Android BLE: Convert ScanResult timestampNanos to System nanoTime

Question

When scanning for Bluetooth Low Energy packets I receive ScanCallback with ScanResult being set. I can get "Device timestamp when the scan result was observed" with result.getTimestampNanos() but this time is not aligned with the Systems.nanoTime(). Is there a way to convert from one to the other?

score 7 · Accepted Answer · answered Dec 03 '15 at 05:37

7

Use the following code to convert the getTimestampNanos() to system millis by using SystemClock.elapsedRealtime():

long rxTimestampMillis = System.currentTimeMillis() - 
                         SystemClock.elapsedRealtime() +
                         scanResult.getTimestampNanos() / 1000000;

This can be converted easily to a Date object:

Date rxDate = new Date(rxTimestampMillis);

Then you then get the time as a string:

String sDate = new SimpleDateFormat("HH:mm:ss.SSS").format(rxDate);

answered Dec 03 '15 at 05:37

Glenn

1,996
2
24
32

Not sure why you prefixed your variables with `rx` or even `s`, but I don't think we need RxJava for this – Louis CAD Feb 23 '17 at 11:05
2

tx and rx are common abbreviations for receive and transmit. I pasted this code from a source file which was using both a 'tx' and an 'rx' timestamp. In this case the question was about receive timestamps so I left the rx prefix. – Glenn Feb 24 '17 at 17:25

score 1 · Answer 2 · answered Sep 18 '20 at 11:41

1

More elegant way to do that

long actualTime = System.currentTimeMillis() - TimeUnit.MILLISECONDS.convert(SystemClock.elapsedRealtimeNanos() - scanResult.getTimestampNanos(), TimeUnit.NANOSECONDS)```

answered Sep 18 '20 at 11:41

Dmytro Batyuk

957
8
15

How could I scan periodically with different timestamps for Wifi since I only receive only one RSSI at one time for each scan – Reyha Nov 02 '21 at 02:59

Android BLE: Convert ScanResult timestampNanos to System nanoTime

2 Answers2