Abstract: A text compression and multi-level display system, including a receiver, a processor, and a display device, is provided. The receiver is adapted to receive a digital audio transmission and generate a digital signal including a text and a text display level corresponding to the text. The processor is in communication with the receiver to receive the digital signal. The processor compares a stored display level with the text display level of the digital signal to generate a display decision. The processor communicates the text to the display device based on the display decision. As such, the text will be displayed based on the stored display level and the text display level.

Abstract: A method for controlling the selectivity of a tuner of a variable bandwidth audio receiver system in which the selectivity of the tuner is set to the wide bandwidth position and the presence of any sub-carrier frequencies are detected through the use of a fast detection method.

Abstract: A method for determining the presence of multiple carrier frequency components in an electrical signal by calculating a value for at least one characteristic of the set of peaks in a defined portion of the frequency spectrum, such as the number of peaks within a defined portion of the frequency spectrum or the average spacing between pairs of peaks, and defining a range of values of the characteristic that would indicate the presence of multiple carrier components, and comparing this calculated characteristic value against the values in the defined range of values.

Abstract: A method and apparatus for normalizing the I and Q components of a complex signal is provided which includes an iterative determination of the multiplier constant required for normalization. The I and Q components are squared and added together to create a digital word A constrained between certain limits. An iterative approach is implemented to arrive at a multiplier constant K which is equal to ##EQU1## without resorting to the use of multipliers. The constant K is then used to normalize the I and Q components.