---
title: normalizedReflectance
framework: sensorkit
role: symbol
role_heading: Instance Property
path: sensorkit/srphotoplethysmogramopticalsample/normalizedreflectance-9aidm
---

# normalizedReflectance

The photoplethysmogram waveform in normalized units.

## Declaration

```occ
@property (nonatomic, strong, readonly, nullable) NSNumber * normalizedReflectance;
```

## Discussion

Discussion The scale of the normalized signal may vary. For more information on how Apple Watch uses photoplethysmography, see the “How Apple Watch measures your heart rate” section in Monitor your heart rate with Apple Watch.

## 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)
- [nanosecondsSinceStart](sensorkit/srphotoplethysmogramopticalsample/nanosecondssincestart.md)
- [conditions](sensorkit/srphotoplethysmogramopticalsample/conditions.md)
- [SRPhotoplethysmogramOpticalSample.Condition](sensorkit/srphotoplethysmogramopticalsample/condition.md)
- [whiteNoise](sensorkit/srphotoplethysmogramopticalsample/whitenoise.md)
- [pinkNoise](sensorkit/srphotoplethysmogramopticalsample/pinknoise.md)
- [backgroundNoise](sensorkit/srphotoplethysmogramopticalsample/backgroundnoise.md)
- [backgroundNoiseOffset](sensorkit/srphotoplethysmogramopticalsample/backgroundnoiseoffset.md)