The Q Code was born in international telegraphy, in the early 20th century, to replace entire phrases with three letters, always starting with Q. It is still used in aviation, amateur radio, and other radio communications because it solves the same problem today: saying more in less transmission time, with a meaning that anyone trained recognizes, in any language.
Each code can be used as a question or as a statement, depending on context. “QRM?” asks whether there is interference; “QRM” (without a question mark) reports that there is interference.
Most useful codes for field operations
| Code | Question | Answer / meaning |
|---|---|---|
| QRM | Is my transmission suffering interference? | There is interference from another station or device. |
| QRN | Is there atmospheric interference? | There is interference of natural origin (static, electrical discharge). |
| QRO | Should I increase power? | Increase transmission power. |
| QRP | Should I decrease power? | Decrease transmission power. |
| QRT | Should I stop transmitting? | Stop transmitting. |
| QRV | Are you ready to receive? | I am ready to receive. |
| QRX | When will you call me again? | Stand by; I will call you again at [time]. |
| QRZ | Who is calling me? | You are being called by [station]. |
| QSB | Is my signal fading? | Your signal is fading (varying in strength). |
| QSL | Do you confirm receipt? | I confirm receipt. |
| QSO | Can you communicate with…? | Communication/contact established between stations. |
| QSY | Should I change channel/frequency? | Change to channel/frequency [X]. |
| QTH | What is your location? | My location is [X]. |
Example
“Base, this is Field Post 1, QRV. QTH Palm Street, near the school. QSB on your signal, over.”
Translation: “Base, this is Field Post 1, ready to receive. My location is on Palm Street, near the school. Your signal is fading. Over.”
When to use Q Code, and when to speak plainly
In an operation with people at different levels of radio experience, such as community leaders and newly trained volunteers, prefer the plain language described in How to operate the radio in an emergency. Reserve the Q Code for teams that already master its use, such as amateur radio operators communicating among themselves.