Nuts & Volts - June 2006

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■ FIGURE 1. The N92 TV cell phone from Nokia. This WCDMA/GSM/GPRS/EDGE phone uses the DVB-H format. It receives TV on 470 MHz which is an available band in Europe.

■ BY LOUIS E. FRENZEL

TV ON A CELL PHONE

I SUPPOSE IT HAD TO HAPPEN. You can do almost everything else with a cell phone these days like play music, take digital photos, send and receive text messages and emails, play games, and even surf the Internet. Why not TV? Some cell phone operators are already supplying short video segments of sitcoms, sports events, and other content for a monthly fee. But such efforts are only just the beginning of what may become a huge new TV industry.

While most people surveyed over the past years said no to cell phone video, we are going to get it nevertheless. This trend is not only technologically driven, but also driven by the need for cell phone operators to develop new streams of revenue to replace the decelerating rate of new cell phone subscribers and the gradual abandonment of regular wired phones for full wireless.

Take a look at Figure 1. It shows one of Nokia’s TV cell phones used in Europe. If that turns you on, you may be interested in how all this works. Read on.

HOW COULD THIS WORK?

Stop and think a minute about the ways that video could be sent to a cell phone. The first thing you might think of is putting a regular TV tuner in a cell phone. TV tuners these days are just a tiny single chip anyway, so it is a good fit. Yet, to get reasonable TV reception, you will need a big antenna. Most over-the-air TV is still mostly in the low VHF bands, so you need an antenna several feet long to get any kind of

acceptable TV reception.

Think rabbit ears on a cell phone. Who wants that? I suppose you could use the earphone cable as the antenna like they do in cell phones with FM radios in them. That will work, but audio reception is far more forgiving than video. Crummy video with noise, snow, distortion, etc., is unacceptable to most. A short wire is just not going to hack it.

Another point to consider is that regular TV is not just formatted for a small screen. Text and screen details are way too small to see on a typical two-inch diagonal LCD screen. On top of that, analog TV is set to be phased out starting next year. The FCC has said that, beginning in 2007, all TVs will be digital using the ATSC (Advanced Television Standards Committee) High Definition (HD) TV standard that is now already in operation in most cities. Few have it, but soon all TVs will be digital only. Converter boxes that translate the HDTV signal into a poorer version for older analog TV sets will be available for those who can’t or won’t buy a new TV.

One thing’s for sure — the com-

plicated HDTV standard was not designed with portable or mobile TVs in mind. While you can jam almost anything into a hand-held, just be ready for the extra size and really short battery life. This standard operates in the existing (mostly VHF) TV bands, so you are still facing the antenna problem. No, HDTV on a handset is not going to happen.

Another obvious solution is just to deliver video over the cell network. This can — and is — being done. Just remember that video eats bandwidth like no other application. A typical digitized color video signal for a QVGA (Quarter Video Graphics Array) 320 x 240 color LCD display put into serialized form needs a transmit rate at a minimum of 30 Mbps. That is just a 15 frames-per-second (fps) display — half the 30 fps we are used to.

Huge bandwidth is required. Luckily, video compression standards like MPEG-2 and MPEG- 4 are now available to greatly reduce that rate, but it still means that you will need a serial data rate of 100 to 300 kbps to make it acceptable.