Apparatus and method for generating filtered multilevel data from NRZ data

Claim 1

An apparatus for generating filtered return to zero multilevel data from binary non-return to zero (NRZ) data comprising: a binary finite impulse response (FIR) filter including a shift register means having a plurality of stages which receives the NRZ data, clock means for providing clock pulses to said shift register means for sampling each bit of NRZ data, a weighting element coupled to each stage for weighting each stage's output, and means for summing groups of said weighting elements to define summed signals, the number of weighting elements in each group not exceeding the number of clock pulses occurring during each bit of NRZ data; means for selectively inverting the polarity of each of said summed signals, said inverting means comprising an operational amplifier for each of said summed signals, and means for selectively biasing each operational amplifier to function either as an inverting amplifier or a noninverting amplifier; means responsive to each NRZ data bit for controlling the polarity selection of said inverting means in accordance with said return to zero multilevel data to be generated; and means for summing each of said polarity selected summed signals to define said filtered return to zero multilevel data.

Claim 2

An apparatus for generating filtered return to zero multilevel data from binary non-return to zero (NRZ) data comprising: a binary finite impulse response (FIR) filter including a shift register means having a plurality of stages which receives the NRZ data, clock means for providing clock pulses to said shift register means for sampling each bit of NRZ data, a weighting element coupled to each stage for weighting each stage's output, and means for summing groups of said weighting elements to define summed signals, the number of weighting elements in each group not exceeding the number of clock pulses occurring during each bit of NRZ data; means for selectively inverting the polarity of each of said summed signals, said inverting means comprising an operational amplifier for each of said summed signals, and means for selectively biasing each operational amplifier to function either as an inverting amplifier or a noninverting amplifier; means responsive to each NRZ data bit for controlling the polarity selection of said inverting means in accordance with said return to zero multilevel data to be generated; and means for summing each of said polarity selected summed signals to define said filtered return to zero multilevel data.

Claim 4

An apparatus for generating filtered return to zero multilevel data having three or more levels from binary data comprising: a binary linear phase response filter for filtering the binary data, said filter sampling each bit of binary data and having an output corresponding to each sample; means for summing groups of said outputs wherein the number of outputs in each group does not exceed the number of times each bit of binary data is sampled by said filter, the output of each summing means defining summed signals; means for amplifying said summed signals by predetermined amplification factors,; means responsive to each bit of binary data for controlling the selection of said amplification factor in accordance with the return to zero multilevel data to be generated, said controlling means comprising a logic means for generating a control signal in response to each bit of said binary data that determines the amplification factor to be used; means for summing each of said amplified summed signals to define said filtered return to zero multilevel data; and means for time delaying said control signal with respect to a given amplifying means for a time duration equal to the number of preceding outputs coupled to said amplifying means divided by the number of times each bit of binary data is sampled.

Claim 5

An apparatus for generating filtered return to zero multilevel data having three or more levels from binary data comprising: a binary linear phase response filter for filtering the binary data, said filter sampling each bit of binary data and having an output corresponding to each sample; means for summing groups of said outputs wherein the number of outputs in each group does not exceed the number of times each bit of binary data is sampled by said filter, the output of each summing means defining summed signals; means for amplifying said summed signals by predetermined amplification factors,; means responsive to each bit of binary data for controlling the selection of said amplification factor in accordance with the return to zero multilevel data to be generated, said controlling means comprising a logic means for generating a control signal in response to each bit of said binary data that determines the amplification factor to be used; means for summing each of said amplified summed signals to define said filtered return to zero multilevel data; and means for time delaying said control signal with respect to a given amplifying means for a time duration equal to the number of preceding outputs coupled to said amplifying means divided by the number of times each bit of binary data is sampled.

Claim 8

A method for generating filtered return to zero multilevel data from binary data comprising the steps of: filtering said binary data by means of a filter having a linear phase response; summing the output signals from the filter in groups wherein the number of outputs in each group does not exceed the sampling rate per bit of binary data, the output of each summed group defining a summed signal; amplifying the summed signals with predetermined amplification factors; selecting the amplification factor to be utilized in response to ech bit of binary data in accordance with the return to zero multilevel data to be generated; permitting the amplification factor to be changed only when all the outputs in a given group being amplified correspond to the same bit of binary data; and summing each of the amplified summed signals to define the filtered return to zero multilevel data.

Claim 9

A method for generating filtered return to zero multilevel data from binary data comprising the steps of: filtering said binary data by means of a filter having a linear phase response; summing the output signals from the filter in groups wherein the number of outputs in each group does not exceed the sampling rate per bit of binary data, the output of each summed group defining a summed signal; amplifying the summed signals with predetermined amplification factors; selecting the amplification factor to be utilized in response to ech bit of binary data in accordance with the return to zero multilevel data to be generated; permitting the amplification factor to be changed only when all the outputs in a given group being amplified correspond to the same bit of binary data; and summing each of the amplified summed signals to define the filtered return to zero multilevel data.

Claim 14

An apparatus for generating filtered return to zero multilevel data from binary non-return to zero (NRZ) data comprising: a binary finite impulse response (FIR) filter including a shift register means having a plurality of stages which receives the NRZ data, clock means for providing clock pulses to said shift register means for sampling each bit of NRZ data, a weighting element coupled to each stage for weighting each stage's output, and means for summing groups of said weighting elements to define summed signals, the number of weighting elements in each group not exceeding the number of clock pulses occurring during each bit of NRZ data; means for selectively inverting the polarity of each of said summed signals; means responsive to each NRZ data bit for controlling the polarity selection of said inverting means in accordance with said return to zero multilevel data to be generated, said controlling means including a logic circuit means for implementing a logic rule for encoding NRZ data into return to zero multilevel data, said logic circuit means controlling the polarlity selection of each of said inverting means such that a change in polarity for any given inverting means can occur only when each of the shift register stages coupled to said given inverting means has the same logic state; and means for summing each of said polarity selected summed signals to define said filtered return to zero multilevel data.

Claim 15

An apparatus for generating filtered return to zero multilevel data from binary non-return to zero (NRZ) data comprising: a binary finite impulse response (FIR) filter including a shift register means having a plurality of stages which receives the NRZ data, clock means for providing clock pulses to said shift register means for sampling each bit of NRZ data, a weighting element coupled to each stage for weighting each stage's output, and means for summing groups of said weighting elements to define summed signals, the number of weighting elements in each group not exceeding the number of clock pulses occurring during each bit of NRZ data; means for selectively inverting the polarity of each of said summed signals; means responsive to each NRZ data bit for controlling the polarity selection of said inverting means in accordance with said return to zero multilevel data to be generated, said controlling means including a logic circuit means for implementing a logic rule for encoding NRZ data into return to zero multilevel data, said logic circuit means controlling the polarlity selection of each of said inverting means such that a change in polarity for any given inverting means can occur only when each of the shift register stages coupled to said given inverting means has the same logic state; and means for summing each of said polarity selected summed signals to define said filtered return to zero multilevel data.

Claim 21

An apparatus for generating filtered return to zero multilevel data from binary non-return to zero (NRZ) data comprising: a binary finite impulse response (FIR) filter including a shift register means having a plurality of stages which receives the NRZ data, clock means for providing clock pulses to said shift register means for sampling each bit of NRZ data, a weighting element coupled to each stage for weighting each stage's output, and means for summing groups of said weighting elements to define summed signals, the number of weighting elements in each group not exceeding the number of clock pulses occurring during each bit of NRZ data; means for selectively inverting the polarity of each of said summed signals; means responsive to each NRZ data bit for controlling the polarity selection of said inverting means in accordance with said return to zero multilevel data to be generated; and means for summing each of said polarity selected summed signals to define said filtered return to zero multilevel data, said means for summing each of said polarity selected summed signals including a predetermined bias reference which is summed with the summed signals, said bias reference defining one state of said multilevel data.

Claim 22

An apparatus for generating filtered return to zero multilevel data from binary non-return to zero (NRZ) data comprising: a binary finite impulse response (FIR) filter including a shift register means having a plurality of stages which receives the NRZ data, clock means for providing clock pulses to said shift register means for sampling each bit of NRZ data, a weighting element coupled to each stage for weighting each stage's output, and means for summing groups of said weighting elements to define summed signals, the number of weighting elements in each group not exceeding the number of clock pulses occurring during each bit of NRZ data; means for selectively inverting the polarity of each of said summed signals; means responsive to each NRZ data bit for controlling the polarity selection of said inverting means in accordance with said return to zero multilevel data to be generated; and means for summing each of said polarity selected summed signals to define said filtered return to zero multilevel data, said means for summing each of said polarity selected summed signals including a predetermined bias reference which is summed with the summed signals, said bias reference defining one state of said multilevel data.

Claim 24

An apparatus for generating filtered return to zero multilevel data having three or more levels from binary data comprising: a binary linear phase response filter for filtering the binary data, said filter sampling each bit of binary data and having an output corresponding to each sample; means for summing groups of said outputs wherein the number of outputs in each group does not exceed the number of times each bit of binary data is sampled by said filter, the output of each summing means defining summed signals; means for amplifying each of said summed signals by predetermined amplification factors; means responsive to each bit of binary data for controlling the selection of said amplification factor in accordance with the return to zero multilevel data to be generated, said controlling means comprising a logic means for generating a control signal in response to each bit of said binary data that determines the amplification factor to be used, said logic means permitting a change in the amplification factor of a given amplifying means only when the outputs coupled to said given amplifying means contain samples corresponding to one bit of said binary data; and means for summing each of said amplified summed signals to define said filtered return to zero multilevel data.

Claim 25

An apparatus for generating filtered return to zero multilevel data having three or more levels from binary data comprising: a binary linear phase response filter for filtering the binary data, said filter sampling each bit of binary data and having an output corresponding to each sample; means for summing groups of said outputs wherein the number of outputs in each group does not exceed the number of times each bit of binary data is sampled by said filter, the output of each summing means defining summed signals; means for amplifying each of said summed signals by predetermined amplification factors; means responsive to each bit of binary data for controlling the selection of said amplification factor in accordance with the return to zero multilevel data to be generated, said controlling means comprising a logic means for generating a control signal in response to each bit of said binary data that determines the amplification factor to be used, said logic means permitting a change in the amplification factor of a given amplifying means only when the outputs coupled to said given amplifying means contain samples corresponding to one bit of said binary data; and means for summing each of said amplified summed signals to define said filtered return to zero multilevel data.

Claim 27

A method for generating filtered return to zero multilevel data from binary data comprising the steps of: filtering said binary data by means of a filter having a linear phase response; summing the output signals from the filter in groups wherein the number of outputs in each group does not exceed the sampling rate per bit of binary data, the output of each summed group defining a summed signal; amplifying the summed signals with predetermined amplification factors; selecting the amplificaiton factor to be utilized in response to each bit of binary data in accdordance with the return to zero multilevel data to be generated and generating a control signal based upon the logic rule for encoding binary data into return to zero multilevel data; and summing each of the amplified summed signals to define the filtered return to zero multilevel data.

Claim 28

A method for generating filtered return to zero multilevel data from binary data comprising the steps of: filtering said binary data by means of a filter having a linear phase response; summing the output signals from the filter in groups wherein the number of outputs in each group does not exceed the sampling rate per bit of binary data, the output of each summed group defining a summed signal; amplifying the summed signals with predetermined amplification factors; selecting the amplificaiton factor to be utilized in response to each bit of binary data in accdordance with the return to zero multilevel data to be generated and generating a control signal based upon the logic rule for encoding binary data into return to zero multilevel data; and summing each of the amplified summed signals to define the filtered return to zero multilevel data.