GPS Development

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GPS Development

How were the GPS functions, which can be said to be main feature of the WSD-F20, created?
This must have been a major undertaking with plenty of behind-the-scenes stories to tell.

Blink-of-an-eye speed

Emerging Business Department Keiichi ImamuraEmerging Business Department
Keiichi Imamura

── One of the major features of the WSD-F20 is its GPS function. Here Keiichi Imamura, who was in charge of specification design, takes through the process that lead to a GPS function capable of being built into a timepiece.

Imamura: As you know, a GPS system receives location information from satellites and then plots your current location on a map. With the WSD-F10, this was accomplished by linking up with the GPS of a smartphone. However, there are quite a few instances where a phone is unusable, such as when the phone is outside its service range, where there is the risk of it being submerged in water, etc. To deal with such conditions, the WSD-F20 has its own independent GPS built-in. Also, by making it possible to use on-screen maps even while off line, the WSD-F20 greatly expands map access to areas where a phone can't receive a signal, and just about anywhere else imaginable.

── Did you have some basic concept to guide your development efforts?

Imamura: The general image we had was one of a person in the great outdoors monitoring their position which was reflected on a map. We wanted to create functions that synchronize in real time with what you are doing right now. By including built-in GPS, we were aiming at improved outdoor gear practicality, in a form that provides plenty of emotional value, which is also very important. As for delivering totally new outdoor experiences, this concept is the same as the WSD-F10. With the WSD-F20, our objectives were to further enhance practicality and enjoyment.

The keyword at the beginning of the development was "speed." A GPS function used during outdoor activities requires performance that can instantly and accurately show your current location no matter where you are or what type of activity you are currently engaged in. Also, since many people these days use phone based map functions on a daily basis, it was thought that map function performance needed to be at least at the level provided by a phone. Rather than having to take out a phone, perform an operation, and wait for the display to refresh, we had an image of being able to find out accurate location information by simply looking at your watch display. The word "speed" includes the meaning of stress-free use under various different conditions.

Concretely, our development objectives started with the receiving sensitivity of the fundamental GPS signals, and also included the accuracy of the current location and tracking data on the display, and other issues. Another major issue was making the power hungry GPS function more efficient in order to stabilize GPS operations.

── How did the actual development work proceed?

Imamura: To develop the GPS system to be built into the WSD-F20, we first set up a project team called the GPS Working Group within the Emerging Business Department. People representing hardware, software, evaluation, and other roles assembled periodically. In the initial stages, ideas were put forth and subjected to frank discussions covering technical issues and the measures required to overcome them, and other topics. We shared an overall image of what we were trying to accomplish and incorporated it into our individual activities.

There were many cases where different opinions came into conflict with each other within the team. GPS development incorporated a wide range of elements, including the shape of the antenna, board layout, control programs, and more, all of which were intimately related to each other. There is an intimate link between apps and the operating system. Often improvement in one area would produce problems in other areas. There were cases where it was necessary to select one course of action over another. However, the group was made up of professional engineers and all the members wanted to meet their responsibilities in their respective field. They were not interested in creating a half-baked product. At the same time, each of the group members strove to achieve a balance with each other, showing mutual respect while remaining true to the needs of their own particular roles and responsibilities.

── It seems that by combining both individuality and team play, you were able to create a synergy that resulted in better product development.

Trial-and-error produces some of the very best that modern technology has to offer.

Emerging Business Department Hiroshi KatsudaEmerging Business Department
Hiroshi Katsuda

Emerging Business Department Munetaka SeoEmerging Business Department
Munetaka Seo

── The development team had to confront a wide array of technical issues. What were some of the special challenges that had to be faced during development? Let's hear about this from Hiroshi Katsuta who worked on antenna development, and Munetaka Seo who was in charge of board mounting design.

Katsuta: The antenna is an essential component of the GPS function. It has a profound effect on speed, accuracy, and the overall performance of a device. Although a GPS function had a history of being used for current time adjustment, it was slated with this new model to play a completely different role, which mean we were starting almost from zero. Also, as an outdoor device, the WSD-F20 needed to be capable of reception under a wide range of different environments. The hurdles we needed to negotiate seemed to get higher and higher.

One example of this is the location where the watch is used. Though signal reception is great on a mountain range or at the top of a mountain where the sky is wide open, it becomes poorer in a valley or along a river surrounded by trees. Because of this, we developed an antenna for the WSD-F20 to enable reception of U.S. GPS signals and Russian GLONASS signals, as well as the Japanese QZSS MICHIBIKI. This ability to pick up signals from multiple satellite systems provides a higher level of stability.

The orientation and direction of the antenna is also an essential consideration for receiving sensitivity. There are virtually unlimited possibilities for the orientation of the antenna while you are engaged in an activity. You may be stationary, walking, or running. You might be riding a bicycle or riding in a kayak. The watch may be facing downwards or upwards. The problem was finding a way to maintain stable receiving sensitivity no matter what the conditions. The easiest way to solve this problem would be to make the antenna larger, but the size of the watch is limited by available space and the battery. We were in constant communication with our subcontractors to settle material, form, directionality, and other issues, and we worked very closely with the relevant department to determine the mounting location.

── What issues did you need to deal with in terms of component mounting?

Seo: GPS signals are extremely weak, so they are easily affected by electromagnetic waves generated from metal board parts, the battery, and the body of the wearer. A number of different issues need to be taken into consideration for proper acquisition of GPS signals. Built-in GPS does not mean simply packing an antenna, chips, and other requisite parts into a watch case.

The antenna may work fine when it is on its own, but receiving sensitivity problems become evident once it is installed in a device. We were engaged in a continual trial-and-error process in which each time the arrangement of parts was changed, we had to deal with grounding and measures to shut out noise. Separating components that affected each other meant longer wiring and a larger board, so board design was much like working on a three-dimensional puzzle. We trimmed things down to the smallest size possible when mounting components for the WSD-F10, so adding a GPS function to a new model that is virtually the same size as before was something that could not be achieved easily.

Once we had prototypes ready, we went out and conducted real-world testing. Katsuta and I would strap prototypes on both of our arms and walk around city streets and the mountains carrying measurement equipment that weighed a number of kilograms. When we climbed Mt. Takao, we went by Trail 6, which runs along a stream, instead of the more popular Trail 1. The Trail 6 course is a tough one to walk, but we took it because we wanted to conduct the test along a stream where receiving sensitivity is not as good as that from a mountain range location. Even though we were carrying heavy equipment, I remember that we were able to make it to the top of Mt. Takao faster than the normally expected course time.

── It sounds like the development project was more of a physical challenge than normal engineering work.

Performance vs power savings

Emerging Business Department Shohei SakamotoEmerging Business Department
Shohei Sakamoto

Emerging Business Department Naotaka HikosakaEmerging Business Department
Naotaka Hikosaka

── Next we will talk with Shohei Sakamoto, who was in charge of software development, and Naotaka Hikosaka, who was in charge of assessment. What points did you focus on during GPS development?

Sakamoto: The software department performed the programming needed to control the GPS chip, to hand location information over to the map app, and to accomplish other tasks that were required with the addition of GPS to the WSD-F20.

In line with the keyword "Speed," the WSD-F20 instantly displays your current location as soon as you display the map. To enable this instantaneous display capability, we needed to achieve both measurement accuracy and power saving at the same time.

The first step in achieving these goals was studying the behavior of GPS. We performed prototyping and evaluation, while working to stabilize GPS chip operation, receiving, data interpretation, and more. In addition, a development plan aimed at achieving lower power consumption was established. These measures were aimed at working towards the final twin goals of measurement accuracy and reduced power consumption.

More exactly, we were able to provide a GPS chip with power consumption that is only 25% of previous chips (according to information available to CASIO), with a variable positioning interval that is changed depending on the function being used. Wasteful operations were minimized for more efficient power management, enabling low power operation that is suitable for outdoor use. To achieve this, power saving functions furnished by the operating system are maximized by applying a range of unique CASIO know-now. The specifications and settings of drivers and other subordinate software and hardware were fine tuned to make them more compatible with the API.

Even though we focused on GPS performance, we also needed to maintain operation of functions that are expected of a wristwatch. Simultaneously achieving the two contradictory goals of performance and power saving took a great deal of effort and time, but we think that this added to the overall value of the final result.

── What type of evaluation and other tasks were performed?

Hikosaka: Our main role was to perform GPS function performance evaluation and operation checks through field tests and other means, and to provide feedback to the relevant persons in charge. As has already been mentioned, a major role of the tests of those in charge of antenna development was to confirm receiving sensitivity. However, we focused our efforts on evaluation of measurement accuracy.

The method used for evaluation of GPS performance is measurement of fixed-point data and track data. Fixed-point data is measured in a static state, and reveals variations in the displayed data within a fixed amount of time. Evaluation and analysis are performed from the viewpoints of precision and degree of accuracy. Actual testing was performed every day on a rooftop with good reception conditions. Since GPS accuracy is affected by weather and other phenomena, we needed to collect as much data as possible. It took plenty of perseverance when it came to collecting data during long cold winter nights.

A track data check confirms that plots are displayed accurately as the wearer moves along a fixed route. We field tested the product in the mountains and on other routes where we expect it to be used. We conducted measurement not only while walking, but also while riding a bicycle or engaging in other activities. We also tested for accurate plotting on the display while engaged in high-speed movement.

If we detected a problem, we immediately reported it. After making the necessary adjustments, we tested again. This process was repeated over and over. We also carefully verified power consumption. One thing we were careful of doing was to change the evaluation method to one that was appropriate for the current development stage and adjustment content. By solving each problem one by one as it occurred, we patiently made improvements and improved overall performance. Now we look forward to seeing how our users put our product to use.

── The WSD-F20 is the smart watch that is designed and engineered for top performance when challenging the great outdoors. It is the product of a sense of mission and a desire to create new technology, which was shared by all of the engineers on the team. The result is a totally new era of the “wearable map” that is always on hand and never needs to be searched for or taken out. The WSD-F20 is the watch that takes outdoor adventuring to new limits.