Category Archives: Computing

Amateur Radio, AREN, AX25, Computing, DTN

DTN and AX.25

2 Comments

Almost 12 months ago Darren, G0HWW sent this post to the linux-hams mailing list. We exchanged some emails discussing how Delay Tolerant Networks (DTNs) could be used for Emergency Communications (being a classic store and forward network). In a DTN network, each sub-net or point-to-point link can operate over whatever stack is available, in this case it is AX25. In August Darren became aware of some work done in Helsinki University of Technology (under Joerg Ott) specifically a paper entitled Opportunistic Email Distribution and Access in Challenged Heterogeneous Environments. Joerg forwarded Darren their DTN Mail Proxy and we started experimenting with it.

Last weekend, we went a step further. Darren sent me on patches to the DTN2 reference implementation that implement an AX25 Convergence Layer. As I had a working 9600 baud AX25 connection we were eager to test it. After some patching, head scratching and recompiling we were able to successfully pass email from my Laptop over AX25 (439.850MHz) to my Linux server, then over the Internet to Darren’s server and on to his mailbox. All using the DTN bundling protocols. Very cool!

Amateur Radio, Computing

TM-D710E and KISS mode.

1 Comment

Happy New Year!

Now Christmas is over, back to business. I spent some time last Saturday testing KISS mode on the TM-D710 to see if Kenwood have improved it. The test scenario was.

Linux Laptop <-> TM-D710E  <-> 439.875MHz <->  SCS-PTCIIex <-> FT-847 <->  Linux Server.

At both sides, the serial ports were running at 57,600bps. I configured both sides to use 9600bps over the RF connection, I used settings of txdelay 100ms, Paclen of 255, maxframe of 7, mtu of 1500, mss of 1460, and tcp window of 2920 as suggested here. Other settings were at their defaults.

I started an FTP download of a (roughly) 1.6MB file from the Linux Laptop to the Linux server, and about 74 minutes later, it completed.  I then downloaded the same file and approximately 70 minutes later it finished.  A quick comparison of the md5 checksums showed the file to be ok.  During the transfers, it seemed to me that the 710 was a bit ‘slow’ in switching from receive to transmit (compared to the PTCIIex which was almost instantaneous).

That said, given my very limited experience with 9600 baud packet, I still think it is respectable, though more testing is needed and I would welcome any suggestions for different parameters to change.

Computing, Technology, Television, Work

Software Defined Radio

Leave a comment

This is very interesting.  Who knows, it may soon be possible to have all the different wireless technologies available on one chipset, all presented as just another ‘ethernet’ device (or maybe many devices.   If  there was an  associated hardware signal to indicate ‘oops.. we’ve had to change networks’ or some other smarts, it would make things very interesting in the whole arena of Terminal/Node Mobility for Internet connected devices

Amateur Radio, Computing

UX-19

Leave a comment

I read this earlier and went looking for information on UX-19.

“Amateurs at the University of Tennessee Amateur Radio Club are launching a balloon with a beacon in the 10 MHz Amateur Band that may travel across the Atlantic during its 5-day mission.

The latest Icarus X mission UX-19, will hopefully launch by next weekend and its goal is to be the first Amateur Radio equiped helium balloon to cross the Atlantic.

The balloon payload will include a GPS unit and CPU that will regulate the balloon’s altitude and send telemetry on 10.123 MHz in CW and RTTY formats.

The 10 MHz transmitter will run 3 watts output into a half wave dipole hung below the balloon.

The students need receiving stations to copy the telemetry data. They have developed a decoding program that anyone can download from the University of Tennessee web site which will relay the values back to the campus server.”

They have quite a cool video from an earlier launch:

The Distributed Tracking and Relay Client (DTRC) application is interesting, as it should be possible to receive reports from anywhere in the world that the signal is received. This means that the students have a very large potential network of ground stations. Their demonstration of the DTRC client seems to be running on a MAC, so I guess it should work fine on parallels. I must try it out later and see if it does.

Amateur Radio, APRS, AREN, Computing

TM-D710 Kiss mode/EMCpup

Leave a comment

Reports on mailing lists seem to indicate that the new Kenwood TM-D710 has a properly working KISS mode and works fine with Airmail. So it should work for TCP/IP as well. Not everyone likes all the new ‘features’, however, as the radio is firmware upgradeable it should get ‘better’ over time.

Much as I would have liked to see smart-beaconing, I have finally given in to temptation, so to make room, the PCR-1000 is departing (no need to learn Python now), with a new TM-D710E on order.


After the Radio Rally, Conor, EI4JN, took away a few copies of the Puppy Linux EMCpup CD and I suggested to him that he try it out himself given he had never used Linux.

He let me know during the week that he had used it for to complete some PSK31 contacts. This is impressive, not that he was able to make the contact, but because he had no experience of Linux before (and ‘afraid’ of it by his own admission) and was able configure the software to suit his specific station with no external help. I’ve suggested to him that he next make his own CD (from the existing one) customised for his own station.

I’m looking forward to getting back home to try it out myself as I’m currently travelling on behalf of WIT/TSSG.

Amateur Radio, AREN, Computing

Linux emcomm PUP

Leave a comment

“Software for the Narrow Band Emergency Messaging System (NBEMS), is now available for testing. This system maximizes the use of radio amateurs for providing emergency communications.

The system works with most soundcard-equipped computers and is completely contained on a “Live” CD (EMCpup), based on Puppy Linux (2.17), flarq (1.0) and fldigi (2.0), Every effort has been made to make the OS transparent to the user, so no Linux experience is required. The system has been in development for the past year and can be downloaded and burned to a CD from: http://www.w1hkj.com/emcpup.html under the link to the CD image. The goal of the NBEMS is just to be able to bridge a widescale disaster area of up to 100 miles, without any reliance on a centralized repeater network, or mailboxes, and use as little space as possible.”

Whats most interesting about this is its a bootable ISO image. No install required. Hopefully I’ll be able to convince some of the AREN membership to try it.

Amateur Radio, Computing, software, Technology

TM-D710E

Leave a comment

As a follow-up to my previous post the Kenwood TM-D710E (E for Europe) is available and shipping. Now there is another question waiting to be answered, is it any good in KISS mode? No one seems to know for sure, but the buffer size has increased. Ok, so they left out Smart-beaconing but the radio is apparently firmware upgrade-able, which means that the potential is there to do upgrades depending on user feedback.

Coming back to KISS mode, invariably. In general we tend to (at least I always have) run the the serial port of the Radio Modem (TNC) at a higher speed than the radio channel, this reduces latency in getting data from the computer out to RF, and the combination of large RAM buffer and RTS/CTS handshaking means that everything happens as efficiently as possible and no buffers overflow.

The predecessor to the TM-D710, the TM-D700 (and TS-2000 and TH-D7G2), all share a common “TASCO” TNC implementation. The problem is that its buffer is quite small, and it seems not to have RTS/CTS implemented. This means that in KISS mode its very easy to overflow the buffer in the TNC, which causes it to lock up completely.

I recently installed a Linux version of the Winlink TelPac (Packet to Telnet) software on the Packet node I maintain in WIT, and over the last few days, for AREN purposes, I have been testing it with Airmail, which works great.

Not having the good sense to leave it alone, I thought I’d try and get the TASCO modems working with Airmail. After many power-cycles of the radio, and much pulling of hair, its now working.

Now, this isn’t for the faint hearted, and, to be honest, for a system to be deployed ‘in the field’, I definitely would NOT recommend using the TASCO TNC in the Kenwood radios (TS-2000/TM-D700/TH-D7) with Airmail , leave them running APRS, like they are designed for.

Anyways, it involves running Airmail, pointing it at a Virtual Serial Port. The HW Virtual Serial port connects to Airmail to AGW Packet Engine linker (AMPE) , which, in turn connects to AGW Packet Engine and finally on to the radio.

After some hints by Demetre, I followed the instructions with AMPE, and it all seems to work, but by any stretch of the imagination, its a nasty, nasty kludge. I’m guessing that the reason it works, is that the virtual serial port software does some kind of flow control, but I really have no idea.

My advice, use a real TNC!

Amateur Radio, APRS, Computing, Travel, Work

GAREC 2007

Leave a comment

I’m just back from the 2007 Global Amateur Radio Emergency Communications Conference (GAREC 2007). Where I presented some initial results from the GAISS project (previous entry here). I was also attending on behalf of AREN and the IRTS (who also partially paid for my attendance the conference).

Listening to the presentations from the Amateur Radio operators that worked (some for months) in the aftermath of Hurricane Katrina and Rita to provide communications in and out of the disaster area was most humbling.

The presentations were excellent overall, I learned quite a lot from other participants, and had a great reaction to my own presentation. Which surprised me a bit. I met a fantastic bunch of people, that I will hopefully be able to keep in contact with as time goes on.

What was most interesting to me is the holistic approach taken to Amateur Radio in countries that have experienced disaster, everyone is competent in all areas whether it be Contesting, VHF, Digital modes, whereas in Europe, people tend to have a more polarised view (i.e. some folk specialise in VHF, some in Digital etc). I have much to learn.

Here are some pictures taken before, during and after, GAREC.

All in all it was a fantastic experience (and I got a mention in the ARRL blog, thanks to Khrystyne, K1SFA).

Computing, IPv6, software, Technology, Work

Mobile IPv6 on the N770

3 Comments

Following up from my earlier post. To save someone the trouble of building MIPL for Linux for the N770, you can find a Linux kernel here and mip6d here.

I’ve been trying the kernel out using the following command to upload the kernel:

flasher -l -b -k zImage-su-18-200730

And powering on the device, the mip6 kernel gets loaded (until the next reboot). Once it boots, its possible to copy mip6d onto the n770, as it appears as a USB storage device. Install X-Term, write a mip6d configure script, and off you go (I’ve not tested with IPsec yet though)!

I remain unconvinced about the usefulness of the n770/n800 type devices. They may be usefule for some remote control applications, although I’m not sure, more testing (using IPv6) is needed ;).