EP0067395A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Modem with low part
Assignee: Hayes Microcomputer Products Inc
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Filing: 1982-06-07
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Granted: —
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Expires: 2002-06-07
Abstract
Abstract An FSK modem for coupling a standard data port (50) to a telephone line (45) in which the signal path between the phone line and the data port passes through a processor (55). The same frequency detection apparatus (83, 192, 180) is used to both demodulate FSK encoded signals and detect the presence of a telephone ringing signal on the line. A pair of impedances (161, 162) provide alternate paths either through an input filtering network (167) or bypassing the network (135, 69) in a manner which allows the ring signals to pass directly to the input (69) of the frequency detector while assuring that only filtered FSK signals reach the input. Also shown in the use of the same frequency synthesizing apparatus (86, 253, 259) for generating FSK output signals and high group DTMF signals with appropriate switchable attenuation (88) provided in this signal path.
Inventors
- 👤 Dale A. Heatherington
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 21:50
CPC Classifications
H; H04; H04M; H04M11/00; H04M11/06; H04L; H04L27/00; H04L27/10; H04L27/26; H04L27/30
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
249 words
In a data communications adapter for receiving an angle modulated data signal from a ,data link including a clock (118) for providing clock pulses; an improved demodulator characterized by: a counter (180); input means (155, 156) for coupling said angle modulated data signal to an input port (83) responsive to provide an interrupt signal (195) upon each occurrence of a transition of a predetermined sense in said data signal; means for connecting (177, 185, 189) said clock, said counter and said input port; counter control means for controlling said counter to store the present count of said counter in a first register (191) as a first register value and subsequently to load.a predetermined initial value (181) in said counter in response to each occurrence of said interrupt signal and for causing said counter to count said clock pulses between occurrences of said interrupt signal; memory control means for storing said first register value in at least one other register (198) in response to said each occurrence of said interrupt signal; averaging means (111) for computing an average count from an even number of successive values of said first register value; and output means including an output port (82, 210) connected to said averaging means for providing a first type output signal to said output port in response to said average count being greater than a predetermined reference count and alternately for providing a second type output signal in response to said average count being less than said reference count.
Claim 2
Dependent Claim
249 words
In a data communications adapter for receiving an angle modulated data signal from a ,data link including a clock (118) for providing clock pulses; an improved demodulator characterized by: a counter (180); input means (155, 156) for coupling said angle modulated data signal to an input port (83) responsive to provide an interrupt signal (195) upon each occurrence of a transition of a predetermined sense in said data signal; means for connecting (177, 185, 189) said clock, said counter and said input port; counter control means for controlling said counter to store the present count of said counter in a first register (191) as a first register value and subsequently to load.a predetermined initial value (181) in said counter in response to each occurrence of said interrupt signal and for causing said counter to count said clock pulses between occurrences of said interrupt signal; memory control means for storing said first register value in at least one other register (198) in response to said each occurrence of said interrupt signal; averaging means (111) for computing an average count from an even number of successive values of said first register value; and output means including an output port (82, 210) connected to said averaging means for providing a first type output signal to said output port in response to said average count being greater than a predetermined reference count and alternately for providing a second type output signal in response to said average count being less than said reference count.
Claim 3
Dependent Claim
85 words
An improved demodulator as recited in Claim 1 wherein said output means is further characterized by: hysteresis means responsive to said output port for setting said predetermined reference count to a first predetermined reference value (175) upon each occurrence of said first type output signal being provided (227) to said output port and alternately for setting said predetermined reference count to a second predetermined reference value (176) in response to each occurrence of said second type output signal being provided (230) to said output port.
Claim 4
Dependent Claim
19 words
An improved demodulation as recited in Claim 1 characterized in that: said even number of successive value is two.
Claim 5
Dependent Claim
180 words
In a data communications adapter including a duplexer (58) for coupling a telephone line (57) to a first point (135) in a signal path, said first point being an input point to a filter network (167), said filter network including an output, and a decoder for decoding signals from said telephone line, an improved circuit for connecting said duplexer, said filter, and said decoder characterized by: a first impedance (161) connecting said first point to a second point (69) (161); means for connecting said output of said filter network to a third point (166) and for providing a low output impedance (168) at said third point; a second impedance (162) connecting said second point and said third point; wherein said first impedance, said second impedance and said output impedance provide a low pass fuanction between said first point (135) and said second point (69); and said output impedance (168) and said second impedance provide a high pass function between said output of said filter network and said second point; and means connecting (70) said second point and said decoding means.
Claim 6
Dependent Claim
180 words
In a data communications adapter including a duplexer (58) for coupling a telephone line (57) to a first point (135) in a signal path, said first point being an input point to a filter network (167), said filter network including an output, and a decoder for decoding signals from said telephone line, an improved circuit for connecting said duplexer, said filter, and said decoder characterized by: a first impedance (161) connecting said first point to a second point (69) (161); means for connecting said output of said filter network to a third point (166) and for providing a low output impedance (168) at said third point; a second impedance (162) connecting said second point and said third point; wherein said first impedance, said second impedance and said output impedance provide a low pass fuanction between said first point (135) and said second point (69); and said output impedance (168) and said second impedance provide a high pass function between said output of said filter network and said second point; and means connecting (70) said second point and said decoding means.
References Cited (Backward Citations)
No citation records indexed.
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