Solar? Radio? GPS? Explaining the differences between the three major technologies you need to know when choosing a watch

When considering purchasing a watch, many readers will likely encounter terms such as "solar," "radio-controlled," and "GPS." So, what technologies do they refer to? In this article, we'll explain the differences that are difficult to distinguish just by looking at the exterior.

The differences between solar watches, radio-controlled watches, and GPS watches

　Solar watches, radio-controlled watches, and GPS watches are terms that are often seen when talking about watch functions. Each has different mechanisms and functions. Understanding the basic structure of these three technologies will make it easier to understand the intended usage environments and strengths of each model.

Fundamental differences

　The difference between the three types is the "power source" or "means of time display."

　Solar watches use a mechanism that converts light into electrical energy, stores it, and moves the hands. Because the power is stored in an internal secondary battery, they can operate continuously for long periods of time as long as they are exposed to a certain amount of light. Another feature is that they do not require regular battery replacement.

　A radio-controlled watch is a wristwatch that receives standard radio waves (in Japan, from Fukushima and Kyushu stations), analyzes the time information, and then adjusts to the reference time. The standard radio waves themselves transmit the precise frequency and time information created by an atomic clock, making it possible to display accurate time. In an environment where radio waves can be received, the time is automatically corrected every day, so there is no need for manual operation. However, please note that reception sensitivity may decrease inside a building, under high voltage, or near electrical appliances.

　GPS watches receive signals from GPS satellites to obtain time and location information. GPS satellites are equipped with atomic clocks, which identify the time zone where the watch is located and display extremely accurate time no matter where you are. GPS signals are used globally, so time correction is possible even overseas. However, because satellite signals arrive from the sky, reception is more stable outdoors. When traveling between regions with time differences, a convenient feature is that once a signal is received, the watch automatically adjusts to the local time.

　These differences result in differences in the intended use and price of the watch, although most radio-controlled watches and GPS watches are solar-powered.

Digging deeper into solar watches

　Due to their unique characteristics, solar watches have a solar cell located under the dial that converts light into electrical energy. They can be charged not only by sunlight but also by indoor light such as fluorescent lights, making them easy to continuously secure power in everyday environments. Watches powered by primary batteries such as button cells require periodic battery replacement, but solar watches can be recharged and generate electricity, so they can be used repeatedly. Although the time varies depending on the model, once charged they can run for a long period of time, so there is no need to connect them to a charger every day like with a smartphone. However, with continued use, the battery will deteriorate and its capacity will decrease, so maintenance is necessary.

　Solar watches have the challenge of having to use transparent materials such as polycarbonate for the dial because light must pass through the solar cell. However, in recent years, Japanese watch brands have made remarkable progress in overcoming this constraint by adding original decorations and using metal materials.

Deep dive into radio-controlled clocks

　Radio-controlled watches are a major feature in Japan, likely due to their ability to receive standard time signals transmitted within Japan. Outside of Japan, base stations that transmit standard time signals include the United States, the United Kingdom, Germany, and China. Depending on the manufacturer and model, some watches receive standard time signals only within Japan, while others are compatible with six stations worldwide.

　If you are in an environment where you can receive radio waves, the watch will receive radio waves several times a day at set times and automatically correct the time, so you will hardly need to bother adjusting the time or calendar on a daily basis. However, it may be difficult to receive radio waves inside reinforced concrete buildings or under high-voltage lines. When you are not in an environment where radio waves can be received, the watch will keep time as a quartz watch.

Deep Dive into GPS Watches

　As mentioned above, GPS watches receive signals from GPS satellites, which orbit the Earth. As long as you are in an environment where GPS satellites can be received, the watch will obtain and correct the time information for the time zone of your location, no matter where you are.

　However, there are some drawbacks, such as high battery consumption during reception and limitations on design due to the placement and size of the antenna. Furthermore, radio-controlled watches tend to be priced higher than models that only use radio-controlled watches.

　Hybrid models that can also receive standard radio waves are also available.

Understand the differences between solar, radio, and GPS watches to find the best one for you

We explained the differences between the three technologies: solar, radio, and GPS. Solar watches convert light into electrical energy and store it, allowing for long-term continuous operation. Radio-controlled watches receive standard radio waves transmitted from a base station to correct the time. GPS watches use satellite signals to correct the time in a wide range of regions, including overseas.

　If you are thinking about buying a watch, we hope this will help you choose the one that best suits your lifestyle, preferences, and budget.