10

In the International Code of Signals (an International system of maritime communication, including radiotelegraphy), AAA (over-bar) is designated for both full stop and for decimal point. (See flashing light procedure signaling, page 20.)


8

You can find the code in packjt77.f90. Callsign encoding (for "standard" callsigns that don't require hashing) is in function pack28. A quick summary: Adjust a few strange prefixes that don't follow the usual arrangement of letters and numbers. Swaziland 3DA0* will be encoded as if it was 3D0* instead, and Guinea 3XA1A will be encoded as if it was ...


6

The web sites of Kent Morse Keys and of the AC6V reference compendium document use of the Morse letter 'R' (dit-dah-dit) as an abbreviation for 'decimal point.' 'R' can have other meanings, of course, but I have used and heard it used to represent a decimal point in numbers - particularly when specifying a frequency - for 50 years.


4

There is no officially recognised way to distinguish between uppercase and lowercase characters in Morse code. When you look at old telegrams printed on paper strips they would all be in capitals.


4

There is no upper/lower case differentiation in Morse code; just the alphabet. There is a reference to the military recently approving lowercase letters for navy messaging. Use of uppercase-only dates from days of Morse code communications.


4

I found the answer in this article in the Wikipedia: types of radio emissions. From that article you can construct the different codes for different modes but there's a list of common examples: A3E: AM speech communication – used for aeronautical communications F3E: FM speech communication – often used for marine radio and many other VHF communications 20K0 ...


4

Is it safe to define that Data Whitening is always X-ORing a payload with a pheudorandom sequence known to both receiver and transmitter? No, but that's a very common way of doing it. However, you can scramble and whiten a sequence by pushing it through an appropriate Linear Feedback Shift Register, and I'd assume that this is even more commonly applied in ...


3

PM is actually quite similar to FM in terms of modulation effects. With phase modulation, the change of the phase angle is proportional to the message that is to be modulated onto the signal. With frequency modulation, on the other hand, the instantaneous change in frequency is proportional to the message that is to be modulated onto the signal. So with a ...


3

Imagine your data is not white. That means that at certain periods, it contains more variance, and hence information, than on others. That's bad, because now certain frequencies become more sensitive to noise than others. Other than that: Many things that a receiver needs to do (AGC, equalization, synchronization) depend on the temporal stochastic ...


2

Phase-modulated voice is equivalent to FM, modulo differences in frequency response. An FM transmitter contains a pre-emphasis circuit to counteract this effect, making the two effectively equivalent on the air. From the US extra class question pool: E7E06 (A) Why is de-emphasis commonly used in FM communications receivers? A. For compatibility with ...


2

Assuming you are doing something like recording the audio output from an SSB radio, then the audio recording is just the RF spectrum shifted down in frequency. So, you could calculate the RMS average of the audio file, square it (since power is proportional to the square of voltage), and you'd have some measurement of power. However, this requires that the ...


1

That doesn't depend on the text-to-audio modulator, but on the audio-to-baseband / audio-to-RF modulator. With AM, audio amplitude is proportional to received signal strength, with FM, the received signal strength has absolutely no effect on audio signal (and hence, you can't recover the received power at all; that info is simply lost on the way). In any ...


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