Signal detector and bit synchronizer

Claim 2

A means for detecting the presence of a signal having transitions between symbols occurring at a predetermined baud rate, the means comprising: a multiplicity of counting registers; means for establishing an integer number of sample windows per symbol, each sample window having a corresponding unique combination of a plurality of counting registers within said multiplicity of counting registers; means for sensing the transitions of a received signal, the transitions occurring within each established sample window; means for counting in the counting registers corresponding to each sample window in which a transition is sensed; and means for generating a presence signal in response to a counting register having a predetermined number of counts.

Claim 5

The method according to claim 2 wherein said step of generating generates the presence signal in response to the counting register having the predetermined number of counts within the occurrence of a predetermined number of edges.

Claim 6

The method according to claim 2 further comprising the step of generating an absence signal in response to any counting register not having the predetermined number of counts within the occurrence of a predetermined number of edges.

Claim 7

The method according to claim 2 further comprising the step of generating, in response to the presence signal, a sample signal indicative of the center of a symbol wherein the center is determined as a function of the counts in the multiplicity of counting registers.

Claim 8

The method according to claim 2 wherein: the integer number of sample windows corresponds to four; the plurality of counting registers corresponds to two; the multiplicity of counting registers corresponds to four; the first of the four sample windows has a corresponding combination of the first and second of the four counting registers; the second of the four sample windows has a corresponding combination of the second and third of the four counting registers; the third of the four sample windows has a corresponding combination of the third and forth of the four counting registers; and the fourth of the four sample windows has a corresponding combination of the forth and first of the four counting registers.

Claim 9

The method according to claim 2 further comprising the step of: initializing the multiplicity of counting registers to a predetermined value; and said step of counting counts by decrementing a corresponding counting register; and said step of generating generates the detect signal in response to a count register being equal to zero, thereby having a number of counts corresponding to the predetermined value.

Claim 10

The method according to claim 2 further for rejecting a second signal having transitions between symbols occurring a second baud rate, the second baud rate being an integer divisor of the predetermined baud rate wherein: said step of establishing further establishes from the integer number of sample windows, an integer number of second sample windows corresponding to an initial symbol and symbols occurring at an integer number of symbols thereafter, the integer number of symbols corresponding to the integer divisor, wherein the number of second sample windows have a corresponding unique combination of a plurality of second counting registers within a multiplicity of second counting registers; said step of counting additionally counts in the second counting registers corresponding to each second sample window in which a transition is sensed; and said step of generating generates the presence signal in response to the counting register having a predetermined number of counts, and a second counting register, corresponding to the count register having the predetermined number of counts, having more than a second predetermined number of counts and less than a third predetermined number of counts.

Claim 11

The method according to claim 8 wherein the baud rate of the second signal corresponds to one half the baud rate of the predetermined baud rate and said step of counting counts in a first direction in the second counting registers in response to a transition sensed in the second sample windows producing a count value therein, and the second predetermined number of counts and third predetermined number of counts correspond to second and third predetermined values, respectively.

Claim 12

The method according to claim 9 further comprising the step of: initializing the second counting registers to a value of zero; and wherein said step of counting counts in a second direction, opposite the first direction, in the second counting registers in response to a transition sensed in sample windows exclusive of the second sample windows and in response to the third predetermined value having an identical magnitude and opposing polarity of the second predetermined value.

Claim 13

A means for detecting the absence of a signal having transitions between symbols occurring at a predetermined baud rate, the means comprising: a multiplicity of counting registers; means for establishing an integer number of sample windows per symbol, each sample window having a corresponding unique combination of a plurality of counting registers within said multiplicity of counting registers; means for receiving a received signal having transitions; means for sensing the transitions of the received signal occurring within each established sample window; means for counting in the counting registers corresponding to each sample window in which a transition is sensed; and means for generating an absence signal in response to all of the counting registers exceeding a predetermined number of counts.

Claim 14

A means for detecting the absence of a signal having transitions between symbols occurring at a predetermined baud rate, the means comprising: a multiplicity of counting registers; means for establishing an integer number of sample windows per symbol, each sample window having a corresponding unique combination of a plurality of counting registers within said multiplicity of counting registers; means for receiving a received signal having transitions; means for sensing the transitions of the received signal occurring within each established sample window; means for counting in the counting registers corresponding to each sample window in which a transition is sensed; and means for generating an absence signal in response to all of the counting registers exceeding a predetermined number of counts.

Claim 17

The method according to claim 12 wherein said step of generating generates the absence signal in response to all of the counting registers exceeding the predetermined number of counts within the occurrence of a predetermined number of edges.

Claim 18

The method according to claim 12 further comprising the steps of generating a presence signal in response to any of the counting register not exceeding the predetermined number of counts within the occurrence of a predetermined number of edges.

Claim 19

The method according to claim 14 further comprising the step of generating a sample signal indicative of the center of the symbol signal in response to the presence signal wherein the center is determined as a function of the values in the multiplicity of counting registers.

Claim 20

The method according to claim 14 further for rejecting a second digital signal having transitions between digital symbols occurring a second baud rate, the second baud rate being an integer divisor of the predetermined baud rate wherein: said step of establishing further establishes from the integer number of sample windows, an integer number of second sample windows corresponding to an initial symbol and symbols occurring an integer number of symbols thereafter, the integer number of symbols corresponding to the integer divisor, wherein the predetermined number of second samples windows having a corresponding unique combination of a plurality of second counting registers within a multiplicity of second counting registers; said step of counting additionally counts in the second counting registers corresponding to each second sample window in which a transition is sensed; and said step of generating generates the presence signal in response to the counting register having a predetermined number of counts, and a second counting register, corresponding to the count register having the predetermined number of counts, having more than a second predetermined number of counts and less than a third predetermined number of counts.

Claim 21

The method according to claim 16 wherein the baud rate of the second signals corresponds to one half the baud rate of the predetermined baud rate and further comprising the step of: initializing the second counting registers to a value of zero; and wherein said step of counting counts in a first direction in the second counting registers in response to a transition sensed in the second sample windows, and counts in a second direction, opposite the first direction, in the second counting registers in response to a transition sensed in sample windows exclusive of the second sample windows and the third predetermined value having an identical magnitude and opposing polarity of the second predetermined value.

Claim 22

A means for selectively detecting the presence or absence of a signal having transitions between symbols occurring at a predetermined baud rate, the means comprising: a multiplicity of counting registers; means for establishing an integer number of sample windows per symbol, each sample window having a corresponding unique combination of a plurality of counting registers within said multiplicity of counting registers; means for selecting either presence detection or absence detection; means for receiving a transmitted signal and producing a received signal having transitions; means for sensing the transitions of the received signal occurring within each established sample window; means for counting in the counting registers corresponding to each sample window in which a transition is sensed; and means generating a presence signal in response to the selection of presence detection and a counting register having a first predetermined number of counts; and means for generating an absence signal in response to the selection of absence detection and all of the counting registers exceeding a second predetermined number of counts.

Claim 23

A means for selectively detecting the presence or absence of a signal having transitions between symbols occurring at a predetermined baud rate, the means comprising: a multiplicity of counting registers; means for establishing an integer number of sample windows per symbol, each sample window having a corresponding unique combination of a plurality of counting registers within said multiplicity of counting registers; means for selecting either presence detection or absence detection; means for receiving a transmitted signal and producing a received signal having transitions; means for sensing the transitions of the received signal occurring within each established sample window; means for counting in the counting registers corresponding to each sample window in which a transition is sensed; and means generating a presence signal in response to the selection of presence detection and a counting register having a first predetermined number of counts; and means for generating an absence signal in response to the selection of absence detection and all of the counting registers exceeding a second predetermined number of counts.

Claim 26

The method according to claim 19 wherein: said step of generating the presence signal generates the presence signal in response to the counting register having the predetermined number of counts within the occurrence of a first predetermined number of edges; and said step of generates generates the absence signal in response to all of the counting registers exceeding the second predetermined number of counts within the occurrence of a second predetermined number of edges.

Claim 27

The method according to claim 19 further comprising the steps of: generating the absence signal in response to the selection of presence detection and any counting register not having the predetermined number of counts within the occurrence of a first predetermined number of edges; generating a presence signal in response to the selection of absence detection and any of the counting register not exceeding the predetermined number of counts within the occurrence of a second predetermined number of edges.

Claim 28

The method according to claim 21 further comprising the step of generating a sample signal indicative of the center of the baud signal in response to the presence signal wherein the center is determined as a function of the values in the multiplicity of counting registers.