BLE Advertising Interval
The BLE advertising interval is the time between successive advertising packets from a beacon. The Bluetooth Low Energy advertising model lets a device broadcast without a connection. Industrial iBeacon-style tags often sit at 100 to 350 milliseconds: fast enough for a moving forklift, slow enough that a coin cell lasts years. At 350 ms the air holds about 2.9 packets per second per beacon. That is the yardstick. A scanner that reports 2.5 per second is keeping most of the radio. A scanner at 1.2 per second is throwing more than half away.
The interval is a battery decision on the beacon. The scan is a firmware decision on the tablet. Plants mix them up. They buy beacons at 350 ms, set the Android app to low-latency scan, and assume the location engine sees 2.9 RSSI samples a second. OEM firmware can still duty-cycle the radio for battery and memory. Unique beacon count stays high because each tag is heard eventually. Update rate and delivery lag do not.
How that shows up on two Android tablets in the same room is in Lenovo TB305XU limits iBeacon scan versus Teclast T50 Mini.
Key Components
Configured interval: The period the beacon firmware is set to advertise, often 100, 200, or 350 ms in plant RTLS kits.
Expected packet rate: Roughly 1000 divided by the interval in milliseconds. 350 ms is about 2.86 packets per second before air loss.
Capture ratio: Packets the scanner actually delivers in a window, divided by expected packets. Score this per MAC, not as a hall-wide callback total.
Scan duty cycle: How much of the time the tablet radio is listening. Android scan mode requests a duty cycle. Chip firmware and OEM power policy can still cut it.
Applications in Manufacturing and Logistics
Passive RTLS on a forklift tablet is interval versus scan. Beacons on columns or the roof advertise. The truck-mounted Android device scans and sends RSSI into the location engine. If the interval is 350 ms and the tablet keeps 80 percent of packets, the pin can follow a travel aisle. If it keeps 30 percent, the pin lags, spaghetti thins, and a no-go alert fires after the truck is already in the lane.
The same interval math applies to a technician phone and to a tablet used for material call-off. The job changes. The radio contract does not: the device must catch a known fraction of advertisements or the twin is interpolating, not tracking.
Benefits and Challenges
A longer interval extends beacon battery life. That is why plants do not run 20 ms advertising on every tag. A shorter interval gives the engine more RSSI samples and smoother motion. The honest install picks an interval the scanner can actually keep, then benches the tablet against that number.
The failure mode is a healthy unique-beacon count with a poor capture ratio. IT sees Android, Bluetooth on, battery unrestricted, and an app that says Scanning. The hall sees a late pin. Firmware throttle is invisible unless you measure packets versus the interval.
Related Terms
Advertising is the broadcast mode of BLE. Each packet carries an identifier and an RSSI at the receiver. Delay from air to callback is latency. The resulting locations feed an indoor positioning system. Beacon hardware itself is defined under beacon (RTLS).
Frequently Asked Questions
What interval should a forklift beacon use? Common plant kits sit between 100 and 350 ms. Faster burns battery. Slower starves a moving truck. Pick the interval, then prove the tablet capture ratio against it on a bench, not after go-live.
If unique beacons match, is the interval captured? No. Unique count only means each MAC was seen at least once. Capture ratio is packets per second versus 1000 divided by the interval.
Does Android LOW_LATENCY guarantee the interval? No. That scan mode is an API request. OEM firmware can still limit listen time. Measure the device you will mount.
Can I fix a weak scanner by advertising faster? You raise expected packets and beacon current. If firmware is dropping a fixed share of listen time, you still lose a similar fraction, and batteries die sooner. Fix the scanner first.