EP0333419A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Transceivers
Assignee: Lucent Technologies Wireless Ltd
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Filing: 1989-03-14
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Granted: —
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Expires: 2009-03-14
Abstract
Abstract A time division duplex transceiver incorporating a dual conversion superheterodyne receiver, and in which the first receiver local oscillator (6) doubles as the frequency source for the transmitter. The oscillator (6) is a voltage controlled oscillator VCO forming part of a mixer-type phase locked loop (21). Frequency deviation in the loop is achieved by mixing the VCO output with a selected harmonic of the output of the second receiver local oscillator (11). The reference oscillator is a crystal controlled oscillator (41) whose output is switched as between transmit mode and receive mode at a switch (55) before being passed to the loop phase detector (28). The transceiver is able to rapidly and repeatedly alternate beween transmit and receive modes and is thus well suited to time division multiplex operation.
Inventors
- 👤 Graham Edgar Beesley
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 11:31
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/38; H04B1/40; H04B1/54; H04B1/56; H04B1/403; H04B1/408
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
52 words
A time division duplex transceiver comprising a transmitter section and a receiver section, and wherein some of the circuitry in the transmitter section is common to that in the receiver section, and wherein switch means are provided for switching the common circuitry alternately as between the two functions at transmit/receive alternation frequency.
Claim 2
Dependent Claim
52 words
A time division duplex transceiver comprising a transmitter section and a receiver section, and wherein some of the circuitry in the transmitter section is common to that in the receiver section, and wherein switch means are provided for switching the common circuitry alternately as between the two functions at transmit/receive alternation frequency.
Claim 3
Dependent Claim
93 words
A transceiver as claimed in Claim 1 wherein the receiver section is of the superheterodyne type and comprises a local oscillator and a mixer, and IF stage, said mixer receiving an incoming signal from an aerial and a signal from the local oscillator, which signals are mixed to produce a difference frequency for application to the IF stage, and wherein the transmitter section comprises an oscillator which is common to the local oscillator in the receiver section and an RF amplifier for amplifying the output of said oscillator for application to the aerial.
Claim 4
Dependent Claim
51 words
A transceiver as claimed in Claim 2 wherein the local oscillator is switchable between a first frequency for receive and a second frequency for transmit, and wherein the frequency difference between said first frequency and said second frequency is equal to the frequency of the IF stage, or a multiple thereof.
Claim 5
Dependent Claim
83 words
A transceiver as claimed in Claim 3 wherein the local oscillator comprises a voltage controlled oscillator VCO forming part of a main phase locked loop said phase locked loop further comprising a phase detector for detecting the phase difference between a first input derived from the output of the VCO and a second input derived from a reference oscillator, and a loop filter for low pass filtering the output of said phase detector for application to the frequency control input of said VCO.
Claim 6
Dependent Claim
31 words
A transceiver as claimed in Claim 4 in which the reference oscillator for the main phase locked loop comprises a crystal controlled oscillator having switchable output frequencies for transmit and receive.
Claim 7
Dependent Claim
76 words
A transceiver as claimed in Claim 5 wherein the crystal controlled reference oscillator itself comprises two further phase locked loops, each loop incorporating a programmable divider whose division ratio is set, one for transmit and one for receive, and switch means for selecting the output from one or the other of said further phase locked loops depending upon whether the transceiver is in transmit mode or receive mode for application to the main phase locked loop.
Claim 8
Dependent Claim
60 words
A transceiver as claimed in either one of Claims 5 or 6 in which the main phase locked loop is of the mixer type and additionally incorporates a mixer which mixes the VCO output frequency with the output from a further oscillator, and filter means for filtering the frequency difference output from said mixer for application to the phase detector.
Claim 9
Dependent Claim
86 words
A transceiver as claimed in any one of Claims 2 to 7, wherein the receiver section is of the dual conversion type and comprises a further (hereinafter referred to as second) local oscillator, a further (hereinafter referred to as second) mixer and a further (hereinafter referred to as second) IF stage, the second mixer receiving a signal from the first IF stage and a signal from the second local oscillator, which signals are mixed to produce a difference frequency for application to the second IF stage.
Claim 10
Dependent Claim
58 words
A transceiver as claimed in Claims 7 and 8 in which said further oscillator is the second local oscillator and means are provided for switching between a first multiple of its output frequency and a second multiple of its output frequency for application to said mixer according to whether the transceiver is in transmit mode or receive mode.
Claim 11
Dependent Claim
37 words
A transceiver as claimed in either one of Claims 8 or 9 wherein the transmitter section further comprises fsk modulator means for modulating the frequency of the second local oscillator with an analogue signal to be transmitted.
Claim 12
Dependent Claim
40 words
A transceiver as claimed in any one of Claims 2 to 10 wherein the receiver section further comprises detector means for demodulating received fsk signals, and amplifier means for amplifying the demodulated signals for application to a loudspeaker or earpiece.
References Cited (Backward Citations)
No citation records indexed.
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