IEC 62070 pdf download.Broadcast digital video tape recorders – Identification method for recording and/or reproduction error status
This International Standard specifies methods for indicating the record and/or reproduction error status of broadcast-grade digital VTRs utilizing a Reed Solomon product error correction code. (This code is hereinafter referred to as RS.) This standard also specifies methods of measuring the error rates in record and/or reproduction modes to indicate the error status. The following two indicators are specified herein: Go/No go indicator (hereinafter GNGI) for operational use. Error rate indicator (hereinafter ERI) for maintenance use. NOTE This standard may be applicable to other digital television equipment using an RS product error correction code.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of IEC and ISO maintain registers of currently valid International Standards. IEC 60050(702):1992, International Electrotechnical Vocabulary (IEV) – Chapter 702: Oscilla- tions, signals and related devices ITU-R Recommendation BT.601-5: Studio encoding parameters of digital television for standard 4:3 and wide-screen 16:9 aspect ratios
3 Terms and definitions
For the purpose of this International Standard, the following terms and definitions apply. 3.1 Definitions 3.1.1 bit (binary digit) a number of a set of two elements used to represent information 3.1.2 bit error rate the error rate for a binary signal 3.1.3 block unit which separates the information byte series into n bytes for adding error correction code 3.1.4 block error rate error rate for a signal constructed from block units 3.1.5 byte 8-bit byte an ordered set of eight binary digits [IEV 702-05-09] 3.1.6 byte error rate error rate for a signal constructed from byte units 3.1.7 error concealment method of error control in which the subjective effects of detected but uncorrected errors can be reduced NOTE Error concealment may be effected, for example, by interpolation of adjacent error-free sample values. 3.1.8 error rate ratio of the number of erroneous elements to the total number of elements reproduced and/or transmitted during a given time interval NOTE The elements may be, for example, digits, code words or blocks. 3.2 Abbreviations ERI Error rate indicator GNGI Go/No go indicator
4 Go/No go indicator (GNGI) NOTE The GNGI is provided to assist the operation of the VTR.
4.1 Colour of the indicator The GNGI shall consist of lights of three colours: red, yellow and green. More than one colour shall not light simultaneously. 4.2 Meaning of the colours The meaning of the three colour indicators shall be as follows. Green: Normal reliable operation. Errors are corrected without resort to concealment. No artifact due to errors occurs in video and/or audio.Yellow: Marginal operation. Errors are severe enough to result in artifacts in video and/or audio. Corrective action such as maintenance is required for the VTR and/or tape. Red: Normal operation impossible. Errors are severe enough not to be recovered by the error correction and concealment. Significant degradation of video and/or audio may occur. The technique used to estimate the severity of the error rate, and hence the status signalled by the GNGI, will vary according to the design of a particular VTR. An example of error estimation is given in annex B. 4.3 Holding time of the light Holding time of the red light shall be no less than 0,5 s.
5 Error rate indicator (ERI)
The unit for the ERI shall be the byte error rate. The byte error rate shall be calculated from the result of the decoding for the Reed Solomon (RS) product error correction code (see annex A). NOTE The ERI is provided to a VTR as a maintenance aid. The error rate is indicated for each channel or each head.