Digitally implemented modulators

Claim 2

A digitally implemented modulator apparatus for generating a bandlimited modulated output signal from an input binary data signal, characterised in that said apparatus comprises: a reference table memory means for storing sets of component wave form sample values at memory locations corresponding to the value of said input binary signal, means for addressing said memory means responsive to an input digital signal, wherein, said addressing means addresses a plurality of said sample values, means for summing said addressed sample values to generate said bandlimited modulated output.

Claim 3

A digitally implemented modulator apparatus as claimed in Claim 1, characterised in that it further comprises digital-to-analog conversion means for converting said bandlimited modulated output into an analog signal.

Claim 4

A digitally implemented modulator apparatus for generating a bandlimited modulated output signal from an input binary data signal, characterised in that said apparatus comprises: microprocessor means (100) for generating said modulated output signal, said microprocessor employing a read only memory for storing a reference table containing sets of component wave form sample values, means for coupling said input digital data stream to said microprocessor, digital-to-analog conversion means for converting said modulated output signal to an analog waveform, communication channel means for coupling said microprocessor to said conversion means, addressing means for processing said input binary data in groups of n bits to produce an address sequence which is a function of values representative of the groups.

Claim 5

A digitally implemented modulator apparatus for generating a bandlimited modulated output signal from an input binary data signal, characterised in that said apparatus comprises: microprocessor means (100) for generating said modulated output signal, said microprocessor employing a read only memory for storing a reference table containing sets of component wave form sample values, means for coupling said input digital data stream to said microprocessor, digital-to-analog conversion means for converting said modulated output signal to an analog waveform, communication channel means for coupling said microprocessor to said conversion means, addressing means for processing said input binary data in groups of n bits to produce an address sequence which is a function of values representative of the groups.

Claim 6

A digitally implemented modulator apparatus for generating a bandlimited modulated output signal from an input binary data signal, said apparatus characterised in that it comprises: means for forming said input data into a plurality of groups of bits, and encoding each group into respective pairs of x and y values, wherein each said pair of values represents an amplitude and phase; means for storing a sequence of m pairs of respective x and y values; means for determining the position, in time, of a sample of said bandlimited modulated signal, said position being taken with reference to the moment in time when it is required to send a new group of bits from said inputted binary data signal; means to provide a set of m waveform sample values, comprising a reference table accessed in accordance with said position and said stored sequence of m pairs of x and y values; and summation means for said set of m waveform sample values, said summation means providing a sample of said bandlimited, modulated output signal.

Claim 7

A digitally implemented modulator apparatus for generating a bandlimited modulated output signal from an input binary data signal, said apparatus characterised in that it comprises: means for forming said input data into a plurality of groups of bits, and encoding each group into respective pairs of x and y values, wherein each said pair of values represents an amplitude and phase; means for storing a sequence of m pairs of respective x and y values; means for determining the position, in time, of a sample of said bandlimited modulated signal, said position being taken with reference to the moment in time when it is required to send a new group of bits from said inputted binary data signal; means to provide a set of m waveform sample values, comprising a reference table accessed in accordance with said position and said stored sequence of m pairs of x and y values; and summation means for said set of m waveform sample values, said summation means providing a sample of said bandlimited, modulated output signal.