A novel use for microprocessors in designing single and multi-tone generators, ringing generators and inverters

A method is proposed for producing precise single or multi-frequency tones for telephone office ringing generators, tone generators, and general purpose inverters, by using microprocessors and digital technology. The system comprises microcontrollers, counters, timers, random access memory (RAM), analog to digital converters (A/D), and digital to analog converters (D/A), which are combined to produce tone signals. These signals are then amplified to produce the required ringing or tone power. The microcontroller is programmed with a mathematical equation to derive timing and voltage levels for the output signal. This equation is converted to digital words that are passed to the data portion of RAM and is converted to a digital word that sets a timer controlling the address portion to RAM. The RAM output is converted to an analog signal by the D/A converter. This signal is used by a power amplifier to condition the signal for use on the telephone lines. By using a microcontroller, the terms of the equation (ie frequencies and the voltage levels of each frequency independently) are input as variables, thus giving the user complete control of the output signal.<>