Superheterodyne tranceiver with bilateral first mixer and dual phase locked loop frequency control
First Claim
1. A transceiver operable in alternate receive and transmit modes, which comprises:
- a first conversion stage including a first mixer having an input terminal, an output terminal and an injection terminal, means for coupling the input terminal of the first mixer to antenna means for receiving and transmitting radio frequency signals, first means for generating frequency signals, first means for generating frequency signals at a numerically controlled frequency of a first range of frequencies coupled to the injection terminal of the first mixer for applying to the injection terminal of the first mixer an injection signal at a frequency for a frequency up-conversion during periods of operation of the transceiver in a transmit mode, and at a frequency for a frequency down-conversion during periods of operation of the transceiver in a receiver mode; and
a second conversion stage selectively coupled with said first conversion stage including a second mixer having an input terminal, an output terminal and an injection terminal, second means for generating frequency signals at a numerically controlled frequency of a second range of frequencies, frequency ratio circuit means for providing in response to a voltage controlled oscillator signal first and second frequency output signals at a two-to-one ratio, respectively, means for coupling a generated frequency signal from the second frequency generator to the frequency ratio circuit means, means for coupling the first frequency output signal to the output signal to the output terminal of the first mixer upon the transceiver being operable in the transmit mode and for coupling the second frequency output signal to the injection terminal of the second stage upon the transceiver being operable in the receive mode.
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Accused Products
Abstract
A transceiver which operates in separate transmit and receive bands has a first conversion stage for generating a first IF signal translation of a receive signal, which first conversion stage also functions as a first and final, hence, single conversion stage for generating a transmit signal at its transmission frequency. A modulated transmit signal component used in the single conversion to the transmission frequency of the transmission signal has harmonics which lie outside the transmission band and is of a frequency which permits a substantial overlap of transmit and receive injection frequencies generated by a first numerically controlled signal generator which are applied to a first mixer of the first conversion stage during respective transmit and receive mode operations.
287 Citations
12 Claims
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1. A transceiver operable in alternate receive and transmit modes, which comprises:
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a first conversion stage including a first mixer having an input terminal, an output terminal and an injection terminal, means for coupling the input terminal of the first mixer to antenna means for receiving and transmitting radio frequency signals, first means for generating frequency signals, first means for generating frequency signals at a numerically controlled frequency of a first range of frequencies coupled to the injection terminal of the first mixer for applying to the injection terminal of the first mixer an injection signal at a frequency for a frequency up-conversion during periods of operation of the transceiver in a transmit mode, and at a frequency for a frequency down-conversion during periods of operation of the transceiver in a receiver mode; and a second conversion stage selectively coupled with said first conversion stage including a second mixer having an input terminal, an output terminal and an injection terminal, second means for generating frequency signals at a numerically controlled frequency of a second range of frequencies, frequency ratio circuit means for providing in response to a voltage controlled oscillator signal first and second frequency output signals at a two-to-one ratio, respectively, means for coupling a generated frequency signal from the second frequency generator to the frequency ratio circuit means, means for coupling the first frequency output signal to the output signal to the output terminal of the first mixer upon the transceiver being operable in the transmit mode and for coupling the second frequency output signal to the injection terminal of the second stage upon the transceiver being operable in the receive mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A satellite communications system comprising;
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a first receiver means for receiving a first satellite signal from a plurality of satellites; and a transceiver having a second receiver stage and being operable in alternate receive and transmit modes, wherein the transceiver further comprises a first conversion stage including a first mixer having an input terminal, an output terminal and an injection terminal, means for coupling the input terminal of the first mixer to an antenna means for receiving and transmitting radio frequency signals, a first phase locked loop circuit including first phase detector and a first voltage controlled oscillator having a signal output terminal coupled to the injection terminal of the first mixer, and a numerically controlled frequency generator circuit coupled through the first phase detector to the voltage controlled oscillator for driving the voltage controlled oscillator alternatively at a frequency for a frequency up-conversion signal, and at a frequency for a frequency down-conversion signal during periods of operation of the transceiver in a transmit mode and in a receive mode, respectively, and a second conversion stage, selectively coupled with said first conversion stage, including a second mixer having respective input, output and injection terminals, a second phase locked loop circuit, the second phase locked loop circuit including a second phase detector and a second voltage controlled oscillator having a signal output terminal, circuit means for providing first and second signals at first and second frequencies at a two-to-one frequency relationship, respectively, the signal output terminal of the second voltage control led oscillator coupled to and forming part of the circuit means for providing first and second signals, means for alternatively coupling the first signal to the output terminal of the first mixer and the second signal to the injection terminal of the second mixer in response to the transceiver being operable, respectively, in the transmit mode and in the receive mode, a numerically controlled digital frequency synthesizer circuit coupled through the second phase detector to the second voltage controlled oscillator for driving the voltage controlled oscillator at a predetermined frequency corresponding to a channel-select injection signal, the channel-select injection signal having data modulation in response to the transceiver being operable in a transmit mode. - View Dependent Claims (11, 12)
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Specification