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Tuner improves reception of free-to-air satellite signals

Posted: 17 Aug 2005 ?? ?Print Version ?Bookmark and Share

Keywords:zl10039? in paytv? free-to-air? satellite tv? zarlink?

Many world markets offer Free-to-Air satellite signals, and, until now, STB have been challenged to find a low-cost, good-quality receiver IC to satisfy customers and engineering budgets.

In PayTV, satellite signal strength and the quality of the customer premises equipment (CPE) is well defined, whereas in the Free-to-Air satellite-TV environment, this is not the case and there is a great variation in the quality of the components and installation. As a result, the satellite signal is often significantly attenuated by the time it reaches the receiver.

For manufacturers of STBs in this space, a key priority, then, is to find a receiver with the best sensitivity. Traditionally, these designers use a standard satellite tuner and add a low-noise amplifier (lna) with support circuitry. The problem with this approach is that it requires RF expertise. So, many STB manufacturers instead use an off-the-shelf RF module, which takes up more real estate and costs more money.

In regular PayTV satellite, designers can drop the receiver right on the motherboard. When using an RF module instead, this is not possible. As a result, there are now two distinct satellite receiver markets: using a device on the motherboard for PayTV, and modules for Free to Air. The Free-to-Air market is very competitive, particularly in China, and it is growing in India, the Middle East, Southeast Asia, and other markets.

In response, the team at Zarlink has integrated an external LNA into the receiver chip in the ZL10039, making it possible for STB designers to put a Free-to-Air tuner with the required sensitivity right on the motherboard. This saves money, manufacturing/engineering/test time, and frees up printed circuit board space.

For this part, sensitivity is hands down the most important specification, and the ZL10039 is specified with sensitivity of better than -84.5dBm at 27.5MSymbols/s. "When paired with our zl10313 demodulator, the design is simple to use and requires no alignment or software tuning algorithms," reports Richard Crossley, product line marketing manager with the Consumer Communications group at Zarlink.

Sensitivity is important in the Free-to-Air market because equipment is manufactured at the lowest costs possible, so quality is low and signal strength is compromised. High sensitivity at the receiver end can compensate for that.

"In this market, it is also crucial to be able to manufacture in a repeatable way, so we supply a complete reference design to help them design the parts into the motherboard and achieve a repeatable design," adds Crossley. "In addition, we made sure that the tuner requires no manual alignment or calibration during production, like a typical TV tuner requires."

Another interesting specification for this product is its power consumption. During the design phase, the team at Zarlink managed to halve the power from the previous generation zero-IF tuner, down to 500mW. Although, on the surface, low power is not a huge factor in the Asia/Pacific market, low power does improve reliability, and that is an attractive feature.

The most challenging aspects of this product for the design team were addressing low-cost concerns ("Our customers expect a 20 percent reduction in component cost each year," says Crossley.) and integrating the LNA with comparable performance to an off-chip approach.

How did they do it? Crossley notes, "We always task our engineers to look at every way they can to reduce costs. This often means choosing the right process, packaging, and minimizing die size." In terms of integrating the LNA and optimizing sensitivity, Zarlink credits extensive RF design expertise and sophisticated analog/RF modeling tools.

"Five or 10 years ago, would expect to do two or three spins to get an RF chip right, now we are using tools that allow you to get it pretty much right the first time," Crossley notes.

With the kind of performance this chip achieves, and the way it simplifies Free-to-Air receiver design, it looks like this will be a hot product for Asia/Pacific STBs.

- Janine Love


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