Program segments on a magnetic tape are identified by recording patterns of continuous sine wave signal bursts and blank portions in non-recorded spaces between the program segments, the continuous sine waves all having the same low-frequency relative to the audio frequency band and a selected number of continuous sine waves and a corresponding blank portion of the same length each form one level of a binary signal and a second burst of continuous sine waves and a corresponding blank portion of the same length each form the other level of the binary signal These four elements are arranged to provide an individual address code for each of the program segments on the magnetic tape and are arranged such that they may be read in either direction of tape travel, in order to identify the program segment from either direction, by forming the address code signals as complementary pairs based upon the location of the program segments relative to the ends of the tape

Method and apparatus for identifying recorded information segments on a record medium

Methods and apparatus to extract audio codes are disclosed. An example method includes receiving signals on a plurality of channels (101-104) and ranking the signals based on at least one characteristic of the signals via a signal ranker (108). A first channel from the plurality of channels is selected based upon the ranking of the signals via a channel selector (110). The example method further include determining whether a first signal on the first channel includes at least one code and extracting the at least one code from the first signal when the first signal includes the at least one code.

Methods and apparatus to extract codes from a plurality of channels

The present invention relates to an electromagnetic acoustic transducer excitation system comprising a tone burst generator, the tone burst generator comprising: an oscillator device configured to produce a radio frequency signal; an analog switch configured to produce an output based on the radio frequency signal produced by the oscillator device and a control signal; a pre-amplifier configured to amplify the output of the analog switch and produce a tone burst output signal; and a control module configured to produce the control signal for providing to the analog switch.

Electromagnetic acoustic transducer excitation source with programmable tone burst generator

Digital information is entered, stored on and read off of transmission channels containing audio information. The digital information is stored in the form of discrete audible tone bursts representative of the state of each bit of digital information. Subaudible tone bursts are utilized for keying associated circuitry.

Lewis A

Papers

Audio waveform for digital recording