logo

English

이곳의 프로그래밍관련 정보와 소스는 마음대로 활용하셔도 좋습니다. 다만 쓰시기 전에 통보 정도는 해주시는 것이 예의 일것 같습니다. 질문이나 오류 수정은 siseong@gmail.com 으로 주세요. 감사합니다.

The distance estimate iBeacon signal strength

by lizard2019 posted Oct 25, 2019
?

Shortcut

PrevPrev Article

NextNext Article

Larger Font Smaller Font Up Down Go comment Print
?

Shortcut

PrevPrev Article

NextNext Article

Larger Font Smaller Font Up Down Go comment Print

The distance estimate provided by iOS is based on the ratio of the iBeacon signal strength (rssi) over the calibrated transmitter power (txPower). The txPower is the known measured signal strength in rssi at 1 meter away. Each iBeacon must be calibrated with this txPower value to allow accurate distance estimates.

 

When we were building the Android iBeacon library we had to come up with our own independent algorithm because the iOS CoreLocation source code is not available. We measured a bunch of rssi measurements at known distances, then did a best fit curve to match our data points. The algorithm we came up with is shown below as Java code.

 

Note that the term "accuracy" here is iOS speak for distance in meters. This formula isn't perfect, but it roughly approximates what iOS does.

   

protected static double calculateAccuracy(int txPower, double rssi) {
  if (rssi == 0) {
    return -1.0; // if we cannot determine accuracy, return -1.
  }

  double ratio = rssi*1.0/txPower;
  if (ratio < 1.0) {
    return Math.pow(ratio,10);
  }
  else {
    double accuracy =  (0.89976)*Math.pow(ratio,7.7095) + 0.111;    
    return accuracy;
  }
}   

 

Note: The values 0.89976, 7.7095 and 0.111 are the three constants calculated when solving for a best fit curve to our measured data points. YMMV

TAG •

List of Articles
No. Subject Author Date Views
50 [iOS] Audio Session Setting digipine 2021.11.26 1
49 [iOS] 개발자를 위한 iOS 15의 새로운 기능 file digipine 2021.11.04 18
48 [iOS/macOS] 사설 인증서를 사용한 SSL HTTPS 통신 시 우회처리 digipine 2021.07.06 355
47 [MacOS] Terminal 에서 zsh compinit: insecure directories 경고 제거하기 lizard2019 2021.04.30 162
46 Concurrent vs Serial DispatchQueue: Concurrency in Swift explained lizard2019 2021.04.16 217
45 WatermelonDB 'jsi/jsi.h' file not found 문제 해결 file digipine 2021.04.06 187
44 [iOS/Objective-C] __weak, __block 사용법 digipine 2021.02.16 167
43 macOS ARP Spoofing Attack file digipine 2020.09.17 315
» The distance estimate iBeacon signal strength lizard2019 2019.10.25 532
41 [MacOS, Swift] 스크롤뷰, NSScrollView 사용법 엉뚱도마뱀 2018.11.01 963
40 [swfit 4] 스위프트 Swift 동시성 동기화 정리 엉뚱도마뱀 2018.09.06 1125
39 [swift 4] 변경 사항 정리 file 엉뚱도마뱀 2018.07.23 867
38 [Objective-C] NSOperation과 NSOperationQueue를 사용하는 방법 - 설명 및 예제 엉뚱도마뱀 2018.03.14 1145
37 MacOS mysql 비밀번호 분실 시 재설정하기 digipine 2017.11.14 700
36 OSX - Screen Serial Terminal - OSX에서 시리얼 터미널 사용하기 digipine 2017.11.03 3937
35 OSX 사파리 최신 버전 폰트 변경하기 file digipine 2017.11.03 1020
34 [Swift 3] TCPIP Socket 통신 클래스 소스 코드 및 사용법 digipine 2017.11.02 3544
33 [Swift 3] HTTP Request 사용하기, 클래스 소스코드 및 사용법 digipine 2017.11.02 3912
32 [macOS] Sandbox 정책 극복기 Accessing Security Scoped Resource file digipine 2017.11.02 1075
31 [Objective C] NSString 앞뒤 공백 문자 및 줄바꿈 문자 제거 digipine 2017.11.02 1213
Board Pagination Prev 1 2 3 Next
/ 3