There any many factors to consider when choosing an Android device that will work with GoChip including Bluetooth read speed and distance, Wi-Fi and cellular bands, Android version and skinning, battery life and price. Beyond the spec sheet, each device has it’s own characteristics that can only be discovered during testing. Zone4’s testing methodology is listed below, and this article will be updated with a more comprehensive list of devices over time.
If purchasing a new devices to use for race timing, Zone4 recommends:
Moto E4 Plus XT1775 (Factory Unlocked)
Zone4 has done considerable research and testing on potential candidate devices to come up with this recommendation. The XT1775 replaces our previous recommendation, the Google Nexus 5.
- Android 5.0 or newer
- Bluetooth 4.0 or newer with Bluetooth Low Energy (BLE) support
- Access to the Google Play Store
- 5GHz Wi-Fi (also called dual-band, 802.11a or 802.11ac)
- Cellular band compatibility in your region
How to Test a Device
To test if an Android device is capable of reading GoChips, Zone4 has developed a set of requirements and/or tests for the important specifications and operations of Android devices. These tests are based around measuring performance and handling typical race conditions.
Bluetooth Read Speed
Bluetooth read speed is the number of Bluetooth packets a device can process in a period of time and the consistency of this processing rate. The read speed must be high enough that the device can process packets from a large group of quickly passing GoChips. The read speed is impacted by the devices Bluetooth radio, processor, drivers and software limitations. It can only be determined by testing.
There is a tool built into the Zone4 Go app that benchmarks the number of packets read, the read rate and population of GoChips read. Quantifying the read speed of a given device cannot be expressed as an absolute value (packets/second), only as relative to a baseline device. This is because the quantity, distance and behaviour of nearby GoChips impacts this read rate significantly.
The read speed of tested devices will be expressed as a percentage of a Nexus 5 baseline device in the same position and orientation as the test device. This is done by using the Bluetooth Read Speed tool in the Zone4 Go app on both devices simultaneously and comparing the Read Speed of both devices. This results in a percentage of Nexus 5 read speed.
The consistency of read rates should also be considered. Some devices tested read packets in blocks and then go idle for a period of time before reading another block. This creates the potential to miss GoChips during the idle time.
Bluetooth Read Distance
Bluetooth read distance is how far away a GoChip can be read by a device. This should be tested by keeping the device and GoChips at the same height and orientation; 4 feet from the ground, 10 GoChips label side facing the back of the device. Open the Bluetooth Read Speed tool in the Zone4 Go app and find the furthest distance between the device and GoChips that consistent reads can be attained.
During testing of some devices, Bluetooth reading would unexpectedly get stopped in such a way that the Zone4 Go app would not be able to restart reading without user intervention. Typically this would happen when switching away from the Zone4 Go app to the homescreen or another app.
It is important that the device’s battery lasts for the duration of a normal race. If a device does not last for the duration of the race, attach a USB battery pack to extend the battery life of the device. Zone4 has used Anker battery packs with great success.
Testing Battery Life
Testing the battery life of a device requires several variables be kept constant. The device should be in proximity to 100 GoChips, screen on at full brightness and have the Zone4 Go app running in the foreground. Run the device from full charge to empty battery and the run time is considered the battery life.
Choosing a device with a long battery life
Battery life of a device is impacted by a handful of factors; hardware speed and optimizations, screen resolution and brightness, battery size and software optimizations.
Newer hardware technology is physically smaller which results in lower power consumption. This resultant reduction is power consumption is offset by increasing the performance of the hardware so it consumes as much power as the previous generation but has higher performance. Lower priced value targeted hardware typically has lower power consumption than higher priced performance hardware.
The device’s screen is the biggest power consuming component in a device. Newer screen technologies such as OLED when displaying specifically designed interfaces may change this. A device with a lower resolution display, turning off the screen or adjusting brightness will have a significant impact on battery life.
Battery size is a very simple way to increase battery life. A bigger battery will make the device larger and heavier which is of little concern to a GoChip specific device. Phoes are increasing becoming available in a ‘plus’ version with a bigger screen and battery.
Software optimization will also increase battery life. However, some optimizations will have a negative performance impact on the Zone4 Go app reducing the ability to read GoChips or transmit data to Zone4’s servers. The Zone4 Go app does what it can work around these optimizations but to ensure the best performance, keep the app open and the screen on.
Android devices range in size from small phones to large tablets. Screen size becomes important when considering using the device as a keypad. Due to the limited options available in tablet sized devices, no devices that meet Zone4’s requirements have been found at a reasonable price. Using a device with a 5″ screen or larger has generally performed well for prolonged keypad use, although the bigger the screen the better.
Screen brightness should also be considered as this impacts readability in outdoor race conditions. Higher resolutions screens will reduced battery life and provide little benefit for GoChip applications. Similarly, screens with better colour quality provide few benefits.
Devices at events get treated rougher and are put through conditions that personal devices don’t experience. Manufacturing material and construction has an impact on the amount of abuse a device can take. Construction of the device has a bigger impact than material used (plastic vs metal), however glass backed devices (for wireless charging) should be avoided.
There are an increasing number of devices available with some degree of water and/or dust resistance or proofing. This is certainly an advantage but devices without this feature can be protected with a simple plastic bag.
The USB port used to charge the device is one of the weakest points. USB C ports are generally tougher than their microUSB predecessor. A device with a big enough battery that doesn’t need to be plugged into an external USB battery at events reduces wear and tear on the USB port.
Connecting to the Internet
The most popular and simplest way to connect to the internet is through cellular networks. When buying a new device, ensure it supports the cellular frequencies used by local carriers. Wilson Amplifiers provides an excellent North American guide to this:
If using Wi-Fi instead of cellular data to connect to the internet, it is important to make sure to use 5GHz Wi-Fi and not the more common 2.4GHz Wi-Fi. GoChip technology uses Bluetooth for communication which shares the same frequencies with the near universally supported 2.4GHz Wi-Fi. Having GoChips in close proximity to 2.4GHz Wi-Fi networks will provide some network degradation. 5GHz Wi-Fi avoids this congestion by using an entirely different frequency.
Devices that support 5GHz Wi-Fi will be listed as having “dual-band Wi-Fi” and should support either 802.11a or 802.11ac standards. This isn’t the only requirements that is needed, an available 5GHz Wi-Fi network is also required. Again these are becoming increasingly common in home and public networks but still have a ways to go. When designing a permanent network installation, ensure a 5GHz Wi-Fi network is included.
Android Version, Skinning and Modifications
The Android operating system has a large amount of fragmentation resulting from a massive variety of devices, variety of update schedules, manufacturer/carrier skins, modifications and restrictions. This fragmentation makes it difficult to predict the behaviour of a similar hardware configuration from different manufacturers.
Newer versions of Android have focused on increasing battery life by adding restrictions that reduce the performance of apps when in the background. The Zone4 Go app performs best when in the foreground but takes advantage of workarounds provided by the Android framework to maintain performance when in the background. There is no recommended Android version other than being Android 5.0 or newer.
Manufacturer skinning can vary from small tweaks that add functionality to complete re-designs of the interface that are barely recognizable. Skins shouldn’t have an impact on the performance of the Zone4 Go app but makes it difficult to support other other skins when the interface is re-arranged, renamed or operates differently. Sticking to a device with a relatively ‘stock’ version of Android is preferred.
Issues resulting from software modification made by the manufacturer (or carrier in locked devices) can be the most difficult to detect and diagnose. These modifications usually target increasing battery performance but don’t conform to Android specifications and cannot be worked around. Additionally, devices that come locked from a carrier typically have a further modified version of Android with restrictions on features that impact their service. Carriers also act as an additional delay and/or risk of the device receiving updates. Devices that are factory unlocked and run a minimally modified version are least likely to experience unexpected behaviour.
What about iPhones and iPads?
Zone4 has done some experimenting with iOS apps but found some show-stopping limitations in the architecture. The development of an iOS app has not been completely ruled out but it will likely be focused on providing a keypad and less so on GoChip.