초록 ▼

The local signal generation arrangement employed in a radio communication system for transmitting and/or receiving an upper sideband (USB) and a lower sideband (LSB) signal, but not simultaneously, employs a method in which the generation and/or detection of both USB and LSB signals is accomplished

The local signal generation arrangement employed in a radio communication system for transmitting and/or receiving an upper sideband (USB) and a lower sideband (LSB) signal, but not simultaneously, employs a method in which the generation and/or detection of both USB and LSB signals is accomplished by utilizing only one bandpass filter, a so-called single sideband (SSB) filter, together with a balanced modulator arranged to receive a carrier signal produced from an oscillator whose frequency is accordance with the characteristic frequency of either of a pair of crystal resonators, which correspond to the upper cut-off and the lower cut-off frequencies of the SSB bandpass filter, respectively. The output signal from the said SSB filter is referred to herein as the intermediate frequency (IF) signal. The local signal generation arrangement includes a phase-locked loop (PLL) including at least a phase comparator, a low pass filter, and a voltage-controlled oscillator (VCO). The arrangement further includes a standard signal oscillator, a frequency divider, and a pair of quartz crystal resonators used for the USB mode and for the LSB mode, respectively. The PLL further includes in its feedback loop a programmable frequency divider the division ratio of which is determined by a digital signal fed in parallel form from a channel selection means. The PLL optionally includes a mixer and a frequency selection means which is adapted to select one of harmonics produced from the mixer. These may be incorporated in order to reduce the frequency of the signal to be divided by the programmable frequency divider. If the mixer and the frequency selective means are used, then the arrangement also includes a frequency multiplier adapted to produce an output signal the frequency of which is an integral multiple of that of the input to said frequency multiplier.

대표청구항 ▼

A single sideband radio transmitter receiver having a transmitting section for selectively producing a transmission signal consisting of an upper sideband output signal and a lower sideband output signal, comprising: a first oscillator; a first pair of crystal resonators; first switch means coupled

A single sideband radio transmitter receiver having a transmitting section for selectively producing a transmission signal consisting of an upper sideband output signal and a lower sideband output signal, comprising: a first oscillator; a first pair of crystal resonators; first switch means coupled to said first oscillator and first pair of crystal resonators for selectively controlling the frequency of oscillation of said first oscillator by a first one and a second one of said first pair of crystal resonators, to thereby selectively produce a first output signal and a second output signal from said first oscillator; balanced modulator circuit means coupled to receive a modulation signal and responsive to said first output signal from said first oscillator for producing an output signal composed of a signal whose frequency is the sum of said modulation signal frequency and said first output signal frequency and a signal whose frequency is the difference between said modulation signal frequency and said first output signal frequency, and responsive to said second output signal from said first oscillator for producing an output signal composed of a signal whose frequency is the difference between said second output signal frequency and said modulation signal frequency and a signal whose frequency is the sum of said modulation signal frequency and said second output signal frequency; a single sideband bandpass filter having an upper cut-off frequency which is close to a resonant frequency of said first one of said first pair of crystal resonators and a lower cut-off frequency which is close to a resonant frequency of said second one of said first pair of crystal resonators, and coupled to receive the output signals from said balanced modulator, for selecting an upper sideband intermediate frequency signal, comprising said signal whose frequency is the sum of said modulation signal frequency and said first output signal frequency, and a lower sideband intermediate frequency signal, comprising said signal whose frequency is the differnce between said second ouput signal frequency and said modulation signal frequency; a standard reference frequency oscillator; a second pair of crystal resonators; second switch means for selectively connecting said standard reference frequency oscillator to each of said second pair of crystal resonators, and linked to said first switch means, for developing a first reference frequency signal from said standard reference frequency oscillator when said first output signal is being produced by said first oscillator and a second reference frequency signal when said second output signal is being produced by said first oscillator; a first frequency divider for dividing the frequency of the output signal from said standard reference frequency oscillator; frequency multiplier means coupled to the output of said standard reference frequency oscillator, for generating a signal whose frequency is an integral multiple of the frequency of the output signal from said standard reference frequency oscillator; a voltage-controlled oscillator, for producing a local oscillator signal, and having a frequency control input; a first frequency mixer having a first input coupled to receive said local oscillator signal from said voltage-controlled oscillator and a second input coupled to receiver the output from said frequency multiplying means; a filter coupled to receiver the output from said first frequency mixer, for selecting a signal of predetermined frequency from said first frequency mixer output; a programmable frequency divider having an input coupled to receiver said selected signal from said filter, and input terminals for receiving a first control signal comprising a digital signal in parallel form, said first control signal determining the division ratio of said programmable frequency divider; a phase comparator having a first input coupled to receive the output signal from said first frequency divider and a second input coupled to receive the output signal from said programmable frequency divider; a low pass filter coupled to receive the output from said phase comparator, for producing a second control signal indicative of a phase difference between said first frequency divider output and said programmable frequency divider output, said second control signal being applied to said frequency control input of the voltage controlled oscillator; and a second mixer coupled to receive said local oscillator signal from the voltage controlled oscillator and to the output of said single sideband bandpass filter, being responsive to said local oscillator signal and said upper sideband intermediate frequency signal for producing said upper sideband output signal; and being responsive to said local oscillator signal and said lower sideband intermediate frequency signal for producing said lower output signal.