cal: Add switch documentation

Add chapter to explain usage of supported switch classes which
handle connection of DUT and measurement devices. Documentation
is done for ManualSwitch (default) and NI switch for devices that
can be used by the niswitch Python package.

Co-authored-by: Martin Braun <martin.braun@ettus.com>

1 files changed, 24 insertions, 2 deletions

diff --git a/host/docs/power.dox b/host/docs/power.dox
index 7ba93fb61..06deb9e75 100644
--- a/host/docs/power.dox
+++ b/host/docs/power.dox
@@ -187,7 +187,7 @@ generated calibration data.
 \section power_usercal Calibrating your own device
 
 If UHD does not ship its own calibration data for a device, or if the power
-calbration must be finely tuned, it is necessary to manually calbrate the device.
+calibration must be finely tuned, it is necessary to manually calibrate the device.
 
 In order to calibrate the transmit power, a calibrated power meter is required.
 To calibrate the receive power, a calibrated signal generator is required. Note
@@ -217,6 +217,28 @@ steps (for more coarse or fine calibration data).
 The tool has hard-coded some sensible defaults for most devices, such as frequency
 and gain steps.
 
+\subsection power_cal_switch Calibrating multiple paths at once
+
+`uhd_power_cal.py` is able to calibrate all RF paths in a single run. Depending
+on the measurement setup it might be necessary to change the cabling between
+the measurement runs for the different paths. For this purpose the script 
+supports a switch parameter.
+
+If no switch is selected the script chooses the "manual" switch as default which
+asks the user to upate the cabeling before a new RF path is measured. If you
+do not have the need to change cabling (e.g. calibrating a single path only)
+you can pass `--switch-option mode=auto` to prevent the script stopping before
+the real measurement.
+
+UHD facilitates devices that supports the niswitch API. These devices are
+enabled using `--switch niswitch`. In default setup the port `comA` is used
+to switch between the RF paths. To use port `X` pass `--switch-option port=comX`
+as parameter. The channels of the switch must be cabled in the order the script
+runs the calibration, so the first RF path goes to `chX1` the second to `chX2`
+and so on. If your setup does not follow this rule you have to pass the order
+of channels to the script using `--channels ch1,ch2` where the channels are
+given in the order they are connected to the switch.
+
 \subsection power_usercal_extend Extending the calibration utility for custom drivers
 
 \subsubsection power_usercal_extend_visa VISA/SCPI based devices
@@ -232,7 +254,7 @@ from PyVISA, exposing your VISA-based device is done by creating a Python
 module for your device. Assume the file is called `myvisa.py` and has the
 following content:
 
-~~~{.py~
+~~~{.py}
 from uhd.usrp.cal.visa import VISADevice
 
 class MyVISADevice(VISADevice):