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Troubleshooting in the Home. Cricket Rico E. Vitale FSE September 26, 2011. QAM-Cricket Training Module – Agenda. Video over IP Basics (review from the previous class) 3 Principles of Video over IP Multi-dimensional, End-to-End, Quality Assurance
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Troubleshooting in the Home Cricket Rico E. Vitale FSE September 26, 2011
QAM-Cricket Training Module –Agenda Video over IP Basics(review from the previous class) 3 Principles of Video over IP Multi-dimensional, End-to-End, Quality Assurance MPEG Transport Streams, TS-Packets, TS-PIDs, Continuity Counters MDI = DF:MLR Measurements & Monitoring QAM Overview Cable Television, CATV, Data over Cable (DOCSIS) QAM Basics 16, 64, 256 QAM Constellation Diagrams Errors, BER, R-S FEC, MER How Good? IneoQuest Solutions QAM Cricket Solutions
Video over IP ReviewPrinciples of Video over IP Given good quality source video, Packet Loss is the only thing an IP transport network can do to affect video quality. MDI = DF : MLR MDI = Media Delivery Index MLR = Media Loss Rate Make sure to check the Quality BEFORE making millions of copies
Video over IP ReviewPrinciples of Video over IP Jitter on a single flow can and will lead to changes in behavior on other flows. Cumulative Jitter does not directly affect video quality, but it is a leading indicator of impending loss. MDI = DF : MLR DF = Delay Factor or Jitter: the variation in arrival times of IP packets
Channels 134- 210 Channels 1- 129 130 131 132 133 134 Video over IP ReviewPrinciples of Video over IP All programs should be inspected continuously to effectively monitor IPTV throughout a network. Multi-Dimensional Video Quality: All Video All Locations All the Time Monitor All Live IPTV flows, What you don’t watch your customer does! MDI = DF : MLR
Service Provider Problem Statement VOD Service Unavailable
Transient Errors Effect Video Service End-to-End Program Flow Headend Core Hub Subscriber Video Passes Across Multiple SubsystemsEnd-to-End Program Flow No matter where the issue is across any subsystem, the effect is seen at the end of the system at the subscriber • Results : • Increased call volume ($) • Truck rolls ($) • Customer Dissatisfaction (Churn) Operational dollars get spent and problem is often not found or fixed….system never improves!
Monitoring Sub SystemsBlind to End-to-End Video Issues Single Video Program Problem Origination Headend Core Hub Subscriber MPEG Monitoring Subsystem Network Monitoring Subsystem Hub Monitoring Subsystem System Reports Good System Reports Good System Reports Good The first time realization that there is an issue is at the customer’s TV, so customer calls and trucks roll.
Multi-Dimensional Video Quality Management™ Using Multi-Dimensional Video Quality Management • Operations now can detect and pin point a video issue • Trouble ticket to specific sub system and use remote troubleshooting to solve issue. • If the customer calls, no need to roll truck since the issue is not at the premise Video issue detected and pinpointed Video Headend Core Hub Subscriber Predict, Detect, Isolate, Solve
Video Transport Quality What to Monitor? • Video/Audio PIDs Continuity Error IP Packet Loss/Jitter • PCR (Jitter) PSI, PAT/PMT Errors TCP/R-UDP Retransmits • Error Indicator count RTP Packet Loss/Jitter Video Control and Transactional activity & Secondary Services • Service Provisioning IGMP Latency HTTP Latency • RTSP Latency Closed Captioning EAS • Teletext Ad cue messages Conditional Access Video Content for confidence monitoring • Headend Confidence Monitoring Ad Verification • Subscriber Video Verification QoE Metrics
All Programs, All Locations, All Times Video Headend Core Hub Subscriber Comprehensive End To End Video Monitoring Solution IQPinPoint™ with VeriFrame™ Technology Broadcast CONTROL VOD TRANSPORT CONTENT SDV CONTENT TRANSPORT CONTROL CONTROL TRANSPORT CONTENT TRANSPORT • Cricket • Plurus ASI • Plurus 8VSB • Cricket ASI • Cricket 8VSB • Geminus IP • Singulus IP • IQDialogue VOD • IQDialogue Secondary Services • IQDialogue SDV • IQDialogue VOD • Geminus IP • Singulus IP • Cricket IP • Plurus QAM • Cricket QAM • Cricket • Geminus IP • Singulus IP Video Monitoring Probes iVMS
IQPinPoint™ Multi-Dimensional Video Quality Management™ iVMS™ VideoManagement System IQPinPoint™a solution that can audit, monitor, analyze and debugfrom a multidimensional perspective; All programs, all locations, all the time. End-to-End Hub Video Headend Core Subscriber
Reports Good Video Reports Bad Video Reports Bad Video Reports Bad Video Reports Bad Video Reports Bad Video Reports Bad Video Reports Bad Video Video over IP Review Multi-Dimensional Management: Detect, Isolate, Resolve 1000s of Video Flows End User Headend Video Core Edge Last Mile Premise Decoder Encoder Hub / VHO Network Servers Network Network Network Network Video Headend IP Transport Last Mile Network Subscriber Single Video Program Problem Origination Video Impairments • Proactive – Multi-Dimensional Video Quality Management, • Operations now can detect a Video issue. • Trouble ticket to isolated sub-system and use remote troubleshooting to resolve issue. • If the customer calls, no need to roll a truck – since this issue is notat the subscriber.
Video over IP Review IneoQuest End-to-End Solutions QAM-Cricket Analysis iVMS Beginning of Last Mile End of Last Mile (Subscriber) Video Headend IP Transport End-to-End Deep MPEG Analysis, IP Video Monitoring, & Remote Troubleshooting Simultaneous IP Video Monitoring & Remote Troubleshooting Last Mile Technologies IP, QAM, HPNA, ADSL2+, VDSL, ASI, Wireless Last Mile Technologies IP, QAM, HPNA, ADSL2+, VDSL, ASI, Wireless
MPEG Stream Types: Elementary Streams, Packetized Elementary Streams, Program Streams, Transport Streams, Program-Specific Data & Timing VideoPES Video ES Video Encoder Packetizer Audio ES Audio Encoder Packetizer AudioPES MultipleProgram TransportStream Transport Stream MUX PSIP Data Video ES VideoPES Video Encoder Packetizer AudioPES Packetizer Audio Encoder Audio ES Video over IP ReviewMPEG Transport Stream Formation Reference Page #(s): 187
Each Program Stream (in MPEG TS) has unique 13-bit Packet Identifiers (PIDs) Control PIDs – per TS: Program Association Table (PAT=0) (Stuffing=8191) (CAT=1) or P-Specific for Encryption Configurable PID’s – per Program Program Map Table (e.g. PMT=480) Video (e.g. V-PID=481) Audio (e.g. A-PID=482) Data (e.g. D-PID=483) Video over IP ReviewProgram & Packet Identifiers (PIDs) MPEG Structure How many Programs? 1 IP Packet 1 IP Packet 4 (4 Video PIDs) 1 IP Packet
QAM-Crickets Video over IP ReviewEnd-to-End Monitoring (iVMS Topology View)
Cable Television, CATV, North America Data over Cable (DOCSIS) QAM Basics, 16 / 64 / 256 QAM Constellation Diagrams RF Noise and Interference Errors (BER), Detection & Correction (R-S FEC) How Good is Good Enough? QAM-Cricket Training QAM Basics
QAM-Cricket Training Cable TeleVision & CATV • Cable Television started (1950) as a way for communities isolated from over-the-air broadcast (by geographic features or distance) to receive television services • They were first called Community Antenna (later Access) TeleVision (CATV) systems • Cable has since expanded services to include: • Digital Video • Digital Voice • High Speed Data / Internet • Video on Demand (VOD) • High Definition TeleVision (HDTV) • Pay Per View (PPV) • Interactive & Personalized Television (advertizing, shopping, games, etc.) • North American (NTSC) – each Channel is assigned a 6 MHz spectrum in frequencies ranging from 50 MHz to over 1 GHz (150 channels) • There are 3 Frequency maps used in NA • Standard (STD), Harmonically Related Carriers (HRC) and Incrementally Related Carriers (IRC) • HRC and IRC are used to decrease inference between the channels • Cable is broadcast in either Analog or Digital (QAM) – all Digital Broadcast by Feb 2009 Triple Play
QAM-Cricket Training North American Cable Frequencies 100 Analog Channels or > 1,000 Digital Channels
Broadcast & Switched Broadcast Systems Switched Digital Video (SDV) • Video networks only make the most viewed channels available to the Set Top Box or receiver at all times • Lesser viewed channels are switched on demand saving bandwidth and increasing channel capacity QAM-Cricket Training • Broadcast video networks must make all channels available to the Set Top Box or receiver at all times • Channel capacity is directly proportional to Plant capacity
CMTS HFC Transport Network Network IP In QAM Out Customer Video Source Enocoding & Multiplexing QAM-Cricket Training Data over Cable • DOCSIS: Data Over Cable Service Interface Specification • CableLabs DOCSIS technology allows cable operators to deploy broadband services (including video) over Hybrid-Fiber-Coax (HFC) networks • Part of the cable network becomes an IP Network (Video over IP) and the last-mile (interface to subscribers) is QAM RF over HFC or coax cable • QAM for downstream data flow and QPSK for the upstream return channel • CMTS (Cable Modem Terminal System) – mediates between the IP-based core network and the RF coax network plant
QAM-Cricket Training QAM Basics • QAM is Quadrature Amplitude Modulation • RF Modulation scheme used to transmit Digital signals over HFC • SCTE standard in North America (ANSI/SCTE 07 2000)r • The primary difference between the QAM signal types is the number of carrier amplitude steps (i.e. 16 QAM has 4 levels of I and Q states) • Two QAM carriers of the same frequency, 90° apart in phase (in quadrature) • one is I (In-phase) carrier • other is Q (Quadrature-phase) carrier • Both I and Q carriers are independently Amplitude Modulated (or keyed) with a digital bit stream. AM has a common number of amplitude steps (states). • The I and Q modulated carriers are then combined (ideally without interfering with each other) for transmission to the receiver
Symbols & Data The junction of the I and Q amplitude states represents a symbol(4 x 4 = 16 QAM) Each symbolrepresents a particular number of bits(4 bits in 16 QAM) and a specific bit sequence (0101, 1011, etc.) 2n= total # of symbol states required to represent all possible bit combinations (n = number of bits/symbol) 16 QAM: 24 = 16 symbols, 4 bits / symbol Q 0100 0000 1100 1000 0001 0101 1101 1001 4 Amplitude Steps on “Q” Carrier I 0011 0111 1111 1011 0010 0110 1110 1010 4 Amplitude Steps on “I” Carrier QAM-Cricket Training QAM Basics Example: 16 QAM I Q
QAM-Cricket Training 64 QAM vs. 256 QAM * 256 QAM Media Bit Rate of 38.8 Mbps: enough for 10 x 3.75 Mbps SD or 3 x 12.5 Mbps HD
Constellation Diagrams Each symbol location has a Magnitude and Phase-angle (from origin 0,0) The total number of symbol states equals the number of decision ‘boxes’ in the Constellation Diagram (64 ‘boxes’ for 64 QAM, etc.) Ideal location of a symbol is center of the decision ‘box’ (less noise, interference) Error Free – if the QAM symbol is within it’s own decision ‘box’ Q I I Q QAM-Cricket Training QAM Basics 64 QAM (64 decision ‘boxes’ for symbols)
Potential QAM Interferers What causes symbols to be received at ‘non-ideal’ locations? While QAM modulators aren’t totally perfect – most problems are related to the “post modulator” HFC network performance: As Carrier to Noise (C/N) degrades – symbols “scatter” (noise adds/subtracts from instantaneous carrier amplitude) Same is true for non-discrete distortions (like amplifier distortion of composite triple beat (CTB), composite second order (CSO), etc. Laser Clipping produces bursty interferers Reflections Poor Frequency Response and/or Excessive Group Delay QAM-Cricket Training QAM Basics
Effects of Interference on the Symbols in the Constellation Diagram QAM-Cricket Training QAM Basics
Symbol points that land inside their target ‘box’ do not cause errors ( original bit sequence will be ) perfectly replicated in decoder Any symbol point that lands outside it’s target ‘box’ causes errors QAM-Cricket Training QAM Errors Constellation Diagrams - the Decision ‘box’ - and Errors Each ‘point’ in a constellation display represents a symbol The QAM demodulator reconstructs the bit sequence associated with the particular constellation ‘box’ in which the symbol is received BER gives an indication of how many symbols are received outside their target decision ‘box’
Bit Error Rate (per second) or BER BER = # of Errored Bits Received Total # Bits Transmitted Usually very small numbers, so BER is expressed with scientific notation Example: 388 errored bits received ÷ 38,800,000 total bits transmitted BER = 0.00001 or 1 x 10-5or 1.0E-5 BER is most commonly specified for both Pre-FEC (Corrected) and Post-FEC (Uncorrected). FEC is Forward Error Correction (usually Reed-Solomon). Acceptable Error Rates for Video Distribution: Packet Error Rate, BER of 1.0E-6 Bit Error Rate, BER of 1.0E-9 Digital Video formats (like MPEG-2) are more sensitive to packet error rates (burst errors) than to packet errors QAM-Cricket Training Bit Error Rate (BER)
QAM-Cricket Training Errors: Detection & Correction (FEC) • Error Correction is necessary because conditions on long transmission paths • cannot be controlled. In some systems, error detection is sufficient because it • can be used to request a retransmission. Clearly, this approach will not work • with real-time signals such as digital television or streaming video. • The Forward Error Correction (FEC) used in modern digital cable systems is • usually based on the Reed-Solomon (R-S FEC) codes. • One-dimensional Parity-checking (CRC) tells you an error exists (but no location) • Two-dimensional FEC (R-S) tells you an error exists and the location of the error • Since an error can only be an inversion of logic 0/1, bits can be flipped (corrected) • R-S FEC adds redundancy to the data to make a code word such that when • each symbol is used as a term in a minimum of two simultaneous equations, • the sum (or syndrome) is always zero if there is no error. This zero condition • is obtained irrespective of the data and enables Error Detection + Correction. • In MPEG transport streams, the TS-packets are always 188 bytes long – prior • to the addition of error-correction redundancy. The addition of 16 bytes of R-S • FEC redundancy produces a TS-packet length of 204 bytes (still 7 per IP packet).
BER is all that TRULY matters The goal is to transmit data with a good enough BER that there will not be perceptible (annoying?) flaws in the information that the data represents One problem in digital technology is that BER (Pre-FEC and Post-FEC) have an associated ‘cliff’ effect: First, all is well (no Pre-FEC errors) as signal quality starts to degrade – until near the edge of the ‘cliff’ Further signal quality degradation then causes rapid deterioration in BER (first Pre-FEC errors) At some point, the FEC can not correct all the Pre-FEC errors and the BER continues with uncorrected (Post-FEC) errors – this results in significant video impairment or possible failure FEC effect – is to sharpen the curve (‘cliff’ effect) of BER vs. C/N (or interference) ratio. As noise increases, the recovered signal retains quality longer (due to error correction) – but at some point, the BER and quality will collapse rapidly (due to uncorrected errors) with worsening C/N ratio. QAM-Cricket Training Bit Error Rate (BER)
QAM-Cricket Training 64 QAM . . . . Error Free (Pre-FEC) Greenarea = relative size of a 16 QAM symbol 64 QAMCF: 72 MHzSymbol Rate: 5.056 MS/sData Bit Rate: 26.97Mbps BER = 0 (pre FEC)(MER = 27.9 dB) All symbol points lie within 64 QAM’s larger decision ‘boxes’= No Errors
QAM-Cricket Training 256 QAM . . . . Excessive Errors (Pre-FEC) Greenarea = relative size of a 16 QAM symbol box 256 QAMCF: 72 MHzSymbol Rate: 5.360 MS/sData Bit Rate: 38.81Mbps BER (Pre-FEC) = 1.0E-4BER (Post-FEC) = 0 (corrected)(MER = 27.5 dB) Many symbol points do not lie within 256 QAM’s smaller decision ‘boxes’= Errors (pre-correction) Red area = relative size of a 64 QAM symbol box 256 QAM target area is 4x smaller than 64 QAM Requires ~ 6 dB better C/N than 64 QAM
Modulation Error Ratio While BER gives an indication of how many symbols are received outside their target decision ‘box’ MER gives an indication of how far off the ideal locations the symbols are received MER thus provides a “figure of merit”, allowing you to see relative differences in QAM quality over a fairly wide range of conditions MER is expressed as a power ratio (in dB) - larger values of MER mean better performance (actual vectors closer to ideal vectors) Error Vector actual vector ideal vector QAM-Cricket Training MER (Modulation Error Ratio)
QAM-Cricket Training MER (Modulation Error Ratio) All three examples below have perfect BER No errors, as all symbols are received ‘in the box’ BER = 0 Best MER BER = 0 Good MER BER = 0 Poor MER • When the symbol cluster falls within the decision boundaries (‘in the box’), BER = 0 (no errors). • MER can be used to determine relative quality of these three signals.
MER is good for: Anything that is ‘non-bursty’, either steady state or slowly varying Poor Carrier to Noise, CTB, CSO, Ingress, Response, and Delay will cause MER to degrade before BER starts to degrade BER is best for: ‘Bursty’ interferers, such as those produced by laser clipping Prior to getting really excessive, clipping causes very brief, high-level interferers that do not affect a large percentage of symbols (thus the ‘averaged’ MER measurement is not very helpful) During the brief periods of interference, enough symbols are pushed outside of their decision boxes to cause degraded BER Bottom Line – measure BER (Pre-FEC and Post-FEC) Pre-FEC Errors (BER not = 0) should be Corrected by the FEC – so that the Post-FEC BER = 0 (No Uncorrected Errors) QAM-Cricket Training MER vs. BER
How Good is Good Enough? (at the QAM Rx) QAM-Cricket Training MER and BER Note that many of these requirements are not well documented… Sources: 1 – ANSI/SCTE 40, 2004 ‘Digital Cable Network Interface Standard’ 2 – ‘Digital Video Tests’ wall chart, July 2002 CED Magazine – ‘Acceptable to Excellent’“ listings for Digital Video
QAM Cricket Overview RF Measurements & Monitoring QAM Solutions Hands-on Labs QAM-Cricket Training IneoQuest Solutions –QAM Crickets
QAM Cricket Supports: Local or Centralized Management & Configuration Real-Time Monitoring RF QAM Measurements MPEG Transport Stream – Monitoring & Analysis MPEG Transport Stream – Trigger & Record Capture MPEG post-capture Analysis with IQ-TsXPro TS-Explorer Video Network Management with IQ-iVMS QAM Cricket TrainingQAM Crickets – RF Solutions QAM Cricket Front Panel Rear Panel
Functionality: QAM Cricket is a compact, lightweight test platform that can be used in 24/7 monitoring & analysis, field debug & fault isolation, and trigger/capture recording of faults for further analysis. QAM Cricket can be used as a stand-alone debug tool or as a remote probe for monitoring and analysis. QAM Cricket is ideally suited for RF QAM Confidence Monitoring and MPEG Transport Stream Monitoring & Analysis. Key RF Measurements – provide confidence that the QAM is good or bad. Signal to Noise Ratio (SNR) Reed-Solomon Errors (Corrected / Uncorrected) QAM Carrier (channel) Frequency QAM Symbol Rate (64/256) Alarm Configuration on a per-QAM-frequency basis QAM Cricket TrainingQAM Crickets – RF Solutions
Software Interfaces: QAM Cricket has a built-in HTML (browser) Interface for local configuration, control, analysis, monitoring and trigger/capture/record of video content. QAM Cricket can be controlled via IQ-MediaAnalyzerPro application software, which provides real-time analysis, trending, capture/record capabilities. In 24/7 Monitoring, QAM Crickets can provide real-time status, measurements and management from a central location using the IQ-iVMS system. Offline (post-capture) analysis with IQ-TsXPro provides MPEG-level analysis. QAM Cricket TrainingQAM Crickets – RF Solutions • Hardware Interfaces: • QAM Crickets can be initially configured using a USB interface – and dual Ethernet ports (In-Band, Out-of-Band) for local access, configuration, control. • QAM Cricket provides a QAM RF Cable-In Connector (F-type, 75-ohm) which allows for monitoring and analysis of digital RF QAM signals over coax.
QAM (RF) Confidence Monitoring & Analysis Monitoring of Full QAM-64 or QAM-256 Auto-Learn RF Channels QAM Cricket can be configured to TUNE on a specific QAM Frequency or SCAN all active QAM Frequencies Tuner Signal Loss Alarm RF Signal to Noise ratio Monitoring & Alarming Reed-Solomon Errors (Corrected / Uncorrected), Alarming User Feedback controls Trigger/Capture/Record problems (for off-line detailed analysis) QAM Cricket TrainingQAM Crickets – RF Solutions
Tuner Status(Tune or Scan) – each QAM Frequency is measured for Modulation, Signal to Noise Ratio and Reed-Solomon Errors (Corrected / Uncorrected) in addition to identifying the number of Programs (Total / Encrypted) in a MPTS. QAM Cricket TrainingQAM Crickets – RF Solutions QAM Tuner Status – Display All Channels, Frequency, QAM, Programs, R-S Errors% (HTML)
Reed-Solomon (RS) Errors: Raw value of Corrected / Uncorrected Errors. If RS Uncorrected (RS-UN) Errors exist – the MPEG Transport Stream will be impacted and Media Loss will occur – resulting in video impairment. QAM Cricket can Alarm on Unacceptable R-S Corrected / Uncorrected Errors QAM Cricket TrainingQAM Crickets – RF Solutions QAM RF Census & Alarms – Shows SNR, R-S Cor/Uncor Errors, Payload Errors (HTML)