Anyone know how this compares to the mesh network?
If by Mesh Network you mean Meshtastic, they have very different use-cases.
Meshtastic requires regular nodes/repeaters within its somewhat smaller effective range to be effective (putting repeater stations atop hills or mountains can drastically extend that effective range), it also exclusively operates via text, not audio.
NVIS is just a small long-range portable radio that bounces radio waves directly off the ionosphere which is reflected in a circular radius of 150 to 300 miles from the transmitting antenna, and is not reliant on being atop mountains to attain that range due to the reflected bouncing. The video gives details on how it is generally used.
Thanks for dropping the abbreviation. :) For those who want text:
https://en.wikipedia.org/wiki/Near_vertical_incidence_skywave
Summary for those in hurry: with NVIS, the ionosphere is your reflector, but you must use bloody low frequencies (e.g. 8 MHz in daytime, 4 MHz at night, because the ionosphere changes properties in sunlight). This will require loooong antennas (which may be horizontal, e.g. between trees) and the full wavelength is about tens of meters long, so you can’t really use full-wave antennas (quarter wave is practical) and all of this will limit the data rate considerably. Overcrowding of the narrow range of good frequencies may occur if it becomes popular.
Linking this with some sound modem to transmit text data, ideally with some automatic repetition to remove errors, will probably be much nicer to communicate with. But cool concept overall.
What makes me worry is the size of the “reflector”. I wonder what symbol rate it is possible to get if the “reflector” is literally everywhere above you - the time delay between start of reflection and end of reflection might be considerable.
I found a resource with practical advise about using NVIS, including using meteorological data (ionograms) to determine the best frequency, antenna diagrams and such. (His drawings are in Spanish, but I think most English-speakers can decode Spanish antenna diagrams with a few clues, since meter is metro, and frequency is frecuencia.)
https://www.ipellejero.es/hf/NVIS/english.php
Some additional interesting antenna designs (vertical yagi on ropes, spiral antenna, etc) and propagation shemes, can be found in this research paper.
They have a passage which addresses data rates, and the data rates are poor…
In [110] two alternative channel access technologies are tested and compared in wireless mesh networks: Automatic Link Establishment (ALE) and fixed-frequency MAC protocols. These are also described in the book of Johnson et al. [111]. In [112] we find measurements on a MIL-STD-188-110C [113] link over distances of up to 160 km, providing the users with bit rates up to 9.6 kbps in 6–9 kHz RF bandwidth. The standard gives the option of selecting bandwidth and modulation, and includes wideband modulation with up to 24 kHz bandwidth with elaborate coding and interleaving.
So, some military radios use a narrow slice of 6…9 KHz for each channel and push 9 kilobits per second. Widening the slice used will give more speed. Enough to send SMS, I would say. A text of 1000 characters could be 8 kilobits, and would require initial air time for 1 second (+ exponential back-off resends, most likely). Let’s assume a total of 3 transmission events per message. An hour contains 3600 seconds, divide by 3 --> a channel at 100% capacity could accommodate 1200 messages per hour.
