This paper presents the results of a graduate research project that is required in partial fulfillment for obtaining a Master of Electronic Engineering degree from Monmouth University. The objective of this project was to investigate the infrared (IR) signal characteristics for a television remote control and to analyze techniques for developing an IR interface between a personal computer (PC) and television. The paper describes an approach and the challenges associated with creating this interface. Additionally, the paper proposes how to integrate commercially available voice recognition software to create a voice-activated IR remote television controller.

While predominantly a digital communications problem, the project also drew on physics principles associated with IR data transmission and circuit design. The communications development work was divided into the following areas: the IR transmitter, the interface between the IR transmitter and the computer, i.e., the hardware and software Application Program Interface (API); and a Graphical User Interface (GUI). Development consisted of the following components: a Compaq 250 MHz computer (and a 486 microprocessor used for low-level development work), the breadboard-build infrared transmitter and an RCA television.

A literature search was conducted both on the Internet and through various library resources. Information obtained in the search was used in formulating an approach for analyzing the IR signals, building the transmitter, establishing the link between the transmitter circuit and the PC, and for the C programming methods needed to generate the communications API. Finally, for the voice recognition capability, a Visual Basic program was developed using a commercial voice recognition software package, which was integrated into the application.

A key finding of this research project was the ability to determine the unique frames for all remote controller commands and to successfully transmit a bitstream control code out the parallel port and through the IR circuit. It was also noted that the television IR signal has both analog and digital characteristics, with a variable time domain and pulse magnitude fluctuations. As a result, developing the communications API was the most challenging task of this project. It was also concluded that code development of this type is best accomplished with a simple operating system that allows direct control over the microprocessor and the communications port as opposed to a higher-level operating system (e.g. Windows 95), which is currently provided with most personal computers.