amateur-radio

BARC AGM 2008, and other AR news

Last Friday (23rd), was the night of the Brisbane Amateur Radio Club Annual General Meeting. Anyone who has been involved in a small club or community group, knows how dangerous it can be to attend these meetings — if you don’t intend to stand for a position, especially when most of the people holding executive positions are stepping down. 😉

Well, needless to stay, the vast majority of the membership was away… leaving about 8~9 of us in the room. One of the newer members wound up with job of President, along with myself scoring the job of editor for QSP, the club newsletter. There will be more on this in the next issue of QSP. I’m still toying with ways I can produce that newsletter efficiently — the three options I’m looking at are (in order of preference): LaTeX, OpenOffice.org and Scribus. I put Scribus last as I’m not familiar with it, and at last check, didn’t easily run on Win32. LaTeX is available for Win32 as part of Cygwin amongst other sources, as is OpenOffice.org.

In any case, this is a new role for me, and I look forward to the challenge.

News items for QSP can be sent directly to the new email alias I have for this: qspnews@longQlanRdcMlan.yi.org (remove the interference). Preferred formats for text are plain ASCII text (just put it in the body of the email), OpenDocument Text (as produced by OpenOffice.org), HTML, LyX and LaTeX. Preferred formats for diagrams are PDF, SVG, EPS, PNG or JPEG (the last one is best reserved for photos) — just indicate in the text roughly where you want these diagrams put, and I’ll try to fit them in as best I can.

In other news, I now have some HF kit. BARCfest saw me acquiring a second hand transceiver, a Kenwood TS-120S. Presently I’ve just got it hooked to a simple 40m dipole, and I mainly hover around the WICEN frequency on 40m (7.075MHz LSB). The eventual plan is to set up a full-wavelength 40m loop in the ceiling space of the house (we have a tiled roof) and hook that up to an ATU. I have purchased an ATU, and hope that will arrive some time this week, so before long, I should be contactable on HF. I’m permitted 10W PEP on 80m, 40m, 15m and 10m, and am able to transmit USB, LSB and (once I learn morse), CW.

Messing with Bluetooth SCO

Some of you may recall a recent post in which I described my idea for building my own high-fidelity wireless headset. The recommendation from most people was just to buy a bluetooth headset. Today I was in the hardware store here in The Gap, looking around actually for something totally unrelated — mounting brackets for an antenna (which I didn’t find) — I happened to see they were selling some earmuffs with builtin bluetooth headset and AM/FM radios for about AU$100. This is cheaper than I had seen similar sets elsewhere… so I figured I’d bite the bullet and give them a shot. At worst, I’d have a pair of earmuffs (may come in useful if I start working in a noisy environment), with a radio built in.

Bullant ABA700 Headset They’re manufactured by Bullant, and can come in three forms: bluetooth headset only, radio only, and radio+bluetooth headset (model ABA700). They apparently provide about 85dB attenuation, meeting AS/NZS SLC80:11:Class1. Protocol wise, they support the SCO profile, and the documentation (single double-sided A4 page) seems to suggest support for A2DP (quote: “You can also listen to music stored on your Bluetooth Mobile Telephone if your Mobile Telephone has that feature” — I can’t imagine people wanting to listen to music at 8kHz, mono, 16-bit).

It took me a while to figure out how to get them going at first. What I didn’t realise, is to hear anything out of the Bluetooth component, one must first turn on the radio and tune it to some station — slightly annoying, but I can live with that. Audio quality with a local FM station is quite good — on-par with most consumer wideband FM receivers. (And noticeably better than the amateur set I’ve been using lately… but that’s hardly surprising given its purpose.)

However, I was right to be concerned about compatibility. Windows XP won’t talk to them at all — okay, no great loss, I hardly use that “OS” these days. They do work in Linux, both using the old snd-bt-sco+btsco driver, and using the newer bluez ALSA plugins. Audio quality is limited to what SCO is capable of, again, annoying as I prefer to record voice at 16kHz as clarity is slightly better, but I can live with 8kHz — I’ll have to read up on how to get A2DP working. However, I’m so far, only able to reliably use them, with apps that natively support ALSA.

Using the snd-bt-sco driver… I find parts of my speech get cut off. This was tested using Qtel (EchoLink client) and joining the *ECHOTEST* conference (an EchoLink conference that exists purely for testing a station).

Using the newer ALSA plugin, things seem to work okay, but nothing OSS-based will talk to it. Audacity is very hit-and-miss in detecting the headset. Qtel won’t talk to it properly even via the aoss wrapper. I suspect my portaudio v19-based lecture recording app will have similar problems, as it generally only seems to work properly with OSS.

It’s a great start… but I’m not sure this is quite the holy grail I’m after. I’ve been testing this on my father’s laptop, which has onboard Bluetooth. So naturally this means I’ll have to also invest in a cheap USB Bluetooth dongle for my laptop. I may wind up continuing down the path of homebrewing my own set, since it looks like the more flexible solution, and least likely to suffer compatibility issues with the applications I use. Still, it’s been a worthwhile exercise, and certainly I’ll have to keep an eye out for developments in Bluetooth support in future. 🙂

Postscript: Now that I have a Bluetooth headset, I’m in the market for a simple Bluetooth transceiver (using H2DP or SCO) that provides input/output jacks that can be hooked to standard analogue devices such as my amateur transceiver (Kenwood TH-F7E) and my non-Bluetooth enabled mobile phone (Nokia 3310).  I’m aware of RPF Communication’s TalkSafe devices — that’s the sort of thing I’m after.  If anyone knows of something similar to that, available here in Australia, I’d be most interested.

Amateur Repeater Map

As seen/heard on this week’s WIA National News service

GOOGLE A REPEATER

Stuart Longland is in the process of putting together a Google Map of repeater
usage in VK.

This database is based on information determined from the WIA’s list of
repeaters, with GPS locations screen-scraped from ACMA’s online database.

It’s very much a work in progress at this stage and it is only useful for
browsing — no changes you make are actually saved by the application.

Hopefully before long, people will be able to add, edit and remove repeaters.

In addition, Stuart hopes to integrate information on which repeaters are
linked (graphically), including IRLP and EchoLink nodes.

If people wish to get in touch with Stuart, VK4FSJL there’s a number of modes
of contact on his website, or those in the Brisbane area, can get him on
VK4RBC (438.525MHz)

The site is online at http://ham.longlandclan.yi.org/

At present, it only covers VK repeaters, and is presently read-only. Those who look at the JavaScript that drives it, will probably notice it’s also very ugly behind the scenes. The perl script that runs server-side (under mod_perl) isn’t much better.

But, it’s a start… early days at the moment. When I’ve cleaned things up, I’ll release the source code for people to inspect/make changes. Once I get write support added into the DB, that should open the way for repeater information from other countries to be added. The DB has scope for adding other repeaters, as well as representing D-Star, EchoLink and IRLP nodes, however the actual code to drive this is yet to be written.

Anyway… here it is… enjoy. 🙂

Update 20080303

It is now possible to add and modify nodes. So if you know of repeaters in your area — please add them. If you see any mistakes, please correct them. I’ve also added the EchoLink and IRLP node numbers to some of the repeaters, although I suspect there may be other links I’m not aware of.

Deleting nodes is still not possible, so if something is to be deleted, specify “DELETE” in the notes field of the frequency or repeater to be deleted, and I’ll handle those manually.

Open Standards

People who know me, will know I’m quite a keen supporter of open source projects. I’m not nearly as fanatical about it as others, such as Richard Stallman, but I try to support open source as much as I can.

However, I suppose I’m a much bigger supporter, of open standards, than open source. I don’t mind if a project implementing a standard is proprietary commercial software — if the underlying standards it is built on, are open, that makes it possible for an open source implementation to be created. This gives users a choice — they may choose for various reasons to go for a commercial solution, or they may choose open source, it’s entirely up to them.

Now I realise that many of you will be reading this on planet.gentoo.org, and thus I’m likely preaching to the converted. I’m mainly aiming this at organisations that are completely blind to the issues faced. I’m hoping some of those might see this post.

Some might ask, what’s wrong with closed standards? There are a number of issues regarding closed standards.

  • Vendor lock-in: it locks people in to buying from particular vendors, for better or worse.
  • Inflexibility: If you don’t know how it works, how can you modify it to make it do what you want?
  • Control: Who controls what you do with the application? Or the data produced?

If you’re using some closed system, and you run into technical difficulties, the only people who can help, are the makers of that product. You can’t easily switch to another product, and you’re completely at that vendor’s mercy. Some charge extortionate rates to fix even trivial problems, if they help at all. Now granted, there are some good players out there, and if you strike one, great… but if things change for the worse, you’re stuffed.

The ability to understand how a system works is particularly important. Not just with troubleshooting… but also with experiments. Users of a system may have ideas that you as a company have not even considered. Now if it’s open, they can either modify themselves, or hire someone to modify, the system to suit their needs.

Experimentation in one’s spare time is a great way to learn too — university can’t teach you everything. But if the system is closed, how can they experiment? The ability to learn about a system is greatly stifled, when you can’t play with the deep internals at the protocol level.

Control over what you can do with the data produced by a system is a hassle. Remember that you, as the vendor, do not own the data produced by someone using your product. As far as the user is concerned, it’s their data. If I put an audio or video clip of my own work up on my site (which I have done on occasions), it’s not companies like Fraunhofer, or Microsoft, or Apple that own the content, it’s me. And I want the right to be able to share that clip under my terms.

The only reason why the Internet is popular today, is because of open standards. You would likely not be reading this, had it not been due to open protocols such as IEEE802.11b, OpenVPN, Ethernet, TCP/IP and HTTP, and open formats such as HTML. Look at what happened to Compuserve… The Microsoft Network… AOL… Ring a bell? They were all closed networks, that died out because the open wild of the Internet was more appealing to their users.

It isn’t just an issue in the information technology realm. Allow me to look at the problem in another context. Amateur radio, would not exist today as a hobby, if it were not for open communications standards.

If you look past the obvious social and competitive aspects of amateur radio, you see there’s another aspect, the experimentation side. As defined by the ACMA LCD (I’m sure it’s similar in other countries) …

6. Use of an amateur station

The licensee:

  1. must use an amateur station solely for the purpose of:
    1. self training in radiocommunications; or
    2. intercommunications; or
    3. technical investigations into radiocommunications; or
    4. transmitting news and information services related to the operation of amateur stations, as a means of facilitating intercommunication

The two points I’ve highlighted in bold above, are rather important. Put in layman’s terms… if you’re not in the hobby to talk to people, it’s mainly there for experimenting with the technology.

There’s another restriction here too … we’re not allowed to use cryptography, or any kind of secret code, it must be public domain. (e.g. I could, for instance, theoretically use UTF-8 on CW, encoding ones as a dash, zeros as a dot, and using RS-232-like encapsulation. Morse users would get confused however.)

Now suppose FM, for example, were a closed standard — that is, you had to pay some company royalty fees to use them. (Yes, I know that almost did happen way back in the 1930s, but anyway.) How well do you think that’d sit with radio amateurs, who typically like to build homebrew equipment? I don’t think it’d be liked much at all. In fact, if it were secret, it may very well be illegal in some countries. Thankfully this isn’t the case, and even emerging standards like D-Star, are fully open.

Now… back to the IT situation. We can see that a system where the protocols and standards used are fully open, can work. I have to ask why IT thinks it’s special, and insists on closed standards?

Looking at the educational environment … it’s here more than any other place, where we need open standards. How can students be expected to learn about something, if they can’t conduct their own experiments? Experimenting in one’s own time is a good way to gain a better understanding of the topic of study. It’s people graduating from these universities, that will be carrying the industry forward, and I really do think the present industry, should assist by being as open as possible.

Why is it, that universities like inflicting this poor choice of closed systems on its students? Yes, I’m looking at you, Queensland University of Technology, with your extensive use of Microsoft Office, Windows Media codecs (for recorded lectures), Cisco VPNs, Microsoft .NET framework, and numerous proprietary apps/standards.

QUT have a number of labs for each faculty, but also central labs. The central labs have OpenOffice installed, however the labs for Faculty of Engineering, and Faculty of IT, do not. So sure, I can work on some assignment on my personal laptop (running Gentoo Linux of course) — but if I have to email it to the lecturer, I have to either convert it to a PDF (my preferred method), or some have the gaull to ask for it in Microsoft Office formats.

If I comment that I don’t have the money to purchase Microsoft Office, the comment usually is something along the lines of, “Ohh, well you’ll just have to use the computers here.” Yeah well… how about I email my stuff in OpenDocument (ISO26300) format, and see how YOU like walking out of your cozy little office, into the library, and using a computer other than your own to view some file you’re expected to read. Exactly, you don’t like it … why should we be expected to put up with it?!

If that isn’t bad enough, they’ve now dropped using Java apparently for a teaching language. They instead use Scheme for the first years, then go throw them in the deep end with .NET. Way to go for consistency! Probably worth noting that they know nothing about Mono, and expect everyone to use VisualStudio.NET.

I really do think this is highly hypocritical of the university, and it’s an attitude that really disgusts me. Sadly I know they’re not the only ones doing this — some are even worse in this regard. (Then again, some are really open source friendly.) I have good reasons for using the software I do. I at least give you, the choice of using anything that opens OpenDocument formats — which is quite a lot — just sad that your office suite of choice isn’t among them by default. That’s not my fault, and you shouldn’t blame me for that.

I’ve complained directly to them about this before … so I’m now taking this complaint onto the world stage. Don’t like it? Tough.

I try to practice what I preach. One site I maintain, the Asperger Services Australia site, does make use of open standards. Sure Microsoft Office is used internally to write the documents that get uploaded (I’m working on that, give me time), they are converted to PDF. PDF of course is another open standard, ISO32000.

Any multimedia on the site, uses the XIPH foundation codecs Theora and Vorbis. Sure, I get the odd question from a Windows or Mac user about how to play the files, but thanks to the Cortado player applet, and ITheora, I’m able to make the video play for 99% of users out-of-the-box, and cater for the other 1% by allowing them to download the file and play it any number of players that support Theora and Vorbis.

This is handled automatically in most cases, the user isn’t even aware of the underlying architecture. However, if curious, the underlying architecture is open and present for them to look at.

I think it somewhat ridiculous, when looking at science fiction shows such as Star Trek, depicting (fictional) alien craft, produced by completely different lifeforms, are somehow 100% compatible at every layer of the OSI stack. We haven’t even got this today, and every computer on this planet was built by the same species!

I really do think this closed-standards war is hurting more than it’s helping. It’s about time we cut the nonsense, and actually started working together. Protocols and formats, used by systems really should be open for anyone to implement. I don’t mind closed implementations of those standards, that’s fine, but the standards themselves should be open.

Anyway… that’s enough of my ranting… glad to get that out of my system. 🙂

My station setup … and findings

Well… I’ve now been on-air for a little over a month. It has been over that time, I’ve made a number of observations, both about the equipment I have, the technologies, and the underlying culture of amateur radio.

Cultural observations…

Since becoming an operator… it’s amazing how many other radio amateurs you see crawling out of the woodwork… it’s like a secret society. 😉 For the most part, the house of a serious radio amateur is covered with numerous verticals, dipoles, loops and other assorted types of aerial. Their car often has several whips attached. But if you only know someone via some online means … it’s often surprising when you discover they also indulge in the hobby too.

I’m getting to understand how nets work, and how to participate in the field, the social aspects of amateur radio. Still have trouble catching peoples’ callsigns, especially 7-character ones such as my own. (Believe me … took me a while to get used to saying it properly.) But this is all stuff I’m learning… and I’m quickly picking up how it works. 🙂

Station setup…

Antenna installationI’ve got my station reasonably well set up now. A fellow amateur dropped around with a 2m vertical (see left… it’s that big white stick poking through the yagi TV antenna) to stick on the roof, which seems to do a good job on both 2m and 70cm. Eventually I’ll mount this antenna up a bit higher so it is above the TV antenna (presently, there’s apparently a little bit of interference when I have a QSO) using proper mounting brackets, but this does the job for now.

Amateur Station: VK4FSJLUsing BNC-terminated RG58 (surplus from the days when we ran a computer network using the stuff), some T-pieces and 50ohm terminators, I’ve been able to run a feed out to the front verandah of the house where I do most of my work during summer (see right), and another feed into my bedroom.

This works well… my line-of-sight is crap in this part of Brisbane, but with the antenna up high, I’m able to work a couple of repeaters in my local area — namely, VK4RBC and VK4RBN. Out on the verandah, I’ve also got the bonus that it’s nice and cool, with plenty of fresh air, and natural light. 2W of power gets me into VK4RBN reliably… and while the ACMA recently upped the limit on Foundation license holders to 10W on all modes (previously, we were limited to 3W on FM), I still prefer to use only what is required to communicate — I stay QRP where practical. 😉

The equipment…

I’ve mentioned the rig I’m using before… it’s a handheld, a Kenwood TH-F7E. So far, it hasn’t been too bad to use, does everything I want. I use it to listen to and talk with stations on the 2m and 70cm bands, but also, as a portable AM/FM radio (commercial stations), HF radio receiver and UHF CB scanner. Some of the facilities such as visual scanning are really handy. There are a couple of niggles, however…

PSU for TH-F7E... Seriously Kenwood... what is that?!My biggest niggle with this set, would be its power supply (see left). It’s a wall-wart power supply, designed for the two-pin power outlets used throughout Europe and Northern Africa (Thanks Tim, again :-D). This is fine… you could get a decent adaptor that will take the weight of the PSU, but it seems that’s not how Kenwood do things. They instead, provided this pissy little converter consisting of a 5cm length of cable, with an Australian power plug on one end, and a line socket on the other. I have to rest the thing on the floor to use it.

The stock power supply is underpowered — sure, you can charge the radio with it… but forget transmitting. Plus, notice the toroidal core? I had to put that in, otherwise when tuned to Triple M (104.5MHz WFM), I’d instead hear ABC Classic FM (106.1MHz) and Triple J (107.7MHz). My advice to people buying this radio — get yourself a 12v switchmode PSU, capable of at least 2A. I’m using a 4A one sold by Jaycar, which works — no tuning inaccuracies, no noise, and I can transmit a full 5W whilst charging without the PSU raising a sweat.

The other niggle, is that the power levels are perhaps a little awkward. When powered by external DC power, I can transmit on 5W (high power), 2W (low power), or 500mW (“economy low” power). If I use the lithium ion battery pack it came with, this becomes a choice between 5W (high power), 500mW (low power) or 50mW (“economy low”). On alkaline batteries, it’s even worse: 500mW, 300mW or 50mW. It’d be nice to transmit on 2W when mobile — this was particularly a bad limitation when my limit was only 3W prior to the ACMA lifting this restriction.

EchoLink experiments…

More recently, I’ve started playing around with EchoLink, a system for linking repeaters via the Internet. It’s similar in many ways to IRLP, however has the added feature of being accessible from a computer with an internet connection. The official EchoLink client is a proprietary Windows-only client, however, there are a couple of free/open-source implementations of the client. I tried two… namely:

Qtel seems to work quite well, except when idle, it does seem to chew CPU time for no apparent reason. EchoLinux didn’t seem to want to play nice at all, and had many sharp edges. For what it’s worth, the svxlink package in Portage is a little dated now, you’ll find however that renaming the ebuild file to svxlink-080102.ebuild and running the usual ebuild foo.ebuild digest ; emerge foo dance will work just fine. I’m not sure what’s being done to maintain this package — I can’t, as it’s impossible for me to test the sysop functions in it (I’m not permitted to run an automatic station on a Foundation radio license).

The other night I connected to the EchoLink node KB9OHY-R which AFAIK is in the same general territory as former developer cshields — I wasn’t on for long as it was getting fairly late at night… but we may just make contact at some point in the future. (Yes… what was that about not making contact due to being only on VHF/UHF?)

The purists would probably say I’m cheating using the internet to contact people, but hey… in my situation, it’s about the only way I make reliable contact with people outside of Brisbane. And yes, if either one of VK4RBN or VK4RBC were on EchoLink or IRLP, I’d use the network that way. 😉

Anyway… some time at the end of the year, I might look into getting a HF rig. The hamfests are apparently a good way to pick up gear like this, so I’ll wait and see. There’s one coming up in a few months organised by the Brisbane Amateur Radio Club, a club I’m now officially a member of. My big concern is where to put the enormous antennas needed, I suppose I’ll figure that out in due course too.

Looking around for a practical hilbert transform implementation

I’ve been pondering this idea for a while now. When I’m at home, I like to listen to my music… and sometimes, talk to people using VoIP. One big bug-bear I have, however, is being tethered to a desk by the cord of a headset.

Now… I basically have a few options:

  • Cordless headphones (either infra-red or radio) — but these usually are receive-only. I’d need to rig up some sort of cordless microphone to transmit a signal the other way.
  • Bluetooth headset — but they’re much too expensive, and I have no idea how well Linux works with them.

I’ve heard comments that both of the above options, have somewhat lesser audio quality, than a wired set. Many cordless headphones operating on radio, use stereo wideband FM to transmit a signal with a bandwidth of approximately 15KHz/channel. This is okay for what I want, but if I can do better, I might as well aim for it. 😉

Bluetooth headsets offering the A2DP profile, may do better, but they do it through the use of lossy compression. To be honest though, I’m also concerned with compatibility — I don’t have any Bluetooth interfaces on my computers so I’m up for a dongle. My phone (a Nokia 3310… yes, I’ve had it since 2001) doesn’t support Bluetooth, thus the only device I’d be able to use it with, is my laptop. I don’t have a lot of money to experiment — and headsets of this nature cost around AU$250 or more.

So I’m looking at homebrewing a set. Looking at the ACMA radio frequency class licenses, it would seem these devices are classed under the LIPD class license. I’ll have to double check with the ACMA on this… but looking at the gory details, it would seem there are a few bands that are allocated under this license for this purpose…

  • 88MHz – 108MHz (FM broadcast band) with 180kHz bandwidth and maximum EIRP of 10µW
  • 174MHz – 230MHz (VHF television) with 330kHz bandwidth and maximum EIRP of 3mW
  • 520MHz – 820MHz (UHF television) with 330kHz bandwidth and maximum EIRP of 100mW

Now… out of these… the 520MHz-820MHz band has the most liberal power limit of the three, and is also the least populated of the three bands. The catch is… all three of these have to use FM.

There are three signals to be transmitted in two different directions for this project…

  • Two 25kHz audio channels, transmitted by base station to be received by the headset.
  • A single 25KHz audio channel, transmitted by headset back to the base station.

For the headset microphone->base station path, this is trivial… I’ll just use one frequency to transmit a 25kHz mono signal, modulated on a wideband FM carrier. Easy. The difficult bit, is the other direction.

Stereo FM is normally achieved through the use of a subcarrier technique. The left and right channels are transformed into two signals that I call the mono signal (left + right), and the differential (left – right). They’re both band-limited to 15kHz. The mono signal is sent at baseband, with the differential modulated using a DSBSC subcarrier at 38kHz. The entire modulating signal has a bandwidth of 53kHz, generated by these two 15kHz sources.

My idea… is to use single sideband to conserve the bandwidth a bit. I’m undecided as to how I’ll transmit the left and right channels, whether I transmit them separately, or using the mono+differential technique discussed earlier. However it’s done… the plan is that one signal will be transmitted at baseband, and the other… using upper-sideband at approximately 30kHz. The entire modulating signal will have a bandwidth of approximately 55kHz, generated from two 25kHz sources. By reducing the bandwidth of the modulating signal, I hope to improve the noise immunity of my system so I can rely on minimal transmission power.

I have covered the principles behind single-sideband transmission, including simulating a Hartley modulator using Matlab. But looking around, I can’t see any schematic or notes on a Hilbert transform. It should be noted that a real-world Hilbert transform is an approximation, since the theoretical one is non-causal — this is why Harley modulators have a compensating delay.

There’s notes on how to implement them using discrete signal processing techniques, but I really don’t want the complexity of a DSP in something so trivial. I know it can, and has, been implemented using analogue electronics. If anyone knows of a simple, easy-to-follow schematic or notes on the topic… I’d be greatly interested. 🙂

Looking around I’ve found these documents… but if people know of others, I’m all ears. 😉

Getting out of a hole

Well, so far, people may have noticed I’ve been rather quiet on the Mt. Glorious VHF repeater, much to my frustration. Google Maps in the Terrain view, shows why…

Terrain blocking my path to VK4RBN

In red, are the mountain ranges in my way. In blue, the attempted path of transmission. The green arrow shows my transmission location.
(Map Source: Google. Map data ©2008 MapData Sciences Pty Ltd, PSMA)

I can get into VK4RBC without any difficulty whatsoever. It’s a UHF repeater, and as it turns out, the rubber ducky antenna on my handheld, is just 10mm shy of 1/4 wavelength at the required transmit frequency (433.525MHz, the wavelength is approximately 692mm). So 0.5W gets in without any trouble. But… the antenna is not efficient at VHF — it’s a lot shorter than the 500mm required for efficiency, and I’m also far too low for my already weak signal to make it.

Now… if I take a bus over the hill to Keperra, I can get into VK4RBN with only 0.5W of power. No problem. However, here in The Gap, the only way I’ve been able to do so, is using my transceiver at full power (5W; 2W higher than permitted under a Foundation license) and I have to practically sit on the roof to get my signal over the range.

The broomstick special… dodgy dipole for 2m bandUsing a 1/4 wavelength dipole, strapped to an old broomstick (pictured right), I was able to get in to VK4RBN. But only just … the signal was weak, and apparently, very crackly. Aiken (regular in #hamradio on Freenode) confirmed this — we could make contact, but only just. Thus it was necessary to construct a better matched antenna, and mount it up high, preferably on the TV antenna mast.

Whilst talking with Grant on VK4RBC yesterday, he mentioned an antenna design commonly called, the “Slim Jim” which can be constructed from a strip of 300? flat antenna cable, often used to connect TV antennas. They are fed with 50? coaxial cable — very convenient for my set — and can be rolled up for storage. So for a portable antenna, they’re ideal.

Asking around in #hamradio, Magne pointed to this site, which explains the theory behind the “Slim Jim”. Apparently it’s one of many forms of J-Pole antenna, which is itself, related to the Zeppelin antenna (used with the aircraft of the same name). They perform pretty much identical to the end-fed folded dipole antenna — in theory.

The Slim Jim 2m antennaThis afternoon, I wandered into the electronics store, and bought a soldered BNC socket, and 5m of outdoor-type 300? twin-lead cable (Dick Smith Electronics are selling it for about 80c/m, other places may have it cheaper).  About 10 mins of work, and I soon had my antenna constructed.   I soldered it to the BNC plug I had purchased.  The constructed antenna is shown to the left (click for larger image).

For the feedline… we used to run a Ethernet local area network on coax cable, and still had literally oodles of this BNC-terminated RG-58 cable lying around doing nothing.  A small SMA->BNC adaptor on the top of my handheld, and I was soon reaching VK4RBN on the 2m band.

Performance was significantly better than the rubber ducky I had been using.  I still had to use 5W of power, but it got through!  I had some interference trouble at points, the cause is unknown at this stage, certainly my questionable antenna building skills can’t be ruled out, but despite this, I had a around a one hour QSO with Ken on the VK4RBN repeater (a regular on this repeater).  This means I should finally be able to join in with the BARC net on Wednesday nights, instead of just siting back as a spectator.

My one observation —  I had planned to tape the antenna up to a fiberglass rod (originally from a tent — the rods themselves have some cracks in them, thus need replacing) and use that as a mast — however I soon discovered that this particular antenna did not like this kind of treatment.  Doing so yielded very poor signal strength, and seemed to cause the receive frequency to shift — picking up some foreign radio station (not amateur).

Whether the two metal cylinders that link the segments of the rod together are upsetting the EM fields, not sure.  I’ll have to experiment further, but if I let the antenna dangle in the open air, with the matching end up the top — it works fine.

Certainly in future, I’ll have to look at something more substantial, but this at least gets me to the local repeater. 😉

Australia Day Long Weekend Basecamp: Basket Swamp

Note: This story has been unwittingly picked up by John Edwards’ Election Blog. Please note the individual I speak of in this post is another chap entirely, and just happens to have the same name, as the US election candidate.

Well, this last few days, I’ve been camping once again. This time, at Basket Swamp National Park, which is about 20km northeast of Tenterfield, NSW. We left Brisbane early in the afternoon. On route to our destination, we happened to stop at a service station outside Warwick — whilst getting some ice for our water cooler, I happened to look around, and see this vehicle:

My father said “Go on, take a photo, you won’t see that vehicle again for a long time.” Not being quite the geek I’m made out to be, I said “No, you like it so much… you go take it.” and handed him the camera. He shot the photos you see above (click to enlarge). Well, it wasn’t the last time we saw it… we saw it parked right beside us when we stopped for dinner in Stanthorpe, parked in the campsite the following morning, and again parked in a carpark at the start of the walk to Wellington Rock. Apparently Linus has seen it, and was quite impressed at the time.
We had some fun finding the actual entrance to the national park… the GPS unit in our car had no idea about the roads inside the national park (funnily enough, it did know the roads at Gibraltar… ahh well), thus it directed us to go travel cross-country through the scrub. Some distance down the road, we found the true entrance, which had suffered some erosion during the recent storms in the area. We set up camp around 9:00PM that evening (Queensland time… we don’t pay attention to that DST nonsense).

Day One saw us walking down to the Basket Swamp Falls, which were flowing rather spectacularly after the recent rain. On route, we saw some trees with an odd foreign growth on the top — the photos below show what I mean:

As for the falls… well… the photos speak for themselves… the creek was flowing well…

On Day two much of the group climbed up to Wellington Rock. John & Di Edwards were doing some exploration elsewhere, but we had amateur radio contact. In fact, my first ever successful amateur radio contact, was with John this weekend — apparently his set would only transmit at 0.5W, but despite this, I received a very strong clear signal (S8~9/5) about 1~2km through the scrub. Some of the adventurous ones in the group actually climbed on top of Wellington Rock, which apparently offered some stunning views. I stayed put, capturing some shots of the group that stayed behind:

Kym Schluter happened to notice that Little Wellington Rock was nearby on the map… and in his words, “had to be walked to.” So after some bush bashing, we arrived at the aforementioned rock. I managed to get an almost 180-degree panorama — which I’ll put up once I’ve constructed it. In the meantime, the pieces are here:

My father managed to get a bit further along the rock, and caught these snapshots:

Later that afternoon, we drove up to Timbarra Lookout. Sadly the ladder up to the top of the actual lookout was locked, thus we couldn’t see any of the really stunning views from the top. However, I did manage to get this panorama… which again is in pieces for now.

Last trip I went on, we complained about leeches… well… it seems trip leader, Brian Reid, scored the ultimate prize in leech collection… taking off his gators, he watched this whopper roll out onto the ground. Beside is a 1920 six-pence coin as a size reference… the leech is so fat it can’t move, it just squirms on the spot.

The weather had been pretty good so far. I had the “dodgy dipole” 40m-band antenna (made from 15m of speaker wire — a knot tied at 10m and the pairs split out) and figured I’d go and see what I could hear on the shortwave bands. Well, in the distance we saw the thunderstorms roll in. It at first got windy… then it started to spit… then it poured… then… hale!

Some of the tent sites got a little damp after that… being mostly decomposed granite (similar to Gibraltar) much of the water drained away, however there were still some significant puddles left in certain spots around the camp.

Day three most of us packed up. The weather was glorious as we pulled down our tents, which was great — on the Gibraltar camp, it poured with rain on the last day, thus we had to spend a good week drying out the tent. A few of the group planned to stay until tomorrow, but for the rest of us, the trip out was uneventful.

VK4FSJL: On Air

Well… I’ve done it. I can now add “amateur radio operator” (or HAM radio operator) to my skillset. I’ve kept pretty quiet about this thus far, but needless to say, I’ve been curious about radio for a very long time. Longer than I’ve been into computers.

It’s only recently that I’ve bothered to do anything about it. Having learned about the various modulation techniques (SSB, FM, PM, VSB, DSB) work, I’ve been keen to put some of these theories to practice and actually get a real-world understanding of them. Well, I’m now an amateur operator on a foundation license — this doesn’t give me the ability to build my own transmitters, but the plan is I’ll stick with this for a year, then I’ll upgrade to an advanced license (ditching the rather awkward F in my callsign) after some study. I figured I’d start with the basics that I knew I could achieve, while for the advanced license, there are some gaps in my knowledge that I’d like to fill in first.

Scratching the itch…

If you’ve got the itch too, like I did… this is what you do to go scratch it. This applies to those in Australia only.

1. Get the Foundation License Manual

The Wireless Institute of Australia sell a softcover book entitled “Your Entry Into Amateur Radio — The Foundation License Manual”. Get it, and have a good read. It covers all the basic principles of radio transmission sufficient to pass the Foundation license exam. Much of what’s covered will be familiar to those who have done 2nd year Electrical Engineering at university.

Once you’ve read through it, and made sure you’re clear on the regulations, and how to connect transceiver, SWR meter, ATU and antenna together, and the procedure for tuning the assembly, you should be set for the next step.

2. Do the exam

This may be organised via the local radio club — the exams are set by the Wireless Institute of Australia. To sit the exam, you must first book in advance — if you’re not affiliated with any radio club, you can usually contact one of the group leaders and they can often refer you onto someone who organises the bookings.

You’ll need the following organised for the exam:

  1. Government issued photo ID: Either a driver’s license, passport, or 18+ proof-of-age card*
  2. A passport photo (dimensions: 35mm×45mm) to be sent with the license application
  3. About $100 for the examination, and to cover the cost of licensing (payment made in cash, cheque, credit card…etc)

(* For minors without a passport, guardians can certify a child’s identity, but must bring their own photo ID)

The exam for the foundation license consists of two parts:

  • a practical examination, where you’re asked to identify basic electronic schematic symbols, types of cable/connector, how to hook the station up, and basics such as Q-codes and how to give signal reports.
  • a 25-question multiple-choice written examination, where you’re asked about basic theory and regulations (the latter, mostly common sense!). Pass mark is 18/25.

Note you won’t need to know about morse code, but you’re welcome to learn about it if you wish. It’s no longer a requirement.

The exam paper will be marked shortly after the exam, and you’ll know that day if you passed or not.

3. Application and Payment

If you’re unlucky enough to fail, there’s no charge, just go back to step 2 and try again. Otherwise, you’ll be able to fill in the forms to actually apply for a license and callsign, the licensing and exam cost is about $100 (a little less, so bring about $10 in change to cover if you’re paying in cash).

The photo you provide will need to be signed in permanent ink across an area of the photo that doesn’t obscure your mugshot. And make sure it’s the right dimensions (35mm×45mm) — I made the mistake of signing a larger one, and had to rush a correct-sized version to the post office to be sent via express post to the WIA in Victoria.

4. The wait

This will be sent to WIA’s exam service in Victoria for processing. This takes a few weeks (limited resources). The WIA will notify you via post when they forward your details onto the ACMA to assign you a callsign.

In my case, my exam happened on the 16th of December last year. On the 14th of this month (Monday) they forwarded my details onto the ACMA, with this notification arriving in the post today. The ACMA were particularly fast in my situation, looking up my surname in their Register of Radiocommunications Licenses revealed that my license had been approved, that my callsign had been assigned, and was valid from now until the 15th January, 2009.

The ACMA apparently send you a license in the mail, about a week after it appears on the site.

Catching me on-air

If you’re up for a QSO, there are a few repeaters in my area (two of them IRLP nodes) that I should be able to access. Sadly, I can only participate on the 2m and 70cm bands, as I lack transmission equipment for HF (the Kenwood TH-F7E I use can receive, but can’t transmit on HF… and I’m not sure where I can string 20m of cable up in the air in our yard). The repeaters I listen to:

  • Mt. Glorious Repeater — 147.000MHz FM: This one is geographically closest to me, and I should definitely be around Wednesday evenings when the Brisbane Amateur Radio Club have their weekly net.
  • VK4RBA UHF Repeater — 438.950MHz FM: This is the club repeater operated by the Brisbane Amateur Radio Club. Not sure whether this is accessible from my home location, but I may be able to pick it up when I’m mobile.
  • VK4XH IRLP Node 6139 — 146.450MHz FM: This one is located on the South side of Brisbane, thus I may be able to pick it up when mobile.
  • VK4ACN IRLP Node 6406 — 146.575MHz FM: This is one is geographically close to where I live in Brisbane.

I’m not sure what other repeaters are in my area… I dare say I’ll learn of their existence over time. I’m rather new to all of this, having just recently joined the community… but as I say, I’m happy to meet up with people on the amateur bands, now that I’ve got my license. 🙂