Q-code · CW operating
QRM in Morse code
Specifically man-made interference: other stations, electrical noise from devices, switched-mode PSUs.
Morse rendering
--.- .-. --
QRM sent as a normal three-letter group (inter-letter gaps included).
As a question
QRM? — Is there man-made interference on my signal?
As an answer
QRM — There is man-made interference (QRM).
When this is used
Contrast with QRN (natural noise, static). The ITU scale is appended straight after the code, from QRM1 (nil) to QRM5 (extreme): QRM3 means moderate interference.
Examples
| On the air | Plain English |
|---|---|
| QRM? | Am I being interfered with? |
| QRM | Yes, there's man-made QRM. |
| QRM5 QSY | Severe interference; let's change frequency. |
Sending QRM
| Letter | Morse | Units |
|---|---|---|
| Q | --.- | 13 |
| R | .-. | 7 |
| M | -- | 7 |
With the normal three-unit gaps between letters, QRM is 33 units long. Adding a question mark to make it a question (QRM?) takes it to 51 units.
| Speed | 5 WPM | 13 WPM | 20 WPM | 25 WPM |
|---|---|---|---|---|
| Time to send | 7.92 s | 3.05 s | 1.98 s | 1.58 s |
What the references say
In ITU-R M.1172, the ITU list of abbreviations and signals for the maritime mobile service, QRM is a question asking whether your transmission is being interfered with, answered on a five-step scale.
| Reply | Meaning | Morse |
|---|---|---|
| QRM1 | nil | --.- .-. -- .---- |
| QRM2 | slightly | --.- .-. -- ..--- |
| QRM3 | moderately | --.- .-. -- ...-- |
| QRM4 | severely | --.- .-. -- ....- |
| QRM5 | extremely | --.- .-. -- ..... |
The standard does not say what kind of interference. Amateurs use QRM for man-made interference and QRN, the neighbouring code, for static.
How any Q-code is sent
- Followed by a question mark, a Q-code becomes a question; any extra details go before the question mark.
- Some Q-codes take C (yes) or NO straight after them to give an affirmative or negative sense.
- Where a Q-code has numbered meanings, the figure is sent immediately after it, with no space.
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