Apparatus and method for sync detection in digital data

Claim 1

An apparatus for locating a sync pattern in a digital data stream, comprising: means, responsive to said digital data stream, for detecting the sync pattern, for generating a first signal in response to a condition in which said sync pattern occurs at a position in said digital data stream within a window about an expected position of said sync signal and for setting a width of said window in accordance with a value of a threshold signal; and means, responsive to said first signal for generating said threshold signal to have (a) a first value causing said window to have a first width in response to a condition in which said first signal occurs within a predefined interval, and (b) a second value causing said window to have a second width greater than said first width in response to a condition in which said first signal does not occur within said predefined interval.

Claim 2

An apparatus for locating a sync pattern in a digital data stream, comprising: means, responsive to said digital data stream, for detecting the sync pattern, for generating a first signal in response to a condition in which said sync pattern occurs at a position in said digital data stream within a window about an expected position of said sync signal and for setting a width of said window in accordance with a value of a threshold signal; and means, responsive to said first signal for generating said threshold signal to have (a) a first value causing said window to have a first width in response to a condition in which said first signal occurs within a predefined interval, and (b) a second value causing said window to have a second width greater than said first width in response to a condition in which said first signal does not occur within said predefined interval.

Claim 5

An apparatus for locating a sync pattern, comprising: converting means, for receiving serial data, and for converting said serial data into parallel data; means, arranged to receive said parallel data, for detecting said sync pattern in said parallel data, for generating a sync pulse in response to the detection of said sync pattern, for determining an actual position of said sync pattern, and for generating a position signal indicative of said actual position; means, arranged to receive said position signal, for comparing said actual position with an expected position indicated by an expected position signal, and for generating a slip signal indicative of a degree of slip between said expected position and said actual position; first signal generating means, arranged to receive said slip signal, for generating a sync-in-window signal when said degree of slip is within an acceptable window; second signal generating means, coupled to said detecting means and said first signal generating means, for generating a syncfound signal in response to the generation of both said sync pulse and said sync-in-window signal; means, arranged to receive said syncfound signal and said position signal, for latching said position signal to generate a shift signal in response to said syncfound signal; third signal generating means, coupled to said first signal generating means, said second signal generating means, and said comparing means, and responsive to said syncfound signal, for generating a select signal indicative of said expected position, for generating a threshold signal having a value corresponding to a width of said acceptable window, for supplying said threshold signal to said first signal generating means to set said width, and for causing said threshold signal to assume (a) a first value if said syncfound signal has been generated in a predefined interval, and (b) to assume a second value greater than said first value if said syncfound signal is not generated during said predefined interval; and means responsive to said latching means and said third signal generating means, for generating said expected position signal on the basis of said shift signal and said select signal.

Claim 6

An apparatus for locating a sync pattern, comprising: converting means, for receiving serial data, and for converting said serial data into parallel data; means, arranged to receive said parallel data, for detecting said sync pattern in said parallel data, for generating a sync pulse in response to the detection of said sync pattern, for determining an actual position of said sync pattern, and for generating a position signal indicative of said actual position; means, arranged to receive said position signal, for comparing said actual position with an expected position indicated by an expected position signal, and for generating a slip signal indicative of a degree of slip between said expected position and said actual position; first signal generating means, arranged to receive said slip signal, for generating a sync-in-window signal when said degree of slip is within an acceptable window; second signal generating means, coupled to said detecting means and said first signal generating means, for generating a syncfound signal in response to the generation of both said sync pulse and said sync-in-window signal; means, arranged to receive said syncfound signal and said position signal, for latching said position signal to generate a shift signal in response to said syncfound signal; third signal generating means, coupled to said first signal generating means, said second signal generating means, and said comparing means, and responsive to said syncfound signal, for generating a select signal indicative of said expected position, for generating a threshold signal having a value corresponding to a width of said acceptable window, for supplying said threshold signal to said first signal generating means to set said width, and for causing said threshold signal to assume (a) a first value if said syncfound signal has been generated in a predefined interval, and (b) to assume a second value greater than said first value if said syncfound signal is not generated during said predefined interval; and means responsive to said latching means and said third signal generating means, for generating said expected position signal on the basis of said shift signal and said select signal.

Claim 13

A method of locating a sync pattern in a digital data stream, comprising the steps of: detecting the sync pattern; generating a first signal in response to a condition in which said sync pattern occurs at a position in said digital data stream within a window about an expected position of said sync pattern and for setting a width of said window in accordance with a value of a threshold signal; and generating said threshold signal to have (a) a first value causing said window to have a first width in response to a condition in which said first signal occurs within a predefined interval, and (b) a second value causing said window to have a second width greater than said first width in response to a condition in which said first signal does not occur within said predefined interval.

Claim 14

A method of locating a sync pattern in a digital data stream, comprising the steps of: detecting the sync pattern; generating a first signal in response to a condition in which said sync pattern occurs at a position in said digital data stream within a window about an expected position of said sync pattern and for setting a width of said window in accordance with a value of a threshold signal; and generating said threshold signal to have (a) a first value causing said window to have a first width in response to a condition in which said first signal occurs within a predefined interval, and (b) a second value causing said window to have a second width greater than said first width in response to a condition in which said first signal does not occur within said predefined interval.

Claim 17

A method of locating a sync pattern, comprising the steps of: converting serial data into parallel data; detecting said sync pattern in said parallel data; generating a sync pulse in response to the detection of said sync pattern; determining an actual position of said sync pattern as detected; generating a position signal indicative of said actual position; comparing said actual position with an expected position; generating a slip signal indicative of a degree of slip between said expected position and said actual position; generating a sync-in-window signal when said degree of slip is within an acceptable window; and generating a syncfound signal in response to the generation of both said sync pulse and said sync-in-window signal.

Claim 18

A method of locating a sync pattern, comprising the steps of: converting serial data into parallel data; detecting said sync pattern in said parallel data; generating a sync pulse in response to the detection of said sync pattern; determining an actual position of said sync pattern as detected; generating a position signal indicative of said actual position; comparing said actual position with an expected position; generating a slip signal indicative of a degree of slip between said expected position and said actual position; generating a sync-in-window signal when said degree of slip is within an acceptable window; and generating a syncfound signal in response to the generation of both said sync pulse and said sync-in-window signal.

Claim 19

An apparatus for locating a sync pattern in a stream of serial data comprising: means, responsive to said serial data, for dividing said serial data into parallel data; means, responsive to said parallel data, for detecting sync patterns in said parallel data and for generating a position signal for each detected sync pattern indicative of an alignment of said each sync pattern with respect to word boundaries in said parallel data; means for determining whether a detected sync pattern is valid; means, responsive to said determining means, for latching a position signal of said sync pattern if said sync pattern is determined to be valid; and means, responsive to said determining means, for counting a number of words in said parallel data occurring since a most recent previous occurrence of a valid sync pattern, and for generating a select signal indicative of words occurring within a predetermined range of an expected count of a beginning of a next sync pattern; said determining means comprising means for determining validity of a current sync pattern on the basis of the latched position signal of the most recent previous valid sync signal, a current position signal of said current sync pattern, and said select signal.

Claim 20

An apparatus for locating a sync pattern in a stream of serial data comprising: means, responsive to said serial data, for dividing said serial data into parallel data; means, responsive to said parallel data, for detecting sync patterns in said parallel data and for generating a position signal for each detected sync pattern indicative of an alignment of said each sync pattern with respect to word boundaries in said parallel data; means for determining whether a detected sync pattern is valid; means, responsive to said determining means, for latching a position signal of said sync pattern if said sync pattern is determined to be valid; and means, responsive to said determining means, for counting a number of words in said parallel data occurring since a most recent previous occurrence of a valid sync pattern, and for generating a select signal indicative of words occurring within a predetermined range of an expected count of a beginning of a next sync pattern; said determining means comprising means for determining validity of a current sync pattern on the basis of the latched position signal of the most recent previous valid sync signal, a current position signal of said current sync pattern, and said select signal.

Claim 24

A method of locating a sync pattern in a stream of serial data, comprising the steps of: (a) dividing said serial data into parallel data; (b) detecting a first sync pattern in said parallel data; (c) generating a position signal for said first sync pattern, said position signal being indicative of an alignment of said sync pattern with respect to word boundaries in said parallel data; (d) latching a position signal of said first sync pattern; (e) counting a number of words in said parallel data occurring since said first sync pattern; (f) generating a select signal indicative of words occurring within a predetermined range of an expected count of a beginning of a second sync pattern; (g) detecting a second sync pattern in said parallel data; (h) generating a current: position signal for said second sync pattern; (i) determining whether said second sync pattern is valid based on said latched position signal, said current position signal, and said select signal.

Claim 25

A method of locating a sync pattern in a stream of serial data, comprising the steps of: (a) dividing said serial data into parallel data; (b) detecting a first sync pattern in said parallel data; (c) generating a position signal for said first sync pattern, said position signal being indicative of an alignment of said sync pattern with respect to word boundaries in said parallel data; (d) latching a position signal of said first sync pattern; (e) counting a number of words in said parallel data occurring since said first sync pattern; (f) generating a select signal indicative of words occurring within a predetermined range of an expected count of a beginning of a second sync pattern; (g) detecting a second sync pattern in said parallel data; (h) generating a current: position signal for said second sync pattern; (i) determining whether said second sync pattern is valid based on said latched position signal, said current position signal, and said select signal.