Resources Contact Us Home
Method and apparatus for decoding two frequency (f/sf) data signals

Image Number 10 for United States Patent #5298897.

A two-frequency data signal, also known as a biphase or F/2F signal, is accurately decoded by sampling the signal and digitizing the samples to provide a series of digital values representing the signal. An intelligent digital filter manipulates the digital values to decode the signal, by detecting the peaks in the sampled signal and decoding the signal by analyzing the location and amplitudes of the peaks. Only peaks which are outside a guard band may be detected. If the signal cannot be properly decoded with a wide guard band, the guard band may be repeatedly narrowed, until a minimum guard band is reached. Bits are identified by comparing the displacements between peaks to a bit cell width. An even number of displacements indicates a `0` bit, and an odd number of displacements indicates a `1` bit. After decoding, the bits are converted into bytes. Parity and longitudinal redundancy code checks are used to correct bad bits. During decoding, many indications of a degraded signal may be obtained. If a degraded signal is indicated, the host computer is notified, even though the signal was properly read. Card replacement can then be initiated at the first signs of signal degradation, before the data signal becomes unreadable.

  Recently Added Patents
Changing sound alerts during a messaging session
Tap and linking module TDO register, gating for TCK and TMS
Uni-directional transient voltage suppressor (TVS)
Package for product
Obviation of recovery of data store consistency for application I/O errors
Rotating-body electrification mechanism, image carrier unit, process cartridge, image forming apparatus, and method for electrifying image carrier unit
Systems and methods of device-free motion detection and presence detection
  Randomly Featured Patents
Tread surface and periphery of a footwear unit sole
Weighing system
Methods and systems for assigning interchange rates to financial transactions using an interchange network
Media streamer with control node enabling same isochronous streams to appear simultaneously at output ports or different streams to appear simultaneously at output ports
Dynamic allocation and partitioning of compute nodes in hierarchical job scheduling
Device for cutting sheet materials
Sensor for converting a distance to optical and further to electrical energy, and surface scanning apparatus using same
Paper transport and paper stabilizing system for a multicolor electrostatic plotter
Casing brake construction for sausage discharge horn
Fuel system for internal combustion engine