RADIO NERD AND CW - OTHER MODES COMPARISON!
(2024)

The Radio Nerd!
The Radio Nerd is a special person. He does not have any social skills and is only interested in simple "Barefoot" Radio projects! The Nerd is not interested in luxe and comfort, he wants a sober, minimalist life. He goes barefoot on the ice cold tiled floor of his lab. Barefoot is simple and efficient! No static electricity and no unecessary shoes and socks. He even has a Portable QRP station on bare feet in the snow! The Nerd has way too cold bare feet and horribly cold toes. But that is not a problem for the Nerd, but a challenge, an exciting way of life!
He loves CW of course! Morsecode is extremely simple and flexible and efficient! Simple equipment, no computer, the decoder is in his head! Morsecode is simple and the Nerd wants to know how good that Morsecode is compared to other modes!


The Radio Nerd is only interested in simple "Barefoot" Radio projects!
He even has a simple Portable QRP station on bare feet in the snow! But...
Never go barefoot in the snow when it is colder than -3C to -4C (26F)!

WHY SHOULD WE TEST IT, WE CAN ALSO DO A SIMPLE CALCULATION!

How good is Morse code compared to other modes? No test yet but first our own calculations to get an estimate. We know that we need 9 dB to 10 dB above the noise level in the SIGNAL bandwidth, not in the 2500 Hz standard bandwidth that is used. Why? That 9 to 10 dB Signal to Noise Ratio (SNR) is the threshold for Frequency Modulated signals. Below the threshold of 9 to 10 dB the decoded signal suddenly disappears in the noise. Also digital modes have such a threshold of approximately 9 to 10 dB. It can be extended sometimes to 7 dB in special cases and when special decoding methods are used.
So when we know the SIGNAL bandwidth, we only have to make a correction between the SIGNAL bandwidth and the 2500 Hz standard bandwidth and add 9 to 10 dB to calculate the sensitivity! And the SIGNAL bandwidth is the baud rate or symbol rate.

WSPR:
50 EFFECTIVE bits in 120 sec. that is 0.4166 baud. There are 162 bits, but 112 are used for error corrections.
0.4166 baud; 10 x log(0.4166 / 2500) = -37.8 dB plus 9 dB to 10 dB = -28.8 dB to -27.8 dB so very close to the -29 dB SNR given by PA3FWM found on the internet! On the WSJT Home Page -31 dB SNR is mentioned, not really a huge difference.
QRSS 6 seconds dot time, that would be 0.17 baud. But with such a narrow bandwidth, the shift transitions are blurred too much. So we take 2 to 3 seconds effective, take 2.5 seconds that is 0.4 baud:
0.4 baud; 10 x log(0.4 / 2500) = -38 dB plus 9 dB to 10 dB = -29 dB to -28 dB, very close to the already found value of -27.5 dB SNR during a previous NERD test!
NAVTEX (Navtex is a kind of 100 baud Telex):
100 baud; 10 x log(100 / 2500) = -14 dB plus 9 dB to 10 dB = -5 dB to -4 dB, very close to the already found value of -5 dB during a previous NERD test!
FELD-HELL:
122.5 baud; 10 x log(122.5 / 2500) = -13.1 dB plus 9 dB to 10 dB = -4.1 dB to -3.1 dB, quite far from the -7 dB peak power given by KB9II found on the internet. This value is also the peak power during a pixel just as I use in my calculation.
SLOW-HELL:
14 baud; 10 x log(14 / 2500) = -22.5 dB plus 9 dB to 10 dB = -13.5 dB to -12.5 dB. No data available...
PSK31:
31.25 baud; 10 x log(31.25 / 2500) = -19.0 dB plus 9 dB to 10 dB = -10.0 dB to -9.0 dB, very close to the value of -9 dB peak power given by KB9II found on the internet.
MORSE CODE:
This is more difficult, we have to make an estimation of the bandwidth of the human hearing. How? We can use the following program, a HTML script. The dash is replaced by a dot with a little higher pitch.

DFCW TRANSMISSION WITH YOUR WEBBROWSER

We can clearly distinguish two tones with a difference of 25 Hz. But 10 Hz is difficult, however, it is the bandwidth for a 12 wpm Morse signal (100 ms dot time). So let's assume that the bandwidth is 10 to 25 Hz.
10 x log(10 / 2500) = -24 dB and 10 x log(25 / 2500) = -20 dB. Plus the 9 dB to 10 dB that means somewhere between -15 dB and -10 dB. KB9II gives -12 dB. KF6HI gives -15 dB for CW(DX).

Link to the site of Pieter-Tjerk PA3FWM

Link to the site of John Matz KB9II

Link to the site of KF6HI

WE ALSO WANT TO DO A TEST OF COURSE!

A simple test combined with available data
The comparison test has to be very simple and efficient! Not an expensive test by a certified lab, but a simple cheap test by a Radio Nerd! The Nerd has an idea! He made already a program in Python that does create a WAV file of a Morsecode signal and adds noise. The Nerd can precisely calculate the noise level in the standard 2500 Hz bandwidth and the level of the Morse signal can also be precisely adjusted. And so we know exactly the Signal to Noise Level (SNR) of the test signal in a 2500 Hz bandwidth!
The Nerd now only has to use his ears to determine whether the Morse signal is still audible and decodable. Indeed not completely objective, because the Nerd loves Morsecode!

Available data
The Nerd has already some data of other communication modes, found on the website of KI4SGU:

SSB: +6 dB SNR average power and +10 dB peak power for Casual SSB, 6dB lower for DX SSB found on the websites of KB9II and KF6HI
RTTY45: -5db SNR found on the website of KI4SGU
FeldHell -7db SNR found on the website of KI4SGU
PSK31 -10db SNR found on the website of KI4SGU

Link to the site of KI4SGU

The Nerd has calculated that the SNR in a 2500 Hz bandwidth should be in the range between -10 dB and -15 dB. So that is a nice estimation about the test signals that have to be made!

Morsecode test signals!
The Nerd decides to make test signals for -10 dB SNR, -12 dB SNR and -14 dB SNR. And also -5 dB SNR for the CW(CASUAL) value given by KF6HI. The speed is 6 words per minute (dot time 0.2 sec.). Here below you can listen to these test signals.

Audio file -10 dB SNR, 6 words per minute

Audio file -12 dB SNR, 6 words per minute

Audio file -14 dB SNR, 6 words per minute

Audio file -5 dB SNR CASUAL CW, 6 words per minute

Conclusion!
CW: -10dB to -12 dB SNR as -10 dB SNR is just decodable and perhaps also the -12 dB SNR. And the -14 dB SNR? I cannot decode it but a more experienced ham could!
PSK31 is similar but not so simple! Morse Code is clearly an extremely simple and flexible and efficient mode!
For SSB you need something like 10x to 20x more peak power...
However... it's just a simple experiment performed by a Radio Nerd in his simple lab!

How to make QRSS test signals with noise!

We can do that with a Python test software program QRSSsimwav-v02b.py!
The QRSS signal is set to 1%. How much percentage noise do I need?

First we have to make a correction for the bandwidth of the WAV signal with a sample rate of 6000, that is a bandwidth of 3000 Hz and we need the noise in a 2500 Hz bandwidth:
Correction for 3000 to 2500 Hz bandwidth:
Correction factor 1: 10 x log(3000 / 2500) = +0.79 dB

And a correction for the difference of the Crest factor of the QRSS signal (a sine) and the Noise:
Crest factor of a sine: 1.414 and the Crest factor of the Noise can be compared with a triangle wave: 1.732
Correction factor 2: 20 x log(1.732 / 1.414) = +1.76 dB

Now we can make the following simple table to set the Noise percentage. The QRSS signal is set to 1%:
-10 dB SNR: 10.0 + 0.79 + 1.76 = 12.55 dB = 4.24%
-12 dB SNR: 12.0 + 0.79 + 1.76 = 14.55 dB = 5.34%
-14 dB SNR: 14.0 + 0.79 + 1.76 = 16.55 dB = 6.72%

SOFTWARE

Before you are using this program, you have to install Python. That is very simple. But read first something about Python by clicking the following link:

WHAT IS PYTHON AND HOW DO YOU INSTALL PYTHON

As the source code of Python is written in ASCII, it is very simple to modify the program to you own requirements. Think for example about the size of the screen, the colors etc.

Required Python version:

Required external modules (site-packages for the correct Python version!):

Link to download the ZIP file with "QRSSsimwav-v02b.py" and configuration files to make the WAV test files

Index PA2OHH