Silicon for better DTV tuning, PIP, speed and size - Embedded.com

Silicon for better DTV tuning, PIP, speed and size

The digital TV switchover in the U.S. has been, and continues to be a gentle transition. Most cable and satellite subscribers will be unaffected thanks to digital set-top-boxes (STBs). Even the most basic level of cable subscriber, without a STB, will have time to adjust as broadcasters continue to provide analog signals alongside digital for up to three years after the February 2009 “switch.”

TV manufacturers must are also transitioning tuner architectures. The question, however, is no longer digital versus analog. That transition is set. Analog tuners are making way for hybrid analog/digital tuners and later on to digital-only tuner solutions in the 2011/2012 timeframe. The real question now is CAN versus silicon.


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Figure 1: Simplified DTV block diagram

Silicon digital tuners arrived on the scene with lackluster fanfare. Initial tuners lacked the performance and picture quality delivered by their bulky CAN tuner counterparts. Not all silicon tuners are created equal, however, and improvements have changed things around. Today, Xceive's production-proven, second-generation silicon tuners exceed CAN tuner performance and picture quality, while delivering additional benefits and differentiators.


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Figure 2: Hybrid 2-in-1 silicon tuner

Performance and the cliff effect
The addition of digital reception introduces new issues surrounding tuner performance and signal reception quality. With analog, TV signals deteriorate slowly over distances. The same is not true for digital. Digital signals are either received or not — on or off. If the TV is too far from the broadcast transmitter, only a blank screen will be seen. Likewise, buildings, hills and other geographical features can obstruct digital TV signals. This dramatic and sudden picture loss is what we refer to as the cliff effect.

A recent study by Centris shows that digital TV coverage is more limited than initially expected due to the cliff effect. The study found that 24 percent of viewers in difficult reception areas with only an indoor antenna will receive no digital reception. More than 50 percent of U.S. over-the-air (OTA) only TV households live in these difficult reception areas. The firm estimates that 9.2 million of the nation's 17 million OTA only TV households could experience digital TV reception challenges.

These households face blank screens when OTA analog broadcast ceases and are replaced by digital signals vulnerable to the cliff effect. The only option for these households is to migrate to cable or satellite, which may not be available due to remote locations or geographic obstructions blocking line of site from satellite reception.

The limited reception performance of CAN tuners enhances the cliff effect. With 3dBm difference in sensitivity compared to leading CAN tuners, Xceive silicon tuners counter the cliff effect and can be situated further from digital transmitters without picture degradation. In fact, an Xceive-enabled TV can be situated two times the coverage area of the equivalent CAN tuner.

Assume that a TV has been purchased and the owner lives outside of the original reception area of a traditional CAN tuner, but within the additional coverage area of the Xceive solution. This could be the difference between that TV set being enjoyed in the owner's new digital living room or returned to the store for a costly refund process.

Figure 3: Original catchment area and enlarged area with more sensitive tuner

This is an imminent challenge facing the television manufacturing industry as cable or satellite access is not guaranteed. For the digital transition to be successful, a silicon tuner must capture digital signals over larger coverage areas.

The above is true for legacy analog reception as well as digital. While the signal for an equivalent CAN tuner will be received, at 3dBm the signal quality of the Xceive silicon tuner will be superior to that of the CAN. The picture seen by the viewer will be cleaner, crisper and contain better color with fewer artifacts.

Next: Case study, tuner size
CAN vs. smart silicon: A case study comparison
The Xceive silicon tuner has now been field-proven for performance in some of the world's most challenging environments in Europe, Asia and USA. Recent trials showed examples where the Xceive tuner's performance was superior to and more robust than the leading CAN tuner. One of the easiest ways to demonstrate this is using over-modulation and carrier locking.

Two identical tier-one TV company boards were used in a side-by-side comparison. One board used a smart silicon tuner from Xceive while the other used a CAN from the company's own in-house tuner division. A comparison of the boards using an over-modulated signal showed extreme video distortions exhibiting a loss of horizontal video stability making viewing impossible. The same smart silicon tuner solution was able to receive and display the same signal through the same “backend” MPEG and video processor engine. The resulting image through the smart silicon tuner was robust, solid and stable. The comparison proved that the silicon tuner can handle much higher over-modulated signals compared to the CAN (e.g. 140%+ compared to the CAN's 125%).

Other examples of the silicon tuner's superior performance include superior ATSC/NTSC co-channel performance by 1-2dB, better channel search sensitivity, etc. Due to less field issues, the smart silicon tuner is becoming the preferred solution over the anachronistic CAN tuner.

Tuner size matters
Beyond the digital transition, evolving consumer demands force TV manufacturers to evaluate silicon tuners for their space efficiency. Consumer tastes call for bigger, flatter and lighter TV sets. Bulky CAN tuners cannot meet the trend as the TV chassis shrink in depth even as they expand in screen size. At some point, the desire to have the screen so thin excludes the use of a CAN tuner by design.

Figure 4: CAN Tuner Shown Next to an Xceive Silicon Tuner

Used in many current TV designs, CAN modules consist of large numbers of discrete components including multiple ICs, many small surface mount passives, variable capacitors, and multiple air-coil inductors. Due to the size, power consumption and complexity of these modules, designers are seeking out alternatives.

While monolithic silicon tuner ICs have been available for several years, they have not been able to match the performance and integration of CAN modules until recently. Monolithic silicon tuners have not been widely used in TV applications due to the difficulties in meeting all of the simultaneous demands of analog and digital, terrestrial and cable, tuning and demodulation at the levels required by TV manufacturers.

New silicon tuner ICs from manufacturers such as Xceive are meeting both the integration and performance levels previously only met by CAN tuner modules. A huge space savings clearly exists with Xceive's monolithic silicon tuner. The CAN tuner is cumbersome, while the Xceive silicon tuner offers performance meeting the rigorous requirements of leading TV manufacturers and also integrates all the hybrid TV receiver functions including the analog demodulator in a small 7mm by 7mm surface mount package. At less than 950mW power consumption is also substantially lower than currently available CAN modules that are typically in the 1350mW range.

The height of CAN tuners excludes its use in the new form factors of ultra-thin TV sets, or forces the relocation of the tuner into a separate box, which demands more cabling and yet another box adding to the home entertainment center setup.

The small size of silicon tuners also benefits TV applications needing small packaging due to shrinking screen sizes. Most small-screen TVs, such as kitchen or some bedroom sets, are now forced to add digital reception to the existing analog reception. This increases the size of the CAN tuner, making it difficult to fit into shrinking form factors. The solution is to migrate to silicon tuners as an enabling technology.

Next: Reducing manufacturing complexity
Reducing manufacturing complexity
CAN tuners are unique in size, material and soldering requirements compared to other components on a printed circuit board. Other board-mounted components tend to be “surface mount” these days and perhaps “through hole” on smaller layer boards for power supply components. However, the can tuner is unique in size, shape, material and mounting needs. This single subsystem component demands unique handling and mounting during the TV board production. TV manufacturers need specialized equipment to position CAN tuners, and to solder them onto the board. In many cases, CAN tuners are soldered by hand. This increases complexity, decreases yield and necessitates specialized handling equipment and manufacturing processes.

Silicon tuners require no special handling or materials. Manufacturers can leverage the same equipment used to mount other integrated chips on the circuit board. This reduces complexity and cost, while increasing yield.

The semiconductor process technology at the heart of Xceive silicon tuners also features much tighter tolerances than CAN tuners. This is especially true for the coils within CAN tuners that need to be adjusted manually during the manufacturing of the tuner. As a result, CAN tuners are particularly susceptible to product-to-product variance.

Tolerance and aging
CAN tuners are usually made from up to five larger components and up to 150 smaller components. These components all have their own individual production tolerances'. Some of these may be reasonable at +/-5% but others can be +/-10% or even +/-20%. Added together these tolerances make for a tuner solution that in production may vary in performance significantly from one unit on the production line to the next. This variation has been pretty dramatic. In some cases CANs have fallen outside of the expected operating range and have on rare occasions even resulted in recalls of the TV products in the field.

Additionally as the CAN tuner ages, its individual components wear at different rates. For example, coils age differently than resistors, which age differently than capacitors. This creates unpredictable reception and reduces functionality over time, which could ultimately degrade or eliminate signal reception in certain environments. Consumers demand better longevity as the cost of TV sets increase and feature-sets expand.

On the other hand, silicon tuner technology is a robust semiconductor device with extremely tight operating behavior that can withstand the test of time. Silicon tuners acceptable to the TV industry use a single, monolithic die with no separate “pieces,” meaning little change is experienced over time due to aging components. This ensures tighter performance variations for TV sets and results in a longer overall product lifetime.

It should also be noted that some silicon tuners may not be a monolithic die and may have components within the chip package. These will again wear differently over time, and may also have some vibration concerns. Not all silicon tuners are created equal and many are not suitable for use in TVs.

Streamlining inventory management
Manufacturers cannot scale effectively to worldwide broadcast requirements without a worldwide platform. With broadcast standards varying from region to region and the digital conversion occurring at different times, TV tuners applicable to worldwide standards help TV manufacturers reduce inventory and manufacturing costs, or at least minimize any possible redesign necessary for the different markets. As the silicon TV tuner can be used in Europe, USA or Asia, the tuner is no longer an obstacle to meeting regional requirements.

Xceive silicon tuners deliver one chip for all regions worldwide regardless of the transmission being analog or digital. This simplifies product design, enabling a single platform design for multiple markets. There is no need to manage different chips for different regions. The chip for Europe will work in Asia and in the Americas. Xceive silicon tuners handle worldwide broadcast standards, simplifying inventory management and costs.

Next: PIP features, combining IP content delivery
Combining IP content delivery with today's industry standards
Until now, adding broadcast TV reception capabilities to an audio/video IP-based delivery solution would require the introduction of regional standards. This negates the worldwide reach of IP. Internet reception is universal from a hardware point of view. Xceive's worldwide platform enables a single worldwide TV architecture to be merged into a system receiving IP services, creating new applications not previously possible.

Custom tuning
Manufacturers benefit further from Xceive's DSP-based architecture. This is not common to silicon tuners, but is unique to Xceive. A DSP exists within the architecture and runs firmware that defines tuner performance, characteristics and behavior.


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Figure 2: Hybrid 2-in-1 silicon tuner (repeated)

This allows tuner performance to be adjusted by Xceive even after production has started. It also enables the performance and characteristics to be modified by Xceive for specific needs, including customer differentiation. The feature makes it possible for TV manufacturers to update performance even in the field.

Additional PIP features
Eliminating manufacturing complexity is not enough to push manufacturers to “kick the CAN.” In the end, consumer demand drives the market. Xceive silicon tuners have gained tremendous ground among emerging TV brands. These brands differentiate their TV product lines through the advanced feature-sets of silicon tuners.

Xceive silicon tuners deliver high picture quality and deliver unique features to address common consumer demands. ChannelVista and QuickTune are two examples.

ChannelVista provides multiple picture-in-picture (PIP) capabilities with just one tuner. This is commonly known as “virtual tuners” due to its ability to display more than one channel on the same screen with only one tuner. By time-slicing the tuner across multiple channels, the TV system-on-chip (SoC) can update the screen with more than one channel “at the same time.” This gives the illusion of PIP without the cost of additional tuners.

QuickTune uses the ultra-fast per-signal detection of Xceive tuners to provide a complete channel scan of more than 100 channels in less than five seconds. With QuickTune, there is no need to wait up to 50 minutes for the channel scan setup (after consumers invest thousands of dollars for their ultimate TV) The five-millisecond channel detection time of QuickTune also enables fast channel changing, perfect for viewers switching from one ChannelVista picture to another.

Next: PIP favorite channels
PIP favorite channels
Another implementation is to offer a visual favorite channel list that displays simultaneous video from all the viewers' favorite channels on the same screen. The viewer can then select a favorite channel based on real-time video and not program descriptions. This fine-tunes the viewing experience and also allows the viewer to avoid changing the channel during an advertisement.


Figure 5: Video-based favorite channels (bottom) versus text (top)

In dual-tuner environments, ChannelVista enhances the viewer experience further by providing the ability to watch four, eight, twelve or any number of broadcast channels simultaneously. The real-time PIP displays surround the main channel display, creating a rich media center application.

Figure 6: ChannelVista in a dual-tuner environment

Conclusion
TV manufacturers face a paradigm shift to meet digital transition requirements. The traditional “switch” moniker is a misnomer as reality calls for a gentle transition from analog to hybrid to digital. At the same time, consumers are demanding sharper images with more color and advanced broadcast features. To remain at the top, TV manufacturers are differentiating products based on performance and feature sets. This requires higher-end digital TV reception while still appealing to a cost-sensitive mass-market. Silicon tuners are positioned to lead the charge. As the most highly integrated hybrid silicon tuner available on the market today, Xceive delivers the performance, quality and features required for TV markets worldwide.

About the author
Neil Mitchell is Vice President of Marketing for Xceive. He holds more than 20 years of business and marketing management experience in the digital TV and semiconductor industries. To learn more about Xceive and silicon tuners, please visit Xceive. He can be reached at .

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