---
title: backgroundNoiseOffset
framework: sensorkit
role: symbol
role_heading: Instance Property
path: sensorkit/srphotoplethysmogramopticalsample/backgroundnoiseoffset
---

# backgroundNoiseOffset

The white noise variance estimate in the background noise signal.

## Declaration

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

## Discussion

Discussion This value represents the white noise variance estimate per Hz in the backgroundNoise signal (Normalized Units²/Hz). Apply the noise equivalent bandwidth factor to account for in-band noise for your setup.

## 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)
- [normalizedReflectance](sensorkit/srphotoplethysmogramopticalsample/normalizedreflectance-9aidm.md)