CW Mode Explanation Request

Asher - K0AU

On CW what's the relationship between: Receive zero beat? Yellow cursor line? Displayed frequency? Pitch control? Receiver passband? Transmit carrier frequency? It all seems to work, but I'm not quite sure what it's all doing.

Tim - W4TME

On CW, the actual received and transmitted frequency, which is the frequency shown in the frequency readout in the Slice control panel is on the slice carrier line (red or yellow if the slice is "active"). Pitch control is the frequency of the CW tone at that frequency. It is no longer offset from actual demodulator (slice) frequency. You can set the CW pitch to what ever pitch frequency is your preference. The RX passband is the filter width centered on the carrier line, so a 50 Hz filter will have 25 Hz above and below the slice carrier line. You zero beat in the signal of interest by tuning it on the signal in the spectrum display (panadapter)

Asher - K0AU

Tim: thanks. Sorry for being a bit slow, but can you just walk me through an example. XYZ is calling cq on a carrier frequency of 14.010.000. Pitch control is set to 600 Hz and filters are set to 400 Hz. When the carrier line is centered on the panadapter carrier display: Frequency reads: Transmit Carrier: Audio tone for received signal: ? Filter lower edge: ? Filter upper edge: ? If I change the Pitch control what changes? If I change the filter what changes?

Tim - W4TME

No problem, Asher. If XYZ is calling on 14.010.000, you will see a signal peak @ 14.010.000. You tune the slice to 14.010.000. When you do this, the yellow carrier line will be directly on top of the signal peak. Now you are zero beated in on their frequency. The filter in your example is 400 Hz wide, centered on 14.010.000 (200 Hz on either side of the slice frequency readout.). What you are hearing in the speaker/headphones is a all of the demodulated RF signals in that bandwidth; from 14.009.800 to 14.010.200. If you change the filter to a 200 Hz filter, the center frequency of the slice receiver does not change (unless you change the slice frequency buy click tuning, using your mouse or a FlexControl). What does change is the bandwidth of the demodulator. With a 200 Hz filter (+/- 100 Hz) you are hearing all signals from 14.090.900 to 14.010.100 MHz. Narrowing the filter allows you to remove QRM for a near by signal by filtering it out (removing) it from the demodulator's passband. Now, you do not like the sound of the CW "note" at a 600 Hz pitch, you like a 1000 Hz "note", so change the pitch to 1000 Hz. The audio frequency (AF) signal you hear in the speakers is now "playing" at 1000 Hz, but the RF frequency (14.010.000) of where you are actually receiving/transmitting has not changed. Did this explanation help?

Andrew VK5CV

Tim, I assume that higher frequencies in the passband have a higher pitch. Like with CWU or USB. So 14.010.050 with be heard at tone plus 50Hz. Have I got it right? Andrew

Eric-KE5DTO

This is correct.