longwave and FM mode

[AlphaFive]

For weeks I have been attempting to educate myself regarding longwave by studying many receiver specifications, R.R. wiki articles, and general online articles regarding the subject. I have spent time navigating around the LWCA website. I find it fascinating because I know very little about the subject. There is a piece of information that I am curious about. In reading at least 100 descriptions of different receiver capabilities, I do notice that FM mode is not often included in older units.
Now, I cannot find specific information that explains whether there are any frequent transmissions in the traditional LW range that are able to be received in FM mode, whether it is NFM, FM , or WFM. My uneducated guess is that not much exists in that mode. I do believe that I have grasped the fact that the lowest end of LW comes from Asia and Europe, and FM is line of sight, therefore receiving in FM mode makes no sense.. but, as I said, I know nothing about it, and could easily be misunderstanding the whole thing. If FM is not important regarding a receiver in LW, I would rather not fork over the cash for it...
If someone can point me to an article or site that discusses FM in longwave, I would really appreciate it. Take care.

 

[NDRADIONUT]

Fm is too wide for lower freqs... The swr gets too high from one end of the signal to the other... Also a waste of space and really ineffecient....

 

[AlphaFive]

longwave and Fm

Thank you for that, I do appreciate it.

 

[yaesu_dave]

I owned a pair of Radio Shack AC intercoms in the early 1990's that transmitted around 200 kHz in narrow band FM. I never did understand why they operated on long wave instead of a higher frequency range--maybe because long wave is so sparsely used in the US and Rad Shack figured there would be less interference. In any event, that's the only time I've heard of FM mode being used on long wave.

 

[mm]

FM is not always line of site,

HF and vhf low FM stations operating BETWEEN 25 and 54 MHz have similar propagation characteristics as those of lower HF frequencies.

VHF FM LO band and UPPER HF FM stations frequently propagate at distances of 1000 to 10000 miles.

As ndradionut said FM is spectrally iineffecient and at vlf frequencies it is orders of magnitudes worse.

The major issue is the very narrow percent operating bandwidths of antenna systems operating at VLF frequencies which dictates similarly very narrow modulation systems.

This can be attributed to issues such as the extremely narrower VSWR bandwidths of antenna systems when operating at VLF frequencies that are in the order of KHZ or less whereas suitable FM modulation systems require bandwidths of 10's of KHZ and typically considerably more.

 

[AlphaFive]

FM on LW

Ahhh, interesting information, thank you all. So, the very nature of the modulation system itself makes the use of it in longwave not practical. The current antenna systems in use do not capture wide modulation.
Me sees a "which came first, the chicken or the egg" scenario popping up here. Why should anyone manufacture an antenna for non existent transmissions,, or why build a transmitter when no one is there with an antenna to receive it? If an FM transmitter sends a signal in the LW woods, does it make a sound?? Sorry about that, couldn't resist, thank you all again, I am getting a little better understanding.