- Interval Basics
- Interval and signal ability
- How Interval affects indoor positioning accuracy
- When should you use a low Interval setting?
The “Interval” setting determines how often your beacon will transmit its advertising packet (i.e. basically telling nearby devices “I'm here!”). This is usually measured in milliseconds (ms), but can be measured in seconds (s) at the very highest interval ranges.
In practice however – you’ll generally only be concerned with the differences in milliseconds. There are (as of this writing) not many applications where using a seconds-long interval is particularly useful. This may of course change in the future.
Effect of interval on battery life
|Interval||Interval used in:||Tx Power||Expected range||Expected Battery life1|
|100ms||Apple iBeacon preset2||-12 dBM||35 m||Up to 7 months|
|350ms||Kontakt Beacon preset2||-12 dBM||35 m||Up to 2 years|
|200ms||Kontakt Eddystone™ profile||-12 dBM||35 m||Up to 2 years|
|1000ms||-12 dBM||35 m||Up to 4 years|
1 Assuming optimal environmental conditions.
2 Learn how to bulk update Beacons with predefined profiles.
Interval and signal ability
In our own lab analysis, we have determined that higher interval settings (over 700ms) actually cause major issues with signal stability. However we have also determined that using the 100ms interval setting recommended for iBeacon, is actually overkill for this issue.
We've determined that 350ms offers the perfect balance between signal stability and battery life for the Kontakt.io Beacon preset – which is why we use this setting as our default option.
How Interval affects indoor positioning accuracy
There are some cases where you do actually want to sacrifice your battery life for the sake of indoor positioning accuracy. In fact, there are cases where you’ll want your interval to be as low as 20ms!
How do you know the right choice for your needs? It all depends on how accurate, or how finely you need to determine the positioning of a device interacting with your beacon network.
The illustration below shows you conceptually the difference the Interval setting makes:
- There is a customer walking through a venue with four shelf units.
- The path taken by the customer is the same in all four venue representations.
- The only difference is the Interval setting used by the beacons installed in the venue, to track the path of the customer through the venue.
- Each “dot” on the path, conceptually represents a signal broadcast, which is used to determine the precise position of the customer as they journey through the venue.
So as you can see, the interval can make quite a big difference to positioning accuracy. Since this customer is a person travelling at normal walking speed – there isn’t much practical difference in accuracy between the 20ms and 350ms setting (our default).
However you can also see that with an Interval of 1000ms (or 1 second) – the positioning accuracy drops substantially, and you cannot tell precisely what path the customer was taking. This may or may not be a big deal for your use-case, but it is important to understand the distinction.
When should you use a low Interval setting?
We define a low Interval setting as 100ms or less. There are a few particular cases when using a very low Interval setting is useful (to the point of sacrificing battery life).
- The object you are tracking tends to move quickly – for example we have some cases with auto manufacturers who need to accurately track the location of a moving car.
- It makes a big difference where the object is located by very small distances i.e. positioning by inches / centimeters is important, compared to using feet / meters.