WO2001069270A1 - Ameliorations apportees a un appareil de traitement de signal interferometrique - Google Patents

Ameliorations apportees a un appareil de traitement de signal interferometrique Download PDF

Info

Publication number
WO2001069270A1
WO2001069270A1 PCT/AU2001/000277 AU0100277W WO0169270A1 WO 2001069270 A1 WO2001069270 A1 WO 2001069270A1 AU 0100277 W AU0100277 W AU 0100277W WO 0169270 A1 WO0169270 A1 WO 0169270A1
Authority
WO
WIPO (PCT)
Prior art keywords
signal
port
coupling means
produce
oscillator
Prior art date
Application number
PCT/AU2001/000277
Other languages
English (en)
Inventor
Eugene Nikolay Ivanov
John Hartnett
Michael Edmund Tobar
Original Assignee
Poseidon Scientific Instruments Pty Ltd
The University Of Western Australia
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AUPQ6257A external-priority patent/AUPQ625700A0/en
Priority claimed from AUPR0986A external-priority patent/AUPR098600A0/en
Application filed by Poseidon Scientific Instruments Pty Ltd, The University Of Western Australia filed Critical Poseidon Scientific Instruments Pty Ltd
Priority to AU2001240360A priority Critical patent/AU2001240360A1/en
Publication of WO2001069270A1 publication Critical patent/WO2001069270A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
    • H03L7/00—Automatic control of frequency or phase; Synchronisation
    • H03L7/02—Automatic control of frequency or phase; Synchronisation using a frequency discriminator comprising a passive frequency-determining element
    • H03L7/04—Automatic control of frequency or phase; Synchronisation using a frequency discriminator comprising a passive frequency-determining element wherein the frequency-determining element comprises distributed inductance and capacitance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
    • G01R29/26—Measuring noise figure; Measuring signal-to-noise ratio
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/28—Measuring attenuation, gain, phase shift or derived characteristics of electric four pole networks, i.e. two-port networks; Measuring transient response

Definitions

  • This invention relates to improvements in interferometric signal processing apparatus.
  • Interferometric signal processing apparatus use an interferometric technique to minimise the noise contributions of the signal processing elements acting on the input signals, so that finer details of the difference between the input signals can be analysed with less limitation.
  • Interferometers make use of carrier suppression to achieve their sensitivity.
  • Interferometers have been used since Michelson and Morely to make precision measurements using electromagnetic waves. Interferometers perform a real time vector sum and difference of the two signals incident on their input ports.
  • Interferometers have two outputs. At one output the output corresponds to the sum of half of the power of each input port, this is the “Summing” or Sigma port. The other output corresponds to the difference of the power of each input port, this is the “Difference” or Delta port.
  • the frequency discriminator bridge described by Whitwell et al consists of a four port bridge in which one port is designated an input port, a second port designated an output port, a third port of the bridge is connected to a cavity and a fourth port of the bridge is connected to a variable attenuator and a tuneable short circuit.
  • Whitwell et al describes that the variable attenuator and tuneable short circuit are used to ensure an equal division of power between the third and fourth arms of the bridge and to ensure that any reflections arising in the third and fourth arms as a result of mismatches between the cavity at the carrier frequency are self-cancelling at the output port.
  • This configuration uses only reflected signals. Moreover, by equally dividing power between the arms of the bridge, the sensitivity of the interferometer is limited for a given power input.
  • an interferometric signal processing apparatus responsive to a first signal having a carrier frequency, comprising: coupling means responsive to the first signal to produce a second signal and a third signal therefrom;
  • frequency dispersive means connected to said coupling means and responsive to the second signal and the third signal to produce at least a reflected second signal from the second signal and at least a reflected third signal from the third signal;
  • said reflected second signal and said reflected third signal being input to said coupling means which produces a carrier-suppressed signal therefrom;
  • mixing means responsive to the carrier-suppressed signal and to a carrier-dominated signal to produce an output signal.
  • the frequency dispersive means comprises a bi-directional frequency dispersive element having a pair of ports, said second signal being incident on one port and said third signal being incident on the other port to produce a reflected second signal and a transmitted third signal at said one port and a reflected third signal and a transmitted second signal at said other port.
  • the first signal is input to a first port of the coupling means to produce the second and third signals at second and third ports of the coupling means, respectively, said one port of the frequency dispersive element being connected to the second port of the coupling means and said other port of the frequency dispersive element being connected to the third port of the coupling means.
  • the frequency dispersive element comprises a resonator.
  • a first phase shifter and a first attenuator are provided between the second port of the coupling means and the frequency dispersive element.
  • a second phase shifter and a second attenuator are provided between the third port of the coupling means and the frequency dispersive element.
  • said frequency dispersive means comprises:
  • mismatched termination means responsive to the third signal to produce the reflected third signal.
  • the first signal is input to a first port of the coupling means to produce the second and third signals at second and third ports of the coupling means, respectively, said frequency dispersive element being connected to the second port of the coupling means and said mismatched termination means being connected to the third port of the coupling means.
  • the coupling means is arranged such that a majority of the first signal is produced as the second signal at the second port and a minority of the first signal is produced as the third signal at the third port.
  • the frequency dispersive element is close to critically coupled.
  • a first phase shifter and a first attenuator are provided between the second port of the coupling means and the frequency dispersive element.
  • the mismatch termination means comprises a short circuit, and a second phase shifter and a second attenuator are provided between the third port of the coupling means and the short circuit.
  • the coupling means comprises a four-port coupler.
  • an amplifier is provided before the mixing means to provide an amplified, carrier-suppressed signal to the mixing means.
  • said apparatus further comprises a control circuit responsive to the output signal to produce a control signal, and one of the first phase shifter or the second phase shifter being responsive to the control signal to control operation thereof and maintain carrier suppression.
  • said apparatus further comprises a control circuit responsive to the output signal to produce a control signal, and one of the first attenuator or the second attenuator being responsive to the control signal to control operation thereof and maintain carrier suppression.
  • an oscillator comprising a signal source that produces a first signal having a carrier frequency, and an interferometric signal processing apparatus according to the first aspect of this invention, responsive to the first signal.
  • said oscillator further comprises a control circuit responsive to the output signal from the mixing means and arranged to produce a control signal therefrom, the signal source responsive to the control signal in producing the first signal to reduce amplitude and/or phase noise in the first signal.
  • an oscillator comprising an amplifier, a filter, and a circulator arranged in a loop, and an interferometric signal processing apparatus according to the first aspect of this invention, responsive to a first signal from the oscillator having a carrier frequency, wherein the frequency dispersive element of the interferometric signal processing apparatus is provided in said loop of the oscillator such that a portion of the second or third transmitted signal from the frequency dispersive element circulates around said loop.
  • the first signal is input to a first port of the coupling means to produce the second and third signals at second and third ports of the coupling means, respectively, said one port of the frequency dispersive element being connected to the second port of the coupling means and a directional coupler is provided in the loop at the other port of the frequency dispersive element, whereby a portion of the second transmitted signal passes though the loop and the remainder passes to the third port of the coupling means.
  • said oscillator further comprises a variable attenuator and/or a variable phase shifter provided in said loop of the oscillator, and a control circuit responsive to the output signal from the mixing means to produce a control signal, said control signal being input to the variable attenuator and/or phase shifter to control operation thereof to reduce amplitude and/or phase noise in the oscillator.
  • Figure 1 shows a cavity-stabilised oscillator incorporating an interferometric signal processing apparatus according to a first embodiment of the invention
  • Figure 2 shows a cavity-stabilised oscillator incorporating an interferometric signal processing apparatus according to a second embodiment of the invention
  • Figure 3 shows a cavity-stabilised oscillator incorporating an interferometric signal processing apparatus according to a third embodiment of the invention
  • Figure 4 shows a loop oscillator incorporating an interferometric signal processing apparatus according to a fourth embodiment of the invention
  • Figure 5 shows a loop oscillator incorporating an interferometric signal processing apparatus according to a fifth embodiment of the invention
  • Figure 6 shows a Pound-stabilised loop oscillator incorporating an interferometric signal processing apparatus according to a sixth embodiment of the invention.
  • Figure 7 shows loop oscillator incorporating a Pound-stabilised interferometric signal processing apparatus according to a seventh embodiment of the invention.
  • the first embodiment is directed towards a cavity-stabilised oscillator that incorporates an interferometric signal processing apparatus (interferometer) 10.
  • the oscillator and the interferometer 10 are shown in figure 1.
  • the interferometer 10 shown in Figure 1 is also arranged to be used as a read-out system since the interferometer provides signals corresponding to amplitude and phase noise in the signal source.
  • the interferometer 10 comprises a four-port coupler 12 in the form a 3dB hybrid power combiner having first through fourth ports 12a - 12d, respectively.
  • a signal source S produces a first signal that is input to the first port 12a of the four port coupler 12, which produces a second signal at the second port 12b denoted by the arrow labelled with the numeral 2 and a third signal at third port 12c denoted by the arrow labelled with the numeral 3.
  • the interferometer 10 further comprises a cavity resonator 14 having two ports A and B.
  • the ports A and B of the cavity resonator 14 are connected to the ports 12b and 12c of the four-port coupler 12, respectively.
  • a first phase shifter 16 and a first attenuator 18 are provided between the second port 12b of the four-port coupler 12 and the port A of the cavity resonator 14.
  • a second phase shifter 20 and second attenuator 22 are provided between the third port 12c of the fourth port coupler 12 and the port B of the cavity resonator 14.
  • the cavity resonator 14 is used as a frequency dispersive element. That is, the cavity resonator 14 alters the phase of signals passing through the cavity resonator 14 or reflected at ports A and B depending upon the frequency of the signal.
  • An amplifier 24 is connected to the fourth port 12d of the four port coupler 12. The output of the amplifier 24 is split and input to the RF ports of two mixers 26a and 26b.
  • a carrier-dominated signal is provided to the LO port of the mixers 26a and 26b.
  • the carrier-dominated signal is the first signal obtained via the coupler 28 and phase shifter 30.
  • the mixers 26a and 26b produce outputs at their IF ports which are base-band signals corresponding to the phase noise, amplitude noise or combination thereof according to the phase difference between the signals appearing at the LO and RF ports of the mixers 26a and 26b.
  • the output at its IF port will correspond with the amplitude noise present in the first signal. If the signals appearing at the LO and RF ports of a mixer are in quadrature (i.e. a phase difference of 90 degrees), the output at its IF port will correspond with the phase noise in the first signal. Phase differences between in phase and quadrature will correspond with the output of the mixer representing a mixture of the amplitude noise and phase noise.
  • the mixer 26a is arranged such that the signals appearing at its LO and RF ports are in phase so that the output of the mixer, shown in figure 1 as I, represents the amplitude noise in the signal source S.
  • the mixer 26b is arranged such that the signals appearing at its LO and RF ports are in quadrature so that the output of the mixer 26b, shown in figure 1 as Q, represents the phase noise in the signal source S.
  • the phase difference between the signals appearing at the LO and RF ports of the mixers 26a and 26b can be achieved by adjusting the relative path length of the signals.
  • the phase shifter 30 can be replaced with a pair of phase shifters, one before each of the mixers 26a and 26b to allow separate adjustment of the relative phase of each of the mixers 26a and 26b.
  • the source signal is input to the first port 12a of the four port coupler 12, which results in the second and third signals 2,3 appearing at the ports 12b and 12c.
  • the second signal 2 passes through the first phase shifter 16 and the first attenuator 18, into the port A of the cavity resonator 14. Some of the second signal 2 will be transmitted through the cavity resonator 14 to appear at the port B as a transmitted second signal presented by the arrow labelled 2T, and a portion of the second signal 2 will be reflected at the port A to produce a reflected second signal denoted by the arrow labelled 2R.
  • the third signal 3 passes through the second phase shifter 20 and the second attenuator 22, into the port B of the cavity resonator 14. A portion of the third signal 3 is transmitted through the cavity resonator 14 to produce a transmitted third signal denoted by the arrow labelled 3T at port A, and a portion of the third signal 3 will reflected at port B to produce a reflected third signal denoted by the arrow labelled 3R.
  • the transmitted third signal 3T and the reflected second signal 2R pass through the first attenuator 18 and the first phase shifter 16 and are input to the second port 12b of the four port coupler 12.
  • the reflected third signal 3R and the transmitted second signal 2T pass through the second attenuator 22 and the second phase shifter 20 and are input to the third port 12c of the four port coupler 12.
  • the four port coupler 12 acts to produce a signal corresponding to the vector difference between the signals appearing at the second and third ports 12b and 12c at the fourth port 12d, and to produce a signal corresponding to the sum of the signals input to the second and third port 12b and 12c at the first port 12a. Consequently, the signal appearing at the fourth port 12d is a carrier-suppressed signal and the signal appearing at the port 12a is carrier-dominated signal.
  • the carrier-suppressed signal at the port 12d is amplified by the amplifier 24 and input to the RF ports of the mixers 26a and 26b.
  • a carrier dominated signal is supplied to the LO ports of the mixers 26a and 26b via the coupler 28 and phase shifter 30.
  • coupler 12 may be used, and the coupling on the ports of the cavity resonator 14 would then be adjusted such that the power of the reflected and transmitted signals 2R + 3T, and 2T + 3R, input to the coupler 12 produce a carrier-suppressed signal at the input to the amplifier 24.
  • the carrier-dominated signal is derived from the source signal, it should be appreciated that the carrier-dominated signal could also be the signal appearing at the port 12a.
  • the interferometer configuration used in this embodiment makes use of reflected and transmitted signals form the cavity resonator 14, and therefore offers increased sensitivity compared with existing interferometer configurations.
  • the oscillator in addition to the interferometer 10 and the signal source S, further comprises first and second control circuits 40a and 40b, respectively.
  • the first and second control circuits 40a and 40b are responsive to the outputs of the mixers 26a and 26b via switches 42a and 42b, respectively.
  • the control circuits 40a and 40b apply appropriate signal conditioning to the output of the mixers 26a and 26b and apply the condition signals to the signal source S in order to control the amplitude and phase noise in the signal source S, respectively.
  • One example of how this can be achieved is by the use of voltage control attenuators and voltage control phase shifters within the signal source S.
  • the switches 42a and 42b allow the independent, selective enabling of the control circuits 40a and 40b. Further, the switches 42a and 42b can be configured to pass the signals I and Q to an output for external measurement. In other embodiments, the switches 42a and 42b may be omitted or replaced with a permanent connection, as desired.
  • the signal source S is stabilised to the limits imposed by the stability of the cavity resonator 14 and the noise of the remaining components in the interferometer 10 and the oscillator.
  • a coupler 44 is provided between the signal source S and the coupler 28 to provide an oscillator output at 46.
  • the second embodiment is directed towards a cavity-stabilised oscillator 100 incorporating an interferometric signal processing apparatus 110, and is shown in figure 2.
  • a cavity-stabilised oscillator 100 incorporating an interferometric signal processing apparatus 110, and is shown in figure 2.
  • the interferometer 110 of the second embodiment differs from the interferometer 10 of the first embodiment in that the cavity resonator 114, the phase shifters 116 and 120 and the coupler 112 are arranged such that the carrier-suppressed signal is produced at the first port 112a and a carrier-dominated signal is produced at the fourth port 112d.
  • the interferometer 110 of the second embodiment further comprises a matched termination 132 connected to the fourth port 110d to dissipate the carrier- dominated signal.
  • the interferometer 110 further comprises a circulator 134 provided between the signal source S and the first port 112a of the coupler 112.
  • the circulator 134 is arranged such that the first signal from the signal source S passes through the circulator 134 to the first port 112a, whilst the carrier-suppressed signal produced at the first port 112a passes from the circulator 134 to the amplifier 124 that is connected to the circulator 134.
  • the carrier-dominated signal for the mixers 126a and 126b could be provided from the fourth port 112d if desired.
  • the oscillator 100 of this embodiment operates in a similar manner to the oscillator described in relation to the first embodiment.
  • the third embodiment is directed towards a cavity-stabilised oscillator 200 incorporating an interferometric processing apparatus 210.
  • the oscillator 200 and the interferometer 210 in this embodiment are of a similar form to those shown in the second embodiment, and like reference numerals are used to denote like parts to those in the second embodiment with 100 added thereto.
  • the third embodiment differs from the second embodiment in that the cavity resonator 214 used in the fifth embodiment has a single port A that is connected to the second port 212b of the coupler 212. Further, the third port 212c is connected to the second attenuator 222 and the second phase shifter 220, and is then terminated by a mismatched termination in a form of a short circuit 236.
  • mismatched termination can refer to any non-impedance matched termination. Any non-impedance matched termination will produce a reflected signal that may also be phase shifted. In some embodiments, if the phase shift present from the mismatched termination is of a desired quantity, the second phase shifter 220 may not be necessary. However, it is preferred that the second phase shifter 220 is retained to allow fine adjustments and tuning of the interferometer.
  • interferometer 210 shown in figure 3 appears to be quite different from the configuration of the interferometer 110 shown in figure 2, the two are quite similar.
  • the interferometer 210 differs from the interferometer 110 in the second embodiment in that the first attenuator 118 and the first phase shifter 116 are not present in the interferometer 210.
  • the cavity 214 is directly connected to the port 212b of the coupler 212. Amplitude and phase matching of the reflected signals from the cavity resonator 214 and the short circuit 236 can be achieved by adjusting the second phase shifter and second attenuator 220 and 222, respectively.
  • the interferometer 210 operates in the same general manner as the interferometer 110 described in figure 2 with the following exceptions.
  • the second signal appearing at port 212b passes in to the port A of the resonator 214. Since the coupling of port A is close to 1 , most of the carrier power in the second signal passes in to the resonator 214.
  • a reflected signal, 2R is produced at port A of the resonator 214 due to the non-perfect coupling of port A and also due to any non-carrier components in the second signal.
  • the reflected signal 2R passes in to the second port 212b of the coupler 212.
  • the third signal produced at port 212c passes through the second attenuator 222 and the second phase shifter 220 and to the short circuit 236.
  • a reflected signal, 3R is produced at the short circuit 236 because of the impedance mismatch, and the reflected signal 3R passes through the second phase shifter 220 and the second attenuator 222 to pass into the third port 212c of the coupler 212.
  • the coupler 212 acts on the reflected signals from the resonator 214 and the short circuit 236 to produce a carrier suppressed signal at the first port 212a and carrier-dominated signal at the fourth port 212d.
  • the interferometer 210 is does not make use of transmitted signals, the sensitivity of the interferometer can be improved by arranging the coupler 212 so that the majority of the first signal appearing at port
  • the coupling at port A of the resonator 214 can be tuned to provide an insertion loss of 20dB or more. As a result, the power of the carrier present in the signal reflected from port
  • A is 20dB less than the carrier power present in the second signal at port 212b, while the noise close to the carrier is reflected without significant attenuation.
  • the reflected signal appearing at port 212c does not need to contain much power in order to achieve carrier suppression.
  • the interferometer 210 can achieve increased sensitivity.
  • the fourth embodiment is directed towards a loop oscillator 300 incorporating an interferometric signal processing apparatus (interferometer) 302.
  • the loop oscillator 300 comprises an amplifier 304, a circulator 306, a filter 308, a voltage-controlled attenuator 310 and a voltage-controlled phase shifter 312 arranged in a loop.
  • a directional coupler 314 is provided between the filter 308 and the voltage-controlled attenuator 310 to provide an output signal from the loop oscillator 300 at 316.
  • the interferometer 302 comprises a four-port coupler 318 in the form a hybrid power combiner having first through fourth ports 318a - 318d, respectively.
  • the four-port coupler 318 is provided in the loop of the oscillator 300 after the circulator 306, such that a first signal from the amplifier 304 passes through the circulator 306 to the first port 318a of the four-port coupler 318.
  • the four-port coupler 318 produces a second signal at the second port 318b denoted by the arrow labelled with the numeral 2 and a third signal at third port 318c denoted by the arrow labelled with the numeral 3.
  • the interferometer 302 further comprises a cavity resonator 320 having two ports A and B.
  • the cavity resonator 320 is also provided in the loop of the oscillator 300, with the port A of the cavity resonator 320 connected to the second port 318b of the four-port coupler 318, and the port B of the cavity resonator 320 connected to the filter 308.
  • the interferometer 302 further comprises a phase shifter 322, an attenuator 324 and a mismatched termination 326 in the form of a short circuit that are connected to the third port 318c of the four-port coupler 318.
  • the cavity resonator 320 is used as a frequency dispersive element. That is, the cavity resonator 320 alters the phase of signals passing through the cavity resonator 320 or reflected at port A depending upon the frequency of the signal.
  • a matched termination 328 is connected to the fourth port 312d of the four-port coupler 318.
  • An amplifier 330 is connected to the circulator 306 such that any signals output from the first port 318a of the four-port coupler 318 are input to the amplifier 330 via the circulator 306.
  • the output of the amplifier 330 is split and input to the RF ports of two mixers 332a and 332b.
  • a carrier-dominated signal is provided to the LO port of the mixers 332a and 332b.
  • the carrier-dominated signal is the signal in the loop oscillator obtained via a directional coupler 334 provided in the loop of the oscillator 300 at the output of the amplifier 304.
  • Two phase shifters 336a and 336b are provided between the directional coupler 334 and the LO port of the mixers 332a and 332b, respectively.
  • the mixers 332a and 332b produce outputs at their IF ports that are base-band signals corresponding to the phase noise, amplitude noise or combination thereof in the loop oscillator, according to the phase difference between the signals appearing at the LO and RF ports of the mixers 332a and 332b.
  • the output at its IF port will correspond with the amplitude noise present in the first signal. If the signals appearing at the LO and RF ports of a mixer are in quadrature (i.e. a phase difference of 90 degrees), the output at its IF port will correspond with the phase noise in the first signal. Phase differences between in phase and quadrature will correspond with the output of the mixer representing a mixture of the amplitude noise and phase noise.
  • the mixer 332a is arranged such that the signals appearing at its LO and RF ports are in phase so that the output of the mixer, shown in figure 4 as I, represents the amplitude noise in the loop oscillator 300.
  • the mixer 332b is arranged such that the signals appearing at its LO and RF ports are in quadrature so that the output of the mixer 332b, shown in figure 7 as Q, represents the phase noise in the loop oscillator 300.
  • the phase difference between the signals appearing at the LO and RF ports of the mixers 332a and 332b can be achieved by adjusting the phase shifters 336a and 336b, respectively.
  • a portion of the signal output from the amplifier 304 is coupled from the loop via the directional coupler 334 and input to the phase shifters 336a and 336b.
  • the remainder of the signal from the amplifier 304 passes through the circulator 306 and is input to the first port 318a of the four-port coupler 318. This results in the second and third signals 2,3 appearing at the ports 318b and 3 8c.
  • the second signal 2 is incident on port A of the cavity resonator 320. Some of the second signal 2 will be transmitted through the cavity resonator 320 to appear at port B as a transmitted second signal presented by the arrow labelled 2T, and a portion of the second signal 2 will be reflected at the port A to produce a reflected second signal denoted by the arrow labelled 2R.
  • the third signal 3 passes through the phase shifter 322 and the attenuator 324 is incident on the short circuit 326. A portion of the third signal 3 will be reflected at the short circuit 326 because it is a mismatched termination, to produce a reflected third signal denoted by the arrow labelled 3R.
  • the transmitted second signal 2T passes from port B of the cavity resonator 320 to the filter 308, and from there through the variable attenuator 310 and the variable phase shifter 312 to the amplifier to complete the loop.
  • the centre frequency of the cavity resonator 320 determines the frequency of the loop oscillator 300.
  • the reflected second signal 2R is input to the second port 318b of the four-port coupler 318.
  • the reflected third signal 3R passes through the attenuator 324 and the phase shifter 322 and is input to the third port 318c of the four-port coupler 318.
  • the four-port coupler 318 acts to produce a signal at the first port 318a corresponding to the vector difference between the signals appearing at the second and third ports 318b and 318c, and to produce a signal corresponding to the sum of the signals input to the second and third port 318b and 318c at the fourth port 318d. Consequently, the signal appearing at the first port 318a is a carrier-suppressed signal and the signal appearing at the fourth port 318d is carrier-dominated signal.
  • the carrier-suppressed signal at the first port 318a passes to the amplifier 330 via the circulator 306.
  • the carrier-suppressed signal is amplified by the amplifier 330 and is input to the RF ports of the mixers 332a and 332b.
  • a carrier dominated signal is supplied to the LO ports of the mixers 332a and 332b via the coupler 334 and phase shifters 336a and 336b.
  • the mixers 332a and 332b produce output signals I and Q, respectively, corresponding to the amplitude and phase noise in the loop oscillator 300.
  • the oscillator 300 further comprises first and second control circuits 338a and 338b that are responsive to the outputs of the mixers 332a and 332b via switches 360a and 360b, respectively.
  • the control circuits 338a and 338b apply appropriate signal conditioning to the output signals I and Q and apply the conditioned signals to the variable attenuator 310 and the variable phase shifter 312 in order to control the amplitude and phase noise in loop oscillator 300, respectively, using negative feedback.
  • the interferometer 302 in this embodiment makes use of reflected signals only from the second and third signals 2 and 3.
  • the sensitivity of the interferometer 302 can be increased.
  • the sensitivity of the interferometer 302 may be sufficient that the amplifier 330 may be omitted.
  • the fifth embodiment is directed towards a loop oscillator 400 incorporating an interferometric signal processing apparatus 402.
  • the loop oscillator 400 and the interferometric signal processing apparatus 402 are of the same general form as the oscillator 300 and interferometer 302 described in the fourth embodiment.
  • Like reference numerals are used to denote like parts to those used in the fourth embodiment, with 100 added thereto.
  • This embodiment differs from the fourth embodiment in that the attenuator 410 is not a voltage-controlled attenuator.
  • the attenuator 422 that is connected to the third port 418c of the four-port coupler 418 is a voltage-controlled attenuator in this embodiment.
  • the output from the control circuit 438a is input to the voltage-controlled attenuator 422 to maintain carrier suppression at the input of the amplifier 430.
  • phase shifter 424 is a voltage-controlled phase shifter.
  • a control signal can be applied to the voltage-controlled phase shifter 424 from an input 440.
  • the control signal from the input 440 allows for externa) adjustment of the oscillator frequency, allowing the oscillator to be phase locked to an external source.
  • the sixth embodiment is directed towards a Pound-stabilised loop oscillator 500 having an interferometric signal processing apparatus 502 incorporated therewith.
  • the loop oscillator 500 and the interferometer 502 are of the same general form as the oscillator 400 and interferometer 402 described in the fifth embodiment.
  • Like reference numerals are used to denote like parts to those used in the fifth embodiment, with 100 added thereto.
  • the sixth embodiment differs from the fifth embodiment in that the loop oscillator 500 in the sixth embodiment is a Pound-stabilised oscillator and accordingly includes a local oscillator 550. Outputs from the local oscillator 550 and the controi circuit 538b are feed into a summing circuit 552 which provides a summed signal to the voltage-controlled phase shifter 512. By feeding the output from the local oscillator 550 to the voltage-controlled phase shifter 512, the loop frequency of these signals in the loop oscillator 500 varies with the signal from the loop oscillator 550. This technique is referred to as Pound-stabilisation.
  • the loop oscillator 500 is Pound-stabilised, information concerning the signal in the loop will appear at both the baseband frequency and at the oscillation frequency of the local oscillator 550. Accordingly, the output signal from the mixer 532b, in addition to being input to the control circuit 538b, is input to an amplifier 554. The output of the amplifier 554 is input to the RF port of a further mixer 556. The local oscillator 550 provides the LO input for the mixer 556. The output of the mixer 556 provides information concerning any drift in the frequency of the oscillator 500 from the centre frequency of the cavity resonator 520, and is labelled Q' in figure 6. This signal Q' is input to a further control circuit 538c, the output of which is also passed to the summing circuit 552 to eliminate this drift and improve the long term stability of the oscillator 500.
  • the seventh embodiment is directed towards a loop oscillator 600 incorporating an interferometric signal processing apparatus (interferometer) 602.
  • the loop oscillator 600 and interferometer 602 are of a similar form to the loop oscillator 500 and interferometer 502 described in relation to the sixth embodiment. Accordingly like reference numerals are used to denote like parts to those in the sixth embodiment, with 100 added thereto.
  • the current embodiment differs from the sixth embodiment in that the loop oscillator 650 is not fed to the voltage-controlled phase shifter 612 in the loop oscillator 600. Instead, the local oscillator 650 is fed to the phase shifter 624 of the interferometer 602. This arrangement allows the frequency in the loop oscillator 600 to operate without being modulated by the local oscillator 650, but still provide the advantages of a Pound-stabilised system in order to provide signals Q and Q' to the voltage-controlled phase shifter 612.
  • the short circuit 626 in the sixth embodiment has been replaced with a directional coupler 658 in this embodiment that is provided at port B of the cavity resonator 620.
  • the interferometer 602 acts as a bi-directional interferometer, with signals passing through the cavity 620 in both directions, and the interferometer making use of both transmitted and reflected signals from the cavity resonator 620.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Instruments For Measurement Of Length By Optical Means (AREA)

Abstract

Cette invention a trait à un appareil de traitement de signal interférométrique (10, 110, 210, 310, 410, 510, 610). On fournit un premier signal à un coupleur (12, 112, 212, 312, 412, 512, 612) qui subdivise ce premier signal afin de produire un deuxième (2) et un troisième (3) signal. Ces deux derniers (2, 3) sont envoyés à des éléments de dispersion de fréquence, tels qu'un résonateur (14, 114, 214, 314, 414, 514, 614) et une terminaison désadaptée (236, 336, 436, 536). Ces éléments de dispersion de fréquence, qui produisent des signaux réfléchis (2R, 3R), peuvent également produire des signaux émis (2T, 3T) par le deuxième et le troisième signal (2, 3). Les signaux réfléchis (2R, 3R) et les signaux émis (2T, 3T), s'ils existent, sont introduits dans le coupleur (12, 112, 212, 312, 412, 512, 612) afin de produire un signal à suppression de porteuse utilisé pour produire des signaux de sortie (I, Q). On peut, en agissant sur la quantité relative de puissance du deuxième et du troisième signal (2, 3), et/ou en utilisant les signaux réfléchis et les signaux transmis (2R, 3R, 2T, 3T), augmenter la sensibilité de l'interféromètre. Cette invention a également trait aux applications de l'interféromètre, y compris un oscillateur à stabilisation de cavité et un oscillateur à boucle.
PCT/AU2001/000277 2000-03-14 2001-03-14 Ameliorations apportees a un appareil de traitement de signal interferometrique WO2001069270A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001240360A AU2001240360A1 (en) 2000-03-14 2001-03-14 Improvements in interferometric signal processing apparatus

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
AUPQ6257A AUPQ625700A0 (en) 2000-03-14 2000-03-14 Improvements in interferometric signal processing apparatus
AUPQ6257 2000-03-14
AUPR0986A AUPR098600A0 (en) 2000-10-24 2000-10-24 Improvements in interferometric signal processing apparatus
AUPR0986 2000-10-24

Publications (1)

Publication Number Publication Date
WO2001069270A1 true WO2001069270A1 (fr) 2001-09-20

Family

ID=25646277

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU2001/000277 WO2001069270A1 (fr) 2000-03-14 2001-03-14 Ameliorations apportees a un appareil de traitement de signal interferometrique

Country Status (1)

Country Link
WO (1) WO2001069270A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016115430A1 (fr) * 2015-01-16 2016-07-21 Raytheon Company Système de réduction de bruit d'amplitude et procédé pour oscillateurs à très faible bruit de phase

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2209221A (en) * 1987-09-01 1989-05-04 Litton Systems Inc A demodulator circuit for an interferometer type of hydrophone
US4881813A (en) * 1988-05-20 1989-11-21 The United States Of America As Represented By The Secretary Of The Navy Passive stabilization of a fiber optic nonlinear interferometric sensor
US5488503A (en) * 1995-02-09 1996-01-30 Hughes Aircraft Company Low-power, stabilized, photonic modulator system
US5555086A (en) * 1991-05-31 1996-09-10 Litton Systems, Inc. Coherence multiplexed interferometric signal processing system and method
US5598264A (en) * 1995-05-18 1997-01-28 Failes; Michael Noise compensated interferometric measuring device and method using signal and reference interferometers
WO1997046890A1 (fr) * 1996-05-31 1997-12-11 Poseidon Scientific Instruments Pty. Ltd. Appareil de traitement interferometrique du signal
DE19820295C1 (de) * 1998-05-07 1999-12-09 Bosch Gmbh Robert Optisches Dämpfungsglied, Anordnung optischer Dämpfungsglieder und Verfahren zum Dämpfen der Intensität optischer Signale

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2209221A (en) * 1987-09-01 1989-05-04 Litton Systems Inc A demodulator circuit for an interferometer type of hydrophone
US4881813A (en) * 1988-05-20 1989-11-21 The United States Of America As Represented By The Secretary Of The Navy Passive stabilization of a fiber optic nonlinear interferometric sensor
US5555086A (en) * 1991-05-31 1996-09-10 Litton Systems, Inc. Coherence multiplexed interferometric signal processing system and method
US5488503A (en) * 1995-02-09 1996-01-30 Hughes Aircraft Company Low-power, stabilized, photonic modulator system
US5598264A (en) * 1995-05-18 1997-01-28 Failes; Michael Noise compensated interferometric measuring device and method using signal and reference interferometers
WO1997046890A1 (fr) * 1996-05-31 1997-12-11 Poseidon Scientific Instruments Pty. Ltd. Appareil de traitement interferometrique du signal
DE19820295C1 (de) * 1998-05-07 1999-12-09 Bosch Gmbh Robert Optisches Dämpfungsglied, Anordnung optischer Dämpfungsglieder und Verfahren zum Dämpfen der Intensität optischer Signale

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
FISHER N.E. ET AL.: "Low-coherence mach-zehender interrogation of fibre fabry-perot sensor incorporating balanced detection", PROCEEDINGS OF THE SPIE- THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING, vol. 3555, 16 September 1998 (1998-09-16) - 19 September 1998 (1998-09-19), pages 190 - 193 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016115430A1 (fr) * 2015-01-16 2016-07-21 Raytheon Company Système de réduction de bruit d'amplitude et procédé pour oscillateurs à très faible bruit de phase
CN107112949A (zh) * 2015-01-16 2017-08-29 雷斯昂公司 用于超低相位噪声振荡器的幅度噪声降低系统和方法
JP2018504042A (ja) * 2015-01-16 2018-02-08 レイセオン カンパニー 超低位相ノイズ発振器のための振幅ノイズ低減システム及び方法
AU2016206585B2 (en) * 2015-01-16 2018-09-13 Raytheon Company Amplitude-noise reduction system and method for ultra-low phase-noise oscillators
CN107112949B (zh) * 2015-01-16 2018-09-25 雷斯昂公司 用于超低相位噪声振荡器的幅度噪声降低系统和方法

Similar Documents

Publication Publication Date Title
US5528196A (en) Linear RF amplifier having reduced intermodulation distortion
US5248982A (en) Method and apparatus for calibrating phased array receiving antennas
US5122765A (en) Direct microwave modulation and demodulation device
GB2296613A (en) Image-reject mixers
EP1059734A3 (fr) Radioémetteur-recepteur pour opération à deux gammes de fréquences
US8416018B2 (en) Variable frequency amplifier
US4457022A (en) Two diode image rejection and pseudo-image enhancement mixer
US6539202B1 (en) Interference canceling device
US8301086B2 (en) Low-power polar transmitter
KR20000023530A (ko) 전기 회로들에 의해 발생되는 왜곡을 감소시키는 제어시스템용 이중 측대역 파이로트 기술
EP2013977A2 (fr) Excitateur numérique à sorties doubles
EP0760954B1 (fr) Detecteur de bruit de phase
WO2001069270A1 (fr) Ameliorations apportees a un appareil de traitement de signal interferometrique
US5847620A (en) Dielectric resonator phase shifting frequency discriminator
US4048568A (en) Wide operating frequency range superheterodyne fm noise analyzer
US7323950B2 (en) Balanced hybrid coupler network
CN1250247A (zh) 用于减小电路产生的失真的控制系统的跳频导频技术
CA2279443C (fr) Detecteur de phase ameliore
JPH0590843A (ja) フイードフオワード干渉回路
JPH07229944A (ja) 歪み特性測定用ｒｆ装置、歪み特性測定方法、及びノイズ源
JP3944117B2 (ja) 高周波増幅回路
JPS61179606A (ja) 非線形補償回路
JPH03198401A (ja) 位相・振幅調整回路
KR19980028878A (ko) 피드포워드 증폭기
JP2551330B2 (ja) ミキサ回路

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP