---
title: nanosecondsSinceStart
framework: sensorkit
role: symbol
role_heading: Instance Property
path: sensorkit/srphotoplethysmogramopticalsample/nanosecondssincestart
---

# nanosecondsSinceStart

The time in nanoseconds since the system turns on the sensor.

## Declaration

```swift
var nanosecondsSinceStart: Int64 { get }
```

## See Also

### Accessing optical data

- [emitter](sensorkit/srphotoplethysmogramopticalsample/emitter.md)
- [activePhotodiodeIndexes](sensorkit/srphotoplethysmogramopticalsample/activephotodiodeindexes.md)
- [signalIdentifier](sensorkit/srphotoplethysmogramopticalsample/signalidentifier.md)
- [nominalWavelength](sensorkit/srphotoplethysmogramopticalsample/nominalwavelength.md)
- [effectiveWavelength](sensorkit/srphotoplethysmogramopticalsample/effectivewavelength.md)
- [samplingFrequency](sensorkit/srphotoplethysmogramopticalsample/samplingfrequency.md)
- [conditions](sensorkit/srphotoplethysmogramopticalsample/conditions.md)
- [SRPhotoplethysmogramOpticalSample.Condition](sensorkit/srphotoplethysmogramopticalsample/condition.md)
- [noiseTerms](sensorkit/srphotoplethysmogramopticalsample/noiseterms-swift.property.md)
- [SRPhotoplethysmogramOpticalSample.NoiseTerms](sensorkit/srphotoplethysmogramopticalsample/noiseterms-swift.struct.md)
- [normalizedReflectance](sensorkit/srphotoplethysmogramopticalsample/normalizedreflectance-15f2k.md)