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Compact, power-efficient ASIC allows location services

Posted: 07 Jan 2016 ?? ?Print Version ?Bookmark and Share

Keywords:SENtrace? PNI Sensor? ASIC? location service? GPS?

PNI Sensor Corp. has recently announced its application specific integrated circuit (ASIC) geared for consumer services, which could allow locating lost children to enhancing activity tracking accuracy for fitness enthusiasts. SENtrace enables wearables to track locations within one meter per 100m travelled while cutting power by 10-fold, according to Becky Oh, president and CEO of the company.

"Our long association with military-grade tracking algorithms enables our tiny [1.7mm x 1.7mm x 0.5mm] custom ASIC to locate wearables with unsurpassed accuracy while drastically cutting their powers consumption," Oh stated prior to CES.

Global positioning systems (GPS) typically locate wearables within 10m, although higher accuracy is possible with military decryption algorithms, or by combining the inputs from multiple GPS satellites. However, by adding the SENtrace ASIC with a three-axis accelerometer, a three-axis gyroscope, a three-axis magnetometer and (optionally) a single-axis altimeter (barometer), its dead-reckoning algorithms enhance the accuracy of wearables. The ASIC combines available beacons and the use of smart-divergence algorithms to sense errors caused by drift and other signals including electro-magnetic interference.

"SENtrace knows when our dead-reckoning algorithms are starting to diverge, which can happen for a variety of reasons," Oh added. "Consequently we send a confidence-level with our location readings to the app processor, so it can decide when to take another power-consuming reading from the GPS chip."

Thus instead of taking a new reading every minute no matter what, thus running down the battery of the wearable, adding the SENtrace's dead-reckoning accuracy and transmitted confidence level can cut down GPS reading intervals to as long as 10 minutes.


SENtrace from PNI attaches as a co-processor between the sensors and application processor to great increase its location accuracy while cutting the costs. (Source: PNI)

"This is especially important in wearables whose battery must last all day, such as for kid's watches in China, which are used to locate them, but can't run the whole day now," Oh stated.

For reliable dead-reckoning indoors where GPS signals are not available, SENtrace uses "signals of opportunity" according to Oh, which today are primarily WiFi, Apple's iBeacon and Qualcomm's iBeacon copycat spinoff Gimbal Inc. Unfortunately, these signal sources are not consistently distributed through all indoor areas (yet) making indoor-navigation accuracy dependent on the beacons available.

How it works

Inside the SENtrace ASIC is a 32bit integer processor with a custom floating-point unit (FPU) and all necessary firmware to boost the accuracy of its sensor-fusion tracking algorithms, tasks ordinarily delegated to the application processor, thus cutting costs and power by allowing less capable app processors to be used.


The SENtrace ASIC measures just 1.7mm x 1.7mm x 0.5mm. (Source: PNI, used with permission)

It requires three MEMS, a three-axis accelerometer, a three-axis gyroscope, a three-axis magnetometer and (optionally) a single-axis altimeter (barometer).

PNI is sampling the SENtgrace and has one customer committed to releasing a SENtrace-based wearable in 2016.

- R. Colin Johnson
??EE Times

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