frequency, subtracting a modulated signal to eliminate a carrier frequency, and then comparing the resulting signal with a reference level signal, thereby outputting demodulated digital data; a transmitting part for power amplifying a modulated transmitting signal, filtering spurious components and then outputting the filtered transmitting signal; a transmission and reception control switch for connecting an antenna to said transmitting part or said receiving part according to an input of a transmission and reception mode signal; a phase locked loop modulator for oscillating the carrier frequency corresponding to an oscillation control signal, outputting the oscillated carrier frequency and generating said modulated transmitting signal by frequency shift keying modulating transmitting data to a frequency band of said oscillated carrier frequency; a selection switch for switching an output of said phase locked loop modulator to said transmitting part or receiving part according to the transmission and reception mode signal; and a control part for detecting the amount of frequency offset of receiving data demodulated in said receiving part or monitoring a state of the carrier frequency oscillated from said phase locked loop modulator, thereby generating the oscillation control signal to regularly maintain said oscillated carrier frequency as well as the transmission and reception mode signal according to an operational state. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A digital radio transmission and reception system applying direct modulation and direct demodulation, comprising:
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an antenna; a switch controlled by a transmitting and receiving mode control signal for selectively connecting said antenna to one of a receiving part and a transmitting part; said receiving part comprising; first filtering means for outputting a receiving signal by band pass filtering and amplifying a received signal of a desired receiving channel; a mixer for generating a demodulated signal by demodulating said receiving signal passed by said first filtering means by mixing said receiving signal with an oscillated carrier frequency generated by a voltage controlled oscillator; second filtering means for outputting a filtered demodulated signal having a constant output level by removing high frequency noise and limit amplifying said demodulated signal; and a comparator for outputting received digital data by comparing said filtered demodulated signal to a reference level; a controller for generating an oscillation control signal and a bit decision control pulse; a first integrator for outputting a DC signal by integrating said oscillation control signal; means responsive to said DC signal for generating an oscillator control signal for controlling said voltage controlled oscillator; a second integrator for outputting said reference level by integrating said bit decision control signal; and said transmitting part comprising; a Gaussian low pass filter for outputting transmitting data by receiving digital data to be transmitted and removing spurious noise components therefrom; said voltage controlled oscillator outputting a FSK signal by frequency shift keying said transmitting data in response to a reference signal generated by a phase locked loop; power amplifying means for outputting an amplified FSK signal by amplifying said FSK signal output from said voltage controlled oscillator; and low pass filter means for outputting a filtered FSK signal to said switch, wherein said switch provides said filtered FSK signal to said antenna in response to said transmitting and receiving mode control signal. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A digital radio transmission and reception system applying direct modulation and direct demodulation, comprising:
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an antenna; a first switch controlled by a transmitting and receiving mode control signal for selectively connecting said antenna to one of a receiving part and a transmitting part; said receiving part comprising; means for variably band pass filtering and amplifying a reception signal of a desired receiving channel received via said antenna, demodulating the amplified reception signal by mixing the amplified reception signal with an oscillated carrier frequency generated by a voltage controlled oscillator, and outputting recovered digital data by comparing the demodulated signal to a reference level signal; a controller for generating an oscillation control signal and a bit decision control pulse; a first integrator for outputting a DC signal by integrating said oscillation control signal; means responsive to said DC signal for generating for generating an oscillator control signal for controlling said voltage controlled oscillator; a second integrator for outputting said reference level signal by integrating said bit decision control signal; said transmitting part comprising; said voltage controlled oscillator outputting a FSK signal by frequency shift keying digital data to be transmitted in response to a reference signal generated by a phase locked loop; and a second switch controlled by said transmitting and receiving mode control signal for selectively connecting an output terminal of said voltage controlled oscillator to providing said oscillated carrier frequency to said means of said receiving part or said FSK signal to said first switch. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification