User Guide

9
Accuracy
Circular tests accuracy against medical grade gold standard device while building
each of the tracked metrics. Pulse oximeter for SpO2, holter monitor for heart
metrics and foot pods which are the best source of “truth” for Steps.
Factors That May Impair Data Accuracy
Sport sessions
For certain exercises, such as Crossfit, weightlifting or riding a bike, it may be difficult
to auto-detect sport sessions. This is because when you’re lifting heavy weights for
an extended period of time or gripping something tightly, it’s more difficult for the
heart rate sensor to get a clear reading. This is because the sensor is being pushed
against your skin which becomes compressed and harder to see through.
It is recommended to turn the flat part of the ring on the top of your finger during an
activity as Crossfit, weightlifting or riding a bike.
Another factor that can impair signal quality is temperature, as in cold weather
blood can retreat from your fingers, which can also make it difficult for the heart rate
sensor to get a clear reading.
Heart metrics
Regarding heart metrics, Circular will only report average measurements per
minute, so if the max HR is not sustained over a span of a minute or so, the minute
average for that time will be lower than what other trackers can report, as they can
report HR with higher temporal resolution.
There is a trade-off between higher temporal resolution and battery life.
Steps during transportation
The vibrations of your transportation on the road or on the rail line may sometimes
transfer to your hand and look like steps to the ring. Especially when your ring-
wearing hand is resting on the door, window or the steering wheel.
Requirements for Use of the Circular Services
The full Circular experience requires Circular products, internet access to the Mobile
App and Websites, and other required software (if any). Periodic updates to any of
these elements may be required for improved performance, and the performance of
the whole may be affected by the performance of any of these elements. You are
responsible for obtaining your own internet access and mobile device to access the
Circular Services.