For those who want a more entertaining mobile-computing experience, the Pinnacle USB stick adapter allows for reception of the EurAsia-centric DVB-T programming on a notebook or other USB-2.0-enabled computer. The DVB-T (digital video broadcast--terrestrial) protocol is based on an MPEG-2 transport stream for delivering television in digital form vs. the analog modulation of traditional broadcast TV.

Started in 1993 by a group of European companies, the DVB Project's mandate is to agree on specifications for digital media delivery, including satellite, cable, terrestrial and other forms of broadcasting. Now, casting a presence that extends well beyond Europe, DVB is said to have resulted in placing more than 100 million receivers worldwide. As with the planned 2009 sunset of analog television broadcast in the United States, 2003 saw the first analog broadcast switched off in Berlin and a transition to all-digital.

Pinnacle Systems is behind the marketing of this DVB-T device, with manufacturing (and possibly reference-design work) done in Taiwan. The PCTV Stick, as the product is called, measures 82 x 32 x 15.5 mm, just slightly larger than most examples of the more familiar USB memory stick. A coaxial plug connector is recessed into the opposite end of the product from the USB connector to accept the cable for the included 120-mm whip antenna with magnetic mount. After installing software on any Windows machine and plugging in the hardware, you're good to go (assuming available service, of course).

Given the small size of the adapter and a modest $60 street price, a low chip count was anticipated and indeed found. In a nutshell, internal design reflects the advanced state of tuner silicon and targeted ASICs from both big names and smaller players.

Starting at the antenna input, there is an MT2060 single-chip tuner from Microtune. Capable of tuning over a surprisingly broad 48- to 860-MHz range and out- putting channels to an intermediate frequency (IF) between 30 MHz and 60 MHz, the tuner uses a two-stage down-conversion heterodyne architecture. A serial interface provides for control of the internal oscillators used in mixing, such that tuning to a specific channel is accomplished. An external intermediate-frequency surface-acoustic-wave filter and reference crystal oscillator dominate the handful of surrounding components that implement the RF front end.

Once tuned to a specific channel at IF, signals go next to a Zarlink ZL10353 coded orthogonal frequency-division-multiplexing terrestrial demodulator. COFDM is the modulation technique employed in DVB-T, selected for its ability to deal with multipath signals, which are a problem with terrestrial broadcasts in areas with multiple sources of reflected signals (think buildings and crowded urban settings). The device performs analog-to-digital conversion on the incoming IF signal and then demodulates to produce the MPEG transport stream. While branded as a Zarlink component in the unit deconstructed, the part is now actually under the Intel brand following the company's acquisition of Zarlink's RF front-end consumer business unit late last year. The purchase represents concrete evidence of Intel's play to expand beyond the microprocessor and move into the "entertainment silicon" arena. The new Intel part number for the demodulator, which is CE (for consumer electronics) 6353, pretty much says it all.

Controller role
The final major block of silicon comes from eMPIA of Taiwan. The EM2870 USB video capture device takes output from the demodulator and manages the audio and video streams as well as the physical USB 2.0 interface. As the PCTV Stick comes with software and a remote control to implement digital video recorder functions when plugged into a host PC, the EM2870 also supports the infrared (IR) interface whose sensor is located in the stick. Essentially providing all controller functions along with transport stream interface and video scaling, the device clearly targets the PCTV Stick and like products. Using a 0.22-micron CMOS process with 2.5-V core and 3.3-V I/O, the device also illustrates the capabilities enabled by a rising tide of IC design and fabrication resources worldwide.

Besides the three main devices, other components are limited to smaller-scale power management and a 512-byte serial E²PROM (Atmel AT24C02) whose interface can be switched between the EM2580 and ZL10353 parts by way of a Pericom PI3C3306 2-bit bus switch.

Of late, DVB-H has emerged as a standard to extend DVB into the power-sensitive domain of handhelds (the "H" in DVB-H). Looking at the design of the Pinnacle adapter--which goes to great lengths to spread and dissipate power from the Microtune component in particular--the need for power management becomes clear in more-portable scenarios. With an estimated power consumption of roughly 1 watt, the tuner and associated other components of the design are within budget for power-over-USB but out of scope for the small-form-factor batteries characteristic of the ultramobile world. To a first order, a DVB-T receiver would drain a cell phone battery in a couple of hours--not a viable scenario. DVB-H moves to a time-sliced Internet Protocol datacasting variation of DVB such that the tuner in particular operates in burst mode with substantially lower duty cycle and attendant power reductions.

Core components in the DVB-T adapter are estimated to sell for about $10, and DVB-H will likely be built at a comparable level. With trials for DVB-H now under way and commercial service rollouts planned for this year, the DVB-T device analysis is of interest both by itself and for the simple message it telegraphs: TV is coming to handhelds and will not necessarily break the bank or the battery.

Component Focus
As a USB-port-powered gadget, the Pinnacle stick has a finite power limit to work with given the 5-V at 500-mA standard for power-over-USB. The Microtune component requires about 1 watt of total power at 3.3 V, so regulation is needed to rework the 5-V supply to the target level.

The tuner power alone creates heat spreading and dissipation issues in the small USB dongle case, however, so a switching stepdown supply was chosen for its power-conversion efficiency. A simpler linear regulator would have added considerably more heat to an already difficult thermal situation. The switching dc/dc converter, meanwhile, drives the use of coils and filter capacitors-an added cost, but well worth it to save the burden of an overcooked product. When the chips push thermal issues to the edge, the passives-intensive dc/dc converter comes in to keep them from going over it.

David Carey is president of Portelligent. The Austin, Texas, company produces teardown reports and related industry research on wireless, mobile and personal electronics. (www.teardown.com).

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