US5253271A — Method and apparatus for quadrature amplitude mod…

Claim 1

Independent Claim 203 words

A transmitter for acquiring digital input data and modulating the data onto an analog transmission carrier signal, comprising: means for acquiring the digital input data; mapping means coupled to the acquiring means for mapping the digital input data into a series of symbols representing points in signal space, and for outputting the location of the points as two digital coordinate streams representing the x and y coordinates of the points; modulation means for quadrature amplitude modulating the x and y digital coordinate streams to orthogonal carrier signals and combining the orthogonal carrier signals, the modulation means being a finite state implementation without microprocessors and including table means for storing product values where the multiplication factors in the product values are said digital coordinate stream value multiplied by said digital sample value of the respective orthogonal carrier signal, the product values of the table means being the product of the respective coordinate stream value, a digital sample value of an orthogonal carrier signal, and a pulse shaping filter coefficient, and means for adding the x and y product values to form digital sampled waveform sums; and digital to analog converter means, for converting the digital sampled waveform sums into an analog transmission carrier signal.

Claim 2

Dependent Claim 203 words

A transmitter for acquiring digital input data and modulating the data onto an analog transmission carrier signal, comprising: means for acquiring the digital input data; mapping means coupled to the acquiring means for mapping the digital input data into a series of symbols representing points in signal space, and for outputting the location of the points as two digital coordinate streams representing the x and y coordinates of the points; modulation means for quadrature amplitude modulating the x and y digital coordinate streams to orthogonal carrier signals and combining the orthogonal carrier signals, the modulation means being a finite state implementation without microprocessors and including table means for storing product values where the multiplication factors in the product values are said digital coordinate stream value multiplied by said digital sample value of the respective orthogonal carrier signal, the product values of the table means being the product of the respective coordinate stream value, a digital sample value of an orthogonal carrier signal, and a pulse shaping filter coefficient, and means for adding the x and y product values to form digital sampled waveform sums; and digital to analog converter means, for converting the digital sampled waveform sums into an analog transmission carrier signal.

Claim 3

Dependent Claim 27 words

The transmitter of claim 1, wherein the filter coefficients are stored in a digital storage device and are operable to reduce interference between adjacent coordinate stream values.

Claim 4

Dependent Claim 31 words

The transmitter of claim 1, the modulation means including a random access memory device, a read only memory device, a multiple-bit adder, a clock oscillator, and a digital to analog converter.

Claim 5

Dependent Claim 24 words

The transmitter of claim 1, wherein the mapping means comprises a coordinate lookup table storing the x and y coordinate values for each symbol.

Claim 6

Dependent Claim 29 words

The transmitter of claim 4, wherein the coordinate lookup table accesses and outputs the stored x and y coordinate value depending on the phase of the orthogonal carrier signals.

Claim 7

Dependent Claim 42 words

The transmitter of claim 5, wherein the x coordinate values are accessed and output if the carrier signal phase is 0 or 180 degrees and the y coordinate values are accessed and output if the carrier phase is 90 or 270 degrees.

Claim 8

Dependent Claim 34 words

The transmitter of claim 1, wherein the digital sample values of the carrier signals represent samples at a sample rate of 210 kilohertz and the carrier frequency of the carrier signals is 52.5 kilohertz.

Claim 9

Independent Claim 165 words

A method of transmitting acquired digital data over a bandpass channel comprising the steps of: mapping the acquired digital data into a series of symbols representing locations in signal space at a symbol rate where a certain sequence of digital bits is represented by a unique symbol; outputting the location of the symbols in signal space as x and y digital coordinate streams; modulating orthogonal carrier signals with the x and y coordinate digital streams to produce a digital transmission waveform at a sample rate including the steps of: storing product values in a table storage device, where multiplication factors in the product values include a coordinate stream value and a digital sample of the respective orthogonal carrier signal, the product values including a filtering factor to restrict bandwidth and adjust pulse shaping, and adding said product values to form digital sampled waveform sums; converting the digital sampled waveform sums to an analog transmission waveform; and transmitting the analog transmission waveform over the bandpass channel.

Claim 10

Independent Claim 165 words

A method of transmitting acquired digital data over a bandpass channel comprising the steps of: mapping the acquired digital data into a series of symbols representing locations in signal space at a symbol rate where a certain sequence of digital bits is represented by a unique symbol; outputting the location of the symbols in signal space as x and y digital coordinate streams; modulating orthogonal carrier signals with the x and y coordinate digital streams to produce a digital transmission waveform at a sample rate including the steps of: storing product values in a table storage device, where multiplication factors in the product values include a coordinate stream value and a digital sample of the respective orthogonal carrier signal, the product values including a filtering factor to restrict bandwidth and adjust pulse shaping, and adding said product values to form digital sampled waveform sums; converting the digital sampled waveform sums to an analog transmission waveform; and transmitting the analog transmission waveform over the bandpass channel.

Claim 11

Dependent Claim 55 words

The method of claim 8, in said mapping step each symbol being used to find a location in a lookup table storing the x and y coordinates for that symbol, said outputting step comprising serially outputting two coordinate streams, one stream comprising the stored x coordinates and the other stream comprising the stored y coordinates.

Claim 12

Dependent Claim 33 words

The method of claim 9, the carrier signals having a carrier frequency and the digital samples of the carrier signals being taken at a sample rate that is four times the carrier frequency.

Claim 13

Dependent Claim 26 words

The method of claim 10, wherein the two orthogonal carrier signals have a carrier phase which is an integer multiple of π/2 during each sample time.

Claim 14

Dependent Claim 17 words

The method of claim 10, where the sample rate is an integer multiple of the symbol rate.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1996-10-11	1997-04-12	1997-10-12	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2000-10-11	2001-04-12	2001-10-12	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2004-10-11	2005-04-12	2005-10-12	$7700.00	Window Closed / Lapsed

Method and apparatus for quadrature amplitude modulation of digital data using a finite state machine

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag