1. ALPS The Acoustic Location Processing System
Patrick Lazik, Niranjini Rajagopal,
Oliver Shih, Bruno Sinopoli and Anthony Rowe
Electrical and Computer Engineering Department
Carnegie Mellon University
For the past years my colleagues and I have been performing research on the topics of ranging and indoor localization for mobile devices. This has lead us to look closely at time synchronization, with smart phones and tablets, which is what I am going to talk about today.

2. Overview Use near-ultrasound communication
Decodable using existing mobile hardware
Provide accurate indoor localization
Sub-room level (sub meter)
Pulse compression
Highly-scalable
Easy to deploy
Combination of SenSys

3. System Architecture Beacon BLE Data 802.15.4 Sync Beacon Ultrasound
Let’s address some of these problems, first and foremost: how do we achieve accurate ranging?
Beacon Ultrasound
Network Master
Phone

4. Generation 3 (IPSN ‘14 Loc. Comp.)
Hardware Revisions
Generation 2
Generation 1 (SenSys ‘12)
Generation 4 (RTAS ‘15)
Generation 3 (IPSN ‘14 Loc. Comp.)

5. Generation 5

6. Ultrasound Transmitter PCB

7. Ultrasound Transmitter PCB with BLE

8. Receiver

9. Underspecified Ranging
From TDOA to TOF
Underspecified Ranging
Obstacles
Once you have TOF, you can get accurate ranging in underdefined cases.
Take location – via TDOA, synchronize, then TOF ?
Time Synchronization

10. ALPS in Action

11. Coming Soon…
Auto floor-plan mapping/setup
IMU based tracking

12. Thank You!
Questions?