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A correction on the radio terminology used in the article... SSB (Single Sideband) is a modulation system, not a frequency range like VHF (Very High Frequency).

A correction on the radio terminology used in the article... SSB (Single Sideband) is a modulation system, not a frequency range like VHF (Very High Frequency). SSB is a variation of AM (Amplitude Modulation). If you look at the frequency spectrum of an AM signal, you will see a peak in the middle – the carrier frequency – and two “sidebands” above and below the carrier that have the actual signal. Each sideband is a mirror image of the other. This fairly inefficient since most of the transmitter power goes into the carrier frequency, and the power that goes into the sidebands is duplicated for each. A Single Sideband transmitter removes the carrier frequency and one of the sidebands, and then the receiver adds the carrier back in to demodulate the signal. The reason the SSB radio can bounce signals off the ionosphere is not because it’s SSB, but because it operates in the HF (High Frequency) range. But any modulation system could do this just as well as SSB – it’s the frequency range that makes the difference. Hams, for example, often use CW (Continuous Wave, aka Morse Code) in the HF range, and a few even use AM. The VHF radio happens to use FM (Frequency Modulation), just like an FM radio station but with a narrower bandwidth. But again, whether it uses FM or SSB is not what determines whether the radio only works line of sight or could also work over the horizon, it’s the frequency range. This is similar to how AM radio stations can transmit much farther than FM stations, especially at night. It isn’t because one is AM and the other is FM, it’s because AM stations operate in a much lower frequency range. (I tried to post this comment on the article page itself but had trouble with the commenting system...)

scoot 9y ago
> Hams, for example, often use CW (Continuous Wave, aka Morse Code) Morse code can be used to modulate a continuous wave, but they are not synonymous.
- Stratoscope 9y ago
  Good point. I was using the terms loosely - which is the wrong thing to do in a comment that attempts to explain some terminology! :-)
- wglb 9y ago
  CW, which is in fact an abbreviation of Continuous Wave, is an often-used phrase used to describe Morse Code on the radio.
- deleted 9y ago
  [deleted]
wglb 9y ago
You are correct about the physics of the radio modulation systems and frequencies, but I think that the article is quoting folks that are talking about common conventions of where SSB is likely to be used over AM.
- Stratoscope 9y ago
  That is true, and if the article is any indication, it sounds like the marine community uses "SSB" to mean "an HF radio with SSB", and "VHF" to mean "a VHF radio with FM". A bit like the way the ham community uses "CW" and "Morse code" somewhat interchangeably, even though as scoot pointed out they are not the same thing. In fact, the ICOM IC-M700PRO shown in the article bills itself as an "SSB Radio Telephone", but it also supports other modes including AM, CW, and FSK (frequency shift keying). http://www.icomamerica.com/en/products/marine/ssb/m700pro/ http://www.icomamerica.com/en/products/marine/ssb/m700pro/ (Note that where the specifications mention USB, they are not talking about Universal Serial Bus. They refer to Upper Sideband. Since there are two sidebands for every AM signal, when you use Single Sideband you have to pick which one you want to use - the upper sideband, USB - or the lower sideband, LSB. This radio only supports upper sideband, not lower. Ham radios use either one depending on the convention for the ham band you're using.) But still, the article really conflates SSB modulation with the HF frequency range: "[Ham radio] covers a broader array of wavelengths than SSB..." "...they’re both using SSB frequencies..." It's not a big deal, and obviously the author knows far more about sailing than I do. But the article specifically calls out propagation differences for different kinds of radios, and it's worth knowing the actual reason for those differences.
  - wtallis 9y ago
    > it sounds like the marine community uses "SSB" to mean "an HF radio with SSB", and "VHF" to mean "a VHF radio with FM". It's a little bit more specific than that. ITU has specific frequency allocations for maritime use that imply several of those details that are not explicitly stated when a sailor refers to his VHF radio, and GMDSS standards also help dictate what kind of equipment and features are expected for different bands.
  - 9y ago
Theodores 9y ago
A correction on sharks: not that many of them lay eggs and do a runner. Most shark varieties have the eggs develop in the womb, sometimes with a 'cord' and sometimes not. In the latter type there is the small matter of oophagy. Here they have many, many baby sharks inside their womb and the baby sharks eat each other until only one baby shark is left. This shark has murdered scores of its siblings before it emerges into the world hungry.

scoot 9y ago

> Hams, for example, often use CW (Continuous Wave, aka Morse Code) Morse code can be used to modulate a continuous wave, but they are not synonymous.

Stratoscope 9y ago
Good point. I was using the terms loosely - which is the wrong thing to do in a comment that attempts to explain some terminology! :-)
wglb 9y ago
CW, which is in fact an abbreviation of Continuous Wave, is an often-used phrase used to describe Morse Code on the radio.
deleted 9y ago
[deleted]

wglb 9y ago

You are correct about the physics of the radio modulation systems and frequencies, but I think that the article is quoting folks that are talking about common conventions of where SSB is likely to be used over AM.

Stratoscope 9y ago
That is true, and if the article is any indication, it sounds like the marine community uses "SSB" to mean "an HF radio with SSB", and "VHF" to mean "a VHF radio with FM". A bit like the way the ham community uses "CW" and "Morse code" somewhat interchangeably, even though as scoot pointed out they are not the same thing. In fact, the ICOM IC-M700PRO shown in the article bills itself as an "SSB Radio Telephone", but it also supports other modes including AM, CW, and FSK (frequency shift keying). http://www.icomamerica.com/en/products/marine/ssb/m700pro/ http://www.icomamerica.com/en/products/marine/ssb/m700pro/ (Note that where the specifications mention USB, they are not talking about Universal Serial Bus. They refer to Upper Sideband. Since there are two sidebands for every AM signal, when you use Single Sideband you have to pick which one you want to use - the upper sideband, USB - or the lower sideband, LSB. This radio only supports upper sideband, not lower. Ham radios use either one depending on the convention for the ham band you're using.) But still, the article really conflates SSB modulation with the HF frequency range: "[Ham radio] covers a broader array of wavelengths than SSB..." "...they’re both using SSB frequencies..." It's not a big deal, and obviously the author knows far more about sailing than I do. But the article specifically calls out propagation differences for different kinds of radios, and it's worth knowing the actual reason for those differences.
- wtallis 9y ago
  > it sounds like the marine community uses "SSB" to mean "an HF radio with SSB", and "VHF" to mean "a VHF radio with FM". It's a little bit more specific than that. ITU has specific frequency allocations for maritime use that imply several of those details that are not explicitly stated when a sailor refers to his VHF radio, and GMDSS standards also help dictate what kind of equipment and features are expected for different bands.
- 9y ago

Theodores 9y ago

A correction on sharks: not that many of them lay eggs and do a runner. Most shark varieties have the eggs develop in the womb, sometimes with a 'cord' and sometimes not. In the latter type there is the small matter of oophagy. Here they have many, many baby sharks inside their womb and the baby sharks eat each other until only one baby shark is left. This shark has murdered scores of its siblings before it emerges into the world hungry.