Randomizer

Anything which generates random numbers is a randomizer, in at least some sense. Dice or a flipped coin are examples.

In computer programming, a randomizer is a program which generates a random number, for instance a virtual dice program. A randomizer can also be a hardware device.

In telecommunication, the term randomizer has the following meanings:

1. A device used to invert the sense of pseudo-randomly selected bits of a bit stream to avoid long sequences of bits of the same sense (also referred to as scrambler). The same selection pattern must be used on the receive terminal in order to restore the original bit stream. However, the bit stream, despite randomization, often reflects a sinusoidal pattern, tracking the motion of a vibration.
2. [An] analog or digital source of unpredictable (ie, high entropy), unbiased, and usually independent ((ie, random) bits. Randomizers can be used for several different purposes, including key generation or providing a starting state for a key generator. In practice, most randomizer functions (and all software implementations) do not and cannot create a sequence of truly random numbers, as they are programs running on finite state equipment. Instead, they use a seed variable to initialize a pseudo random number generator which actually produces the number sequence.

Technical issues

There are considerable difficulties connected with randomness and its generation. Some applications for random numbers can be adequately met with generators which are known to be non-random (eg, some modeling applications), while others require truly random sequences (eg, most cryptographic applications). Distinguishing between requirements is a common source of confusion and inadequate implementation.

There are several officially suggested designs for random number generators, from various standards organizations. Because of the difficulties in evaluating the randomness quality of such generators, none are ideal for all applications, and each must be carefully evaluated when considered for use in a particular system design.

Randomizers vs Interleavers

In telecommunications, both Randomizers and Interleavers are used.

Interleaving is used in digital data transmission technology to protect the transmission against burst errors. These errors overwrite a lot of bits in a row, so a typical error correction scheme that expects errors to be more uniformly distributed can be overwhelmed. Interleaving is used to help stop this from happening.

However, Interleavers are not Randomizers.

• Interleavers do not alter data, that is to say the data retains the same original number of 1's and 0's it had before it entered the interleaver.
• Randomizers suppress excess DC components in data, an Interleaver can not do this.
• Sometimes, in order to achive optimal signal to noise ratios using an interleaver and a ranomizer is necessary. The CCSDS Space Communications Protocols recommend using both an interleaver and a randomizer to protect the integrity of the downlink.