1、 Rec. ITU-R BT.1363-1 1 RECOMMENDATION ITU-R BT.1363-1 JITTER SPECIFICATIONS AND METHODS FOR JITTER MEASUREMENTS OF BIT-SERIAL SIGNALS CONFORMING TO RECOMMENDATIONS ITU-R BT.656, ITU-R BT.799 AND ITU-R BT.1120 (Question ITU-R 65/11) (1998-1998) Rec. ITU-R BT.1363-1 The ITU Radiocommunication Assembl
2、y, considering a) that many countries are installing digital television production facilities based on the use of serial digital video components conforming to Recommendations ITU-R BT.656, ITU-R BT.799 or ITU-R BT.1120; b) that in order to guarantee the operation of such serial digital interfaces s
3、pecification of jitter parameters and methods to measure jitter is required; c) that to implement the above objectives, agreement needs to be achieved in specifying and measuring jitter in bit-serial interfaces conforming to Recommendations ITU-R BT.656, ITU-R BT.799 and ITU-R BT.1120; d) that the i
4、mplementation of optical interface for the transmission of signals conforming to draft new Recommendation ITU-R BT.1367 requires the specification of jitter parameters and methods to measure jitter, recommends that where interfaces conforming to Recommendations ITU-R BT.656, ITU-R BT.799 and ITU-R B
5、T.1120 are implemented, the jitter should be specified and methods of measuring jitter should be in accordance with the provisions included in Annex 1. NOTE Additional information on jitter specification and measuring methods can be found in Appendix 2 and EBU Tech. 3268. Appendix 2 is a tutorial in
6、 support of this Recommendation. ANNEX 1 Jitter specifications 1 Scope This Recommendation describes techniques for specifying jitter in self-clocking, bit-serial digital systems. It is applicable to sources, receivers, and regenerators. 2 Normative references The following standards contain provisi
7、ons which, through reference in this text, constitute provisions of this practice. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this practice are encouraged to investigate the possibility of applying the most
8、 recent edition of the standards indicated below. 3 Definitions 3.1 alignment jitter: The variation in position of a signals transitions relative to those of a clock extracted from that signal. The bandwidth of the clock extraction process determines the low-frequency limit for alignment jitter. 2 R
9、ec. ITU-R BT.1363-1 3.2 input jitter tolerance: Peak-to-peak amplitude of sinusoidal jitter that, when applied to an equipment input, causes a specified degradation of error performance. 3.3 intrinsic jitter: Jitter at an equipment output in the absence of input jitter. 3.4 jitter: The variation of
10、a digital signals transitions from their ideal positions in time. 3.5 jitter transfer: Jitter on the output of equipment resulting from applied input jitter. 3.6 jitter transfer function: Ratio of the output jitter to the applied input jitter as a function of frequency. 3.7 output jitter: Jitter at
11、the output of equipment that is embedded in a system or network. It consists of intrinsic jitter and the jitter transfer of jitter at the equipment input. 3.8 timing jitter: The variation in position of a signals transitions occurring at a rate greater than a specified frequency, typically 10 Hz or
12、less. Variations occurring below this specified frequency are termed wander and are not addressed by this practice. 3.9 unit interval (UI): Abbreviated UI, it is the period of one clock cycle. It corresponds to the nominal minimum time between transitions of the serial signal. 4 Jitter specification
13、s Equipment jitter specifications fall into three categories: input jitter tolerance, jitter transfer, and intrinsic jitter. A fourth specification, output jitter, is a network specification and may be used to specify jitter limits at equipment interfaces. 4.1 Input jitter tolerance Input jitter tol
14、erance is the peak-to-peak amplitude of sinusoidal jitter that, when applied to an equipment input, causes a specified degradation of error performance. Input jitter tolerance is applicable to most serial inputs. 4.1.1 Input jitter tolerance requirements are specified with a jitter template that cov
15、ers a specified sinusoidal amplitude frequency region (see Fig. 1). This template represents the minimum amount of jitter that the equipment must accept without causing the specified degradation of error performance. Equipment meeting a jitter tolerance requirement must have an actual jitter toleran
16、ce greater than the requirement (see Fig. 2). 4.1.2 Input jitter tolerance requirements are specified with the parameters given in Table 1. TABLE 1 Input jitter tolerance Parameters Units Description Data rate bits/s) (Serial bit rate) f1(Hz) (Low-frequency specification limit) f2(Hz) (Upper band ed
17、ge for A1, low-frequency jitter tolerance) f3(Hz) (Lower band edge for A2, high-frequency jitter tolerance) f4(Hz) (High-frequency specification limit) A1(UI) (Low-frequency jitter tolerance, f1to f2) A2(UI) (High-frequency jitter tolerance, f3to f4) Error criterion (Criterion for onset of errors) T
18、est signal (Test signal used for measurement) Rec. ITU-R BT.1363-1 3 1363-01A1A2f1f2f3f4 20 dB/decade slopeJitter frequencySinusoidalinputjitteramplitudeFIGURE 1Input jitter tolerance template1363-02A1A2f1f2f3f4Jitter frequencySinusoidalinputjitteramplitudeFIGURE 2Jitter tolerance specification and
19、a compliant jitter toleranceActual jitter toleranceTemplate specificationJitter margin4 Rec. ITU-R BT.1363-1 4.1.2.1 Frequency band f1to f2forms the low-frequency jitter tolerance bandpass. At least A1UI of peak-to-peak sinusoidal jitter shall be tolerated over this bandpass without exceeding the sp
20、ecified error criterion. 4.1.2.2 Frequency band f3to f4forms the high-frequency jitter tolerance bandpass. At least A2UI of peak-to-peak sinusoidal jitter shall be tolerated over this bandpass without exceeding the specified error criterion. 4.1.2.3 A1and A2shall be specified in UI. 4.1.2.4 The slop
21、e of the jitter tolerance requirement between f2and f3shall be 20 dB/decade. Frequencies f2and f3are related as follows: f2= f3/(A1/A2). 4.1.2.5 The criterion for reaching the onset of errors shall be specified. Either a BER limit or a maximum number of errored seconds over a specified measurement i
22、nterval should be used. 4.1.2.6 The test signal used for the measurement (to which sinusoidal jitter is added) shall be specified. 4.1.3 Numerical input jitter tolerance values are provided in the appropriate SMPTE standards which reference this practice. The terminology shall comply with 4.1.2. 4.2
23、 Jitter transfer Jitter transfer is jitter on the output of equipment resulting from applied input jitter. Jitter transfer is applicable to a device which produces a serial output from a serial input, such as a regenerator. Jitter transfer can also occur from reference signals applied to equipment,
24、such as analogue black burst. The jitter transfer templates described below are intended for serial input to serial output jitter transfer. 4.2.1 Jitter transfer requirements are specified with a template showing the maximum jitter gain as a function of frequency (see Fig. 3). Equipment meeting a ji
25、tter transfer requirement will have a jitter transfer function that lies within this template (see Fig. 4). 1363-03Pfcf1 20 dB/decade slopeJitter frequencyJittertransfergainFIGURE 3Jitter transfer templateRec. ITU-R BT.1363-1 5 1363-04Pf1fcJitter frequencyJittertransfergainFIGURE 4Jitter transfer sp
26、ecification and compliant jitter transfer functionActual jitter transferJitter transfer specification4.2.2 Jitter transfer requirements are specified with the parameters given in Table 2. TABLE 2 Jitter transfer requirements 4.2.2.1 Frequency band f1to fcforms the jitter transfer bandpass. The maxim
27、um jitter gain over this bandpass shall be P. 4.2.2.2 From frequency fcto at least 10 ( fc), the jitter transfer template shall decrease at 20 dB/decade. 4.2.2.3 P shall be specified in decibels. 4.2.2.4 The test signal used for the measurement (to which sinusoidal jitter is added) shall be specifie
28、d. 4.2.3 Numerical jitter transfer values are provided in the appropriate SMPTE standards which reference this practice. The terminology shall comply with 4.2.2. Parameters Units Description Data rate (bits/s) (Serial bit rate) fl(Hz) (Low-frequency specification limit) fc(Hz) (Upper band edge of ji
29、tter transfer bandpass) P (dB) (Maximum jitter gain, f1to fc) Test signal (Test signal used for measurement) 6 Rec. ITU-R BT.1363-1 4.3 Intrinsic jitter and output jitter Intrinsic jitter and output jitter are both measurements of jitter at an equipment output. They differ in the specification of th
30、e input signal to the equipment. Except for this, they are measured identically. Intrinsic jitter is defined as the amount of jitter at an equipment output when a jitter-free input signal is applied. It is a measure of the amount of jitter generated in the equipment, independent of any jitter transf
31、er. Intrinsic jitter applies to most serial outputs. Output jitter is the amount of jitter at the output of equipment that is embedded in a system or network. It consists of intrinsic jitter and the jitter transfer of jitter at the equipment input. Output jitter is a network specification, not an eq
32、uipment specification. Individual equipment should be specified in terms of intrinsic jitter, jitter transfer, and input jitter tolerance. Network interface specifications may use output jitter. 4.3.1 Intrinsic and output jitter shall be specified as peak-to-peak quantities and measured over defined
33、 jitter frequency bands. Two measurement bands are specified, one is a subset of the other (see Fig. 5). 4.3.2 Intrinsic and output jitter shall be specified with the parameters given in Table 3. TABLE 3 Intrinsic and output jitter 4.3.2.1 The timing jitter measurement bandpass is formed by f1to f4.
34、 The maximum peak-to-peak jitter allowed over this bandpass is specified as A1. 4.3.2.2 The alignment jitter measurement bandpass is formed by f3to f4. The maximum peak-to-peak jitter allowed over this bandpass is specified as A2. 4.3.2.3 A1and A2shall be specified in unit intervals. 4.3.2.4 Bandpas
35、s slopes shall be at least 20 dB/decade and have a minimum phase response unless otherwise specified. Stop band rejection shall be at least 20 dB. Pass band ripple shall be less than +1 dB. 4.3.2.5 A measurement time (tm) may be specified. If this is omitted, then the measurement time will be determ
36、ined by the characteristics of the measurement system. 4.3.2.6 The test signal used for the measurement shall be specified. For an intrinsic jitter measurement, the test source jitter shall be negligible compared to the intrinsic jitter specification. Parameters Units Description Data rate (bits/s)
37、(Serial bit rate) f1(Hz) (Timing jitter, lower band edge) f3(Hz) (Alignment jitter, lower band edge) f4(UI) (Upper band edge) A1(UI) (Timing jitter) A2(s) (Alignment jitter) tm(Measurement time) Test signal (Test signal used for measurement) n (Serial clock divider) Rec. ITU-R BT.1363-1 7 1363-050 d
38、B0 dBf1f3f4f1f3f4Jitter frequencyTimingjitter bandpassFIGURE 5Intrinsic and output jitter measurement bandpassesJitter frequencyAlignmentjitterbandpass4.3.2.7 The serial clock divider, “n”, used in the clock extractor should be specified (see Appendix 1 for information on the Clock extractor and clo
39、ck extractor based measurement methods). The ratio of the serial clock frequency to the clock extractor frequency is “n”. It is meaningful for clock extractor jitter measurement methods, but may not be applicable to other measurement techniques. 4.3.3 Numerical intrinsic and output jitter values are
40、 provided in the appropriate ITU Recommendations which reference this practice. The terminology shall comply with 4.3.2. 8 Rec. ITU-R BT.1363-1 APPENDIX 1 Jitter measurement procedures in bit-serial digital interfaces 1 Scope This Appendix 1 describes methods for measuring jitter performance in bit-
41、serial digital interfaces. 1.1 Introduction Jitter is one of the most important parameters in the performance of serial digital transmission systems. It can cause errors in the transmission and recovery of digital data, and may degrade analogue signal performance if the jitter is transferred through
42、 the digital-to-analogue conversion process. Characterizing and measuring jitter are important for reliable and predictable serial digital system operation. 2 Informative references 3 Definitions 3.1 alignment jitter: Variation in position of a signals transitions relative to those of a clock extrac
43、ted from that signal. The bandwidth of the clock extraction process determines the low-frequency limit for alignment jitter. 3.2 clock extractor: A device which is able to extract the serial data clock from a serial data stream, and outputs a clock-related trigger. It may also provide the serial dig
44、ital data reclocked with the extracted clock. 3.3 DSO: Acronym for digital storage oscilloscope. 3.4 DUT: Acronym for device under test. 3.5 error rate tester: A device that quantifies the error rate of a serial digital signal. Two examples are the classic bit error rate (BER) tester and the field r
45、ate CRC method (EDIT) described in SMPTE RP 165. 3.6 input jitter tolerance: Peak-to-peak amplitude of sinusoidal jitter that, when applied to an equipment input, causes a specified degradation of error performance. 3.7 intrinsic jitter: Jitter at an equipment output in the absence of input jitter.
46、3.8 jitter: Variation of a digital signals transitions from their ideal positions in time. 3.9 jitter generator: A device which produces a serial digital signal containing sinusoidal jitter of adjustable amplitude and frequency. 3.10 jitter receiver: Demodulates and allows measurement of the jitter
47、present on a serial signal. It commonly provides an output proportional to the demodulated jitter. 3.11 jitter transfer: Jitter on the output of equipment resulting from applied input jitter. 3.12 jitter transfer function: Ratio of the output jitter to the applied input jitter as a function of frequ
48、ency. 3.13 output jitter: Jitter at the output of equipment that is embedded in a system network. It consists of intrinsic jitter and the jitter transfer of jitter at the equipment input. 3.14 phase demodulator: A device that provides as its output a signal proportional to the phase difference of tw
49、o input signals. 3.15 SDI: Acronym for serial digital interface, typically referring to Recommendation ITU-R BT.656 system. Rec. ITU-R BT.1363-1 9 3.16 timing jitter: Variation in position of a signals transitions occurring at a rate greater than a specified frequency, typically 10 Hz or less. Variations occurring below this specified frequency are termed wander and are not addressed by this practice. 3.17 unit interval (UI): The period of one clock cycle. It corresponds to the nominal minimum time between transitions of the serial signal. 4 Jitter specification Four methods ar
