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Inside Navman's 'go-wherever' GPS device

Posted: 14 Jun 2006 ?? ?Print Version ?Bookmark and Share

Keywords:David Carey? teardown? Navman? iCN510? GPS?

This is a story of a good product gone bad--namely my own global-positioning system terminal, which suffered an untimely death to serve as the subject for this teardown analysis.

Call it an excuse to upgrade.

GPS has been around for years, starting with government-driven development throughout the 1970s and 1980s. By the 1990s, the commercial application of GPS was in full swing, and companies like Trimble Navigation and Magellan began selling receivers to both public-sector customers and private-sector consumers.

Like any electronics-driven device, GPS receivers have undergone the cost reductions that the silicon technology juggernaut continues to deliver. Core GPS receiver chip sets are now available from a host of semiconductor vendors, with power consumption reduced to levels that allow GPS to be embedded in nearly any mobile product.

So what makes a relatively modern receiver tick? The story, as it turns out, is largely about the elements that surround the GPS devices, and the software and data platforms that come along for the ride. Receivers may have shrunk to a handful of components, but the quality of the user experience rests on the efficacy of tying longitude and latitude coordinates to real-world maps and consumer-friendly applications.

The Navman iCN510 dissected here is a standalone GPS receiver and navigation product, fit into a PDA form factor and sporting a 3.5-inch color touchscreen LCD. Running for several hours or more between charges on the 1,350-mA-hour, 3.7V Li-ion battery, the iCN510 won me over with its go-wherever design.

Featuring an outstanding holster with suction-cup mount, the device moves (or used to move) freely among the cars in our family and even a motorcycle windscreen. I didn't have the scratch for a dedicated in-car navigation system, but the sub-$400 iCN510 did the trick with more flexibility than--and arguably equivalent functionality to--any OEM automotive GPS solution. Using the somewhat dated but good-enough set of mapping CDs included with the product, I was able to buy a 1GByte Secure Digital memory card and preload details for virtually all of the United States. A quick reallocation of storage for any missing map data covers me in cases where something new is required.

The internal design spreads electronics across two printed-circuit assemblies--one for the GPS receiver and the other for all of the associated processing and user interface. As can be seen, the receiver board represents a small fraction of electronics content, supporting a two-chip solution from SiRF Technology Inc. that splits RF reception (GRF2i/LP) and digital processing (GSP2e/LP). A 512KByte nonvolatile memory from Silicon Storage Technology Inc. provides local code store to run the GPS engine.

Navman iCN510

Navman iCN510 GPS device (Click image to view teardown diagram)

Adding only a pair of clock oscillators, a surface acoustic-wave filter and a smattering of discrete components, the receiver itself is complete.

The larger main circuit board is responsible for translating position data into a useful end-user experience. An Intel Corp. PXA255 applications processor handles all data and user interface functions and, by way of a NEC gate array, delivers color 3-D graphics to the 3.5-inch LCD. As with many current GPS navigation units, voice guidance is available to direct by audible instruction once a target destination has been selected. This capability is both reassuring and safety-enhancing in that users can largely ignore the screen while driving. Modern accuracy of the receiver, combined with spot-on map data, allows drivers to keep their full attention on the road while synthesized speech provides the directions.

Code store for the primary processing comes by way of 32MBytes of Intel NOR flash (28F256). Working memory is supplied by 32MBytes of Infineon low-power SDRAM (HYB39L25616).

The audio interface for speech output comes from Wolfson Microelectronics' WM9705 codec, with the same part incorporating the necessary circuits for the touchscreen interface. A small Texas Instruments Inc. audio amplifier drives the single internal speaker of the design, while the Wolfson part directly drives optional headphones.

All these islands of functionality, not to mention the desire for maximum battery life, require a surprising amount of power management. Here, devices from TI, Monolithic Power Systems Inc. and Intersil Corp. tackle front-line energy conversion. Other smaller-scale regulators can also be found to complete the job of creating varied, localized power supplies.

Despite a $300 to $400 retail tag for GPS navigation units like the Navman iCN510, a total production cost below $100 is possible even with a generously sized LCD. Of this total, the GPS engine itself contributes less than $10. That's significant progress for a function of this complexity.

While the antenna remains a size-constraining element of GPS design (the Navman here uses a ceramic patch antenna in a flip-up "wing"), the basic electronics are getting cheap and tiny.

I sacrificed my iCN510 with a heavy heart. But not to worry: An enhanced replacement is ordered and on the way.

I appreciate the quite-capable standalone navigation devices available in portable form, and I enjoy using them to know where I've been, where I am, where I'm going and how to get there. Such useful features may migrate predominantly into the phone or other uber-mobile gadget containing much of the processing wrapper needed around a GPS engine, but time will tell.

No matter what form the future of GPS may take, a rich map set and user interface will continue to be the value-adds to an increasingly modest hardware bill of materials.

- David Carey
President, Portelligent




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