US4481642A
Expired / Lapsed
US
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Integrated circuit FSK modem
Assignee: Texas Instruments Inc
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Filing: 1981-06-02
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Granted: 1984-11-06
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Expires: 2001-06-02
Abstract
Abstract An integrated circuit FSK transmitter and receiver combination form a modem for receiving and transmitting FSK signals. The FSK transmitter has a square wave generator for providing a clock output at a "mark" frequency or at a "space" frequency within a first frequency band. This clock output is shaped through a band pass filter, shared with the FSK receiver, to provide an FSK output signal which is output through a low pass filter. The input FSK signal is received through a low pass filter and then filtered through the band pass filter. One section of the band pass filter accommodates the clock output while another section accommodates the FSK input. The band pass filter is connected to a demodulating means to provide a filtered sine wave thereto at either a mark or a space frequency within a second frequency band. The demodulating means determines whether the sine wave is at a mark or a space frequency.
Inventors
- 👤 Kerry A. Hanson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 10:17
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/10
Claims Analysis
Total Claims: 67
Claim 1
Independent Claim
74 words
An integrated circuit FSK transmitter comprising: (a) clock means for providing a clock output at a desired carrier frequency; (b) sampled analog bandpass filter means having independently controlled phase response and independently controlled amplitude response, connected to the clock means, for receiving the clock output to filter and provide an FSK output signal at the desired carrier frequency; and (c) output means, connected to the bandpass filter means, for transmitting the FSK output signal.
Claim 2
Dependent Claim
74 words
An integrated circuit FSK transmitter comprising: (a) clock means for providing a clock output at a desired carrier frequency; (b) sampled analog bandpass filter means having independently controlled phase response and independently controlled amplitude response, connected to the clock means, for receiving the clock output to filter and provide an FSK output signal at the desired carrier frequency; and (c) output means, connected to the bandpass filter means, for transmitting the FSK output signal.
Claim 3
Dependent Claim
42 words
The FSK transmitter of claim 1 wherein the clock means comprises: (a) (i) oscillator means; and (ii) square wave generating means, connected to receive the output of the oscillator means, for generating a square wave clock signal at the desired carrier frequency.
Claim 4
Dependent Claim
32 words
The FSK transmitter of claim 2 wherein the clock means further comprises: (a) (iii) carrier frequency selection means connected to the square wave generating means for selecting a desired clock signal frequency.
Claim 5
Dependent Claim
17 words
The FSK transmitter of claim 3 wherein the carrier frequency selection means comprises a pseudo-random shift register.
Claim 6
Dependent Claim
18 words
The FSK transmitter of claim 1 wherein the band pass filter means comprises a high band pass filter.
Claim 7
Dependent Claim
18 words
The FSK transmitter of claim 1 wherein the band pass filter means comprises a low band pass filter.
Claim 8
Dependent Claim
32 words
The FSK transmitter of claim 1 wherein the band pass filter means comprises a high band pass filter and a low band pass filter, each selectively connected to receive the clock output.
Claim 9
Dependent Claim
32 words
The FSK transmitter of claim 2 wherein the band pass filter means comprises a high band pass filter and a low band pass filter, each selectively connected to receive the clock output.
Claim 10
Dependent Claim
32 words
The FSK transmitter of claim 3 wherein the band pass filter means comprises a high band pass filter and a low band pass filter, each selectively connected to receive the clock output.
Claim 11
Dependent Claim
16 words
The FSK transmitter of claim 1 wherein the output means comprises a continuous low pass filter.
Claim 12
Dependent Claim
15 words
The FSK transmitter of claim 3 wherein the output means comprises a low pass filter.
Claim 13
Dependent Claim
15 words
The FSK transmitter of claim 7 wherein the output means comprises a low pass filter.
Claim 14
Dependent Claim
17 words
The FSK transmitter of any of claims 1 through 12 wherein the integrated circuit comprises MOS circuitry.
Claim 15
Dependent Claim
20 words
The FSK transmitter of any of claims 1 through 12 wherein the band pass filter means comprise switched capacitor filters.
Claim 16
Dependent Claim
79 words
An integrated circuit FSK receiver, comprising: (a) input means for receiving an input FSK signal; (b) sampled analog bandpass filter means having independently controlled phase response and independently controlled amplitude response, connected to the input means, for receiving the input FSK signal to filter and provide a sine wave output; and (c) demodulating means connected to the bandpass filter means, to receive the sine wave output for determining whether its frequency corresponds to a mark or a space indication.
Claim 17
Dependent Claim
79 words
An integrated circuit FSK receiver, comprising: (a) input means for receiving an input FSK signal; (b) sampled analog bandpass filter means having independently controlled phase response and independently controlled amplitude response, connected to the input means, for receiving the input FSK signal to filter and provide a sine wave output; and (c) demodulating means connected to the bandpass filter means, to receive the sine wave output for determining whether its frequency corresponds to a mark or a space indication.
Claim 18
Dependent Claim
15 words
The FSK receiver of claim 15 wherein the input means comprises a low pass filter.
Claim 19
Dependent Claim
18 words
The FSK receiver of claim 15 wherein the band pass filter means comprises a high band pass filter.
Claim 20
Dependent Claim
18 words
The FSK receiver of claim 15 wherein the band pass filter means comprises a low band pass filter.
Claim 21
Dependent Claim
32 words
The FSK receiver of claim 15 wherein the band pass filter means comprises a high band pass filter and a low band pass filter, each selectively connected to receive the clock output.
Claim 22
Dependent Claim
32 words
The FSK receiver of claim 16 wherein the band pass filter means comprises a high band pass filter and a low band pass filter, each selectively connected to receive the clock output.
Claim 23
Dependent Claim
73 words
The FSK receiver of claim 15 wherein the demodulating means comprises: (c) (i) mark filter means for receiving and filtering the sine wave output; (ii) space filter means for receiving and filtering the sine wave output; (iii) comparison means for comparing the energy output of the mark filter means with the energy output of the space filter means; and (iv) conversion means for converting the output of the comparison means to digital data.
Claim 24
Dependent Claim
64 words
The FSK receiver of claim 20 wherein the demodulating means comprises: (c) (i) mark filter means for receiving and filtering the sine wave output; (ii) space filter means for receiving said filtering the sine wave output; (iii) comparison means for comparing the energy output of the space filter means; and (iv) conversion means for converting the output of the comparison means to digital data.
Claim 25
Dependent Claim
67 words
The FSK receiver of claim 15 further comprising: (d) automatic gain control means connected to the band pass filter means to receive the sine wave output for adjusting the sine wave amplitude to a prescribed magnitude and connected to transmit the adjusted sine wave to the demodulating means; and (e) carrier detect means connected to the demodulator means for detecting the presence of the FSK input signal.
Claim 26
Dependent Claim
67 words
The FSK receiver of claim 22 further comprising: (d) automatic gain control means connected to the band pass filter means to receive the sine wave output for adjusting the sine wave amplitude to a prescribed magnitude and connected to transmit the adjusted sine wave to the demodulating means; and (e) carrier detect means connected to the demodulator means for detecting the presence of the FSK input signal.
Claim 27
Dependent Claim
35 words
The FSK receiver of claim 23 wherein the carrier detect means is connected with the automatic gain control means and the conversion means to provide an indicia output signal when digital data is actually present.
Claim 28
Dependent Claim
35 words
The FSK receiver of claim 24 wherein the carrier detect means is connected with the automatic gain control means and the conversion means to provide an indicia output signal when digital data is actually present.
Claim 29
Dependent Claim
45 words
The FSK receiver of claim 21 wherein the comparison means comprises a positive and negative full wave rectifier and a smoothing filter, and the conversion means comprises a comparator for comparing the output of the smoothing filter with a reference to provide the digital data.
Claim 30
Dependent Claim
45 words
The FSK receiver of claim 23 wherein the comparison means comprises a positive and negative full wave rectifier and a smoothing filter, and the conversion means comprises a comparator for comparing the output of the smoothing filter with a reference to provide the digital data.
Claim 31
Dependent Claim
45 words
The FSK receiver of claim 26 wherein the comparison means comprises a positive and negative full wave rectifier and a smoothing filter, and the conversion means comprises a comparator for comparing the output of the smoothing filter with a reference to provide the digital data.
Claim 32
Dependent Claim
15 words
The FSK receiver of any of claims 15-29 wherein the integrated circuit comprises MOS circuitry.
Claim 33
Dependent Claim
18 words
The FSK receiver of any of claims 15-29 wherein the band pass filter means comprise switched capacitor filters.
Claim 34
Dependent Claim
156 words
An integrated circuit FSK modem for receiving and transmitting FSK signals, comprising: (a) clock means for providing a clock output at a frequency within a first frequency band; (b) input means for receiving an input FSK signal at a frequency within a second frequency band; (c) sampled analog bandpass filter means having independently controlled phase response and independently controlled amplitude response, connected to the clock means and to the input means, having a first section for receiving the clock output to filter and provide an output FSK signal, and having a second section for receiving the FSK input signal to filter and provide a sine wave output; (d) output means, connected to the bandpass filter means, for transmitting the output FSK signal; and (e) demodulating means, connected to the bandpass filter means, to receive the sine wave output for determining whether its frequency within the second frequency band corresponds to a mark or a space indication.
Claim 35
Dependent Claim
156 words
An integrated circuit FSK modem for receiving and transmitting FSK signals, comprising: (a) clock means for providing a clock output at a frequency within a first frequency band; (b) input means for receiving an input FSK signal at a frequency within a second frequency band; (c) sampled analog bandpass filter means having independently controlled phase response and independently controlled amplitude response, connected to the clock means and to the input means, having a first section for receiving the clock output to filter and provide an output FSK signal, and having a second section for receiving the FSK input signal to filter and provide a sine wave output; (d) output means, connected to the bandpass filter means, for transmitting the output FSK signal; and (e) demodulating means, connected to the bandpass filter means, to receive the sine wave output for determining whether its frequency within the second frequency band corresponds to a mark or a space indication.
Claim 36
Dependent Claim
41 words
The modem of claim 32 wherein the clock means comprises: (a) (i) oscillator means; and (ii) square wave generating means, connected to receive the output of the oscillator means, for generating a square wave clock signal at the desired carrier frequency.
Claim 37
Dependent Claim
31 words
The modem of claim 33 wherein the clock means further comprises: (a) (iii) carrier frequency selection means connected to the square wave generating means for selecting a desired clock signal frequency.
Claim 38
Dependent Claim
16 words
The modem of claim 34 wherein the carrier frequency selection means comprises a pseudo-random shift register.
Claim 39
Dependent Claim
14 words
The modem of claim 32 wherein the input means comprises a low pass filter.
Claim 40
Dependent Claim
41 words
The modem of claim 36 wherein the clock means comprises: (a) (i) oscillator means; and (iii) square wave generating means, connected to receive the output of the oscillator means, for generating a square wave clock signal at the desired carrier frequency.
Claim 41
Dependent Claim
31 words
The modem of claim 37 wherein the clock means further comprises: (a) (iii) carrier frequency selection means connected to the square wave generating means for selecting a desired clock signal frequency.
Claim 42
Dependent Claim
67 words
The modem of claim 32 wherein the band pass filter means comprises: (c) (i) input multiplexer means for selecting the first section for receiving the clock output and the second section for receiving the FSK input signal; and (ii) output multiplexer means for selecting the output FSK signal for transmission to the output means, and for selecting the sine wave output for transmission to the demodulating means.
Claim 43
Dependent Claim
41 words
The modem of claim 39 wherein the clock means comprises: (a) (i) oscilltor means; and (ii) square wave generating means, connected to receive the output of the oscillator means, for generating a square wave clock signal at the desired carrier frequency.
Claim 44
Dependent Claim
31 words
The modem of claim 40 wherein the clock means further comprises: (a) (iii) carrier frequency selection means connected to the square wave generating means for selecting a desired clock signal frequency.
Claim 45
Dependent Claim
67 words
The modem of claim 38 wherein the band pass filter means comprises: (c) (i) input multiplexer means for selecting the first section for receiving the clock output and the second section for receiving the FSK input signal; and (ii) output multiplexer means for selecting the output FSK signal for transmission to the output means, and for selecting the sine wave output for transmission to the demodulating means.
Claim 46
Dependent Claim
25 words
The modem of claim 42 wherein the first section comprises a high band pass filter and the second section comprises a low band pass filter.
Claim 47
Dependent Claim
25 words
The modem of claim 42 wherein the first section comprises a low band pass filter and the second section comprises a high band pass filter.
Claim 48
Dependent Claim
14 words
The modem of claim 32 wherein the output means comprises a low pass filter.
Claim 49
Dependent Claim
14 words
The modem of claim 33 wherein the output means comprises a low pass filter.
Claim 50
Dependent Claim
14 words
The modem of claim 37 wherein the output means comprises a low pass filter.
Claim 51
Dependent Claim
14 words
The modem of claim 40 wherein the output means comprises a low pass filter.
Claim 52
Dependent Claim
72 words
The modem of claim 32 wherein the demodulating means comprises: (c) (i) mark filter means for receiving and filtering the sine wave output; (ii) space filter means for receiving and filtering the sine wave output; (iii) comparison means for comparing the energy output of the mark filter means with the energy output of the space filter means; and (iv) conversion means for converting the output of the comparison means to digital data.
Claim 53
Dependent Claim
72 words
The modem of claim 33 wherein the demodulating means comprises: (c) (i) mark filter means for receiving and filtering the sine wave output; (ii) space filter means for receiving and filtering the sine wave output; (iii) comparison means for comparing the energy output of the mark filter means with the energy output of the space filter means; and (iv) conversion means for converting the output of the comparison means to digital data.
Claim 54
Dependent Claim
72 words
The modem of claim 37 wherein the demodulating means comprises: (c) (i) mark filter means for receiving and filtering the sine wave output; (ii) space filter means for receiving and filtering the sine wave output; (iii) comparison means for comparing the energy output of the mark filter means with the energy output of the space filter means; and (iv) conversion means for converting the output of the comparison means to digital data.
Claim 55
Dependent Claim
72 words
The modem of claim 40 wherein the demodulating means comprises: (c) (i) mark filter means for receiving and filtering the sine wave output; (ii) space filter means for receiving and filtering the sine wave output; (iii) comparison means for comparing the energy output of the mark filter means with the energy output of the space filter means; and (iv) conversion means for converting the output of the comparison means to digital data.
Claim 56
Dependent Claim
72 words
The modem of claim 48 wherein the demodulating means comprises: (c) (i) mark filter means for receiving and filtering the sine wave output; (ii) space filter means for receiving and filtering the sine wave output; (iii) comparison means for comparing the energy output of the mark filter means with the energy output of the space filter means; and (iv) conversion means for converting the output of the comparison means to digital data.
Claim 57
Dependent Claim
44 words
The modem of claim 49 wherein the comparison means comprises a positive and negative full wave rectifier and a smoothing filter, and the conversion means comprises a comparator for comparing the output of the smoothing filter with a reference to provide the digital data.
Claim 58
Dependent Claim
44 words
The modem of claim 51 wherein the comparison means comprises a positive and negative full wave rectifier and a smoothing filter, and the conversion means comprises a comparator for comparing the output of the smoothing filter with a reference to provide the digital data.
Claim 59
Dependent Claim
44 words
The modem of claim 53 wherein the comparison means comprises a positive and negative full wave rectifier and a smoothing filter, and the conversion means comprises a comparator for comparing the output of the smoothing filter with a reference to provide the digital data.
Claim 60
Dependent Claim
66 words
The modem of claim 32 further comprising: (d) automatic gain control means connected to the band pass filter means to receive the sine wave output for adjusting the sine wave amplitude to a prescribed magnitude and connected to transmit the adjusted sine wave to the demodulating means; and (e) carrier detect means connected to the demodulator means for detecting the presence of the FSK input signal.
Claim 61
Dependent Claim
66 words
The modem of claim 40 further comprising: (d) automatic gain control means connected to the band pass filter means to receive the sine wave output for adjusting the sine wave amplitude to a prescribed magnitude and connected to transmit the adjusted sine wave to the demodulating means; and (e) carrier detect means connected to the demodulator means for detecting the presence of the FSK input signal.
Claim 62
Dependent Claim
66 words
The modem of claim 53 further comprising: (d) automatic gain control means connected to the band pass filter means to receive the sine wave output for adjusting the sine wave amplitude to a prescribed magnitude and connected to transmit the adjusted sine wave to the demodulating means; and (e) carrier detect means connected to the demodulator means for detecting the presence of the FSK input signal.
Claim 63
Dependent Claim
34 words
The modem of claim 57 wherein the carrier detect means is connected with the automatic gain control means and the conversion means to provide an indicia output signal when digital data is actually present.
Claim 64
Dependent Claim
34 words
The modem of claim 58 wherein the carrier detect means is connected with the automatic gain control means and the conversion means to provide an indicia output signal when digital data is actually present.
Claim 65
Dependent Claim
34 words
The modem of claim 59 wherein the carrier detect means is connected with the automatic gain control means and the conversion means to provide an indicia output signal when digital data is actually present.
Claim 66
Dependent Claim
14 words
The modem of any of claims 32-62 wherein the integrated circuit comprises MOS circuitry.
Claim 67
Dependent Claim
17 words
The modem of any of claims 32-62 wherein the band pass filter means comprises switched capacitor filters.
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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) | 1987-11-06 | 1988-05-07 | 1988-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-11-06 | 1992-05-07 | 1992-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-11-06 | 1996-05-07 | 1996-11-06 | $7700.00 | Window Closed / Lapsed |