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Digital Television, Part I: Making Sense of it all

by Thomas Ricker, posted Jan 17th 2006 at 12:23PM

Retro binary TV

Digital Television (DTV) is upon us friends — some of you already lie prostrate at its feet, a few of you cower in terror at its approach, and we’ll lay odds that most of you, whether you live in Amsterdam or New Amsterdam, are confused as hell about what it all means. So let’s all gather ‘round this phosphorescent global campfire, and we’ll tell you a scary story which makes that man with a hook-hand sound as passive as Bo Peep.

First, prepare yourself for a pig’s breakfast of acronyms son, there’s just no way around it: DAB, T-DMB, DVB-T, DVB-H, ATSC, and ISDB-T. At least these are the tastiest of the morsels under global mastication. Come on, don’t sweat it, you managed PCMCIA didn’t you, and that’s six whole letters! Besides, you really only need to learn the couple selected by the country you call home to effectively talk down to your local hi tech sales goon, mkay? So do join us as we take an extensive, in-depth look at what's really going on with the world of digital television.


Misconceptions

Let’s clear up a few things right away: 1) DTV is not HDTV, and 2) if you are a reader of Engadget, your TV is not likely to go black once your friendly government pushes the big red button labeled “analog switch off.”

See, HDTV is simply the highest quality format of digital television -- that “D” is for definition, not digital. Your digital broadcaster may in fact choose to broadcast in Standard-Definition (SDTV) format which offers an equivalent pixel resolution as the best analog signal, but allows broadcasters to squeeze more channels down the same analog TV pipe. Broadcasters could also enhance the quality a bit to EDTV (Extended-Definition, similar to DVD resolution), or, god willing, throw down that good HDTV fix we’ve all got the jones for.

Ok, that’s a bit more clear, now how about your TV’s viability after the analog switch off? Well, that old Emerson boob-o-tube you watch while bleeding pigs in the barn might have some trouble only if your Hee Haw reception requires adjustment to the rabbit ears. However, if you’re pumping a cable or satellite signal into that old set then the accompanying set-top box provided by Cablevision, DirecTV, etc. is already doing the analog-to-digital signal conversion for you. Oh, and if all else fails you’ll likely be able to appeal to GeeDub or other governmental body for a free signal convertor. After all, they stand to make billions (and billions) in revenue as they auction off the reclaimed analog spectrum which sits in the wireless sweet-spot — offering low transmitter density due to long signal propagation while avoiding the worst effects of man-made interference.

Analog TVs will also continue to work with cable, satellite, VCRs, DVD players, camcorders, video games consoles and other devices for many years to come. However, at some point you’ll have to throw down for a swank new digital television if you really want to explore your favorite starlets in all two million pixels of pockmarked glory. By 2007, it will be tough to find a new analog set in the US since by then the FCC will have mandated the inclusion of digital tuners in all new TVs larger than 13-inches.

Oh, and one more thing — that sweet, sweet digital TV we’ve seen on those Korean cellphones does not run over 3G. Mobile DTV is broadcast independently of the existing carrier signal. See, mobile DTV solutions offer a one-to-many broadcast service (i.e. digital terrestrial broadcasting) whereas 3G and other cellular technologies are one-to-one solutions. Even UMTS’ Multimedia Broadcast Multicast Service (MBMS) can easily become overloaded when broadcasting popular video programs. Not that this is really an issue since voice and data is going to fetch far more revenue per minute per subscriber than video anyway. If you really want to broadcast the evening news to rush hour commuters, then 3G just ain’t gonna cut it. And unless you live in Japan, mobile DTV handsets require a separate broadcasting standard from that which pumps DTV into your living room TV, at least if you expect your battery to last more than a few minutes.

Why switch?

Besides superior picture quality and your irrational lust for the latest-and-greatest, DTV consumers also stand to gain all the CD quality sound, on-demand-video, and digital broadcast content we sick TV lovin’ bastages could ever hope for. Likewise, DTV’s ability to deliver data enables broadcasters to provide sophisticated, web-like functionality overlaying programming as well as rich, IMDB-like electronic program guides -- you know, the good stuff required before committing to two-hours of a made-for-TV movie (even if it is “based on real life events”). The options are thick and will just keep coming as those analog frequencies become available for reuse, bringing to market the advanced wireless consumer services we crave and improvements in public safety services we need.

As already mentioned, governments stand to make mad fists of cash as they reclaim and then auction off the analog spectrum. The US sale should generate anywhere between $10 and $30 billion with similar cha-chinging sounds resonating from Europe. Makers of DTV set-top boxes like Philips and Thomson are already doing booming business with Nokia and others testing the waters as well. And let’s not forget conventional broadcasters who see the opportunity to diversify and sell more ads. And when DTV goes mobile in 2006, even cellular operators will get in on the action.

Of course, all this goodness comes at a price. Standards must be agreed under intense political lobbying, broadcast frequencies must be allocated in an already very crowded radio spectrum, and then there’s that small matter of paying to replace the analog production, transmission, and reception equipment required for full digital implementation. Oh, and expect to operate DTV and analog TV services in parallel for several years during the cutover.

And the economics of DTV are still risky — are viewers willing to pay more for extra lines of resolution, and more importantly, do they really want to receive TV on their cellphones? Well, the industry is counting on you to squint dutifully into your cellphone for several minutes at a time with research firms like Juniper estimating that as many as 65 million people will tune-in globally by 2010 — each prepared to fork-over a fixed fee of about $5-10 per month. The draw: sports, weather updates, news briefs, and all the latest social intercourses for your afternoon commute consumption.

But if the carrots of higher quality television and mobile reception aren’t enough to convince peeps to switch, there’s always the stick. Big-mama governments everywhere are setting hard switch-off dates into law by which analog broadcasts must cease. These dates range from 2006 for the Netherlands to well, like-forevah for countries still weighing the benefts vs. cost vs. demand vs. available standards. Yes, like any good standard…you have several substandards to choose from.

Broadcasting standards

Fortunately, the standards battle for bringing digital TV into your home has pretty much been fought and won. Yeah, you may not be happy with your country’s selection (cough, USA) but at least we can get on with the teevee bidness in the living room. However, the landscape is not nearly so tidy in the fight to bring TV to mobile devices like cellphones.

See, DTV reception must cover two primary audiences: fixed devices inside buildings that have ample power and rarely move, and those mobile handheld devices powered by batteries (cellphone / PMP / laptop) that might be in or outdoors, or even travelling down the autobahn. As such, we have either fixed or mobile handset broadcasting standards which require a bit of explaining. So, let’s bump uglies with these two technologies awhile shall we?

Fixed Reception

Let’s start easy by talking about digital broadcast standards targeting fixed reception devices, since these decisions are pretty much set in stone for those blooper-loving first-world countries. At the moment, North America and South Korea are on-board with Advanced Television Systems Committee (ATSC) and pretty much the rest of the world (besides Japan) has gone Terrestrial Digital Video Broadcasting (DVB-T). Japan has chosen to go it alone with Terrestrial Integrated Services Digital Broadcasting (ISDB-T), which they are not pushing as a global standard even though Brazil has shown interest. Here’s a very high level summary of those standards head-to-head.


 

ATSC

ISDB-T

DVB-T

Video

MPEG-2

MPEG-2

MPEG-2

Audio

AC-3

AAC

AC-3 or AAC

Disadvantages

ATSC signal cannot adapt to changes in propagation conditions

Cannot broadcast to either handheld or mobile devices, unless of course, you fancy carrying around your 42-inch plasma

Almost all TV broadcasts are encrypted with copy-once protection — tuners and TVs are relatively expensive

Requires lots of power to transmit a signal into rural areas

Can not transmit to handheld devices due to severe battery drain

Advantages

Requires as little as half the transmission power for same reception quality of DVB-T

Good for simultaneously broadcasting both a robust HDTV signal and one for handset/mobile reception

Open global standard which offers better reception in urban areas

Can transmit to mobile devices such as bus TVs

Not much sense in going into why each country selected which. Let’s just say that DVB is European developed and ATSC patents holders reside in The States… ‘nuff said.

Mobile Handset Reception

If you’re a fan of format wars a la Betamax vs. VHS or more recently, Blu-ray vs. HD DVD then you’ll love what’s coming with mobile DTV. In one corner, we’ve got the DAB (Digtal Audio Broadcasting) boys teamed up with South Korea’s Samsung, LG, and HTC manufacturing muscle pushing the Terrestrial Digital Multimedia Broadcasting (T-DMB) standard, while Nokia, Motorola and others are staunchly backing Digital Video Broadcasting for Handhelds (DVB-H) in the other. This battle is going to be big for broadcast digital video… the way that children think of God as big.

Nokia is making it absolutely clear that they are committed to making DVB-H the global standard. They claim DVB-H is in pilot in about 40 countries worldwide — er, we found 15, and some of those are completed already but you can define “pilot” pretty broadly these days a la Google and “beta.” Nevertheless, Nokia equips nearly all these pilots with their own 7710 handset and are also developing an end-to-end IP-Datacasting (IPDC) service (available to the pilots) which schedules and processes the incoming video and audio services and transforms them into a DVB-H signal. With their recent launch of the N92, they have even started taking public shots at DMB saying “we think DMB is going to be Korea-based from here to eternity.” In fact, you’ll hear a lot about DVB-H being the ”European standard” especially if you listen to Nokia execs. True, it is the ETSI (European Telecommunications Standard Institute) mobile TV recommendation for Europe with the keyword here being “recommendation” — ETSI recommendations are not compulsory. Hell, DMB is also an ETSI standard for mobile TV. As such, countries can still do as they please, and they are.

But this isn’t just a two horse race, particularly in the US where Qualcomm is coming up hard on the outside with their MediaFLO mobile DTV offering. They are already busy testing and deploying the $800 million MediaFLO network across the nation in Qualcomm’s 700 MHz spectrum, which they purchased from the FCC for an additional $70 mil. Volume shipments of FLO handsets are expected next year as Qualcomm begins its commercial rollout in partnership with Verizon. The next natural step then, is for Qualcomm to start stamping out chipsets and license the technology to their CDMA buddies in Asia and go after the standards-lovin’ GSM boys in Europe all over again.

And as we already mentioned, Japan has their ISDB-T digital broadcast solution which also covers mobile and handheld devices nicely but will remain an exclusively Japanese phenomena — nothing new to see here, so we’ll move along.

So let’s take a look at the biggies side-by-side with one caveat: there is enormous disagreement regarding the differences in these technologies. This is only further exasperated by the particular frequencies governments allocate for broadcasting (affecting handset antenna design, transmitter density/coverage, interference, etc) as well as limitations introduced by sub-optimal handset designs (Nokia 7710). One thing is certain — MediaFLO was designed specifically for mobile DTV handset reception whereas T-DMB and DVB-H are modifications to existing technologies to make them suitable to the task. However, as we well know, the best technology rarely doesn’t always win.


 

T-DMB

DVB-H

MediaFLO

Video

MPEG-4 (H.264)

MPEG-4 (H.264)

MPEG-4 (H.264)

Audio

BSAC

AAC

AAC

Core Technology

Eureka 147 Digital Audio Broadcasting (DAB) with additional error correction — DAB is already popular in Europe particularly in the UK and Germany

DVB-T with time-slicing and operating in IP environment — DVB-T already rolling out in Europe and elsewhere

Proprietary Qualcomm multicast technology technology called Forward Link Only (FLO)

Disadvantages

The L-Band frequencies (1452 - 1467.5 MHz) already set aside for DAB require a much higher density of transmitters to provide adequate coverage — and scaling up for large amounts of services would require additional frequency allocation

DAB-happy UK and others have rolled out digital radio in band III (around 221 MHz) which could mean large antennas strapped to their DMB enabled cellphones should these countries choose to ride their DMB broadcasts on top of DAB transmissions

Maximum data rate of 1.152 Mbps in about 1.5 MHz of bandwidth

Current Korean handsets have long telescoping antennas that westerners would reject

More susceptible to signal variations and synchronization problems

Requires higher transmitter powers

UHF frequencies (470-860 MHz) are ideal for DVB-H but these are tied up with analog TV transmissions — other frequency bands can also be used

The Nokia 7710 used in European tests has demonstrated poor battery life and delays of 12-to-15 seconds between channel changes — delays are in part due to DVB-H time slicing technology

Proprietary, isolated technology currently without the backing of the larger wireless industry — will be difficult to get a foothold globally without industry support

Qualcomm has yet to trial the technology publicly keeping it tightly held until it matures in-house

Designed to work in UHF from 450 MHz to 3 GHz some of which is currently allocated to analog television broadcasts — only the US has allocated the 700 MHz frequency for MediaFLO, all other countries would have to assign spectrum

Advantages

Open standard with wide-backing from wireless industry in Asia and DAB community in Europe

L-Band frequencies are already set aside for DAB so DMB could take advantage of these where available with little legislation

Time Division Multiplexing delivery inherent in DMB transmits specific content at specific time intervals which allows the receiver to be shut down in between these intervals to save power

Channel switching time of about 1.5 seconds on current T-DMB devices

Open standard with wide-backing from the wireless industry, particularly in Europe

Maximum data rate of 15 Mbps in 5-8 MHz of bandwidth down to 5 Mbps if robust reception required

Time-slicing helps conserve battery power since the receiver is only on when viewing the channel of interest

While DVB-H can be transmitted on a dedicated channel, it is designed to share a multiplex with DVB-T and can take advantage of the hierarchical transmission capability of DVB-T

Built from the ground up for transmitting content to handheld devices — technologically superior to both T-DMB and DVB-H

Claim average channel switching time of 1.5 seconds

Claim to fit more channels per chunk of bandwidth thereby offering access to more than twice as many channels as DVB-H (which DVB-H disputes)

Like T-DMB, MediaFLO uses Time Division Multiplexing to conserve power

More aggressive error correction and a form of hierarchical transmission called “layering” provides a more robust signal reception even in poor signal areas

That's a good amount for today -- come back tomorrow and we’ll look at implementation status on a global scale. So stay tuned, as they say!


Filed under: Cellphones, Handhelds, HDTV, Home Entertainment, Portable Video

Tags: features

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