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Clamshell handset receives DVB-H TV programs

Posted: 15 May 2007 ?? ?Print Version ?Bookmark and Share

Keywords:DVB-H TV programming? mobile TV handset? Samsung SGH-P920?

As the sinkhole for ever-expanding feature sets, the cellphone never sleeps. Having moved well beyond voice to high-speed data, e-mail, cameras, music players and the like, the mobile just keeps on packing it in. Samsung's SGH-P920, for example, adds to an already impressive feature set the ability to receive DVB-H TV programming.

Launched originally for Telecom Italia Mobile in a promotional tie-in to the 2006 World Cup, this 3G UMTS phone also features still-image and video capture using a built-in rotating 1.3Mpixel camera, along with video recording, an MP3/AAC music player, Bluetooth, ring tones, an electronic program guide and dual speakers for stereo audio.

Towards mobile DVB
Terrestrial DVB (think conventional antenna towers) has been in use for some time in Europe, with DVB-T being the standard adopted for most TV viewing on regular sets. But as an "always-on" data broadcast architecture, DVB-T does not play well in the power-sensitive mobile environment, since continuous operation of the receiver is required. In extending the DVB experience for the living room down to the handheld level, changes were needed to address the limited energy resources and smaller screens of the mobile environment.

DVB-H was created as an extension of DVB-T with the objective of "mobilizing" DVB service. Paramount among the technical details is the use of burst-mode instead of the continuous transmission of DVB-T. By time-slicing the data, the DVB-H receiver is able to shut down between bursts, with an attendant savings in power.

So what does DVB-H (and mobile TV in general) do to the design of a handset? Not surprisingly, it means more semiconductor content and some collateral additions to the user interface and industrial design, at least for the Samsung phone looked at here.

 Samsung SGH-P920

Samsung's SGH-P920 adds to an already impressive feature set the ability to receive DVB-H TV programming.
View teardown diagram

Starting with reception, the P920 adds a telescoping antenna for reception of DVB-H signals in the UHF band. The antenna is situated in the upper half of the phone's clamshell design, along with the two displaysa 2.2-inch main LCD and a smaller OLED panel visible when the phone is closed up.

To enhance the TV-viewing experience, the P920 adds a 90 swivel screen to the folding design to provide a traditional landscape-TV orientation without turning the phone sideways. Here the TV function adds some cost and complexity, both in the hinge and swivel hardware and in the additional signals for TV that must be sent through these articulated mechanical interfaces.

A sophisticated set of flex circuits (for the displays) and a coaxial cable (for the antenna) both pass through the swivel mechanism and the folding hinge. Here, a sizable design challenge emerges to manage costs while ensuring electrical connections that do not suffer from fatigue-related failures after repeated motion in and through the articulation hardware. Complicating the electromechanical design is the swivel camera module built directly into the hinge itself.

Fistful of connections
When all is said and done, Samsung had to manage a fistful of connection activity to get from the primary electronics in the lower half of the clamshell to the "visual elements" of the P920 in the upper half. While the double-hinge mechanism increases product bulk, Samsung chose to use the available extra thickness to incorporate sizable side "ears" that house speakers for stereo audio in the flip hinge.

On the main electronics assembly, much of the component set is dedicated to fulfilling the UMTS 2,100MHz and GSM 900-, 1,800- and 1,900MHz communications capability. Based around Qualcomm's MSM6250A platform, the P920 uses four chips for the cellphone proper, along with separate RF power amplifiers for the W-CDMA and GSM communications pathways. The MSM6250A baseband represents Qualcomm's respin of the popular 130nm MSM6250 into a 90nm process. The process move was undertaken to reduce die area and lower manufacturing costs.

Received signals from the telescoping UHF antenna first enter a tuner module (probably implemented by Murata) that builds in all passive and support components needed to go with Freescale's MC44CD02 DVB-H tuner IC. As is often the case with additions to cellphone metafunctions, Samsung used a shrink-wrapped tuner module to simplify testing and handset design by aggregating all of the mixed-signal tuner electronics in a single SMT assembly.

Once the appropriate DVB-H signals have been isolated in the tuner, they are passed to the DiBcom DIB7000-H mobile DVB-H/DVB-T receiver, which implements signal demodulation and decoding. Based on 130nm CMOS, the DIB7000-H consumes a claimed 20mW during DVB-H operation (DVB-T mode requires 10 times that figure), providing decapsulated audio and video streams for the next stop in the signal chain, the Nvidia GoForce 5500 media processor.

Nvidia-powered
The Nvidia chip serves as the central component for all visual I/O, including DVB-H signals and the camera interface on the input side, and the two display panels on the outbound side. A total of 2Mbytes of SRAM supports local working-memory needs of the DiBcom chip, and 2Mbytes of discrete SDRAM are added internally to the Nvidia stacked package.

Toshiba provides the system memory, shared by both the MSM6250A and the GoForce 5500, in a two-dice stacked package (TY9000A800E0GG) containing 128Mbytes of Toshiba NAND flash and 64Mbytes of DDR SDRAM from Elpida. While expansion memory by way of a TransFlash slot is possible, internally bulked-up memory footprints are designed to handle the video-recording aspects of the design, including the P920's TiVo-like time-shifting digital video recording capability.

Depending on where one draws the line on TV-related additions in the P920, the DVB-H mobile TV functions add $10 to $25 in manufacturing cost. Beyond the direct costs from upping memory and adding a separate media processor to accommodate the DVB-H solution, Samsung is attempting to enable new service provider revenue while also likely enhancing equipment margins.

The future of TV?
But is mobile TV the next big thing? While it seems like a good possibility, global mobile TV standards to drive better pricing have yet to emerge, and several formats are competing depending on geography. AT&T's recent decision to adopt the rival Qualcomm MediaFLO standard for mobile TV in the U.S. potentially dampened the prospects for DVB-H.

Of course, the other challenge is to overcome incremental service costs. DVB-H is not free, and for mobile users who already find their monthly bills to be quite large, the extra costs for TV may limit consumer demand.

Nonetheless, almost everyone "gets it" when it comes to TV, and if all parties in the food chain can overcome cost issues, mobile TV may indeed provide the boost the cellular industry seeks.

- David Carey
President, Portelligent




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