1、 Copyright 2015 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 3 Barker Avenue, White Plains, NY 10601 (914) 761-1100 Approved September 1, 2015 Table of Contents Page Foreword . 2 Intellectual Property 2 Introduction 2 1 Scope . 3 2 Conformance Notation . 3 3 Normative References . 3 4 D
2、efinitions 4 5 Jitter Specifications 5 5.1 Input Jitter Tolerance . 5 5.2 Jitter Transfer . 8 5.3 Intrinsic Jitter and Output Jitter 9 Annex A Terminology Changes (Informative) . 12 Annex B Derivation of Probabilistic Peak-to-Peak Jitter (Informative) . 13 Annex C Bibliography (Informative) . 18 Pag
3、e 1 of 18 pages SMPTE RP 184:2015 Revision of RP 184-2004 SMPTE RECOMMENDED PRACTICE Specification of Jitter in Bit-Serial Digital Systems SMPTE RP 184:2015 Page 2 of 18 pages Foreword SMPTE (the Society of Motion Picture and Television Engineers) is an internationally-recognized standards developin
4、g organization. Headquartered and incorporated in the United States of America, SMPTE has members in over 80 countries on six continents. SMPTEs Engineering Documents, including Standards, Recommended Practices, and Engineering Guidelines, are prepared by SMPTEs Technology Committees. Participation
5、in these Committees is open to all with a bona fide interest in their work. SMPTE cooperates closely with other standards-developing organizations, including ISO, IEC and ITU. SMPTE Engineering Documents are drafted in accordance with the rules given in its Standards Operations Manual. SMPTE RP 184
6、was prepared by Technology Committee 32NF. Intellectual Property At the time of publication no notice had been received by SMPTE claiming patent rights essential to the implementation of this Engineering Document. However, attention is drawn to the possibility that some of the elements of this docum
7、ent may be the subject of patent rights. SMPTE shall not be held responsible for identifying any or all such patent rights. Introduction This section is entirely informative and does not form an integral part of this Recommended Practice. This Recommended Practice (RP) defines the parameters for mea
8、suring jitter in serial digital video systems. The companion SMPTE RP 192 defines the methods and architectures of the measuring equipment. The intent of these two RPs is to allow equipment manufactures to make consistent measurements that reflect system performance, and to educate users on how to e
9、valuate systems. SMPTE RP 184:2015 Page 3 of 18 pages 1 Scope This Recommended Practice describes techniques for specifying jitter in self-clocking, bit-serial digital systems. It is applicable to sources, receivers, and regenerators. It is specifically intended for, but not limited to, 270 Mb/s to
10、12 Gb/s serial systems as defined by: SMPTE ST 259, SMPTE ST 292-1, SMPTE ST 424, SMPTE ST 435-3, SMPTE ST 2036-4, SMPTE ST 2081-1, and SMPTE ST 2082-1. Methods for measuring these specifications are found in SMPTE RP 192. 2 Conformance Notation Normative text is text that describes elements of the
11、design that are indispensable or contains the conformance language keywords: “shall“, “should“, or “may“. Informative text is text that is potentially helpful to the user, but not indispensable, and can be removed, changed, or added editorially without affecting interoperability. Informative text do
12、es not contain any conformance keywords. All text in this document is, by default, normative, except: the Introduction, any section explicitly labeled as “Informative“ or individual paragraphs that start with “Note:” The keywords “shall“ and “shall not“ indicate requirements strictly to be followed
13、in order to conform to the document and from which no deviation is permitted. The keywords, “should“ and “should not“ indicate that, among several possibilities, one is recommended as particularly suitable, without mentioning or excluding others; or that a certain course of action is preferred but n
14、ot necessarily required; or that (in the negative form) a certain possibility or course of action is deprecated but not prohibited. The keywords “may“ and “need not“ indicate courses of action permissible within the limits of the document. The keyword “reserved” indicates a provision that is not def
15、ined at this time, shall not be used, and may be defined in the future. The keyword “forbidden” indicates “reserved” and in addition indicates that the provision will never be defined in the future. A conformant implementation according to this document is one that includes all mandatory provisions
16、(“shall“) and, if implemented, all recommended provisions (“should“) as described. A conformant implementation need not implement optional provisions (“may“) and need not implement them as described. Unless otherwise specified, the order of precedence of the types of normative information in this do
17、cument shall be as follows: Normative prose shall be the authoritative definition; Tables shall be next; followed by formal languages; then figures; and then any other language forms. 3 Normative References The following standards contain provisions which, through reference in this text, constitute
18、provisions of this recommended practice. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this recommended practice are encouraged to investigate the possibility of applying the most recent edition of the standar
19、ds indicated below. No references are cited in this document. SMPTE RP 184:2015 Page 4 of 18 pages 4 Definitions 4.1 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 t
20、he low-frequency limit for alignment jitter. 4.2 Independent Samples For band-limited systems, samples are only independent if they are not over-sampled. By the Nyquist criteria this means that for a given bandwidth in Hz, the maximum number of independent samples per second is approximately twice t
21、he bandwidth. Any higher rate of samples will be just giving more information about the same signal components 4.3 Input jitter tolerance Peak-to-peak amplitude of sinusoidal jitter that, when applied to an equipment input, causes a specified degradation of error performance. 4.4 Intrinsic jitter Ji
22、tter at an equipment output in the absence of input jitter. 4.5 Jitter The variation of a digital signals transitions from their ideal positions in time. 4.6 Jitter transfer Jitter on the output of equipment resulting from applied input jitter. 4.7 Jitter transfer function Ratio of the output jitter
23、 to the applied input jitter as a function of frequency. 4.8 Output jitter 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. 4.9 Probabilistic Peak-to-Peak Jitter (p-p-p, Stated as Jitt
24、er at 1 in 10x, ) This is an estimate of the most likely p-p jitter in unit intervals when measured over 10x independent jitter samples. See Annex B for derivation. 4.10 Timing jitter The variation in position of a signals transitions occurring at a rate greater than a specified frequency, typically
25、 10 Hz or less. Variations occurring below this specified frequency are termed wander and are not addressed by this practice. 4.11 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. SMPTE RP 184
26、:2015 Page 5 of 18 pages 5 Jitter Specifications Equipment jitter specifications fall into three categories: input jitter tolerance, jitter transfer, and intrinsic jitter. A fourth specification, output jitter, is a system specification and may be used to specify jitter limits at equipment interface
27、s. At most device outputs in a SDI system, the observed jitter will be output jitter, consisting of the devices intrinsic jitter and any jitter transfer term from the signal driving the device. Output jitter will be at least as large as intrinsic jitter, and may be much greater in cases where there
28、is a significant jitter transfer term. At the time of this publication, the serial interface standards SMPTE ST 259, SMPTE ST 292-1, SMPTE ST 297, SMPTE ST 424, SMPTE ST 435, SMPTE ST 2036-4, SMPTE ST 2081-1 and SMPTE ST 2082-1 only specify intrinsic jitter. Note: System designers are encouraged to
29、define the desired system jitter margin and the allowed output jitter at each point in the system, given the jitter transfer and input jitter tolerance of the devices being used, so that the desired system error performance is reliably achieved. Cascading serial devices can lead to jitter accumulati
30、on. The characteristic of the jitter accumulation depends on the architecture of the serial devices: Many devices implement a reclocker with a very low frequency loop bandwidth, or use an internal or external frequency reference to effectively prevent all input jitter from passing through to the out
31、put. Other reclocking devices have a moderate loop bandwidth for the reclocking function, they attenuate jitter well above this bandwidth and pass through any jitter well below this bandwidth. At jitter frequencies near the loop bandwidth, reclockers may peak up and amplify input jitter. In addition
32、, reclockers have a jitter contribution of their own that may add to the low frequency jitter they pass through from the input, and which is typically the main source of high-frequency jitter on the reclocker output. Devices without reclocking pass all input jitter and can add jitter at any frequenc
33、y. Cascading multiple devices of the same type can lead to exaggerated effects; e.g., if several reclockers have peaking at the same frequency. Some devices are not prone to this behavior. 5.1 Input Jitter Tolerance Input jitter tolerance is the peak-to-peak amplitude of sinusoidal jitter that, when
34、 applied to an equipment input, causes a specified degradation of error performance. Input jitter tolerance is applicable to most serial inputs. Input jitter tolerance requirements are specified with a jitter template that covers a specified sinusoidal amplitude/frequency region (see Figure 1). This
35、 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 tolerance greater than the requirement (see Figure 2). Input jitter tolerance r
36、equirements are specified with the parameters given in Table 1. Frequency band f1 to f2 forms the low-frequency jitter tolerance bandpass. At least A1 UI of peak-to-peak sinusoidal jitter shall be tolerated over this bandpass without exceeding the specified error criterion. Frequency band f3 to f4 f
37、orms the high-frequency jitter tolerance bandpass. At least A2 UI of peak-to-peak sinusoidal jitter shall be tolerated over this bandpass without exceeding the specified error criterion. A1 and A2 shall be specified in UI. The slope of the jitter tolerance requirement between f2 and f3 shall be 20 d
38、B/decade. Frequencies f2 and f3 are related as follows: F2 = f3/(A1/A2). SMPTE RP 184:2015 Page 6 of 18 pages 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 interval should be used. The test si
39、gnal used for the measurement (to which sinusoidal jitter is added) shall be specified. Numerical input jitter tolerance values are provided in the appropriate SMPTE standards which reference this practice. The terminology shall comply with Table 1. Table 1 Input jitter tolerance Parameters Units De
40、scription Data rate f1 f2 f3 f4 A1 A2 Error criterion Test signal (bits/s) (Hz) (Hz) (Hz) (Hz) (UI) (UI) (Serial bit rate) (Low-frequency specification limit) (Upper band edge for A1, low-frequency jitter tolerance) (Lower band edge for A2, high-frequency jitter tolerance) (High-frequency specificat
41、ion limit) (Low-frequency jitter tolerance, f1 to f2) (High-frequency jitter tolerance, f3 to f4) (Criterion for onset of errors) (Test signal used for measurement) A1A2f1 f2 f3 f4S inuso ida l I nputJ it t e r A m p l it udeJ it t e r F re qu e ncyF igu re 1. In p ut j it ter t oler an c e t e m p
42、lat e-20 dB /de c a des lo peFigure 1 Input jitter tolerance template SMPTE RP 184:2015 Page 7 of 18 pages A1A2f1 f2 f3 f4S inus o ida l I npu tJ it t e r A m p l it udeJ it t e r F re qu e ncyF ig u re 2. Ji t t e r t ol er an c e s p ec if ic at i on an d aTe m pl a t e S p e c i f i c a t i onA c
43、 t ua l J i t t e r T ol e r a nc eJ i t t e r M a r g i nc om p li an t j it t e r t ol er an c eFigure 2 Jitter tolerance specification and a compliant jitter tolerance 5.2 Jitter Transfer Jitter transfer is jitter on the output of equipment resulting from applied input jitter. Jitter transfer is
44、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, such as analog black burst. The jitter transfer templates described below are intended for serial input to serial output jitte
45、r transfer. Jitter transfer requirements are specified with a template showing the maximum jitter gain as a function of frequency (see Figure 3). Equipment meeting a jitter transfer requirement will have a jitter transfer function that lies within this template (see Figure 4). Jitter transfer requir
46、ements are specified with the parameters given in Table 2. Frequency band f1 to fc forms the jitter transfer bandpass. The maximum jitter gain over this bandpass shall be P. From frequency fc to at least 10 (fc), the jitter transfer template shall decrease at 20 dB/decade. P shall be specified in de
47、cibels. The test signal used for the measurement (to which sinusoidal jitter is added) shall be specified. Jitter Transfer shall be measured as probabilistic peak-to-peak quantities on the input and output of the device. SMPTE RP 184:2015 Page 8 of 18 pages Numerical jitter transfer values are provi
48、ded in the appropriate SMPTE standards which reference this practice. The terminology shall comply with Table 2. PJ i t t e rT ra ns fe rG a i nf1 fcJ i t t e r F re que nc y-20 dB/de c a de s l o peF igu re 3. Jit t e r Tr an s f e r Te m p l at eFigure 3 Jitter transfer template PJ it t e rT ra ns
49、 fe rG a inf1 fcJ it t e r F re que ncyF igu r e 4. Ji tte r T rans f er S p ec if i cati on an d ac om p l ian t Jit t e r Tr an s f e r F u n ctio nA c tua l j it t e r t ra ns fe rJ it t e r tra ns fe r s pe c i fic a ti o nFigure 4 Jitter transfer specification and a compliant jitter transfer function SMPTE RP 184:2015 Page 9 of 18 pages Table 2 Jitter transfer requirements Parameters Units Description Data rate f1 fc P Test signal (bits/s) (Hz) (Hz) (dB) (Serial bit rate) (Low-frequency specification limit) (Upper band edge
