Data Recording and Transmission: Part 18 - Modulo Counting

The mathematics of finite fields and sequences seems to be a long way from everyday life, but it happens in the background every time we use a computer and without it, an explanation of modern error correction cannot be given.

Fig.1 - In two's complement, the circular number field is redefined to begin half a turn away from zero, so zero is in the middle of the scale and positive or negative values can be encoded.

Fig.2 - A three bit twisted ring counter and the sequence it goes through. Mathematically it is raising the starting value a to higher and higher powers.

Fig.3 - The addition, modulo-2, of a pseudo-random sequence to serial data breaks up long run-lengths and reduces any DC component.

Fig.4 - The randomizer used in DVB.

Fig.5 - Here a twisted ring counter is used to calculate redundancy on four data bits A -D to make a 7,4 code. The three redundant bits are left in the register after the data are clocked in.

Computer Security: Part 1 - What Is Computer Security?

Computer security is always a hot topic, but what do we mean by security and why do systems seem to be ever vulnerable. Comparing hardware to software helps understand vulnerabilities in software security.

Data Recording and Transmission: Part 25 - Encryption Strategies

As in all systems where there are opposed ideologies, there is a kind of cold war in which advances on one side need to be balanced by advances on the other. In encryption, the availability of increased computing power at…

Data Recording and Transmission: Part 24 - Message Integrity

Once upon a time, the cause of data corruption would be accidental. A dropout on a tape or interference picked up on a cable would damage a few bits. Error correction was designed to deal with that.

The Sponsors Perspective: Storage - How To Solve 5G’s Biggest Challenge

The arrival of 5G brings both opportunities and challenges to communications, media and entertainment companies, as well as the original equipment manufacturers (OEMs) working to support them.

Data Recording and Transmission: Part 23 - Delivering Data

The requirements for data transmission have changed out of all recognition since the early days of computing where the goal was simply to make something that worked. Today that’s the easy part.