Shape modulation transmit loop with digital frequency control and method for same

A method of reducing the frequency spectrum consumed by the instantaneous changes in a digital data stream comprising:

• generating a sequence of specified steps;
• storing a plurality of values that determine the shape of the transition signal between pulses of said digital data stream in a programmable memory means;
• feeding said specified steps into a said programmable means memory;
• and
• stepping through an entire cycle of said plurality of values by counting through a plurality of specified steps until reaching a predetermined value.

A method of reducing the frequency spectrum consumed by the instantaneous changes in a digital data stream comprising:

• generating a sequence of specified steps;
• storing a plurality of values that determine the shape of the transition signal between pulses of said digital data stream in a memory means;
• feeding said specified steps into said memory means;
• feeding the output from said memory means to an adder;
• and
• stepping through an entire cycle of said plurality of values by counting through a plurality of specified steps until reaching a predetermined value.

A method of reducing the frequency spectrum consumed by the instantaneous changes in a digital data stream comprising:

• generating a sequence of specified steps;
• storing a plurality of values that determine the shape of the transition signal between pulses of said digital data stream in a memory means;
• feeding said specified steps into said memory means;
• feeding the output from said memory means to an adder;
• feeding the output of said adder to a phase accumulator that contains a plurality of phase values relating to the shape of said transition signal;
• and
• stepping through an entire cycle of said plurality of values by counting through a plurality of specified steps until reaching a predetermined value.

A method of reducing the frequency spectrum consumed by the instantaneous changes in a digital data stream comprising:

• generating a sequence of specified steps;
• storing a plurality of values that determine the shape of the transition signal between pulses of said digital data stream in a memory means;
• feeding said specified steps into said memory means;
• feeding the output from said memory means to an adder;
• feeding an output of a phase accumulator to an input of said phase accumulator;
• and
• stepping through an entire cycle of said plurality of values by counting through a plurality of specified steps until reaching a predetermined value.

A single chip synthesizer/transmitter/modulator for high speed GSM application comprising:

• a modified Direct Digital Synthesizer with internal spectrum shaping with slew rate control, said DDS having an input terminal that receives a digital data stream and an output terminal with a shaped FSK waveform;
• a phase comparator coupled to the output of said DDS and configured to compare the phase difference between the DSS output and the output of a frequency shifter, said frequency shifter coupled to the output of said phase comparator;
• a loop filter coupled to the output of said comparator and used to filter out any unwanted aliases;
• and
• a voltage controlled oscillator coupled to the output of said loop filter and providing a GMSK output at a predetermined channel frequency.

A method of reducing the slew rate in transition from a first RF frequency to a second RF frequency comprising:

• generating a digital transition ramp;
• determining at least one digital value which is a function of instantaneous amplitude of said first frequency;
• combining said transition ramp and said at least one digital value which is a function of instantaneous amplitude of said first frequency to generate a series of steps;
• correlating a corresponding series of phase values by sequential accumulation of said steps;
• assigning an analog signal amplitude counterpart to each of said phase values;
• and
• using said steps to control an analog to digital converter to generate a controlled transition from said first RF frequency to said second RF frequency.

In a frequency modulation system, a method of smoothing out the transition between a “mark” pulse and a “space” pulse to reduce the frequency spectrum consumed by instantaneous changes in said pulses, said method comprising the steps of

• generating a series of steps that fit within the amplitude range defined by said “mark” pulse and said “space” pulse;
• the series of steps correlating to a corresponding series of phase values by sequential accumulation of said steps;
• assigning an analog signal amplitude counterpart to each of said phase values;
• and
• generating an RF waveform having amplitude values and phase values as calculated.