Extend unsigned to signed docs (#4448)

Author: alejoe91

doc/how_to/unsigned_to_signed.rst

@@ -53,7 +53,6 @@ For users that receive an error because their :code:`Recording` is unsigned, the
 
 Now with the signed dtype of the :code:`Recording` one can use a SpikeInterface pipeline as usual.
 
-
 If you are curious if your :code:`Recording` is unsigned you can simply check the repr or use :code:`get_dtype()`
 
 .. code:: python
@@ -89,6 +88,39 @@ while converting the data from unsigned to signed.
     recording_signed = spre.unsigned_to_signed(recording_unsigned, bit_depth=12)
 
 
+Reading an unsigned binary file
+-------------------------------
+
+If you have a binary file saved in unsigned integers, you can use the ``si.read_binary`` function to read it into
+SpikeInterface:
+
+.. code:: python
+
+    recording_unsigned = se.read_binary(
+        file_path,
+        sampling_frequency=30000.,
+        dtype=np.uint16,
+        num_channels=384,
+        gain_to_uV=3.05176,
+        offset_to_uV=0,
+    )
+
+Note that the ``offset_to_uV`` is not meant to be used to correct for the unsigned nature of the data,
+but rather to correct for any additional offset that may be present in the data (e.g., due to the recording equipment).
+
+The ``unsigned_to_signed`` function will take care of the conversion from unsigned to signed, so you can simply pass
+the ``recording_unsigned`` to it:
+
+.. code:: python
+
+    recording_signed = spre.unsigned_to_signed(recording_unsigned, bit_depth=12)
+
+
+When retrieving traces and scaling them to µV, first the data will be converted from unsigned to signed using the
+specified bit depth, and then the gain and offset (in this case 0) will be applied to convert the data to µV.
+This ensures that the data is correctly centered around 0 and scaled to the appropriate units for further analysis.
+
+
 Additional Notes
 ----------------