US3773975A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fsk digital transmitter
Assignee: Unisys Corp
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Filing: 1971-12-17
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Granted: 1973-11-20
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Expires: 1991-12-17
Abstract
Abstract A digital transmitter used in data sets for digitally constructing sine waves to transmit mark and space information signals over a communication channel. A medium frequency oscillator supplies the basic timing for selecting consecutive segments of a sine wave and an amplitude selector generates signals representing the amplitudes of each segment to be supplied to a digital to analogue converter. Through several steps of frequency division, the phase angle error at the frequency shifts, due to mark and space transistion, is reduced to an extremely small angle. The apparatus shown is applicable to the several frequency ranges of data sets.
Inventors
- 👤 L Koziol
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:56
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/10; H04L27/12; H04L27/122
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
223 words
In a data set, a digital transmitter for transmitting at least two substantially sinusoidal frequency modulated electrical signals each cycle of said signals comprised of segments along a communication channel comprising: means for receiving binary encoded information wherein one value is a mark signal and the other value is a spae signal, said pulse repetition frequency being the least common product of the frequencies of transmission and the number of segments per cycle of said sinusoidal electrical signals, frequency selection means including counting means responsive to said pulses generated by said pulse generating means for dividing said pulse repetition frequency according to the value of said received binary encoded information and control means for switching the counting means according to the received binary encoded information to provide an electrical pulse signal having a minimum phase angle error during the switching of said counting means, sinusoidal segment selection means responsive to said electrical signal from said frequency selection means for selecting consecutive segments of a sinusoidal electrical signal and for further minimizing phase angle error, segment amplitude selection means responsive to said selected segment for generating at least one digital-binary signal representing the signal amplitude of said selected segment, and a digital to analogue converter responsive to said digital signals for constructing a sinusoidal frequency modulated electrical signal for transmission along the communication channel.
Claim 2
Dependent Claim
223 words
In a data set, a digital transmitter for transmitting at least two substantially sinusoidal frequency modulated electrical signals each cycle of said signals comprised of segments along a communication channel comprising: means for receiving binary encoded information wherein one value is a mark signal and the other value is a spae signal, said pulse repetition frequency being the least common product of the frequencies of transmission and the number of segments per cycle of said sinusoidal electrical signals, frequency selection means including counting means responsive to said pulses generated by said pulse generating means for dividing said pulse repetition frequency according to the value of said received binary encoded information and control means for switching the counting means according to the received binary encoded information to provide an electrical pulse signal having a minimum phase angle error during the switching of said counting means, sinusoidal segment selection means responsive to said electrical signal from said frequency selection means for selecting consecutive segments of a sinusoidal electrical signal and for further minimizing phase angle error, segment amplitude selection means responsive to said selected segment for generating at least one digital-binary signal representing the signal amplitude of said selected segment, and a digital to analogue converter responsive to said digital signals for constructing a sinusoidal frequency modulated electrical signal for transmission along the communication channel.
Claim 3
Dependent Claim
65 words
In a data set, a digital transmitter for transmitting substantially sinusoidal frequency modulated electrical signals along a communication channel according to claim 1 wherein said counting means is a dual modulo counter having a single input and a single output being operatively connected together by a first counting path for one of said counters and the second counting path for the other of said counters.
Claim 4
Dependent Claim
45 words
In a data set, a digital transmitter for transmitting sinusoidal frequency modulated electrical signals along a communication channel according to claim 1 wherein said sinusoidal segment section means is a four stage modulo sixteen counter responsive to the output pulse from said logic control means.
Claim 5
Dependent Claim
58 words
In a data set, a digital transmitter for transmitting substantially sinusoidal frequency modulated electrical signals along a communication channel according to claim 3 wherein said frequencies of transmission are 1300 hertz and 2100 hertz and the number of segments for each cycle of the transmitted electrical signal is 16 and said oscillator has a frequency of 436,800 hertz.
Claim 6
Dependent Claim
55 words
In a data set, a digitaL transmitter for transmitting substantially sinusoidal frequency modulated electrical signals along a communication channel according to claim 3 wherein said digital to analogue converter is bipolar for generating an electrical signal wherein each half cycle is dependent upon the state of the fourth stage of said sinusoidal segment selection means.
Claim 7
Dependent Claim
120 words
In a data set, a digital transmitter for transmitting substantially sinusoidal frequency modulated electrical signals along a communication channel according to claim 1 wherein said counting means comprises: a dual modulo counter having a common input and output and dual counting paths wherein one path is responsive to said mark signal and the other path is responsive to said space signal and further where each of said paths begin at the common input and terminate at said common output, and said control means is a logic unit responsive to said space and mark signals received by said receiving means to operatively select the other of said count paths immediately upon receipt of the transistion between said mark and space signals.
Claim 8
Dependent Claim
130 words
In a data set, a digital transmitter for transmitting substantially sinusoidal frequency modulated electrical signals along a communication channel according to claim 1 wherein said frequency selection means comprises: a first modulo counter responsive to said pulse generating means for dividing the frequency of said pulse generating means by a first factor, a second modulo counter responsive to said pulse generating means for dividing the frequency of said pulse generating means by a second factor, logic means responsive to said binary encoded information for selecting one output from either of said counters, and a third modulo counter responsive to said selected output from said logic means for dividing said output by a third factor for reducing the phase angle error at the frequency shift due to mark and space transistion.
Claim 9
Dependent Claim
63 words
In a data set, a digital transmitter for transmitting substantially sinusoidal frequency modulated electrical signals along a communication channel according to claim 1 wherein said control means of said frequency selection means includes a state machine responsive to said received information for switching said counting means between predetermined count paths within said counting means according to the binary value of said received information.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-19 | 1977-05-21 | 1977-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-19 | 1981-05-21 | 1981-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-19 | 1985-05-21 | 1985-11-20 | $7700.00 | Window Closed / Lapsed |