# 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.

# 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: SpycerNode Harnesses High Performance Computing

In 2018, ​​Rohde & Schwarz announced a new multi-user shared access storage system called SpycerNode. It offers a radically different approach to coping with broadcast & media storage requirements. In this article, we take a closer look to see how its app…

# 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.

# Data Recording and Transmission: Part 22 - Reed Solomon Codes

The Reed Solomon codes are defined by what the decoder expects to see and the encoder has to be configured to suit that.