Checking if Frequency is in Use: How to Do it Right?

As part of our advanced practices for Quality True Telegraphists, we will take a look at the traditional and current practices of checking a frequency is free before using it, and how we might improve upon these practices.

So, you are now ready to make a CQ call.

How do we check if the frequency is in use before making our call?

The traditional way is to send “QRL?” but there’s something important we should do before that, and let’s see how to also improve upon the technique.

The very first thing we must do, having found the frequency we wish to use, is to listen intently for a least ten seconds and ideally much longer, to see if we hear any signals on the frequency. If we do, that means it is occupied.

If we don’t hear anything, it still is not yet time to send “QRL?”, first, we must open up the wide filter again, switch off that narrow filter for a moment. Otherwise, if we are interfering with someone on a nearby frequency outside of our narrow filter, how will we hear them respond with “YES”, “QSY” or “QRL”.

So now, we are ready to actually ask if the frequency is in use: first, we listened and heard nothing with the PRE AMP ON, the RF GAIN UP FULL, and then we also switched OFF any narrow filters so we can hear up and down in the wide filter. So, how do we now ask, do we send QRL?

Most operators do, but this is not necessarily the BEST practice. Let us look at better ways and techniques, to minimize QRM if there is indeed someone there, and using best CW etiquette.

If we send QRL? this is quite a long transmission, and if anyone is on frequency hearing a weak station and in QSO with them, maybe even they are S9 and near by to you but you did not hear them yet as they’re listening to a long over from the weak station, your “QRL?” may cause annoyance. So, let’s first do something shorter and more tentative, a simple, short: “?”

Yes, the very first thing we send after having listened as above described, is send only a “?” as it is short, and if there is another station they may respond with <AS>. If you hear nothing after sending “?” you can now send “QRL?” (Are you busy?) or an even shorter “QRT?” (Shall I stop sending?) or an also correct but much longer “QSY?” meaning (Shall I change frequency?).

And if you still hear nothing, you should again repeat the “QRL?” or QSY? or QRT?

Why, you may ask, all this fuss. If you have any idea about HF radio propagation you would know that what YOU cannot hear, someone else on frequency most likely CAN hear. So, at this point a few reminders:

1. You not hearing anything doesn’t mean the frequency is clear
2. Due to QSB, your first “?” and first “QRL?” may not be heard

And, if we are keen to improve our operating even further, we can use something better than “QRL?” After all, although traditional among radio amateurs, the professional would take issue with this abuse of the Q code.  “QRL?” means “Are you busy?” Which is actually appropriate among radio amateurs, because someone IS busy if they are in a QSO. It does not however exactly mean “Is the frequency in use?” it means “Are you busy?” although this amounts to the same thing.

The issue we may have with “QRL?” however, from a practical point of wanting to minimize QRM while checking, is it is still quite a long Q code. We mitigate this by first using “?” alone. But we could also substitute “QRL?” with “QRT?” which is a shorter code, and also very accurate: “Should I stop sending?”

QRT is one of the essential Q Codes that every QTT should master. It is essential as being asked to stop transmitting by another primary user, for example on 30m, the military or government user, must be followed. If you hear QRT you MUST stop sending. So, we can use “QRT?” instead of “QRL?”!

Some operators, instead, send “QSY?” which means “Shall I change my frequency?” – This of course is also an option, but, it is even longer than “QRL?” in CW, and thus even more annoying if another station is on frequency listening to his QSO partner. “QRT?” would be the best option, but it is optional!

No matter which method you use, in summary, you must at very least do ALL of these:

1. Listen. Wide filter, not narrow filter. RF Gain full. PRE AMP ON.
2. After at least 10 seconds to a minute or more, if nothing heard, send “?”
3. If still nothing heard, send “QRL?” or “QRT?” once only and wait.
4. If still nothing heard, send “QRL?” or “QRT?” again and wait.

All of this again with NO narrow filter, RF gain full, and PRE AMP on.

Only then, if you still hear nothing, should you call CQ.

And, no need to bother with any of this if you call on one of the designated QSX (Listening) / Calling Frequencies.