Sunday, February 15, 2009

Flexibility of a HSMM network

KE7FTE, N7QQU and W9ERT show us the "drag and drop" flexibility of a HSMM platform. Offering reliable exchange of large image files, email, word-processing and other files that emergency responders and served agencies find invaluable.

The video does show what HSMM networks can provide for ARES. It should be clarified that this drag and drop flexibility is not exclusive to D-Star. It's a network file sharing protocol being employed between the laptops being used. Any TCP/IP based network can support this.

Yessj What's the range on this thing? It looks quite similar to a wireless peer to peer lan!


One big difference HAMS can use greater power with a upside of distance and robustness. Hams can use up to 1500 watts of power. Where your local wireless network is measured in millawatts to watts. With high gain antennas and lots of power ranges can exceed 50-80 miles. And that's peer to peer! Try that with your wireless LAN! Idea is this can provide emergency backbone for a LAN that is down in an emergency. Not super fast, just robust and proven!

Above are some of the youtube video comments. W7NWH is trying to make this pricey D-Star sound like it's fundamentally superior to common wifi. Yes hams can run more power, but that likely won't accomplish much more. Microwave propagation is microwave propagation. Height is the key item. If you don't have it, the 10 watt D-Star radios at 1.2 GHz won't yield much better paths than the under 1 watt paths that you could do with wifi. I don't know of any 1.2 GHz amplifiers to run more than the stock Icom ID-1 let you anyway. They have been several well publicized examples of 20-30 mile 802.11 links, and one 72 mile path!... One with a ham twist was published in the July 2005 QST, titled, "IEEE 802.11 Experiments In Virginias Shenandoah Valley."

One thing I've noticed is that command posts love telephones and fax machines. Pictured above you see an $30 analog telephone adapter. Talk about seamless to the emergency manager!

Another interesting and smart idea when it comes to repeater linking is to use analog radio adapters and link the repeaters over your HSMM backbone. Most repeaters are on decent tower sites already so linking such sites over microwave HSMM links should be very feasible. Now your linking channel is not just capable of voice, but can act as a high-speed back bone.

IRLP and Echolink linking are pretty prominent and well understood. In many cases there may be multiple repeaters in the same geographic area all linked (maybe even semi-permanently) using such common VOIP networks.

With HSMM backbones you can off-network link these. This is very emcomm friendly in the even a backhoe takes out internet to most of an area.


Anonymous said...

Sip. 'nuff said.

john said...

We've been brainstorming about how this technology might help bring back non-commercial underground radio for the masses. We wonder if the following would be feasible:

1. non-commercial, non-advertising station broadcasts via HSMM in a downtown district

2. same station distributes portable battery-powered iPod-like devices which receive the HSMM signal and convert the signal to audio with stereo audio-out jacks.

I believe I can put my hands on the expertise to create the devices I mention in 2). But the rest is a big blur to me. I don't know what is involved in hacking an 802.11 device to transmit on the Ham freq. Then there's the legality of all of this.

Any insight you can offer would be absolutely welcome.

kb9mwr said...

You forgot to mention your callsign, and a way to get a hold of you. I think a bit of google searching is all it will take to find the answers you seek. I've written quite a bit about how to change the country code to unlock the ham only channels as well as the legal Part 97 issues. HSMM stands for High Speed Multimedia radio, a direction within amateur radio.