This topic may have been disgussed before, but I am still not sure that I understand it.
I use a Yaesu FT-818 for SOTA work. It has two CW settings; CW and CWR.
As I understand it, using CW means that an USB signal is modulated with a LF tone at a specific offset from the carrier, e.g. 800 Hz. Using CWR, the tone is modulated on the LSB signal.
Obviously (?) these two signals will be sendt (when transmitting) at two different HF frquencies.
I have noted that regardless of what setting I use (CW or CWR), the dial frequency is the same, probably indicating the imaginary signal carrier frequency. Which seems reasonable - and understandable.
Now to my question: When a CW frequency is given in a SotaWatch Spot, shall I used the CW setting on my radio - or the CWR setting? Because they receive signals at slightly different frequencies.
It has been discussed before. There is no transmitted tone with normal CW signals (A1A mode). The transmitter produces a double sideband signal which should be spread symmetrically about your radio’s dial frequency. As I understand it the CW / CWR setting on your radio affects only what the receiver does [and is equivalent to LSB / USB].
The LSB/USB setting on your radio is important when receiving a SSB signal because one of the sidebands is suppressed and you need to select LSB or USB to match the unsuppressed sideband of the sender’s transmission. It makes no difference with A1A CW because it is sent with both sidebands.
Thank you, G8CPZ! You are right as to “normal” CW signals (A1A) mode. However, some radios have not implemented/designed CW in the “old fashioned” way. The FT-817/818 being one. Consequently - as far as I understand - it is important to understand - that to be able to properly receive a CW signal - one needs to know whether the CW signal transmitted is a proper A1A (double carrier) signal, or an USB or LSB modulated signal (e.g. from a Yaesu FT-817/818). If a CW signal is transmitted by such a radio, it may be missed completely, if not received on the proper sideband.
Thanks, Andy. So - in order to get Chasers to read CW signals from Activators more reliably; May be there should be some SOTA Watch standard as to how to give/specify CW frequencies? E.g. to only use A1A mode - or USB CW (for those radios that have implemented this in that way - such as the FT-817/818?).
I’ve been using CW for over 25 years and I hear only A1A mode CW signals.
The tone you hear is inserted by your receiver (on CW or CWR) and its pitch depends on the frequency you select for the sidetone. Were someone to transmit DSB with a tone [as is done for some Morse practise transmissions which mix speech and Morse] you would probably hear two tones listening to such a transmission on CW or CWR [the transmitted one and your sidetone].
So, the dial frequency used by the A1A CW sender should be the same [more or less given tolerances of both radios] as the A1A CW receiver.
No, they are not at different frequencies, because the firmware of the radio compensates for the discrepancy you cite. The display shows the frequency at which the actual signal is transmitted. It does not show the value of the notional carrier which is never transmitted.
CW vs CWR makes no difference whatsoever to what is transmitted.
On receive, if the signal you are receiving is exactly on the dial frequency, it also makes no difference to what you hear. You will hear the tone at exactly your chosen CW audio frequency.
The difference comes if the received signal is a bit off frequency, either because it is not properly netted or because it is QRM. In one mode the tone will be higher than nominal, in the other mode it will be lower. CWR mode in effect “mirrors” the audio spectrum.
I believe this question does not arise - in both modes the signal is transmitted at the dial frequency and any replies on the same frequency will be heard. You can flip back and forth between CW and CWR and choose whichever is easier for you to understand.
The “CW” or “CWR” is a function of the receiver. Sometimes it’s to your advantage to use one or the other to help eliminate QRM above
or below the station you’re receiving. I prefer to use “CW”, which on my IC-7600 is the “LSB” side. I like to start up the band and tune downward. On my Yaesu FT-100D, the “CWR” is the “LSB” side.
The transmitted signal is on the same frequency no matter which side you prefer to listen to.
73
John, K6YK
This article seems to give a clear answer, which is that the only difference between CW and CWR is whether the BFO/LO frequency is above or below the received signal. My understanding is that choosing one or the other can be a technique to exclude another very close signal.
Thanks, M0WIV! Great article. “Issue” solved! Case closed. Now I do understand. The CW frequency will be the same, regardless of whether one selects CW or CWR. And the receiver must be in CW or CWR mode before a Chaser sets the required CW frequency given by SotaWatch (and not in USB or LSB as some seem to think.)
