Understanding Web SDR Symbols

[DRBComm]

I am new to HF and trying to understand some of the features before I invest in any equipment. I've been playing around with WebSDR, particularly listening to beacons at http://websdr2.sdrutah.org:8902/index1a.html?tune=14100cw. In particular, my first question is about the tuning markings as seen on the attached photo. Can someone please explain these? I would have assumed that the vertical yellow line would be the 'tune' but I only hear the beacons under the filter symbol. I am tuned to 14.100 MHz on the 20 meter CW band. I can hear the beacons in this configuration.

 

[rabbit108]

I am new to HF and trying to understand some of the features before I invest in any equipment. I've been playing around with WebSDR, particularly listening to beacons at http://websdr2.sdrutah.org:8902/index1a.html?tune=14100cw. In particular, my first question is about the tuning markings as seen on the attached photo. Can someone please explain these? I would have assumed that the vertical yellow line would be the 'tune' but I only hear the beacons under the filter symbol. I am tuned to 14.100 MHz on the 20 meter CW band. I can hear the beacons in this configuration.

View attachment 109193

That offset is normal. If the index line was in the center of the passband, that would be zerobeat with no audio tone.

Video
I use VLC Media Player
Download and play now:
https://www.dropbox.com/s/msxuoabay7pifjh/2021-09-08 12-33-16cwOffset.mp4?dl=0

Download now, play later:
https://www.dropbox.com/s/msxuoabay7pifjh/2021-09-08 12-33-16cwOffset.mp4?dl=1

73

 

[DRBComm]

That offset is normal. If the index line was in the center of the passband, that would be zerobeat with no audio tone.

Video
I use VLC Media Player
Download and play now:
https://www.dropbox.com/s/msxuoabay7pifjh/2021-09-08 12-33-16cwOffset.mp4?dl=0

Download now, play later:
https://www.dropbox.com/s/msxuoabay7pifjh/2021-09-08 12-33-16cwOffset.mp4?dl=1

73

OK, I read your response and watched the video (thanks for taking the time to do that). But now you've just opened Pandora's box of terms I've never heard: passband, zerobeat

I understand what you are saying about the offset, but I don't understand why, or how much offset is normal. If you are up to the challenge in explaining in layman's terms I would appreciate it.

 

[rabbit108]

OK, I read your response and watched the video (thanks for taking the time to do that). But now you've just opened Pandora's box of terms I've never heard: passband, zerobeat

I understand what you are saying about the offset, but I don't understand why, or how much offset is normal. If you are up to the challenge in explaining in layman's terms I would appreciate it.

I'll try.

Zerobeat is when your receiver is tuned exactly to the transmitted frequency. In that case, there will be no difference between the two and you will not hear any audio tones from the CW signal. If your receiver is tuned to a frequency that is 700 Hz higher than the transmitted signal, you will hear 700 Hz audio tones for the CW. This offset is already built into webstr which is why you see the indicator outside of the passband (bandwidth setting) that is centered on the transmitted frequency.





CW Zero-Beating - Ask Dave Episode 4

 

[rabbit108]

I got the bandwidth settings wrong. This is a redo:









I used the 20m beacon a lot when I worked DX at night with my mobile rig.

 

[rabbit108]

OK, I read your response and watched the video (thanks for taking the time to do that). But now you've just opened Pandora's box of terms I've never heard: passband, zerobeat

Ham Radio - What is Zero Beat and how do I use it?

 

[rabbit108]

But now you've just opened Pandora's box of terms I've never heard:

Older receivers had a BFO Beat Frequency Oscillator to receive CW signals. The BFO added a signal that was at a slightly different frequency than the tuned frequency. The difference between the two created the audio tone to copy CW signals.

 

[DRBComm]

I'll try.

Zerobeat is when your receiver is tuned exactly to the transmitted frequency. In that case, there will be no difference between the two and you will not hear any audio tones from the CW signal. If your receiver is tuned to a frequency that is 700 Hz higher than the transmitted signal, you will hear 700 Hz audio tones for the CW. This offset is already built into websdr which is why you see the indicator outside of the passband (bandwidth setting) that is centered on the transmitted frequency.

That is a great answer which I now understand. Thanks for that and all the additional info with visuals.