# Custom Noise Baseline File

If using somatic mode, you can generate a custom noise baseline file. The noise baseline file is built using normal samples that do not match to the subject the samples are from. The recommended number of normal samples is 50.

To generate a custom noise baseline file, use one of the following methods:

* Use the DRAGEN Bio-IT Platform server. See the *DRAGEN Bio-IT Platform Online Help* for instructions.
* Use DRAGEN Baseline Builder App on BaseSpace Sequence Hub. Use the BCL Convert pipeline in BaseSpace Sequence Hub Run Planning to generate FASTQ files. After the sequencing run is complete and 50 samples are available, input the FASTQ files into the DRAGEN Baseline Builder App.

{% hint style="info" %}
For instructions to import noise baseline files to your instrument, refer to the system guide for your instrument `NextSeq 2000 System Guide (document # 1000000109376)`
{% endhint %}


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