GB2165425A - Apparatus for compensating non- linearities in frequency-modulated signal - Google Patents
Apparatus for compensating non- linearities in frequency-modulated signal Download PDFInfo
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- GB2165425A GB2165425A GB08425499A GB8425499A GB2165425A GB 2165425 A GB2165425 A GB 2165425A GB 08425499 A GB08425499 A GB 08425499A GB 8425499 A GB8425499 A GB 8425499A GB 2165425 A GB2165425 A GB 2165425A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/40—Means for monitoring or calibrating
- G01S7/4004—Means for monitoring or calibrating of parts of a radar system
- G01S7/4008—Means for monitoring or calibrating of parts of a radar system of transmitters
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
- G01S13/82—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein continuous-type signals are transmitted
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/40—Means for monitoring or calibrating
- G01S7/4052—Means for monitoring or calibrating by simulation of echoes
- G01S7/4056—Means for monitoring or calibrating by simulation of echoes specially adapted to FMCW
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B23/00—Generation of oscillations periodically swept over a predetermined frequency range
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03C—MODULATION
- H03C3/00—Angle modulation
- H03C3/02—Details
- H03C3/08—Modifications of modulator to linearise modulation, e.g. by feedback, and clearly applicable to more than one type of modulator
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
- G01S1/70—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using electromagnetic waves other than radio waves
- G01S1/703—Details
- G01S1/7032—Transmitters
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B19/00—Generation of oscillations by non-regenerative frequency multiplication or division of a signal from a separate source
Abstract
Apparatus (119) for compensating the effects of non-linearities in a frequency ramp (90, 92) includes a delay element (120) coupled to receive the ramp signal; a signal mixer (122) for mixing together the direct and delayed ramp signals to produce their sum and difference frequencies; a filter (124) selecting the difference frequency; and a device (126) responsive to the difference frequency for producing timing pulses having a frequency which is dependent upon the difference frequency. The timing pulses define the instants of time at which the frequency of the ramp has changed by a prescribed amount DELTA f, and can thus be used as a timing reference in a utilisation device receiving the frequency ramp. In a first embodiment (shown), a transponder system has a transceiver wherein the frequency ramp is transmitted (106) and wherein frequencies received from the transponder are analyzed (118). The timing pulses are then used to strobe the receiver sample-and-hold device (114) and A/D converter (116). In a second embodiment (Fig. 5), the ramp is used to deflect a laser beam using an acousto-optic modulator, and the timing pulses are applied to a Q- switch which controls beam intensity. <IMAGE>
Description
SPECIFICATION
Apparatus For Compensating Non-Linearities In
Frequency-Modulated Signal
The present invention relates to a system having a signal source for generating a signal having prescribed, time varying frequency and a signal utilization device, responsive to the aforementioned signal, which carries out a useful process in dependence upon the frequency of the signal.
As an example of such a system, the signal source may comprise a voltage controlled oscillator which is responsive to a time-varying input signal So(t) to generate an output signal having the prescribed, time varying frequency f(t) that is substantially directly proportional upon the input signal. The signal utilization means may be a laser scanner which employs an acoustic optic modulator to deflect the laser beam by an angle which is proportional to the frequency of an applied signal.
As another example, the signal utilization device may comprise an interrogator-transponder system that transmits an interrogation signal having a frequency which is ramped substantially linearly upward andlor downward within a prescribed frequency range.
In systems of the type described above which are responsive to a monotonically increasing or decreasing frequency, non-linearities in this frequency with respect to time, or non-linearities in this frequency with respect to another signsl or voltage introduces errors in the signal utilization device. Prior attempts to compensate for nonlinearities were primarily concerned with methods and means for linearizing the time or voltage versus frequency function itself. Thus, for example, feedback loops have been provided between the output of the signal source and its control input for correcting non-linearities in the output.
It is an object of the present invention to provide apparatus for compensating for non-linearities in the time behavior of the frequency f(t) of a first signal.
This object, as well as other objects will become apparent from the discussion that follows, are achieved, according to the present invention, by providing a delay element, coupled to receive the first signal, for producing a second signal which is a delayed version of the first signal with a prescribed signal delay (T1); a signal mixer for mixing together the first and the second signals to produce a third signal; and a device, responsive to the third signal, for producing a sampling signal having a frequency which is dependent upon the frequency of the third signal. For reasons which will be explained in detail below, this sampling signal defines the instants of time at which the frequency of the first signal has changed by a prescribed amount Af (where Af=1,T1 or a whole fraction or an integer multiple thereof).
Finally, according to the invention, this sampling signal is supplied to the signal utilization device which is responsive to changes in the frequency of the first signal by the prescribed amount as determined by the sampling signal.
In one preferred embodiment of the invention, the delay element provides a constant signal delayT1. In another embodiment the delay T1 is a known function of the frequency f(t) of the first signal. In the latter case, where the delay T1 is a function of frequency, the prescribed amount of frequency change Af between instants of time defined by the sampling signal will also be frequency dependent.
For a full understanding of the present invention, reference should now be made to the following detailed description of the preferred embodiments of the invention and to the accompanying drawings.
Fig. 1 is a block diagram of the apparatus according to the present invention for compensating non-linearities in a frequency modulated signal.
Fig. 2 is a block diagram of the sub-elements contained in the sampling element in the apparatus of Fig. 1.
Fig. 3 and Fig. 4 are frequency versus time diagrams which illustrate the operation of the apparatus in Fig. 1.
Fig. 5 is a block diagram illustrating the use ofthe present invention with a laser beam scanner.
Fig. 6 is a block diagram illustrating the use of the present invention with an interrogator-transponder system.
Fig. 7 is a block diagram of a passive transponder which may be used with the system of Fig. 6.
Fig. 8 is a representational diagram showing one preferred implementation of the transponder illustrated in Fig. 7.
Fig. 9 is a representational diagram showing a portion of the device in Fig. Sin detail.
Fig. 10 and Fig. 11 are timing diagrams of voltage and frequency, respectively, illustrating the operation of the system in Fig. 6.
Fig. 12 is a frequency versus time diagram further illustrating the operation of the system of Fig. 6.
The present invention will now be described with reference to Figs. 1-12 of the drawings. Identical elements in the various figures are designated by the same reference numerals.
Fig. 1 shows the general system according to the present invention for providing a signal S1 having a monotonically time-varying frequency f1 as well as a sampling 55, having a particular sampling frequency ~5, to a signal utilization device 10. The signal utilization device may be any device which responds to the signal S1 and takes some action or operates in dependence upon the frequency ~1. Two specific examples of this signal utilization device will be described below in connection with Figs. 5--12.
Suffice it to say, for the purpose of this general description, that the signal utilization device 10 is responsive to the time-varying frequency f1 so that deviations between the actual value and the desired value of this frequency result in unacceptable errors in the operation of the signal utilization device.
The signal S1 may be produced by any suitable source 12. For example, this signal source may be a voltage-controlled oscillator (VCO) which produces an output signal S1 of frequency ~1 which is linearly related to an input voltage SO. That is: f1(t)=K50(t)+k, where K and k are constants
As an example, the input voltage So may be a sawtooth signal which repeatedly ramps linearly upward from a minimum value to a maximum value.Such an input signal would result in an output signal S1 having a frequency f, which ramps upward substantially linearly from an initial value #min to a maximum value fmax. In this configuration, there are two sources of deviation of the frequency f, from an absolutely linear upward ramp (df,/dt=constant): 1. The input voltage So is not exactly linear with
respect to time (dfidt=constant); 2. The frequency ft is not exactly linearly related to
the input signal (So(f,=KSo+k).
In many cases, this non-linearity of the signal ft does not adversely affect the operation of the signal utijization device 10. However, for certain applications this non-linearity is unacceptable and it is necessary to correct or compensate for deviations from the desired value off,.
Clearly, it is possible to take certain corrective measures such as improving the quality of the source of the voltage So (e.g. a ramp generator) to improve its linearity and similarly, to improve the quality of the signal source 12 to improve the linearity of the relationship between the frequency f, and the signal So.
Furthermore, it is known to provide a phase lock loop between the output and the input of the signal source 12 to maintain the linearity of the signal source. This solution has the disadvantage of increasing the complexity of the system while failing to compensate for non-linearities in the original voltage signal SO.
According to the invention, the system is provided with separate apparatus 14 which produces and supplies the signal utilization device 10 with a sampling signal S5 that defines instants of time in which the frequency f, of the first signal S, has changed by a prescribed amount.
According to the invention this sampling signal S5 is generated in the following manner:
The original signal Si, of frequency f, is supplied to a four-quadrant mixer 16 both directly and indirectly via a delay element 18 having a delay period T1. The output signal S2 of the delay element 18 having a frequency ~2 is thus also applied to the mixer 16.
It will be understood that, while the signal S, is applied directly to the mixer 16 and to the delay element 18 in this particular embodiment, it is also possible to pass the signal S, through a frequency multiplier, divider or the like to derive a further signal which is applied to the mixer 16 and the delay element 18. The essential feature, according to the invention, is that the frequency of this signal applied.
to the mixer and the delay element be either the same or derived from, related to and synchronized with the frequency f1.
The mixer 16 produces an output signal S3 having frequencies f3 which equal the sum and the difference of the frequencies f, and f2. This signal S3
is applied to a filter, such as a low pass filter 20, which produces a signal S4 containing only the difference frequency contained in the signal 33. This signal S4 is then applied to a sampling device 22 which produces the sampling signal S5 with the sampling frequency f5.
The sampling device 22 may take the form illustrated in Fig. 2. This device comprises one or more frequency doublers 24 so that the sampling frequency f5 will be a multiple of the frequency f4.
The output of the frequency multipliers (e.g.
doublers) 24 is passed to a zero-crossing detector which produces a sampling pulse at every positive or negative-going zero crossing.
The operation of the apparatus 14 shown in Fig. 1 will now be described with reference to the diagrams of Figs. 3 and 4. These diagrams show the frequency f, as a function of time. As may be seen, the frequency f, ramps upward from a minimum frequency fm,n to a maximum frequency fmax and then drops abruptly again to the minimum frequency fmin It is desired that the frequency f, be a linear function oftime between the two limits; that is, df,/dt=constant. However, it would be extremely expensive to provide a signal source with an output frequency which is exactly linear. Figs. 3 and 4 show the non-linearity in the frequency f, with considerable exaggeration to facilitate understanding.
Fig. 3 shows the frequency f2 of the signal S2 in dashed lines. This frequency is identical to the frequencyfi; however, it is delayed by the period T,.
Examining the diagram, it may be seen that the difference in frequency between f, and f2 at any given instant of time (e.g., to) is f4; that is, the frequency of the signal S4 appearing at the output of the low pass filter 20. Since the signal S2 is merely a delayed version of the signal 51,the slope of the curve f, at time to is approximately:
d f1/dt=4,Ti Now, by definition, the slope of the frequency curvef, is
d fi/dt=Af,T#, where Af is in the change in the frequency f, during the period T#ri.
Now, if the period TN is set equal to Tf4 (the period of the signal S4 and frequency ~4) then: f4rFi =AITf Since 4=1/of4, Af rr, constant.
Therefore, for every cycle of the signal S4 (frequency f4 and period T4) the frequency f, changes by a fixed amount Af. Thus, the sampling signal which has a frequencyf5=Mf4, where M is an integer, will define those instants in which the frequency f, of the signal S1 has changed by prescribed amount.
Fig. 4 indicates, in exaggerated form, how the
sampling pulses appear at successive instants of
time t1, t2.. .t7 which specify equal changes Af in the
frequency f1. The magnitude of the change in
frequency Af is determined by T, and the integer M.
Fig. 5 illustrates a system for scanning a laser
beam 40 across a screen or other surface 42. The
scanning is accomplished by an acousto optic
modulator 44.
A voltage controlled oscillator 46 supplies a signal
of frequency f to the plates of the modulator. The
angle 6 of deflection of the beam 40 is directly
proportional to this frequency.
It will be understood that a linear sweep of the
frequency f will result in a constant scanning speed
across the surface 42. However, non-linearities,
which inevitably result, will distort the image
produced by the scanner.
According to the invention, a sampling signal is
supplied to a Q-switch 48, which modulates the
beam, to define increments in time during which the
beam is scanned by equal spacial increments in space AS along the screen 42. These increments in
space may be made as small as desired by proper
choice of the delay period T, and the frequency
multiplier M in the apparatus 50 which generates
the sampling signal.
Figs. 612 illustrate the use of the present
invention in an interrogator-transponderystem
system employing a surface acoustic wave
transponder. A system of this general type is
disclosed in the U.S. patent No. 3,706,094 to Cole
and Vaughn.
The transmitter/receiver and decoder system
shown in Fig. 6 comprises a ramp generator 90
which supplies a sawtooth waveform to a voltage
controlled oscillator (VCO) 92. The VCO produces an
output signal of frequency f which repeatedly ramps
linearly upward from a frequency of 905 MHzto a
frequency of 925 MHz. This signal is amplified by the
RF amplifiers 94 and supplied to a transmit/receive
switch 96. The switch 96 directs the signal either to a
transmitter power amplifier 98 or to a decoding
mixer 100. The switch 96 is controlled by a 100 KHz
square wave signal produced by a clock 102. The
output signal S, from the amplifier 98 is supplied to
an external circulator or transmit/receive (TR) switch
104 and is transmitted as electromagnetic radiation by an antenna 106.
A block diagram of the transponder associated
with the system of Fig. 6 is shown in Fig. 7. The
transponder receives the signal S, at an antenna 107
and passes it to a series of delay elements 109
having the indicated delay periods To and AT. After
passing each successive delay, a portion of the
signal lot 2...1N is tapped off and supplied to a
summing element 111. The resulting signal S2,
which is the sum of the intermediate signals lo.. .lw, is fed back to the antenna 107 for transmission to
the antenna 106 in the system of Fig. 6.
The transponder reply signal S2 is received by the
antenna 106 and passed through the circulator or TR
switch 104 to a receiver amplifier 108. The output S4
of this amplifier 108 is heterodyned in the mixer
with the signal S3 intermittently presented by the
switch 96.
The output Ss of the mixer 100 contains the sum
and the difference frequencies of the signals S3 and
S4. This output is supplied to a band pass filter 110
with a pass band between 1 and 3 KHz. The output
of this filter is passed through an anti-aliasing filter
112 to a sample-and-hold circuit 114.
The sample-and-hold device supplies each
sample to an analog-to-digital converter 116. The A/D converter, in turn, presents the digital value of
this sample to a processor 118 that analyzes the
frequencies contained in the signal by means of a
Fourier transform. The sample-and-hold device 114
and the A/D converter 116 are strobed by a sampling
signal produced by the apparatus 119 according to
the present invention. As explained above, this
sampling signal serves to compensate for the
non-linearity, with respect to time, in the
monotonically increasing frequency f of the VCO
output signal.
The apparatus 119 receives the signal produced
by the VCO 92 via an isolating amplifier 121. The
signal is passed through a delay element 120 with a
constant signal delay Ts. Both the delayed and the
undelayed signals are supplied to a mixer 122 which
produces a signal S7 containing both sum and
difference frequencies. The signal S7 is supplied to a
low pass filter 124 which passes only the portion of
this signal containing the difference frequencies.
The output of the low pass filter is supplied to a
zero-crossing detector 126 which produces a pulse
at each positive (or negative) going zero crossing.
These pulses are used to strobe the sample-and
hold device 114 and the A/D converter 116.
Figs.10~12 illustrate the operation of the circuit of Fig. 6. Fig. 10 shows the 100 KHz output of the
clock 102; Fig. 11 shows the frequency sweep of the signal
produced by the VCO 92. Fig. 12 shows, in solid lines
128, the frequency of the transmitted signal Si and,
in dashed lines 130, the frequency of the signal S2 as
received from the transponder. As may be seen, the
signal 130 is received during the interval between
transmissions of the signal 128. These intervals are
chosen to equal, approximately, the round trip delay
time between the transmission of a signal to the
transponder and the receipt of the transponder
reply.As indicated by the multiple dashed lines, the
transponder reply will contain a number of
frequencies at any given instant of time as a result of
the combined (i.e., summed) intermediate signals
having different delay times (Tot T0+AT, To+2 AT,...T0+NAT).
Figs. 8 and 9 illustrate an embodiment of a
transponder which implements the block diagram of
Fig. 7. This transponder operates to convert the
received signal Si into an acoustic wave and then to
reconvert the acoustic energy back into an electrical
signal S2 for transmission via a dipole antenna 56.
More particularly, the signal transforming element
of the transponder includes a substrate 58 of
piezoelectric material such as a lithium niobate
(LiNbO3) crystal. On the surface of this substrate is
deposited a layer of metal, such as aluminum,
forming a pattern such as that illustrated in Fig. 9.
For example, this pattern may consist of two bus bars 60 and 62 connected to the dipole antenna 56, a "launch" transducer 64 and a plurality of "tap" transducers 66. The bars 60 and 62 thus define a path of travel 68 for an acoustic wave which is generated by the launch transducers and propogates substantially linearly, reaching the tap transducers each in turn. The tap transducers convert the acoustic wave back into electrical energy which is collected and therefore summed by the bus bars 60 and 62. This electrical energy then activates the dipole antenna 56 and is converted into electromagnetic radiation for transmission as the signal S,.
The tap transducers 56 are provided at equally spaced intervals along the acoustic wave path 68 as shown in Fig. 8, and an informational code associated with the transponder is imparted by providing a selected number of "delay pads" 70 between the tap transducers. These delay pads, which are shown in detail in Fig. 9, are preferably made of the same material as, and deposited with, the bus bars 60, 62 and the transducers 64, 66. Each delay pad has a width sufficient to delay the propagation of the acoustic wave from one tap transducer 66 to the next by one quarter cycle or 90 with respect to an undelayed wave at the frequency of operation (circa 915 MHz).By providing locations for three delay pads between successive tap transducers, the phase q) of the acoustic wave received by a tap transducer 66B may be controlled to provide four phase possibilities: 1. No pad between tap transducers 66A and 66B=-90"; 2. One pad between tap transducers 66A and 66B=0"; 3. Two pads between tap transducers 66A and 66B=90 ; and 4. Three pads between tap transducers 66A and 66B=1800.
Referring to Fig. 7 the phase information O (the
phase of the signal picked up by the first tap transducer in line), and (P2...#N (the phases) of the signals picked up by the successive tap transducers) is supplied to the combiner (summer) which in the embodiment of Fig. 8 comprises the
bus bars 60 and 62. This phase information, which is transmitted as the signal S, by the antenna 56,
contains the informational code of the transponder.
There has thus been shown and described a novel
apparatus for compensating non-linearities in a
frequency-modulated signal which fulfills all the
objects and advantages sought therefor. Many
changes, modifications, variations and other uses
and applications of the subject invention will,
however, become apparent to those skilled in the art
after considering this specification and the
accompanying drawings which disclose preferred
embodiments thereof. All such changes,
modifications, variations and other uses and
applications which do not depart from the spirit and
scope of the invention are deemed to be covered by
the invention which is limited only by the claims
which follow.
Claims (17)
1. In a system having (1) signal source means for generating a first signal with a time variable frequency f(t) having a monotonically varying time derivative (df/dt), and (2) signal utilization means, responsive to said first signal, for carrying out a useful process in dependence upon said frequency f(t) of said first signal,
the improvement comprising apparatus for compensating for non-linearities in said time derivative (df/dt) including:
(a) delay means, coupled to receive as an input signal said first signal, for producing a second signal which is a delayed version of said input signal with a prescribed signal delay (Tl); (b) signal mixing means for mixing together said first signal and said second signal to produce a third signal; and
(c) means responsive to said third signal for producing a sampling signal having a frequency which is dependent upon the frequency of said third signal, the sampling times of said sampling signal defining those instants at which the first signal has changed in frequency by a prescribed amount Af(Af=1/T1 or a whole fraction or an integer multiple thereof), wherein said signal utilization means is responsive to said sampling signal for taking desired action when said frequencyf(t) has changed by said prescribed amount Af.
2. The improvement defined in Claim 1, wherein said delay means provides a constant signal delay (to).
3. The improvement defined in Claim 1, wherein said delay means provides a signal delay (T,) which is a function of the frequency f(t) of said first signal.
4. The improvement defined in Claim 1,wherein said mixing means includes (1) heterodyning means, coupled to receive said first and said second signals, for producing an output signal with frequencies equal to the sum and the difference of the frequencies of said first and said second signals, respectively; and (2) a frequency filter, coupled to receive said output signal, for passing only the portion of said output signal containing the difference frequency, thereby forming said third signal.
5. The improvement defined in Claim 4, wherein said frequency filter is low-pass filter.
6. The improvement defined in Claim 1, wherein said signal producing means includes a frequency multiplier.
7. The improvement defined in Claim 6, wherein said frequency multiplier includes a frequency doubler.
8. The improvement defined in Claim 7, wherein said frequency multiplier includes a plurality of frequency doublers connected in series.
9. The improvement defined in Claim 1, wherein said signal producing means includes a frequency divider.
10. The improvement defined in Claim 1, wherein said signal producing means includes zero-crossing detector means for producing a digital sampling signal.
11. The improvement defined in Claim 1, wherein said signal utilization means is a laser beam scanner.
12. The improvement defined in Claim 11, wherein said laser beam scanner includes: (1) a laser for producing a laser beam; (2) a laser beam modulator, arranged in the path of
the said laser beam, for controlling the intensity
of said beam in response to at least one input
signal; (3) a beam deflector, arranged in the path of said
laser beam and coupled to receive said first
signal, for deflecting said beam in proportion to
the frequency f(t) of said first signal; wherein said sampling signal is supplied to said beam modulator as an input signal for determining the beam modulating times in dependence upon said frequency.
13. The improvement defined in Claim 12, wherein said beam modulator is a Q-switch.
14. The improvement defined in Claim 12, wherein said beam deflector is an acousto optic modulator.
15. The improvement defined in Claim 1, wherein said signal utilization means is a system for interrogating a passive transponder carrying encoded information.
16. The improvement defined in Claim 15, wherein said system for interrogating a passive transponder comprises: (1) means for transmitting a fourth signal having a
second frequency, related to said first frequency
f(t), said second frequency successively
assuming a plurality of frequency values within
a prescribed frequency range;
(2) remote, passive transponder means for
receiving said fourth signal and for transmitting
a fifth signal in reply thereto, said transponder
means including signal transforming means,
coupled to receive said fourth signal as an input.
for producing said fifth signal as an output, said
signal transforming means including:
(a) a plurality of signal conditioning means
coupled to receive said fourth signal, each signal
conditioning means providing an intermediate
signal having a known delay and a known amplitude
modification to said fourth signal; and
(b) signal combining means coupled to all of said
signal conditioning means, for combining said
intermediate signals to produce said fifth signal,
said signal conditioning means and said signal
combining means imparting a known information
code in said fifth signal associated with said
transponder means;
(3) means for receiving said fifth signal from said
transponder means;
(4) means, arranged to receive said fourth signal
and said fifth signal, for mixing together said
fourth signal and said fifth signal, thereby to
produce a sixth signal; and
(5) signal processing means, responsive to said
sixth signal, for detecting at least some of the
frequencies contained in said sixth signal,
thereby to determine said information code
associated with said transponder means.
17. Apparatus for compensating for non
linearities in frequency modulated signals,
substantially as hereinbefore described with
reference to the drawings.
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU34004/84A AU568157B2 (en) | 1984-10-09 | 1984-10-08 | Compensating for non-linear frequency variation in a system for interrogating a transponder |
GB08425499A GB2165425B (en) | 1984-10-09 | 1984-10-09 | Signalling system |
ZA847911A ZA847911B (en) | 1984-10-09 | 1984-10-09 | Apparatus for compensating non-linearities in frequency-modulated signal |
DE19843438053 DE3438053A1 (en) | 1984-10-09 | 1984-10-17 | DEVICE FOR COMPENSATING NON-LINEARITIES IN A FREQUENCY-MODULATED SIGNAL |
JP59225069A JPS61103361A (en) | 1984-10-09 | 1984-10-25 | Device for compensating nonlinearity in frequency modulationsignal |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB08425499A GB2165425B (en) | 1984-10-09 | 1984-10-09 | Signalling system |
Publications (3)
Publication Number | Publication Date |
---|---|
GB8425499D0 GB8425499D0 (en) | 1984-11-14 |
GB2165425A true GB2165425A (en) | 1986-04-09 |
GB2165425B GB2165425B (en) | 1988-08-24 |
Family
ID=10567927
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB08425499A Expired GB2165425B (en) | 1984-10-09 | 1984-10-09 | Signalling system |
Country Status (5)
Country | Link |
---|---|
JP (1) | JPS61103361A (en) |
AU (1) | AU568157B2 (en) |
DE (1) | DE3438053A1 (en) |
GB (1) | GB2165425B (en) |
ZA (1) | ZA847911B (en) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1997009777A2 (en) * | 1995-09-07 | 1997-03-13 | Siemens Aktiengesellschaft | Generator for a linearly frequency-modulated signal |
WO1998038524A1 (en) * | 1997-02-28 | 1998-09-03 | Siemens Aktiengesellschaft | Sensor system operating method and a sensor system |
EP1195888A2 (en) * | 2000-06-15 | 2002-04-10 | Alliant Techsystems Inc. | High range resolution radar through non-uniform sampling |
US6531957B1 (en) | 1996-11-29 | 2003-03-11 | X-Cyte, Inc. | Dual mode transmitter-receiver and decoder for RF transponder tags |
US6788204B1 (en) | 1999-03-15 | 2004-09-07 | Nanotron Gesellschaft Fur Mikrotechnik Mbh | Surface-wave transducer device and identification system with such device |
WO2018109444A1 (en) * | 2016-12-14 | 2018-06-21 | Bae Systems Plc | Variable frequency oscillator circuits and methods of generating an oscillating signal of a desired frequency |
US11143746B2 (en) | 2018-02-27 | 2021-10-12 | Nxp Usa, Inc. | Chirp linearity detector for radar |
GB2557637B (en) * | 2016-12-14 | 2022-06-22 | Bae Systems Plc | Variable frequency oscillator circuits and methods of generating an oscillating signal of a desired frequency |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4739328A (en) * | 1986-07-14 | 1988-04-19 | Amtech Corporation | System for identifying particular objects |
DE4138050A1 (en) * | 1991-11-19 | 1993-05-27 | Siemens Matsushita Components | Traffic information indication identification system for road vehicle - has on board active transponder and cooperating passive transponder adjacent traffic information indication |
DE4310531C2 (en) * | 1993-03-31 | 1997-02-13 | Preh Elektro Feinmechanik | Device for the transmission of information in motor vehicle traffic |
CA2231147C (en) * | 1995-09-07 | 2001-08-07 | Siemens Aktiengesellschaft | Apparatus for distance measurement |
US6208062B1 (en) | 1997-08-18 | 2001-03-27 | X-Cyte, Inc. | Surface acoustic wave transponder configuration |
US6114971A (en) | 1997-08-18 | 2000-09-05 | X-Cyte, Inc. | Frequency hopping spread spectrum passive acoustic wave identification device |
US5986382A (en) | 1997-08-18 | 1999-11-16 | X-Cyte, Inc. | Surface acoustic wave transponder configuration |
US6060815A (en) | 1997-08-18 | 2000-05-09 | X-Cyte, Inc. | Frequency mixing passive transponder |
DE19835232C1 (en) * | 1998-08-04 | 2000-04-20 | Siemens Ag | Continuous frequency modulation arrangement |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3706094A (en) * | 1970-02-26 | 1972-12-12 | Peter Harold Cole | Electronic surveillance system |
US4044355A (en) * | 1973-11-20 | 1977-08-23 | Saab-Scania Aktiebolag | Measurement of contents of tanks etc. with microwave radiations |
GB1500289A (en) * | 1974-06-03 | 1978-02-08 | Rca Corp | Homodyne communication system |
US4059831A (en) * | 1975-10-06 | 1977-11-22 | Northwestern University | Passive transponders using acoustic surface wave devices |
US4106020A (en) * | 1977-07-21 | 1978-08-08 | Rca Corporation | FM-CW Radar ranging system |
US4523890A (en) * | 1983-10-19 | 1985-06-18 | General Motors Corporation | End seal for turbine blade base |
AU564844B2 (en) * | 1984-10-09 | 1987-08-27 | X-Cyte Inc. | Saw transponder |
-
1984
- 1984-10-08 AU AU34004/84A patent/AU568157B2/en not_active Ceased
- 1984-10-09 ZA ZA847911A patent/ZA847911B/en unknown
- 1984-10-09 GB GB08425499A patent/GB2165425B/en not_active Expired
- 1984-10-17 DE DE19843438053 patent/DE3438053A1/en active Granted
- 1984-10-25 JP JP59225069A patent/JPS61103361A/en active Granted
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1997009777A2 (en) * | 1995-09-07 | 1997-03-13 | Siemens Aktiengesellschaft | Generator for a linearly frequency-modulated signal |
WO1997009777A3 (en) * | 1995-09-07 | 1997-04-03 | Siemens Ag | Generator for a linearly frequency-modulated signal |
US6531957B1 (en) | 1996-11-29 | 2003-03-11 | X-Cyte, Inc. | Dual mode transmitter-receiver and decoder for RF transponder tags |
WO1998038524A1 (en) * | 1997-02-28 | 1998-09-03 | Siemens Aktiengesellschaft | Sensor system operating method and a sensor system |
US6278398B1 (en) | 1997-02-28 | 2001-08-21 | Siemens Aktiengesellschaft | Sensor system operating method and a sensor system |
US6788204B1 (en) | 1999-03-15 | 2004-09-07 | Nanotron Gesellschaft Fur Mikrotechnik Mbh | Surface-wave transducer device and identification system with such device |
EP1195888A2 (en) * | 2000-06-15 | 2002-04-10 | Alliant Techsystems Inc. | High range resolution radar through non-uniform sampling |
EP1195888A3 (en) * | 2000-06-15 | 2003-03-26 | Alliant Techsystems Inc. | High range resolution radar through non-uniform sampling |
WO2018109444A1 (en) * | 2016-12-14 | 2018-06-21 | Bae Systems Plc | Variable frequency oscillator circuits and methods of generating an oscillating signal of a desired frequency |
US10931231B2 (en) | 2016-12-14 | 2021-02-23 | Bae Systems Plc | Variable frequency oscillator circuits and methods of generating an oscillating signal of a desired frequency |
GB2557637B (en) * | 2016-12-14 | 2022-06-22 | Bae Systems Plc | Variable frequency oscillator circuits and methods of generating an oscillating signal of a desired frequency |
US11143746B2 (en) | 2018-02-27 | 2021-10-12 | Nxp Usa, Inc. | Chirp linearity detector for radar |
Also Published As
Publication number | Publication date |
---|---|
DE3438053A1 (en) | 1986-04-24 |
JPH0448021B2 (en) | 1992-08-05 |
GB8425499D0 (en) | 1984-11-14 |
ZA847911B (en) | 1985-04-10 |
AU3400484A (en) | 1986-04-17 |
DE3438053C2 (en) | 1988-08-11 |
GB2165425B (en) | 1988-08-24 |
JPS61103361A (en) | 1986-05-21 |
AU568157B2 (en) | 1987-12-17 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PE20 | Patent expired after termination of 20 years |
Effective date: 20041008 |