US3715496A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital band-pass filter for a single circuit full duplex transmission system
Assignee: International Business Machines Corp
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Filing: 1971-10-21
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Granted: 1973-02-06
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Expires: 1991-10-21
Abstract
Abstract A full duplex data communications system using a single transmission circuit is shown. Each terminal of the system has its receiver circuit provided with a digital filter to remove from its input circuit, the frequencies being used for data transmission at that terminal. The digital filter is switchable by the data signal to be transmitted and will be set to block from the receiver, the particular frequencies then being used to transmit data. In the preferred embodiment, the signal on the transmission line is converted to a delta modulated signal which is combined with its prior signal delayed by an interval dependent upon the data being transmitted from that terminal to generate a delta modulated filtered signal carrying the received data. The filtered signal is then converted to recover the received data.
Inventors
- 👤 G Jones
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 08:59
CPC Classifications
H; H04; H04L; H04L5/00; H04L5/14; H04L5/143
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
161 words
In a full duplex data transmission system having a single signal carrying circuit between at least two separated stations and wherein each station includes both a data transmitter to impress on said circuit data signals represented by discrete frequencies within one frequency band and a data receiver to translate data signals represented by discrete frequencies within another frequency band in said circuit; the feature comprising a filter for eliminating said discrete frequencies within said transmission frequency band from the input to said reCeiver; said filter including an adjustable signal delaying element to receive the signals in said circuit; switching means controlled by the data signals in said transmitter to set the delay of said delaying element in accordance with the discrete frequency being transmitted; and a signal mixer to combine the output of said delaying element with the signals then in said carrying circuit to supply to said receiver only the circuit data signals which are within said other frequency band.
Claim 2
Dependent Claim
161 words
In a full duplex data transmission system having a single signal carrying circuit between at least two separated stations and wherein each station includes both a data transmitter to impress on said circuit data signals represented by discrete frequencies within one frequency band and a data receiver to translate data signals represented by discrete frequencies within another frequency band in said circuit; the feature comprising a filter for eliminating said discrete frequencies within said transmission frequency band from the input to said reCeiver; said filter including an adjustable signal delaying element to receive the signals in said circuit; switching means controlled by the data signals in said transmitter to set the delay of said delaying element in accordance with the discrete frequency being transmitted; and a signal mixer to combine the output of said delaying element with the signals then in said carrying circuit to supply to said receiver only the circuit data signals which are within said other frequency band.
Claim 3
Dependent Claim
161 words
In a full duplex data transmission system having a single signal carrying circuit between at least two separated stations and wherein each station includes both a data transmitter to impress on said circuit data signals represented by discrete frequencies within one frequency band and a data receiver to translate data signals represented by discrete frequencies within another frequency band in said circuit; the feature comprising a filter for eliminating said discrete frequencies within said transmission frequency band from the input to said reCeiver; said filter including an adjustable signal delaying element to receive the signals in said circuit; switching means controlled by the data signals in said transmitter to set the delay of said delaying element in accordance with the discrete frequency being transmitted; and a signal mixer to combine the output of said delaying element with the signals then in said carrying circuit to supply to said receiver only the circuit data signals which are within said other frequency band.
Claim 4
Dependent Claim
161 words
In a full duplex data transmission system having a single signal carrying circuit between at least two separated stations and wherein each station includes both a data transmitter to impress on said circuit data signals represented by discrete frequencies within one frequency band and a data receiver to translate data signals represented by discrete frequencies within another frequency band in said circuit; the feature comprising a filter for eliminating said discrete frequencies within said transmission frequency band from the input to said reCeiver; said filter including an adjustable signal delaying element to receive the signals in said circuit; switching means controlled by the data signals in said transmitter to set the delay of said delaying element in accordance with the discrete frequency being transmitted; and a signal mixer to combine the output of said delaying element with the signals then in said carrying circuit to supply to said receiver only the circuit data signals which are within said other frequency band.
Claim 5
Dependent Claim
120 words
A filter for a data transmission system as set out in claim 1 and in which said delay element comprises: a shift register having a plurality of positions; a clock controlling the discrete frequencies of said transmitter and shifting said shift register, the transit time of a signal through said shift register being equal to an odd number of half cycles of the lowest frequency of said transmitter; one or more connections to said shift register at positions where the transit time is equal to an odd number of half cycles of other transmit frequencies of said transmitter, said switching means selecting for connection to said mixer, the shift register position corresponding to the frequency being transmitted by said transmitter.
Claim 6
Dependent Claim
126 words
A filter as set out in claim 1 in which the signal on said signal carrying circuit is delta modulated to generate a series of data representing pulses; a clock having a frequency integrally related to all of said discrete transmission frequencies and controlling said delta modulator; a plural order shift register receiving the data pulses from said delta modulator and shifted by the output of said clock; a connection to an intermediate position of said shift register, said switching means connecting the last or said intermediate position of said shift register to an output line; and a double clock speed line controlling said mixer to alternately select the output of said delta modulator or the switched output of said shift register to said receiver input.
References Cited (Backward Citations)
US3577202A
Cited
US3543172A
Cited
US3566031A
Cited
US3649759A
Cited
US3651433A
Cited
US3655915A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-06 | 1976-08-07 | 1977-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-06 | 1980-08-07 | 1981-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-06 | 1984-08-07 | 1985-02-06 | $7700.00 | Window Closed / Lapsed |