US4021653A
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US
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Digital programmable tone detector
Assignee: Motorola Solutions Inc
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Filing: 1975-10-14
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Granted: 1977-05-03
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Expires: 1995-10-14
Abstract
Abstract An improved detection arrangement for detecting the presence of a given tone in a received input signal. A reference generator, in the form of a reference clock and a programmable divider, produces a first reference frequency, equal to the frequency of the tone, and at an arbitrary phase angle thereto. A second generator output is in quadrature to the first. Each reference signal is product detected with the input signal via exclusive OR gates. A unique digital low pass filter, operating in a time multiplex mode, receives the gate outputs, removes all high frequency components therefrom, and produces pairs of output binary number encoded signals, each of which is representative of a vector component of a detected tone. Threshold detector circuitry monitors the outputs indicating an above threshold condition at its output in response to predetermined combinations of the binary numbers. The combinations represent all input vectors whose resultant absolute magnitude exceeds a chosen threshold. A second detector samples the threshold detector output, recording the number of samples over threshold during a given interval. If the number exceeds a selected minimum an output signal is produced which indicates the presence of a received tone.
Inventors
- 👤 Ronald Edward Sharp
- 👤 David Frank Willard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:07
CPC Classifications
G; G01; G01R; G01R23/00; G01R23/02; G01R23/15
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
200 words
An improved digital detector arrangement for detecting the presence of a tone of a given frequency f comprising in combination: reference signal generating means having first and second outputs, the first output producing a signal of frequency f at a first phase reference, the second output producing a signal of frequency f at a second phase reference predeterminedly related to the first phase reference; a first mixer means for mixing the input signal with the reference generator first output; a second mixer means for mixing the input signal with the reference generator second output; means times multiplexing the first and second mixer outputs through a digital low pass filter, said filter producing first and second digital outputs, each digital output representative of a vector component of the amplitude of the input tone; and processing means for processing the filter digital outputs and producing a tone detect signal in response to the presence of predetermined first and second vector components, the processing means including means for determining the resultant vector of said first and second vector components and further comprising means for generating said tone detect signal in response to the amplitude of said resultant vector exceeding a given threshold level.
Claim 2
Dependent Claim
200 words
An improved digital detector arrangement for detecting the presence of a tone of a given frequency f comprising in combination: reference signal generating means having first and second outputs, the first output producing a signal of frequency f at a first phase reference, the second output producing a signal of frequency f at a second phase reference predeterminedly related to the first phase reference; a first mixer means for mixing the input signal with the reference generator first output; a second mixer means for mixing the input signal with the reference generator second output; means times multiplexing the first and second mixer outputs through a digital low pass filter, said filter producing first and second digital outputs, each digital output representative of a vector component of the amplitude of the input tone; and processing means for processing the filter digital outputs and producing a tone detect signal in response to the presence of predetermined first and second vector components, the processing means including means for determining the resultant vector of said first and second vector components and further comprising means for generating said tone detect signal in response to the amplitude of said resultant vector exceeding a given threshold level.
Claim 3
Dependent Claim
158 words
The arrangement of claim 1 wherein the first and second mixers produce binary output signals and wherein the digital filter comprises summer means for summing a pair of binary signals received at its first and second inputs and providing the resultant at its output, first multiplier means for multiplying the first and second mixer produced binary signals by a first predetermined binary constant and passing the resultant signal to the first input of the summer, delay means for producing at its output a predetermined time delay of signals at its inputs, means coupling the summer output to the delay input, and second multiplier means for multiplying the output from the time delay means by a second predetermined binary constant and passing the resultant signal to the second input of the summer, whereby the output from the summer is a binary number signal representative of a low pass transfer of the binary signals from the first and second mixers.
Claim 4
Dependent Claim
54 words
The arrangement of claim 2 wherein the digital filter further comprises a first grouping of half adders providing both the summing and the first multiplier functions, a flip flop array providing the time delay function, and a second grouping of full and half adders, along with corresponding logic gates, providing the second multiplier function.
Claim 5
Dependent Claim
73 words
The arrangement of claim 2 wherein the multiplexing means comprises a multiplex switch operable at a predetermined rate to selectively couple the output from the first or second mixer to the digital filter first multiplier, and second time delay means comprising a flip flop register, said second time delay means having an input coupled to the digital filter time delay means output and an output coupled to the digital filter second multiplier input.
Claim 6
Dependent Claim
28 words
The arrangement of claim 4 wherein the time delay of each delay means is equal to one-half the period of the multiplex switch and is operably synchronous thereto.
Claim 7
Dependent Claim
62 words
The arrangement of claim 1 wherein the filter first and second outputs comprise a pair of binary signals and wherein the processing means comprises a threshold logic circuit means for processing said binary signals, the outputs of which logic circuit assumes a first logic level in response to predetermined combinations of said binary signals, the output otherwise assuming a second logic state.
Claim 8
Dependent Claim
45 words
The arrangement of claim 6 wherein the processing means further comprises means accepting the first and second time multiplexed filter outputs, storing said first filter output signal, and applying said stored signal to the threshold logic circuit together with the second filter output binary signal.
Claim 9
Dependent Claim
77 words
The arrangement of claim 1 wherein the reference generator further comprises clock means and a programmable divider means, the clock producing a stable reference frequency signal, and the divider dividing the clock output by a modulus N, the modulus N programmable in a predetermined manner in response to a selected frequency f whereby the clock signal is divided to the frequency f at first and second outputs, the second output in predetermined phase relationship with the first.
Claim 10
Dependent Claim
18 words
The arrangement of claim 1 wherein the reference generator produces the second signal in quadrature with the first.
Claim 11
Dependent Claim
39 words
The arrangement of claim 1 wherein each mixing means comprises logic means generating a first binary output responsive to the synchronous occurrence of an input signal and a reference signal, and a second binary output responsive to nonsynchronism thereof.
Claim 12
Dependent Claim
35 words
The arrangement of claim 1 further comprising means counting the number of above threshold samples detected during a predetermined time period, including means producing a second tone detect signal in response to a predetermined count.
Claim 13
Dependent Claim
42 words
The arrangement of claim 1 further comprising a plurality of counting means, each such means counting the number of above threshold samples detected during a predetermined time period, including means producing a second tone detect signal in response to a predetermined count.
Claim 14
Dependent Claim
47 words
The arrangement of claim 1 wherein the processing means comprises a plurality of threshold detecting means, each detecting means producing a threshold detect signal in response to predetermined first and second vector components, the arrangement further comprising means to selectively activate one of the desired threshold detectors.
Claim 15
Dependent Claim
202 words
A digital detector which detects the presence of a tone of a given frequency f in an incoming signal, having a reference signal generating means having a first and a second output, the first output producing a signal of frequency f at a first phase reference, the second output producing a signal having a second phase reference in quadrature with the first phase reference; a first mixer for multiplying the reference signal generator first output and the input signal, a second mixer multiplying the reference signal generator second output and the input signal, the improvement comprising: a digital low pass filter means for processing the first and second mixer outputs, said filter means producing first and second digital outputs, each digital output representative of a vector component of the amplitude of the input tone; and processing means for producing the filter digital outputs and producing a tone detect signal in response to the presence of predetermined first and second vector components, the processing means including means for determining the resultant vector of said first and second vector components and further comprising means for generating said tone detect signal in response to the amplitude of said resultant vector exceeding a given threshold level.
Claim 16
Dependent Claim
202 words
A digital detector which detects the presence of a tone of a given frequency f in an incoming signal, having a reference signal generating means having a first and a second output, the first output producing a signal of frequency f at a first phase reference, the second output producing a signal having a second phase reference in quadrature with the first phase reference; a first mixer for multiplying the reference signal generator first output and the input signal, a second mixer multiplying the reference signal generator second output and the input signal, the improvement comprising: a digital low pass filter means for processing the first and second mixer outputs, said filter means producing first and second digital outputs, each digital output representative of a vector component of the amplitude of the input tone; and processing means for producing the filter digital outputs and producing a tone detect signal in response to the presence of predetermined first and second vector components, the processing means including means for determining the resultant vector of said first and second vector components and further comprising means for generating said tone detect signal in response to the amplitude of said resultant vector exceeding a given threshold level.
Claim 17
Dependent Claim
148 words
The improvement of claim 14 wherein the first and second mixers produce binary output signals and wherein the digital low pass filter comprises: summer means for summing received binary signals at its first and second inputs and providing the resultant at its output, first multiplier means for multiplying said mixer binary output signals by a first predetermined binary constant and passing the resultant signal to the first input of the summer, means for producing at its output a predetermined time delay of signals at its inputs, means coupling the summer output to the delay input, and second multiplier means for multiplying the output from the time delay means by a second predetermined binary constant and passing the resultant signal to the second input of the summer, whereby the output from the summer is a binary number signal representative of a low pass transfer of the binary input signals.
Claim 18
Dependent Claim
56 words
The improvement of claim 15 wherein the digital low pass filter further comprises: a first grouping of half adders providing both the summing and the first multiplier functions, a flip flop array providing the time delay function, and a second grouping of full and half adders, along with corresponding logic gates, providing the second multiplier function.
Claim 19
Dependent Claim
66 words
The improvement of claim 15 wherein the processing means includes multiplexing means comprising: a multiplex switch operable at a predetermined rate to selectively couple the output from the first or second mixer to the digital filter first multiplier, and second time delay means having its input coupled to the digital filter time delay means output and its output coupled to the digital filter second multiplier input.
Claim 20
Dependent Claim
28 words
The improvement of claim 17 wherein the time delay of each delay means is equal to one-half the period of the multiplex switch and is operably synchronous thereto.
Claim 21
Dependent Claim
62 words
The improvement of claim 14 wherein the filter first and second outputs comprise a pair of binary signals and wherein the processing means comprises a threshold logic circuit means for processing said binary signals, the output of which logic circuit assumes a first logic level in response to predetermined combinations of said binary signals, the output otherwise assuming a second logic state.
Claim 22
Dependent Claim
63 words
The improvement of claim 19 further comprising: means for time multiplexing the first and second mixer output through the digital low pass filter; and the processing means further comprising means accepting the first and second time multiplexed filter outputs, storing said first filter output signal, and applying said stored signal to the threshold logic circuit together with said second filter output binary signal.
Claim 23
Dependent Claim
77 words
The improvement of claim 14 wherein the reference generator further comprises: clock means and a programmable divider means, the clock producing a stable reference frequency signal, and the divider dividing the clock output by a modulus N, the modulus N programmable in a predetermined manner in response to a selected frequency f whereby the clock signal is divided to the frequency f at first and second outputs, the second output in predetermined phase relationship with the first.
Claim 24
Dependent Claim
18 words
The improvement of claim 14 wherein the reference generator produces the second signal in quadrature with the first.
Claim 25
Dependent Claim
39 words
The improvement of claim 14 wherein each mixing meams comprises logic means generating a first binary output responsive to the synchronous occurrence of an input signal and a reference signal, and a second binary output responsive to nonsynchronism thereof.
Claim 26
Dependent Claim
35 words
The improvement of claim 14 further comprising means counting the number of above threshold samples detected during a predetermined time period, including means producing a second tone detect signal in response to a predetermined count.
Claim 27
Dependent Claim
42 words
The improvement of claim 14 further comprising a plurality of counting means, each such means counting the number of above threshold samples detected during a predetermined time period, including means producing a second tone detect signal in response to a predetermined count.
Claim 28
Dependent Claim
47 words
The improvement of claim 14 wherein the processing means comprises a plurality of threshold detecting means, each detecting means producing a threshold detect signal in response to predetermined first and second vector components, the arrangement further comprising means to selectively activate one of the desired threshold detectors.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-05-02 | 1980-11-01 | 1981-05-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-05-02 | 1984-11-01 | 1985-05-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-05-02 | 1988-11-01 | 1989-05-03 | $7700.00 | Window Closed / Lapsed |