High-frequency Emergency and Rural Multimedia Exchange System

Discussion in 'Survival Communications' started by DKR, Oct 3, 2018.

  1. DKR

    DKR Raconteur of the first stripe

    Source - Hermes // rhizomatica

    The take form the ham community
    NSF/Mozilla contest awards $400K for HF linked EMCOM cell net idea

    Money quote:
    "The solution, which integrates GSM and HF backhaul technology, can provide connectivity to places struck be natural disasters or populations living in remote areas. As the system does not rely on cables or satellites, it could also be used as a backup system for primary communications systems. ... We have essentially married VoIP, GSM and HF so that users can send a text or voice message from their phone across the world without the need for a satellite."

    Also bullet 4 / Resources ("read more" down arrow), Documentation,


    Transmission mode: Single Side Band
    RF signal path: Near Vertical Incidence Skywave (NVIS)
    Channel width: 2.5 kHz
    Frequencies: between 5 and 7 MHz
    Power output: 10 W – 100 W adjustable
    Adaptive digital modulation modes: 4FSK, 4PSK, 16QAM, ranging from 1 to 10 carriers and different symbol rates, all with Reed Solomon Forward Error Correction

    A pico cell (or a full cell using GSM) linked via a NVIS HF SME system.

    Software components from at least two licensed Hams are also referenced here, the ARDOP (Amateur Radio Digital Open Protocol) TNC implementation by John Wiseman (GM8BPQ) and D-RATS is a free, easy to use, multi-platform program for data communications with D-STAR devices by Dan Smith (KK7DS).

    Check the links for the full story.

    Video w/English subtitles
    Dunerunner, Bandit99 and Motomom34 like this.
  2. Bandit99

    Bandit99 Monkey+++ Site Supporter+

    This is a very interesting article! I think I understand most of how it is done; however, details are sketchy. I think the gist is they started they own local cellular network then used HF for the long-haul portion. I don't have time to dig into it now as have a ton of work but hope to do so later to answer such questions as: Must it be GSM? Are the HF links in the amateur band? Could something like this be legally implemented in the US? How does it make the connection into other government and private cellular networks as seems tariffs, gateway costs, lease agreements or etc. would need to be implemented or is it a closed network?

    Anyway, really interesting! The video, while also interesting, isn't very helpful to describe exactly how the network is accomplished and what it's strengths and limitations.
  3. techsar

    techsar Monkey+++

    I'm wondering who the control operators for the HF stations will be...after all, technically they have to be in control of all traffic transmitted from their station....

    Nice concept...but not for me. And that's all I'm going to say.
  4. Idahoser

    Idahoser Monkey+++ Founding Member

    is this significantly different from WinLink? I've been meaning to look into that for years.
  5. techsar

    techsar Monkey+++

    The way i read it is that instead of cell towers, the system uses hf transceivers to link between what would typically be cell sites.
  6. BTPost

    BTPost Stumpy Old Fart,Deadman Walking, Snow Monkey Moderator

    and during the Solar Low we are just heading into, that doesn’t bode well for the connectivity, in the short term... If you are trying to pass Voice then you need 1.2 Khz of bandwidth MINIMUM, and that doesn't care how many Carriers you split it up on...
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