*Disclosure* - I am affiliated with NW Digital Radio, but my comments here concerning features, design decisions, product direction, availability, price, or delivery are not guarantees, announcements, or binding upon the company unless specifically stated as such.
Someone brought up the UDR56K-4 radio announced at Dayton Hamvention® a couple of weeks ago. So let me list some parameters and answer a couple of questions:
- The model announced is specified as a half duplex radio, running 25W on 70cm band. - It has an integrated computer running a standard Linux server (Debian Squeeze) with additional drivers specific to the radio. - The software platform is open source and developers are free to create their own protocols and applications - Additional hardware and options can be added via USB or 10/100 Ethernet. - There will be a daughter card option to hold a vocoder (AMBE family card will be available from NW Digital Radio) - AX.25 and D-STAR network stacks are under development and test, supporting applications that use those network stacks. - Modulation choices include GMSK, FSK, 4FSK, and possibly one or two additional choices. The modulation is performed in a high integration RF IC which talks through a bus directly at digital logic levels (no analog/base-band layer) - The RF IC can accept up to 100 Kbps with bandwidth profiles based on modulation choice. The US regulations limit operation to 56 Kbaud and 100 KHz bandwidth. Higher bit rates that meet those requirements can be supported up to the 100 Kbps rate. The developer/operator is responsible for insuring data rate / modulation choice meet the regulations where the radio is deployed.
Having addressed the basics relative to the radio. The idea is to have a platform to support multiple applications including AMPRnet. There is an interest in other common air interface (CAI) protocols for passing various data including Net-44 packets, we have at least one 3rd party developer who wants to add a low-overhead IP transport to the radio.
Yahoo! Forum for discussions relative to the UDR are at http://groups.yahoo.com/group/UniversalDigitalRadio
One thing to remember is that for a given power one must choose between distance, reliability, and speed. For example, using 4FSK it may be possible to push the raw bit rate above 80 Kbps within 100 KHz, however it might be worth using a forward error correcting code reducing the effective rate back to 56 Kbps while reducing retries on a given path due to bit errors.
I think that Net44 as a replacement for broadband service is not a goal that we should be seeking. In the wireless space there are plenty of consumer devices (Part 15 in the US) that can provide high-speed/local service, e.g. WiFi, or even point-to-point links on some paths.
There are a lot of applications where repurposing consumer devices makes sense, e.g. HSMM on amateur bands, or very local mesh networks in urban areas. Conversely, there are many applications where longer haul, higher power, modest data rate service is a better choice and this is where Amateur Radio can fill a need.
I agree we should work to multi-home Net-44 to the rest of the Internet, but I don't believe we should do this on a LAN level. I think at most it should be the 256 /16 subnets and probably many fewer than that. Local LANs can tunnel using newer tunneling protocols that can use a dynamic IP on at least one end of the tunnel to these BGP'ed routers (with fail-over between them for tunnels from LANs). There is no reason to use roll-your-own routers or protocols -- there are very capable routers with tunneling in the US$60 range that can get the connection over the Internet tunnel to the local LAN, then use our various RF interfaces (WiFi/HSMM, AX.25, DSTAR, ...) out to individual nodes. A did a presentation on this subject earlier this spring -- http://www.microhams.com/digitalconf2012/K7VE_N7IPB_RebootNET44.pdf
------------------------------ John D. Hays K7VE PO Box 1223, Edmonds, WA 98020-1223 http://k7ve.org/blog http://twitter.com/#!/john_hays http://www.facebook.com/john.d.hays
I think the key here is not is this project better or is that project is better the issue is we are hams this resource is allocated to hams, but we are not being allowed to use it due to ampr not properly managing the resource. Saying that part 15 can provide this service is like saying well we dont really need hamradio because we can just use or cell phones. Heck my MiFi is 4G and gives me 10meg down and 10meg up all day long, but when generator runs out of fuel at the cell site It give me 0Kbps. My 2m HT is still going to work right? And if it is set up right so will my HRMMs network.
If you want more info on HRMMs then read on
HSMMs is not a substitute for broad band that is not what we are doing here. It is a backup just like your 2m ht is not a substitute for a cell phone it is a backup in the event of an emergency. No part15 devices can not provide the services like ham radio can we can operate with unlimited antenna gain at much higher power levels. In the US 10watts w/o power control and 100 watts with power control at the antenna input. This and the lower noise floor allow for a much better network than what part 15 can provide.
More info on possibilities of faster than 56K
As I discussed with NWR at Dayton really faster than that is possible. I understand that there are limitations of symbol rate in the ham bands that is a detail that needs to be addressed with the FCC as it is hindering technology development.
I worked for DataRadio in 1999-2001. We were doing 56K on a 25khz channel using 3 Z80 processors. Last I heard they were dong 64 or 68K before Cal Amps obtained them. I feel sure that faster rates can be obtained with open source coding of new modulation techniques. However that is not really the point.
Lin
*Re-purposing *part 15 devices may include higher power, better antennas, etc. and running under part 97 (or equivalent in other countries).
------------------------------ John D. Hays K7VE PO Box 1223, Edmonds, WA 98020-1223 http://k7ve.org/blog http://twitter.com/#!/john_hays http://www.facebook.com/john.d.hays
On Mon, Jun 4, 2012 at 3:28 PM, Lin Holcomb LHolcomb@clearqualitygroup.comwrote:
(Please trim inclusions from previous messages) _______________________________________________ Saying that part 15 can provide this service is like saying well we dont really need hamradio because we can just use or cell phones. Heck my MiFi is 4G and gives me 10meg down and 10meg up all day long, but when generator runs out of fuel at the cell site It give me 0Kbps. My 2m HT is still going to work right? And if it is set up right so will my HRMMs network.
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K7VE - John -
Lin Holcomb