Patent No. 6538586 Data encoding strategy to reduce selected frequency components in a serial bit stream

 

Patent No. 6538586

Data encoding strategy to reduce selected frequency components in a serial bit stream Cavin, et al., Mar 25, 2003

Abstract

Frequency spectrums are determined for all possible codes given a predetermined number of bits in a code. A subset of these codes is formed based on spectral properties of codes in a desired frequency band. This subset of code is then used to encode data prior to transmission over a high-speed data bus to reduce undesirable emissions on targeted frequency bands.

Notes:

FIELD OF THE INVENTION

The present invention relates generally to the field of data communication. More specifically, the present invention relates to methods and systems for reducing selected frequency components in binary data streams.

BACKGROUND

As clock rates of new system bus technologies such as third generation I/O (3GIO) rise due to increasing performance demands, more of the energy in the information passed on the data bus is located in frequency bands that have until now been occupied primarily by wireless technologies.

Although signal on a "wired" data bus is not purposefully transmitted in the typical radio frequency (RF) sense, some of this energy is broadcast as RF noise and may interfere with sensitive RF devices in close proximity. This problem may become an issue in mobile computer systems that are to incorporate both high-speed I/O systems and integrated wireless devices on the same platform.

FIG. 1 is a block diagram illustrating one example of a prior art mobile computer system. The system 10 includes a memory controller 105 that manages data flowing between a central processing unit (CPU) 100, memory 110, and wireless device 120 (e.g., RF device). The wireless device 120 includes an antenna 125. When the system 10 incorporates high-speed I/O systems and integrated wireless devices, undesired coupling, via several paths, is expected between signals on buses 101, 111, and 115 and the wireless device 120, causing interference that will reduce maximum throughput of the wireless device 120. For example, data transmission on the data buses 101, 111 and 115 may cause interference to the signal received by the antenna 125. Since the bus 115 is directly connected to the wireless device 120, it may also cause interference to the wireless device 120. Other interferences to the wireless device 120 may be caused by power plane coupling, waveguide coupling through the motherboard, etc.