Multiple mask arrangement for jumping in pseudo-noise sequences
First Claim
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1. A pseudo-noise sequence (PNS) generator comprising:
- a linear feedback shift register (LFSR) for producing a PNS at an output;
a plurality of LFSR masks each having a mask input and a mask output, the mask input having a version of the PNS and the mask output providing a shifted version of the PNS with respect to the version of the PNS provided to the mask input, the LFSR masks forming a series of previous and subsequent LFSR masks;
a plurality of registers within each of the masks arranged to form a binary shift register, each register a having a register input and a register output sequentially connecting the registers, the registers being operatively configured such that bits defining the version of the PNS will be shifted from a first register to a last register;
a series a switches within each of the LFSR masks operatively connected to receive the register outputs, each of the switches having a switch input and a switch output; and
a series of adders within each of the LFSR masks, each of the adders having at least a first input, a second input and a single output, and wherein the switches selectively controls the adders to operate on the first input and the second input or to pass the second input to the single output, wherein either the version of the PNS or the shifted version of the PNS is output by the series of adders;
wherein the mask input of a first LFSR mask in the LFSR mask series is connected to the output of the LFSR, the mask input of each subsequent LFSR mask in the LFSR series is connected to the single output of the switch of the previous LFSR mask, the single output of the respective switch for a last LFSR mask in the series of LFSR masks, provides a PNS generator output.
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Abstract
Multiple masks are applied in a selected combination to a pseudo-noise sequence (PNS) output from a linear feedback shift register to shift the position of the PNS by a desired amount. Each mask shifts the PNS by a power of 2 and the selected combination of masks adds these shifts to provide the selected shift. The desired bit length of the shift in binary form is directly mapped to a combination of masks to apply the correct masking to the PNS.
27 Citations
18 Claims
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1. A pseudo-noise sequence (PNS) generator comprising:
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a linear feedback shift register (LFSR) for producing a PNS at an output;
a plurality of LFSR masks each having a mask input and a mask output, the mask input having a version of the PNS and the mask output providing a shifted version of the PNS with respect to the version of the PNS provided to the mask input, the LFSR masks forming a series of previous and subsequent LFSR masks;
a plurality of registers within each of the masks arranged to form a binary shift register, each register a having a register input and a register output sequentially connecting the registers, the registers being operatively configured such that bits defining the version of the PNS will be shifted from a first register to a last register;
a series a switches within each of the LFSR masks operatively connected to receive the register outputs, each of the switches having a switch input and a switch output; and
a series of adders within each of the LFSR masks, each of the adders having at least a first input, a second input and a single output, and wherein the switches selectively controls the adders to operate on the first input and the second input or to pass the second input to the single output, wherein either the version of the PNS or the shifted version of the PNS is output by the series of adders;
wherein the mask input of a first LFSR mask in the LFSR mask series is connected to the output of the LFSR, the mask input of each subsequent LFSR mask in the LFSR series is connected to the single output of the switch of the previous LFSR mask, the single output of the respective switch for a last LFSR mask in the series of LFSR masks, provides a PNS generator output. - View Dependent Claims (2, 3, 4, 5)
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6. A transmitter comprising:
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an input for an information signal;
a power supply;
a microcontroller connected to the power supply;
a linear feedback shift register (LFSR) for producing a PNS at an output;
a plurality of LFSR masks each having a mask input and a mask output, the mask input having a version of the PNS and the mask output providing a shifted version of the PNS with respect to the version of the PNS provided to the mask input, the LFSR masks forming a series of previous and subsequent LFSR masks;
a plurality of registers within each of the masks arranged to form a binary shift register, each register a having a register input and a register output sequentially connecting the registers, the registers being operatively configured such that bits defining the version of the PNS will be shifted from a first register to a last register;
a series a switches within each of the LFSR masks operatively connected to receive the register outputs, each of the switches having a switch input and a switch output; and
a series of adders within each of the LFSR masks, each of the adders having at least a first input, a second input and a single output, and wherein the switches selectively controls the adders to operate on the first input and the second input or to pass the second input to the single output, wherein either the version of the PNS or the shifted version of the PNS is output by the series of adders;
wherein the mask input of a first LFSR mask in the LFSR mask series is connected to the output of the LFSR, the mask input of each subsequent LFSR mask in the LFSR series is connected to the single output of the switch of the previous LFSR mask;
a spreader to spread the information signal depending on the output of the switch for a last LFSR mask in the series of LFSR masks; and
transmitter apparatus for transmitting the spread information signal into a medium. - View Dependent Claims (7, 8, 9, 10)
the medium is selected from;
computer media in a media drive of the transmitter, a broadband network connected to the transmitter, and an antenna together with an open space through which radio waves travel; and
the microcontroller includes a processor, a memory, and a clock interconnected by a bus;
each mask shifts the PNS by a different power of 2 bits;
the microcontroller maps the bits of a desired offset onto the switches to provide the desired offset.
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8. The transmitter of claim 6 wherein the series of adders perform modulo-2 addition.
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9. The transmitter of claim 8 wherein an offset is applied to the PNS is determined by a set of values that are applied to the switches.
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10. The transmitter of claim 9 wherein the offset is applied to the PNS is repeatedly done within each of the masks to provide offsets in increasing powers of 2.
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11. A transmitter comprising:
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receiver means for receiving a spread information signal from a medium;
a power supply;
a microcontroller connected to the power supply;
a linear feedback shift register (LFSR) for producing a PNS at an output;
a plurality of LFSR masks each having a mask input and a mask output, the mask input having a version of the PNS and the mask output providing a shifted version of the PNS with respect to the version of the PNS provided to the mask input, the LFSR masks forming a series of previous and subsequent LFSR masks;
a plurality of registers within each of the masks arranged to form a binary shift register, each register a having a register input and a register output sequentially connecting the registers, the registers being operatively configured such that bits defining the version of the PNS will be shifted from a first register to a last register;
a series a switches within each of the LFSR masks operatively connected to receive the register outputs, each of the switches having a switch input and a switch output; and
a series of adders within each of the LFSR masks, each of the adders having at least a first input, a second input and a single output, and wherein the switches selectively controls the adders to operate on the first input and the second input or to pass the second input to the single output, wherein either the version of the PNS or the shifted version of the PNS is output by the series of adders;
wherein the mask input of a first LFSR mask in the LFSR mask series is connected to the output of the LFSR, the mask input of each subsequent LFSR mask in the LFSR series is connected to the single output of the switch of the previous LFSR mask, the output of the switch for a last LFSR mask in the series of LFSR masks, provides a PNS generator output;
a de-spreader to de-spread the spread information signal depending on the PNS generator output to produce a recovered information signal; and
an output for the recovered information signal. - View Dependent Claims (12, 13, 14)
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15. A method of operating a recursive system, with an output depending on a plurality of previous outputs comprising the steps of:
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processing the plurality of previous outputs from a linear feedback shift register to obtain processed values;
storing the processed values within a mask;
determining new outputs within the mask depending on the processed values; and
reverse processing the processed values within the mask to obtain the previous outputs. - View Dependent Claims (16, 17, 18)
placing the plurality of previous outputs within a series of registers within the mask; and
selectively switching values contained within the registers to inputs on a series of modulo-2 adders.
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17. The method of claim 16 wherein the step of reverse processing further comprises controlling the modulo-2 adders to obtain a delayed version of the previous outputs.
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18. The method of claim 17 wherein the steps of storing, determining and reverse processing are repeatedly performed in a series of masks in a sequential manner in order to obtain a desired order of delay within the previous outputs.
Specification