CAT control — Computer Aided Transceiver control — is what lets a program on your computer read and change your radio's frequency, mode, and sometimes power level, over a cable instead of your hands on the dial. It's the backbone of digital modes, logging software that auto-fills frequency, and remote operating. The good news is that setting it up is mostly mechanical: connect a cable, pick the right settings, and confirm the two devices are actually talking. Here's how to do it without guesswork.
What CAT Control Actually Does
When your computer and radio are linked by CAT, software can ask the radio "what frequency are you on" and get an answer, or tell the radio "switch to this frequency and this mode" and have it happen. This is separate from audio — CAT carries commands and status, not sound. You'll usually still need a separate audio connection for digital modes, and a separate push-to-talk (PTT) method, which may or may not ride along the same CAT link depending on your rig and software.
What You'll Need
- A transceiver with a CAT or "remote control" port, or a built-in USB port that carries CAT data
- A USB cable, or a USB-to-serial adapter plus a CAT cable, depending on your rig's design
- A computer with the manufacturer's USB driver installed
- Software that speaks your rig's CAT protocol — this might be a standalone rig control program, or a setting built into logging or digital mode software
- Your rig's manual, specifically the section on CAT or PC connection settings
Step 1: Connect the Cable
Most modern rigs use a single USB cable for CAT, and sometimes audio too. Older or simpler radios may need a separate CAT cable running to a USB-to-serial adapter. Either way, plug it in before you start chasing software settings — a good number of "nothing works" cases turn out to be a cable that was never fully seated, or a USB cable that only carries power and not data. If you have a spare data-rated USB cable on hand, it's worth trying that first if anything seems off.
Step 2: Install the Right USB Driver
Your rig's USB port almost certainly appears to your computer as a virtual serial port, and that requires a driver from the manufacturer — not a generic USB driver. Download the correct one for your exact rig model and your operating system, install it, then reboot. Skipping this step is one of the most common reasons a radio never shows up as a usable port at all.
Step 3: Find Your COM Port
On Windows, open Device Manager and look under "Ports (COM & LPT)" — your rig should appear with a COM number after it. On Mac or Linux, the device typically shows up in the list of serial devices with a name tied to the USB-to-serial chip. If you're not sure which one is yours, unplug the radio, check the list, plug it back in, and see which entry appears. Write the port down; you'll need to enter it in your software exactly as shown.
Step 4: Match the Baud Rate and Rig Settings
Baud rate is the speed the two devices use to talk, and it has to match on both ends — rig menu and software — or you'll get silence or garbled responses. Check your rig's menu for a CAT rate or "PC" baud rate setting, and set the same number in your software. Many rigs also have a separate setting that must be turned on to enable CAT or remote control over that port in the first place; it's easy to miss because it's often buried in a menu unrelated to USB settings. Note the rig's specific CAT protocol as well, since some manufacturers use more than one addressing scheme across their model lineup.
Step 5: Configure Your Software
In your rig control or logging program, select your exact radio model from its list rather than a generic or similar-sounding one — commands differ between models even from the same manufacturer, and picking the wrong one can send instructions your rig doesn't understand. Enter the COM port and baud rate you noted earlier, then apply the settings. If the software offers a "test connection" or similar button, use it before moving on.
Step 6: Test Frequency and Mode Control
This is the moment of truth. Change the frequency on the radio's own dial and see if the software's display updates to match. Then do the reverse: change frequency or mode in the software and watch the radio respond. If both directions work, CAT control is functioning correctly. If only one direction works, or nothing happens, work through the troubleshooting checklist below before changing more settings — changing several things at once makes it hard to know what actually fixed it.
Common Mistakes to Avoid
- Two programs fighting over one port — a serial port can generally only be opened by one application at a time; close others before testing a new one
- Wrong or mismatched baud rate — the single most common cause of a connection that "almost" works
- Charge-only USB cables — they power the radio's USB circuitry but carry no data
- Forgetting to enable CAT in the rig's own menu — the software side can be perfect and still get nothing back
- Selecting the wrong rig model in software — sends commands the radio silently ignores or misreads
CAT Control and Remote Operating
Once CAT control is reliable on the bench, you've already done the hardest part of setting up remote operation. Systems like Remote Rig depend on that same frequency and mode data being passed accurately, just carried over the internet instead of a short USB cable, alongside live audio and PTT. The Station Bridge software exists specifically to tie your radio, your audio interface, and that CAT link together into one coherent remote setup. If you're planning to operate your own station from another room or another city, get CAT working locally first — it's much easier to debug a serial port problem sitting in front of the radio than after you've added a network connection into the mix. For more on what a remote setup actually requires, see Remote Ham Station Basics.
A Note on PTT
Some software uses the CAT connection itself to key the radio, while others use a separate VOX or RTS/DTR signal. Which one is right depends on your rig and your digital mode software, and mixing them up is a common source of a radio that either never transmits or gets stuck keyed. If you want a clear breakdown of the options, CAT vs VOX vs RTS/DTR covers the tradeoffs.
Wrap-Up
CAT control isn't complicated once you see it as a short chain: a cable, a driver, a port, a matching baud rate, and software configured for your exact model. Work through each link in order, test frequency and mode control explicitly rather than assuming it works, and keep a note of your working COM port and baud rate settings for next time. Once it's solid, you've unlocked smoother digital mode operation, automatic logging, and the groundwork for operating your station remotely whenever you're away from the desk. If you hit a setting you don't recognize along the way, the ham radio FAQ is a quick place to check plain-language answers before digging through a full manual.
How HamRadioList can help
Once CAT control is working, check {{svc:propagation|live HF propagation}} before you call CQ, and if you want to operate that same radio from another room or another city, look at {{svc:remote_rig|Remote Rig}} and the {{svc:station_bridge|Station Bridge}} software that ties your radio, audio, and CAT link together. Keep the {{svc:quickref|quick reference page}} handy while you sort out settings.
- Remote Rig - operate your own radio from anywhere on Android, iPhone, Windows or Linux, with live push-to-talk audio and CAT control.
- Station Bridge - the software that connects your radio, audio interface and computer to Remote Rig.
- Ham radio quick reference - bands, modes, phonetics and Q-codes on one page.
- Live HF propagation - see current band conditions before you call CQ.
- Ham radio FAQ - plain answers to the questions new operators ask most.
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