// Status=review

_WSJT-X_ offers CAT (Computer Aided Transceiver) control of the
relevant features of most modern transceivers.  To configure the
program for your radio, select the *Radio* tab.

//image::images/RadioTab.png[align="center",alt="Radio Tab"]
image::images/r4148-cat-ui.png[align="center",alt="Radio Tab"]

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IMPORTANT: Unless you have selected *Monitor off at startup* under the
above tab, _WSJT-X_ expects to seize exclusive rig control upon
startup. You can prevent this by either selecting that option or by
selecting the *Monitor* button on the main window and toggle it. Once
done, _WSJT-X_ relinquishes exclusive rig control (but not the control
port or client connection itself). Since it is extremely convenient to
have all your required station programs running, which can include
radio control software, it is imperative that the operator understand
that any change in a separate radio control program can induce
unwanted effects in _WSJT-X_. If you would like to switch to another
operating mode while leaving _WSJT-X_ on in the background, simply
toggle the *Monitor* button so that _WSJT-X_ is no longer active.
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- Select your radio type from the drop-down list labeled *Rig*, or
*None* if you do not wish to use CAT control.

- Alternatively, if you have configured your station for control by
*DX Lab Suite Commander*, *Ham Radio Deluxe*, *Hamlib NET rigctl*, or
*OmniRig*, you may select one of those program names.  In those cases
the entry field immediately under _CAT Control_ will be relabeled as
*Network Server*.  Leave this field blank to access the default
instance of your control program, running on the same computer. If the
control program runs on a different machine and/or port, specify it
here.  Hover the mouse pointer over the entry field to see the
required formatting details.

- Select *OmniRig Rig 1* or *OmniRig Rig 2* to connect to an _OmniRig_
server running on the same computer.  Note that _OmniRig_ is available
only under Windows.

- Set *Poll Interval* to the desired interval for _WSJT-X_ to query
your radio.  For most radios a small number (say, 1 – 3 s) is
suitable.

- _CAT Control_: To have _WSJT-X_ control the radio directly rather
than though another program, make the following settings:

* Select the *Serial Port* used to communicate with your radio. 

* _Serial Port Parameters_: Set values for *Baud Rate*, *Data Bits*,
*Stop Bits*, and *Handshake* method.  Consult your radio's user guide
for the proper parameter values.

* _Force Control Lines_: A few station setups require the serial
port's *RTS* and/or *DTR* control lines to be forced high.  Check
these boxes only if you are sure they are needed.

- _PTT Method_: select *VOX*, *CAT*, *DTR*, or *RTS* as the desired
method for T/R switching.  If your choice is *DTR* or *RTS*, select
the desired serial port.

- _Transmit Audio Source_: some radios permit you to choose the
connector that will accept Tx audio.  If this choice is enabled,
select *Rear/Data* or *Front/Mic*.

- _Mode_: _WSJT-X_ uses upper sideband mode for both transmitting and
receiving.  Select *USB*, or choose *Data/Pkt* if your radio offers
such an option and uses it to enable the rear-panel audio line input.
Some radios also offer wider and/or flatter passbands when set to
*Data/Pkt* mode.  Select *None* if you do not want _WSJT-X_ to change
the radio's Mode setting.

- _Split Operation_: Significant advantages result from using *Split*
mode (separate VFOs for Rx and Tx) if your radio supports it.  If it
does not, _WSJT-X_ can simulate such behavior.  Either method will
result in a cleaner transmitted signal, by keeping the Tx audio always
in the range 1500 to 2000 Hz so that audio harmonics cannot pass
through the Tx sideband filter.  Select *Rig* to use the radio's Split
mode, or *Fake It* to have _WSJT-X_ adjust the VFO frequency as
needed, just before T/R switching occurs.  Choose *None* if you do not
wish to use split operation.

When all required settings have been made, click *Test CAT* to test
communication between _WSJT-X_ and your radio.  The button should turn
green to indicate that proper communication has been established.
Failure of the CAT-control test turns the button red and displays an
error message.  After a succesful CAT test, toggle the *Test PTT*
button to confirm that your selected method of T/R control is working
properly.