US3590164A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transmission system for two-level signals providing reduced bandwidth requirements
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1968-07-19
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Granted: 1971-06-29
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Expires: 1988-07-19
Abstract
Abstract An electrical communication system wherein two-level analog signals, as in black-and-white or message facsimile, are converted into digital signals for transmission over a transmission channel. The input signal is sampled at twice its maximum frequency (Nyquist Rate) even though the bandwidth of the transmission channel limits the usable bit rate to a substantially lower value. The signal converter circuit employs perceptive coding of the signal to reduce the transmitted bit rate to a value consonant with the capacity of the channel without loss of pulses representing a line or space of one-half the resolution size. Thus the ideal sampling rate may be used where the transmission channel will not accommodate the corresponding bit rate of the digitalized signal.
Inventors
- 👤 Bert F Krauss
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:51
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/41; H04N1/411
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
111 words
A transmission system for two-level analog signals, comprising: means for converting input analog signals into digital code signals, including means for sampling said input signals at a sampling rate greater than the maximum transmission frequency of said system; means for storing said digital code signals; means for comparing two consecutive bits of said digital code signals; means controlled by said comparing means for transmitting bits, each representing said two consecutive bits; and said means controlled by said comparing means connected to said comparing means for providing a previous transmission bit for comparison against said two consecutive bits, whereby said transmission frequency required is reduced without a corresponding reduction in sampling rate.
Claim 2
Dependent Claim
111 words
A transmission system for two-level analog signals, comprising: means for converting input analog signals into digital code signals, including means for sampling said input signals at a sampling rate greater than the maximum transmission frequency of said system; means for storing said digital code signals; means for comparing two consecutive bits of said digital code signals; means controlled by said comparing means for transmitting bits, each representing said two consecutive bits; and said means controlled by said comparing means connected to said comparing means for providing a previous transmission bit for comparison against said two consecutive bits, whereby said transmission frequency required is reduced without a corresponding reduction in sampling rate.
Claim 3
Dependent Claim
50 words
A transmission system according to claim 1, in which the sampling rate is twice the transmission bit rate of the two-level analog signals, and the character of each bit transmitted (1 or 0) is determined by said comparing means after comparing said two consecutive bits and said previous transmission bit.
Claim 4
Dependent Claim
43 words
A transmission system according to claim 1, in which said digital code signal storing means continually stores two consecutive bits of the digitalized input signals and said means controlled by said comparing means continually stores one bit of the digitalized previous transmission bit.
Claim 5
Dependent Claim
97 words
A transmission system for two-level analog signals, comprising: an output circuit; an input circuit for converting input analog signals into digital code signals, including means for sampling said input signals at twice the maximum transmission frequency of said system; flip-flop means for storing each input digital code signal and for storing the previously transmitted signal; and gating means for controlling said flip-flop means and for transmitting digital signals over said output circuit as determined by said stored input digital code signal and said stored previously transmitted signal, whereby said transmitting rate is less than the sampling rate.
Claim 6
Dependent Claim
97 words
A transmission system for two-level analog signals, comprising: an output circuit; an input circuit for converting input analog signals into digital code signals, including means for sampling said input signals at twice the maximum transmission frequency of said system; flip-flop means for storing each input digital code signal and for storing the previously transmitted signal; and gating means for controlling said flip-flop means and for transmitting digital signals over said output circuit as determined by said stored input digital code signal and said stored previously transmitted signal, whereby said transmitting rate is less than the sampling rate.
Claim 7
Dependent Claim
27 words
A transmission system for two-level analog signals according to claim 4, wherein the output transmitting rate is equal to the sampling rate of the input analog signals.
Claim 8
Dependent Claim
68 words
A transmission system for two-level analog signals according to claim 4, wherein said flip-flop means include two flip-flop means for storing two consecutive bits of said digital code signal and one flip-flop means for storing said previously transmitted signal, and said gating means is connected to receive said stored signals and to control said one flip-flop means for selecting the signal to be transmitted over said output circuit.
References Cited (Backward Citations)
US3449675A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-06-28 | 1974-12-28 | 1975-06-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-28 | 1978-12-28 | 1979-06-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-28 | 1982-12-28 | 1983-06-29 | $7700.00 | Window Closed / Lapsed |