I was reading the 1/2008 (March) issue of EURESCOM mess@ge covering The Future Internet today. An article by Milon Gupta introduced the OMEGA project, which is running from 2008 to 2010 and focuses on “Gigabit speed at home without cable clutter”. The project is motivated by the fact that the home network could become the bottleneck in the future, high-speed Internet, as “many devices are limited to wireless transmission rates of 54 megabit per second, or require troublesome wiring to achieve higher rates”. The article proposes the following solution to install comfortable, high-speed home networks: “OMEGA will overcome these limitations by increasing the speed to one gigabit per second and by connecting home devices to the Internet and to each other through power line communications and wireless connections”.

Power line is a technique where, roughly speaking, data is transmitted using electric power lines instead of dedicated but more appropriate network cables. This approach is comfortable as a network of power lines is already installed in today’s homes and devices can be plugged in everywhere to get connectivity without worrying about running network cables. However, using power lines as carrier for wideband signals, such as high-speed network communiction, is a questionable approach as power lines are untwisted and unshielded and thus form a large antenna which will radiate the signals sent over power lines. Therefore, there is a high potential for interfering other radio services or being interfered. Power line communication can make HF Radio services–allowing world-wide communication and thus invaluable services such as emergency networks–unusable. Is it really worth loosing an invaluable resource just to send data using inappropriate wires? More information can be found here:

• “Broadband Over Powerline (BPL) and Amateur Radio” by the American Radio Relay League. A good article covering many details about why amateur radio is concerned about the deployment of BPL.
• “The effects of power-line telecommunications on broadcast reception” by BBC research.
• “Video and Audio recordings of BPL Interference“
• “Track and Solve Electrical Interference“
• “Wireless Institute of Australia review of Power Line Communications (PLC) / Broadband over Power Lines (BPL) in Australia” stating that “from all observations to radiate electromagnetic energy of such intensity that it will substantially interfere with not just Amateur Radio, but all HF and low VHF radiocommunications”
• BPL Flyer by the Wireless Institute of Australia
• “Power line : Potential for Interference“

Is sending wideband signals over untwisted and unshielded wires really the highest of highs in electrical engineering? Maybe research should think about alternatives without suggesting to deploy the next best but inappropriate solution?

PS: Does this highlight the need to revisit the song released by the Buggles in 1979 entitled Video Killed the Radio Star?

I just returned from this years International Packet Radio Conference (IPRT) which was held at Darmstadt University of Technology. The scope of the conference is digital data transmission in amateur radio in general and is not limited to packet radio using the AX.25 protocol as the name might suggest. Their were ten talks in two tracks, a bit less than last year.

In the first talk, Michael Zähringer, DB3MZ, spoke about Galileo, the global satellite navigation system build by the European Union. As amateur radio operators are operating as secondary users on a frequency range (23 cm) also used by Galileo, some interferences are expected. For transmitting the time signal to the receivers used for computing the position their position on the sphere, Galileo is using a 50 MHz wide pseudo noise carrier which is close to the noise limit and will thus not interfere narrow band amateur radio transmissions. However, amateur radio transmissions are likely to interfere Galileo navigation receivers as their Automatic Gain Control (AGC) will react to the strong amateur radio signal  and makes Galileo signals undecodeable. This effect was demonstrated in a test area in Berchtesgaden where six Galileo transmitters are installed at the surrounding mountains. During experiments with prototypic Galileo receivers, their AGC reacted to the narrow band packet radio data transmissions of nearby packet radio digipeaters operating on the 23cm band. As the speaker mentioned, Infineon reacted to this problem by limiting the AGC to broadband signals only.

As this part of DB3MZ’s talk highlighted operational problems, the last part focused on applications of the Galileo time signal. As Galileo has a more accurate phase noise than GPS, it can be used for low power, low bandwidth transmissions. The amateur radio operator W6NEY,  professor at Stanford University, with Coherent CW (CCW) using GPS which only requires 5 to 10 Hz bandwidth and thus enables efficient low power transmissions. These experiments can be continued using the Galileo signal.

A nice story in his talk was about the decryption of the code used by Galileo for encrypted signals.  This code was decrypted by hackers of the German Chaos Computer Club (CCC) and was changed by Galileo. This reminds be a bit to the cat-and-mouse game played by a German pay TV provider, who frequently change his encrypted code whenever someone cracked it. As the latter told us, people are always able to crack the encryption. Thus the question rises up, how often they are going to change it …

Thomas Kleffel, DG5NGI, presented three boards used for transmitting DVB-T/S, gPSK, ATSC, gMSK, … signals in the scope of digital TV and broadband data communication. The MiniMod board he constructed and presented can be used for narrow band DVB-S (> 1.8 Mhz bandwidth) TV signals, as currently used in northern Germany, narrow band DVB-T (> 2 Mhz bandwidth) and gMSK. The latter is a interesting mode for amateur radio operators as the requirements of the power amplifier (PA) in terms of linearity are relaxed and a normal class C PA used for analog FM signals is enough. The second board presented in his talk can be used as an Ethernet over DVB bridge for broadband data communiction (e.g. for D-Start or Echolink access). It is more expensive than using cheap WLAN hardware, but more flexible, as arbitrary frequency ranges can be used as well as linear amplifiers.

Rein Couperus, PA0R, introduced PSKmail which he has developed in the past three years. This mode is used for accessing mail and the Web (”the slowest interface to Google”) via HF on long distance. PSKmail is using PSK for modulation and data transmission along with a ARQ for re-transmission of lost frames. Unlike PSK63 which reduces its bandwidth from 2,4 kHz to 500 Hz when the signal reception decreases, PSKmail reduces its frame size by using a constant bandwidth. PA0R demonstrated how electronic mail can be downloaded from servers and accessed locally by the mail user agent (MUA) Evolution in Linux, or to access the Web (including carrying out Google queries) by wget.

Jochen Berns, DL1YBL, discussed Icom’s Digital Voice system D-Start and the experiences obtained by operating D-Star repeaters in Germany. The subsequent discussion was controversial as the vocoder used by D-Star is closed source and needs to be licensed. This limits the experimentation with a new technology and may contradict the experimental nature of amateur radio.

All in all, it was a nice event and I’m looking forward for next years IPRT, where an anniversary can be celebrated–the 25th IPRT. See you next year!

I just discovered some fancy amateur radio related stuff on the web recently. It all started with AmateurLogic, which is a one hour video podcast published by US hams. I just looked at the Field Day episode (14) this morning. It’s really good edited and comes with a excellent audio and video quality. Moreover, it was interesting to see that the definition of a Field Day is somehow different to the German. What US hams call a Field Day seems to be a fixed, nation wide day of activity. In contrast, the German hams call it a Field Day when joining a group of people to make portable activities. It’s not a fixed day in the calendar when everyone’s out there, nor would one even hear “CQ FIELDDAY” here in DL It’s more like a contest in the US, whereas here it’s just a synonym for portable activities within a group of hams. Pretty interesting.

It also sounds like this kind of activity was unknown to the VK ham participating the show. However, this VK ham also spoke about the foundation license with the WIA (Wireless Institute of Australia), which was pretty interesting to me as I didn’t know that the 4-letters-suffix-guys have HF permissions. And the “Your Entry Into Amateur Radio” book, which is dedicated to exam preparation, also seems to be nicely edited; there is a lot of color, pictures, nice headings, etc. …AND..it seems like there are no tubes in it ;-))) Seems like a good way to get people into the hobby. (and not like: computers? oh my good, all you need is a morse key!

Furthermore, they also mentioned in episode 14 the nicely produced WIA podcast, which is available here: http://feeds.feedburner.com/vk1wia. I totally agree with the Amateur Logic producers; the WIA news sounds like professional broadcasts and is really great work. I’m currently enjoying listening to it. Moreover, they also refered to twiar.org (this week in amateur radio) and soldersmoke.com as another HAM audio podcasts. Unfortunately, it seems like the latter has a bad audio quality. Amateurlogic was really too good edited

Students from the Evangelisches Gymnasium in Lippstadt, Germany had a talk with Commander Bill McArthur, KC5ACR at the International Space Station (ISS) on March 8th. This is actually the fifth contact of a German school with the ISS. Such contacts are arranged by ARIS. There is a report at the ARRL website as well as in the ARRL Letter Vol. 25, No. 11 covering this event. Furthermore, I also want to mention the excellent German Podcast QTH Germany No. 005 produced by Norman, DL6YDY. The show is about 64 minutes long and gives a lot of background informations. There is also a video from a German television report linked at his site as well as a video produced by Norman.