Bit Error Ratio (BER)

BER is a measurement of signal quality after conversion of the ‘RF’ to data. This data determines whether converted pictures and sound can be received uncorrupted. Errors in the data, or bit errors, can be tolerated up to a particular level without an effect on pictures or sound due to the techniques employed which are simply called error correction.

The DTTB transmission and reception path employs built in error correction techniques collectively called Forward Error Correction (FEC). In the receiver, error correction takes place in two distinct stages called inner (or Viterbi) and outer (or Reed – Solomon) decoding. There may be a choice in the measuring instrument at what position to measure the BER. The measurement of BER before Viterbi or ‘Pre – Viterbi’ error correction is used on high quality signals, for example, on Cable and Satellite TV reception. For the more complex and corrupted Terrestrial reception, BER measurement after Viterbi  or ‘Post – Viterbi’ should be monitored.

A Post – Viterbi BER of worse than ‘2E-4’ will exceed the ability of the Reed – Solomon error correction and may result in picture and sound corruption. To provide for a sufficiently robust reception, a Post – Viterbi BER of better than ‘2E-6’ is required at the input and output of the amplifiers.

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