There are a many free (and paid for) CAT control applications available for PC's running Windows, Linux and MacOS. CAT control has been included as an added feature into most modern Digital Mode applications such as WSJT-X, FlDigi etc.

As time has gone by, the CAT control feature set of transceivers have become more sophisticated allowing functions such as Tx/Rx switching, filter selection, memory management and much more.

As modern transceivers have bi-directional CAT data, any change to the transceiver settings from the front panel are also picked up by the software keeping the PC software and transceiver in sync. Great for the automatic logging features which are often built into the CAT control and Digimode applications

So where does the phrase CAT Control come from?

Yaesu introduced the (C)omputer (A)ided (T)ransceiver protocol in the early 1980's. The generic name seems to have stuck despite the protocols and interfaces being very different between manufacturers and transceivers.
 

Yaesu transceivers have a mix of physical CAT ports. Some are TTL level, some RS232 and more modern Yaesu radios have a USB port and the radio presents as an external USB Comm port.  Ultimately, an interface (or cable) is required between the radio and the USB port on your PC.  

Icom followed suit with the CI-V interface for their products. CI-V I hear you ask? Well this actually stands for (C)ommunications (I)nterface version 5. Icom took a different route where the Tx/Rx data is on a common wire and up to 4 transceivers can exist on the same CI-V bus. Icom radios and software use a CSMA/CD (Carrier Sense Multiple Access with Collision Detection) and will resend the data if they detect collisions. Again, the levels are nominally TTL and an interface is required to connect between the radio and your PCs USB port. To allow multiple transceivers to exist on the CI-V bus, Icom transceivers are allocated a CI-V address and software generally expects the transceiver to be set to its default address for communications to work.

Kenwood transceivers also have a CAT system. Some early transceivers required an additional PCB or chips to be installed to enable the function.  The Kenwood CAT interface was broadly the same as Yaesu with separate Tx and Rx data lines. However, the TTL levels are inverted with respect to Yeasu. Later Kenwood transceivers have an RS232 CAT port.
 

Xiegu transceivers such as the X5105 and G90 have a 3.5mm jack socket for CAT control. On both the X5105 and G90 it is on the side of the radio. Don't try to plug it into the COMM port on the rear of the G90. This is only for firmware updates. Again, these are TTL levels with separate lines for TxD and RxD on the tip and ring of the connector. It is important to note the Xiegu radio use 3.3v Logic and so DO NOT connect to one of these radios with a 5V TTL interface. You may damage the radio.

The original Xiegu X108G also has CAT control. This is a USB Micro connector on the rear of the radio and all you need is a USB A to micro USB cable similar to an Android type phone charger lead to utilise it. You need to install the X108G drivers (off the web) to utilise this but it is really easy.

All Xiegu transceivers actually emulate the Icom IC-7000 CAT protocol so when using a Xiegu, set the CAT control options to be an Icom. That said, later Digimode application versions may list the Xiegu Radio in the settings menus but ultimately they do emulate the Icom CI-V system.

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If you have made it this far and need a CAT cable, just visit our Icom, Yaesu, Kenwood and Xiegu shops