A data transmission system includes a programmable portable information device, a frame-scanning graphics display device (e.g., a CRT monitor), and a display device controller (e.g., a personal computer). The display device controller supplies pixel data to the frame-scanning graphics display device which causes the display device to depict a particular changing optical pattern. To display the particular pattern, the frame-scanning graphics display device inherently fluctuates in energy output as different pixel intensities require different degrees of power. As a result, the frame-scanning graphics display device effectively emits an RF carrier signal. The programmable portable information device is equipped with an RF receiver that can receive the RF signal from the display device when the programmable portable information device is within a transmission range. The RF carrier signal is modulated to carry programming data to the portable information device. The portable information device demodulates the RF signal to obtain the digital data stream.