US3749843A
Expired / Lapsed
US
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Digital amplitude modulator
Assignee: AT&T Inc
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Filing: 1972-05-08
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Granted: 1973-07-31
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Expires: 1992-05-08
Abstract
Abstract An envelope modulator which shapes and combines a number of binary input signals by digital means comprises a compact combinatorial logic network, a digital-to-analog converter and a low-pass filter. The logic network operates on the binary input signals to provide at its output a plurality of binary coded bit streams representing a quantized composite of the input signals with a superimposed desired amplitude shaping. The digital-toanalog converter combines the bit streams from the logic network into a quantized signal and the low-pass filter yields a smooth line signal suitable for transmission over bandlimited channels. The elimination of the reactive components required in conventional analog envelope modulators makes this invention capable of operation over a wide range of baud rates.
Inventors
- 👤 T Roycraft
- 👤 J Sheehan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:02
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/02; H04L27/04; H04L25/00; H04L25/38; H04L25/40; H04L25/49; H04L27/18; H04L27/20; H04L27/2032; H04L27/2053; H04L27/206; H04L27/2067; H04L27/2071
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
94 words
An envelope modulator for binary data signals comprising a multichannel source of synchronous binary input signals; a source of control signals defining a repetitive sequence of control states; and means jointly responsive to said input and control signals for producing an output signal whose instantaneous value equals the algebraic sum of products of the sense of each input signal with the particular weight assigned to its channel during each control state, the sequence of such weights, repeating in correspondence to the sequence of control states, defining the desired envelope shaping for the individual channel.
Claim 2
Dependent Claim
94 words
An envelope modulator for binary data signals comprising a multichannel source of synchronous binary input signals; a source of control signals defining a repetitive sequence of control states; and means jointly responsive to said input and control signals for producing an output signal whose instantaneous value equals the algebraic sum of products of the sense of each input signal with the particular weight assigned to its channel during each control state, the sequence of such weights, repeating in correspondence to the sequence of control states, defining the desired envelope shaping for the individual channel.
Claim 3
Dependent Claim
57 words
The envelope modulator of claim 1 in which the said producing means comprises logic means jointly responsive to said input and control signals for producing a plurality of bit streams which collectively encode said output signal, and digital-to-analog conversion means for generating said output signal as a weighted summation of the bit streams from said logic means.
Claim 4
Dependent Claim
129 words
The envelope modulator of claim 2 in which said multichannel source provides two phase-shift keyed signals A and B, whose phase changes occur during alternate synchronous intervals, said control-signal source supplying four binary signals M, N, P and Q respectively at once, twice, four and eight times the synchronous rate and in which the operation of said logic means is defined by the following Boolean equations: Z N + Q + V (1) Y (N + Q)(A + B)(N + P) + V (2) X (N + Q)(A + B)(N + P) + V (3) W (N + Q)(A + B)(N + P) + V (4) V (M . A)(M . B) (5) where signals V, W, X, Y and Z define the bit streams from said logic means.
Claim 5
Dependent Claim
137 words
In combination with a phase-modulated transmission system for digital data differentially encoded in groups of equal numbers of data bits as discrete phase changes occurring between successive synchronous signaling intervals of a squared-up carrier wave, carrier-wave bursts of substantially constant phase corresponding to successive signaling intervals being distributed in rotation among as many signaling channels as there are data bits in each code group, a digital envelope modulator comprising a control signal source providing a plurality of discrete control states during each data signaling interval, logic means jointly responsive to the binary states of each of said signaling channels and to said plurality of control states for combining the carrier waves on all said channels with an envelope shaping programmed for each channel as a set of weights equal in number to said plurality of control states.
Claim 6
Dependent Claim
137 words
In combination with a phase-modulated transmission system for digital data differentially encoded in groups of equal numbers of data bits as discrete phase changes occurring between successive synchronous signaling intervals of a squared-up carrier wave, carrier-wave bursts of substantially constant phase corresponding to successive signaling intervals being distributed in rotation among as many signaling channels as there are data bits in each code group, a digital envelope modulator comprising a control signal source providing a plurality of discrete control states during each data signaling interval, logic means jointly responsive to the binary states of each of said signaling channels and to said plurality of control states for combining the carrier waves on all said channels with an envelope shaping programmed for each channel as a set of weights equal in number to said plurality of control states.
Claim 7
Dependent Claim
35 words
The combination set forth in claim 4 in which said logic means forms as an output a plurality of binarily weighted bit streams encoding a composite phase-modulated carrier wave signal with a superimposed envelope shaping.
Claim 8
Dependent Claim
59 words
The combination set forth in claim 4 in which said logic means produces as an output a plurality of binarily weighted bit streams whose analog value corresponds to the algebraic summation of the products of the envelope-shaping weights assigned to each signaling channel and the instantaneous polarities of the channel signals taken during each of said control signal states.
Claim 9
Dependent Claim
89 words
A waveshaper for binary data comprising a control source synchronized with said binary data for providing a sequence of control-signal states repeated during each binary signaling interval; and means jointly responsive to said binary data and said control-signal states for producing a shaped output signal whose instantaneous value is the product of the instantaneous sense of the binary data and the particular weight assigned thereto during each control-signal state, a set of such weights being preassigned to the sequence of control-signal states to define a desired envelope shaping function.
Claim 10
Dependent Claim
89 words
A waveshaper for binary data comprising a control source synchronized with said binary data for providing a sequence of control-signal states repeated during each binary signaling interval; and means jointly responsive to said binary data and said control-signal states for producing a shaped output signal whose instantaneous value is the product of the instantaneous sense of the binary data and the particular weight assigned thereto during each control-signal state, a set of such weights being preassigned to the sequence of control-signal states to define a desired envelope shaping function.
Claim 11
Dependent Claim
49 words
The waveshaper of claim 7 in which said output-signal producing means comprises logic means for producing a plurality of bit streams collectively encoding said output signal, and digital-to-analog conversion means for combining the elements of said bit streams in accordance with a binary weighting into a single output signal.
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) | 1976-07-30 | 1977-01-29 | 1977-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-30 | 1981-01-29 | 1981-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-30 | 1985-01-29 | 1985-07-31 | $7700.00 | Window Closed / Lapsed |