HDBase-T – Structured Connectivity for Digital AV

Mike JinkersonLegrand North America

Our Learning Objectives• Define digital video (DV) and set the

expectations of connectivity distance • Explore the technical challenges of

“long” point-to-point DV connections• Dissect and review the components of

DV necessary for practical system utility

• Review DV connectivity options and formats

THE LAST 100 METERS“I sense an insatiable demand for connectivity.” − Clifford Stoll

Analog Connections Follow Simple Rules• Analog is continuous in nature

– Signal is varied continuously with respect to the information

• Analog systems have an infinite bandwidth

• Primary disadvantages of analog are noise and non-linearity– Additive noise– Generation loss– Intermodulation noise– Harmonic distortion

Advantages of Digital Signals

• Digital systems use discrete representations of information

• Digital systems exhibit a finite resolution• In a binary system, information payloads

double with each additional bit• Disturbances in a digital communication

do not result in errors unless the disturbance is so large as to result in a symbol being misinterpreted

Digital Connections Leverage Analog Signals!

• A digital signal is a representation of a series of discrete values

• Digital signals in cables leverage analog waveforms

• Clock signals used to synchronize digital circuits often act to limit connection length

The Physics Of Wire• Longer wire = greater resistance

– Cross-sectional area of the wires– Material composition– Pure resistance causes A frequency independent voltage

drop

• Capacitance and inductance are proportional to wire length/construction– Impedance is defined as the frequency domain ratio of

voltage to current– Capacitance and inductance cause a frequency dependent

voltage drop

Characteristic Impedance

• Opposition that a circuit presents to the passage of a current when an AC voltage is applied, expressed in Ohms (Ω) – Determined by the physical material composition

and geometry of the cable assembly

• A precise, constant conductor spacing, is necessary for a cable to function efficiently as a high-frequency transmission line

Skin Effect

• Alternating current in a conductor produces an alternating magnetic field.

• When the intensity of current in a conductor changes, the magnetic field also changes

• The change in the magnetic field creates an electric field which opposes the change in current intensity (counter-EMF).

• The counter-EMF is strongest at the center of the conductor and forces the conducting force to the outside of the conductor.

WHAT IS THE DIGITAL VIDEO PAYLOAD?

“For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled.” - Richard Feynman

The Elements of a Video Signal

• RGB additive color model divides a video signal into 3 ”components” RGB or YPbPr (YCbCr)

• Bandwidth is directly proportional to visual detail In analog systems, the ability to pass higher

frequencies equates to the ability to display finer detail

• Amplitude is directly proportional to color saturation

time

Chroma Subsampling4:4:4 Each R, G, and B channel, or each Y′, CB, and CR channel, is sampled at the same rate. Maximum

color detail is maintained.4:2:2 The color channels are subsampled so that the color resolution is halved. For example, the first

pixel in a line contains Y′, CB, and CR samples. The next pixel contains only a Y′ sample. This pattern repeats. Most professional video formats use 4:2:2 color subsampling.

4:1:1 The color is subsampled so that the color resolution is quartered. The first pixel in a line contains Y′, CB, and CR samples. The next three pixels only contain Y′ samples. This pattern repeats.

4:2:0 This ratio indicates that the CB and CR channels are subsampled both horizontally (as in 4:2:2) and vertically. This reduces color resolution in both the horizontal and vertical dimensions compared to 4:2:2, which only reduces horizontal chroma resolution.There are several methods for locating CB and CR samples relative to Y′ samples, yielding several different 4:2:0 formats.

Chroma Subsampling And The DV Payload

DetailD2K = 2M PixelD4K = 8M Pixel

Chroma Subsampling

Up To 16-Bits Per sRGB Component

4:2:2 YCbCr 4:4:4 “Deep Color”

DV BandwidthData rate * chrominance

decimationData rate = color depths *

vertical resolution * horizontal resolution * refresh frequency

Digital Audio

• Digital audio is not a discrete element of the DV package– Bits are “fungible”– Digital audio is

embedded into the horizontal ancillary data space (HANC) of the

– Audio travels with videoA sound wave, in red, represented digitally, in blue (after sampling and 4-bit quantization).

Digital Rights Protection - HDCP

• High Bandwidth Digital Content Protection (HDCP) is a technology designed to allow digital rights management implementation of AV content

• Converting digital video w/ HDCP is forbidden unless the output supports the HDCP protection

System Control• RS232• CEC is an HDMI feature designed to allow

the user to control enabled devices– Allows for individual CEC-enabled devices to

command and control each other without user intervention

• Infra Red• USB

– If “Interactive” is involved, so is USB!

DDC, EDID and DisplayID• Display Data Channel• Extended Display Identification

Data (EDID)– Enables the display (sink) to communicate

supported display modes to the source via a compact binary file format that describes the monitor's capabilities and supported graphics modes

– Stored in a read-only memory chip programmed by the manufacturer of the monitor

CONNECTION TYPES

“Given a choice between two theories, take the one which is funnier.” − Blore's Razor

Optical Fiber

• Multi-Mode Fiber– Supports many propagation paths

within the fiber– Used for shorter connections with

emphasis on power

• Single-Mode Fiber– Supports only a single transmission

path within the fiber– Used for the longest connections

Twisted Pair

• Differential (balanced) signaling ensures environmental noise rejection

• Differing twist rates (pitch) minimizes crosstalk between pairs

• Cable shield ensures integrity of the eye pattern of the digital signal– Next near end crosstalk– Fext far end crosstalk– AXT alien crosstalk

WHAT DOES “BASE-T” MEAN?

“It is difficult to get a man to understand something when his job depends on not understanding it.” - Upton Sinclair

Baseband

• BASE denotes a baseband transmission– A systems whose range of frequencies is

measured from close to 0 Hz to a cut-off frequency, a maximum bandwidth or highest signal frequency

• “T” denotes twisted-pair (balanced) transmission

Passband• Also known as bandpass, the

signal is sent over a limited frequency range that is a subset of the total signal range

• Passband signals are typically translated to a higher frequency, often for transmission by frequency division multiplexing

• RF and modulated systems are examples of passband technologies

LIFE BEYOND 20 METERS“Luck is the residue of design.” − Branch Rickey

TMDS Over Twisted Pair• Typically Dual UTP Connectivity

– TMDS – RGB and Clock– SCL/SCA I2C, Hot Plug, 5V Power, 5V Ground– No Fundamental Changes Are Made To The Signal

• Carriage Distance Is Inversely Proportional To Signal Bandwidth– 60 Meters For 720P Content– 25 Meters For 1080p/60– 20 Meters For 1080p With 10 Or 12 Bit Color Depth

Content

THE NEWEST IEEE STANDARD!

“The nice thing about standards is that there are so many of them to choose from.” − Andrew S. Tanenbaum

HDBaseT

• HDBaseT Alliance was established in 2010 – LG electronics, Samsung Electronics, Sony

Pictures, Valens Semiconductor

• Working to create a global standard for advanced digital media distribution

• HDBaseT 2.0 standard finalized in August 2013

• HDBaseT standard will support up to 8 “hops” of 100 meters each

HDBaseT and 5-Play

Power Over HDBaseT• Powered by a 50- to 57-volt DC

power supply– All 4 pairs can support power– Defined in the latest high-power PoE

standards, four-pair powering gives PDs two power interfaces

• 1 amp per 2 pairs for up to 100 watts– Backward compatible with IEEE802.3at-

2009– POH enables the PD to identify the

cable length/resistance and draw more power, as long as the overall power consumption does not exceed 100W.

Pulse Amplitude Modulation 16

0000 : 150001 : 130011 : 110010 : 90110 : 70111 : 50101 : 30100 : 11100 : -11101 : -31111 : -51110 : -71010 : -91011 : -111001 : -131000 : -15

0 0 . 5 1 1 . 5 2 2 . 5 3 3 . 5 4-1

-0 . 5

0

0 . 5

1

PAM16 TX Eye Pattern

One Symbol Period

TX D

iff P

eak

4bits

Level

HDBaseT uses PAM16 symbols where each symbol is transmitted using one of 16 discrete, differential voltage

levels, each representing 4 bits of data

HDBaseT Lite• Operational advantages

of HDBaseT at a lower price– 60 meter maximum– Supports UltraHD 2160p

in 4:2:0

HDBaseT Over Fiber• 2nd Generation VS2311 - 5Play™ Gen

2.0 Fiber - HDBaseT over fiber for transmission over much longer distances

– Can be used for single mode (SMF) and multi-mode (MMF) solutions

– Supports MST and HDBT2.0 performance– 600m with OM3 MM fiber / 800m with

OM4 MM fiber / 1Km / 10 Km - standard HDBaseT 2.0 over fiber optics

OTHER EXTENSION METHODS

“All truths are easy to understand once they are discovered; the point is to discover them.”- Galileo Galilei

Modulated PassBand

• Digital television!• Coaxial cable systems using modulated content can

deliver dozens of HD streams simultaneously

Video Over IP• Uses video codec to reduce the program

material to a bitstream– MPEG transport stream

• Uses an Internet Protocol (IP) network to carry that bitstream encapsulated in a stream of IP packets. – Variant of the RTP protocol

• Quality of Service (QoS) places significant demands on system design and implementation

IN CONCLUSION…

“A conclusion is the place where you got tired of thinking.” − Harold Fricklestein

Fascinating…• In all commercial applications, HDBaseT should

be run using S/UTP Cat6• HDBaseT supports up to 8 hops of up to 100

meters (or 60 meters for HDBT Lite)• HDBaseT supports 5-Play• HDBaseT supports 2160p 4K video in a 4:2:0

color space• HDBaseT PoH is based on PoE standards • New HDBaseT “Colligo” solutions can leverage

fiber links

“Live long and prosper.”

Questions?