- April 26, 2016 at 11:27 am #2354
DOES CW GET THROUGH WHEN NOTHING ELSE CAN?
So you’ve gotten on the air and now you want to know why you might learn Morse code and get on CW mode! I listened to the ARRL “The Doctor is In” April 21th, 2016 Podcast. Here is the ideal ‘Elmering” primer on “Does CW Get through When Nothing Else Can.”
Here are my notes from the Podcast:
1 Signal-to-Noise Ratio: Receiver noise is proportional to the bandwidth. On CW you can cut bandwidth to 250 Hz but on SSB you need about 2500 Hz. That means there is 10 times the noise power on SSB. This means 10 watts CW is about equal to 100 watts on SSB.
- SSB required more power for intelligibility, whereas CW is only a carrier switched on and off. CW has a 3 dB to 6 dB to advantage over SSB.
- 100 watts on SSB has an average power output of ~25 watts. But 100 watts CW has 100 watts average power.
- Adding the factors 1, 2, and 3 above means CW has about a 20 dB gain over SSB. This is a power factor of 100 times!
- Digital Modes such as JT-9 and JT-65 are even more effective for weak signals or QRP because of the repetition, encoding, and error detection. The signals can have a 25 dB further advantage over CW!
You must be logged in to access attached files.April 26, 2016 at 3:37 pm #2367
Thanks for the great summary!
- Aron, W1AKIApril 26, 2016 at 4:44 pm #2376
Thanks for the link Layne. I hadn’t listened to the podcast before. I knew that CW got through when phone couldn’t but I didn’t know exactly why. I’ve got a better understanding now.
I also listened to the first podcast about antennas and learned a lot there too.
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