Monday, August 30, 2010

Screenshots and copyright

Yesterday I received a comment in the site guestbook from Murray Greenman, ZL1BPU, which says: "While I appreciate your ad-hoc publicity for ZL2AFP CMSK, it would have been much better if you had asked permission to use my screen-shot on your blog site! While web pictures and text are widely plagiarized, that doesn't make it right to do so. Copyright still applies and the image is still mine." I have removed the image and inserted a comment directing the reader to this posting in its place.

Since I am on holiday at the moment and did not intend making any blog postings I will leave it to readers of the blog to lead the discussion on this issue. But I would just like to say that part of my career has been made publicizing software. I have always found software authors to be glad of the publicity and have never, until today, received a complaint about using their own images to this end. It is not always possible to take your own screenshots. In this case, I was unable to try the software on the air because of its insistence on using the default soundcard and I thought that it was more interesting to readers to see the live screenshot made by ZL1BPU than a blank one made by me.

As to the question of whether I should have asked permission first, I wonder if ZL1BPU understands what blogging is about? Part of the motivation for writing about some new development in a blog is to be one of the first, and if you have got to write an email asking permission and wait for a reply then it's likely that others will pip you to the post. It's not like writing an article, which may take several days to prepare and where time is not of the essence. Blogging is a bit like tweeting, but more verbose.

Finally I would argue that a screenshot is not an original work of art. I'm not depriving anyone of earned revenue by using it. Anyone can install the software and obtain one that is pretty similar. So why make an issue out of copying someone's screenshot, particularly when the purpose of doing so is to give publicity to the software not to use it with any adverse intent?

I shall certainly think twice about giving publicity to any more new ham radio programs in my blog in future. Perhaps all of you bloggers who happily copy people's QSL cards and shack photos to illustrate your stories about contacts should pause for thought as well. Ought this not to count as "reasonable use" - the clause in copyright laws that allows you to quote part of an article when referring to it?

Thursday, August 26, 2010

Hacking a USB GPS

As regular readers will know, I've been playing about with APRS quite a lot in recent weeks and I'm starting to get the urge to build something APRS related. I'm planning to order one of the inexpensive FoxTrak kits, which lets you use a standard VHF FM radio to transmit position reports. To do that you also need a serial GPS and on searching eBay I became aware that serial GPSes seem to be rather more expensive than USB or even Bluetooth devices. This led me to wonder whether it would be possible to hack a USB GPS to use with a tracker like the FoxTrak. My investigations led me to this article by Primiano Tucci on GPS Hacking.

This post is basically an un-loseable bookmark to myself, since it will probably be a few weeks before I get around to working on this and by then I'll have lost the article and never be able to find it again. But it might be of interest to someone else or provoke some interesting comments.

Although I'll probably build the the FoxTrak as-is and test it with one of my 2m rigs I'm really interested in trying HF APRS on the move without having to buy an expensive TNC or lug a laptop around me so I can use AGWPE to generate the 300baud audio. So I'd also be interested to know whether anyone has modified the FoxTrak (or the TinyTrak which I believe is very similar) for the 300baud tones? I know the OpenTracker+ from Argent Data does 300baud "out of the box" but it's quite a bit more expensive, enough more expensive to attract the punitive import fees that will almost double the price.

Cut the quotes, please

Why do some people find it necessary to put some irrelevant quote after their signature in forum and mailing list postings? When you see posts from these people several times a day it becomes incredibly irritating.

One person whose posts I seem to encounter frequently has two quotes after his signature: "Whoever said nothing is impossible never tried slamming a revolving door!" and "A government big enough to give you everything you want, is strong enough to take everything you have."

I can't say I ever found the first one very funny but it has got very old after the 100th viewing. And I didn't join a ham radio mailing list to learn about people's political opinions, whether or not I agree with them. So please, just stop doing it.

Wednesday, August 25, 2010

A new use for old technology

The National Museum of Computing at Bletchley Park has found a use for 30-year-old BBC Micros - teaching students how to write programs. One ICT teacher said: "The computing A-level is about how computers work, but if you ask anyone how it works they will not be able to tell you. Modern computers go too fast. You can see the instructions happening for real with these machines. They need to have that understanding for the A-level."

I often think back wistfully to the days of programming early microcomputers where each instruction or subroutine you wrote had a direct effect on the hardware. Even the way things appeared on the screen were a direct result of my own coding. Today, Windows manages all input and output and actually prevents the programmer from directly accessing the hardware. In modern programming you never see a machine instruction. It's all done using high-level language commands to set the properties of "objects" - software "black boxes" that simplify and speed up complex programming tasks but hide the mechanics of their operation. You couldn't write modern software the old way, but I still miss the simplicity of early computing.

I have pretty similar reasons for being concerned at what developments like SDR and D-Star will do to the ham radio hobby. The technology is so complex that the average amateur will have no understanding of how they work, only how to use them. I miss the days when you could open a schematic and follow the path of a signal from one end to the other.

Of course, you can still buy kits to build simple radios. I hope that there will always be a place in our hobby for simple, analogue radios that the average amateur can understand, and I don't mean just in a museum.

Tuesday, August 24, 2010

A DAB of interference

I think it is important when operating a ham radio station from home to ensure that none of your own domestic equipment suffers from interference. It's a sign that everything is OK, and if a neighbour should complain then it helps to prove the point that it is not your fault if you can demonstrate that your own TV, phone, stereo etc. are not affected by your transmissions. I've been surprised at the amount of power I've been able to run using antennas in the attic without experiencing any problems.

Last night I decided to use the digital DAB band of my radio tuner to listen to the Promenade Concert on BBC Radio 3 because Olga complained of hearing some high pitched noise (inaudible to me) on the analogue FM band, when played through a stereo amplifier and a pair of large 40 year old IMF monitor speakers. For a few minutes it was fine, then there were a couple of interruptions to the broadcast which I guessed were caused by the transmission of my APRS beacons. I think that the DAB transmissions are quite close in frequency to 2m so I shut down the 2m APRS gateway and we enjoyed the rest of the concert without interruptions. I imagine that the neighbours, if they listen to radio at all, will use analogue FM just as we normally do, but it is a bit of a concern that just 10W of 2m FM can cause interference to anything.

The only other known problem caused by my radio transmissions is a neighbour's security lights. I imagine this is a common problem. I installed an identical looking PIR controlled security light at the front of the house a few years ago after a couple of drunk youths wandered up our cul de sac one night and decided to uproot some of the plants in a neighbour's garden. I found that I could turn the lights on with as little as 5W on 20m. The solution was to leave our lamp turned off and hope that the neighbour thought it was the wind blowing the bushes around that was triggering his ones. Fortunately it is often windy here and I didn't used to go on the air in the evening all that often.

But my APRS gateway runs from morning to night and runs 50W output on 30m so the problem will become more evident as the nights draw in unless I adopt the simplest solution which is to shut it down (or switch to receive only) at nightfall. Breaking cover by admitting to a neighbour that I have been causing this to happen risks opening a can of worms that could put me off the air entirely, and remedying the problem would be expensive as his lights are part of a professional security installation that I would not be allowed to tamper with even if I wanted to.

Sunday, August 22, 2010

Time to call it a day has just come back online after another lengthy server outage. Scanning the forums I came across this lengthy personal attack on me by 2W0UZO over postings I made about the ROS digital mode several months ago in this blog.

I thought about how to respond but I decided I could not be bothered to dignify his diatribe with a reply. However it has given me cause to reflect on why I bother writing this blog when it seems that no matter how hard I try to explain the reasons why I hold a particular opinion the usual response from the other side is that I am "against innovation", "against new licensees" or whatever stereotypical old-fart criticism they wish to label me with.

Jeff KE9V has decided to pack in ham radio blogging. I think I'll follow his example. Just think how much more time I'll have to actually do things with the radio.

The Windows Genuine Disadvantage

If you visited a shop whose owner appeared to suspect you of being a thief and sometimes insisted on searching your bags before you left, you would probably take your custom elsewhere. And that's pretty much how I feel about Microsoft. Several times in the last few years since the company developed its obsession with software piracy I have been subjected to heart-stopping moments when, instead of working normally when started up in the morning, one of my computers decided that my copy of Windows wasn't genuine and I had to waste time jumping through hoops to prove that it was.

The latest occurrence was this morning when I switched on the shack computer - an HP mini-tower - in order to start my APRS gateway, Microsoft Security Essentials popped up a message saying "You may be a victim of software counterfeiting" and stating that it would stop working in 30 days unless I did something about it. It offered a link to check the system. This opened in Firefox where I was requested to download a plug-in. After that I was asked to click a Continue button which was supposed to run the validation check. Nothing appeared to happen. Eventually I tried the second option provided for browsers on which the first one wouldn't work, which downloaded an .hta file to my desktop. With no other instruction as to what to do next, I clicked on it - all the time wondering if this wasn't some clever software hoax to trick me into installing malware on my system. Fortunately it wasn't. I was informed that, hoorah, hoorah, my copy of Windows supplied by HP was indeed genuine after all. Thank you, Microsoft, that's ten minutes of my life you just wasted. But by the by, if you must be so anal about pirate copies why do you have to make the checks so intrusive and complicated?

The previous time something like that happened was the trigger for me to dump Windows and install Linux on my shack computer. However, as I have written previously, I found Linux forced me to make too many sacrifices which is why in the end I went back to Windows. Linux the OS is fine, it's the lack of high quality applications (particularly in the ham radio sphere) and the decision by many hardware manufacturers not to provide Linux drivers that makes it frustrating. Having said that, most of the programs I regularly use are either available in Linux versions (like Fldigi) or will run on it under wine (like APRSIS32.) But the truth is, the older I get the more I feel that life is too short for faffing around with computers.

Saturday, August 21, 2010

Garden party

Olga is having a little party on Sunday afternoon to show off her garden to a few friends and neighbours. So there will not be much time for radio this weekend as I will need to be on hand to help tidy things up, fetch anything she suddenly finds she needs whilst preparing, and finally the hard part - drinking wine and being sociable! But I thought you might appreciate seeing some pictures of the garden taken a few days ago.

The photos don't give much of an idea of scale, but the garden is tiny. It is about 20 feet from the back of the conservatory to the thick, high hedge at the bottom of the garden, and about 30 feet from one neighbour's fence to the other. The lack of space, and the desire not to spoil Olga's floral wonderland, are just two of the reasons why I think attic antennas are the best option in the circumstances.

Friday, August 20, 2010

Too many radios

If your better half complains that you have too much radio equipment, just show her this article.

Avoidable Acronym

You've all seen it: a new or prospective radio amateur joins a web forum and posts: "I'm looking for advice on how to get started in HAM radio." HAM is not an acronym. What do they think it stands for? I consulted the Acronym Finder and could find nothing remotely relevant.

Having been in computing for more years than I care to remember, I know that the avoidable acronym is not a new invention. The one that really used to bug me is HELP, as in "Software includes full online HELP." For goodness sake! Help is a word, not an acronym. I don't think it was meant as a cry for assistance: HEEELLLPPP!!!! though I have come across a few programs where that would be appropriate.

Another example is FAX. Again, I can't think of three words it could be an acronym for. It's short for facsimile, so it's just fax.

And ham is short for amateur, so capitalization is not required. There are many suggestions as to why amateur radio became known as ham radio. No-one really knows. Some say it has the same origins as "ham actor", though that's a pejorative term for an actor who overacts and generally isn't very good. Others suggest it comes from British English. Cockneys (working class Londoners) drop the leading H from words like "hurry" or "have", so they would often insert it in front of words where it doesn't belong when trying to "speak posh." Hence "amateur" would become "hamateur" and then "ham".

Who knows? But whatever the origin, ham certainly isn't an acronym.

K3 Killer imminent?

Kenwood Corporation recently announced the October launch of the long-awaited TS-590 HF/6m transceiver. Described in some quarters as a "K3 killer", the new transceiver uses the novel (for modern Japanese radios) approach of a single conversion receiver with a low (11.374MHz) IF on the amateur bands to give what is claimed to be exceptional dynamic range.

The news release bears careful reading, as what it doesn't say is as interesting as what it does. The receiver will have a 6KHz roofing filter directly after the mixer, followed by a 500Hz or 2.7KHz filter (both included as standard) after the post-amplifier. But a footnote states that "For 1.8/3.5/7/14/21MHz amateur bands, when receiving in CW/FSK/SSB modes down conversion is selected automatically if the final passband is 2.7kHz or less" which suggests that a conventional (for the Japanese) up conversion will be used for the short wave bands, AM or FM modes, the WARC bands, 10 and 6m.

I think the current obsession with receiver performance figures is absurd. I am far from being a member of the Elecraft fan club, but even assuming the TS-590 does turn out to outperform the K3 on the main amateur bands, I think anyone considering swapping their K3 for the Kenwood on that basis would be foolish.

As far as I know, the Kenwood will not have an option for a second receiver, nor one for a panadapter. It will not have the transverter and external preamp interfacing (which I use to insert the MFJ noise canceller) nor an independent receive antenna input. I doubt that it will have fully isolated audio inputs for data nor a soft ALC in digital modes that allows you to vary the power output in PSK31 without fiddling with computer mixer settings to avoid IMD problems. I'm sure it won't have an internal 144MHz option either.

Whenever I look at the features of the K3 that I am currently using, I realize that there is nothing else on the market at a price I am willing to pay, nor which would fit on my operating desk, that could do what my K3 is doing.

The price of the TS-590 will be 228,900 Yen, or about £2,000 by the time you have added on VAT (never mind the usual exorbitant UK dealer mark-up.) If it goes on sale here at £2,499 I will not be surprised. Compared to currently available HF radios and Kenwood's previous HF models including the TS-570 to which this new rig bears a considerable similarity, the TS-590 looks overpriced for what in the end is nothing more than a compact HF/6m radio.

A K3 killer? I don't think so!

Wednesday, August 18, 2010

Sound card packet modem

Last night I spent a couple of hours trying a program that had been mentioned by Chris, G4HYG in the Cross Country Wireless Yahoo group called AX25-SCS. It is a sound card modem for 300baud and 1200baud packet which was written by Frank Perkins, WB5IPM for use with a now unsupported APRS program called APRS-SCS (nothing to do with the SCS that makes TNC hardware.) Chris claimed it works better than AGW Packet Engine at decoding HF APRS. It is also freeware. I had never heard of this program before despite quite a bit of time spent searching for packet sound card software. You can get it from the TAPR website, installation is simply a matter of unzipping it into a folder, and there is a .pdf file that tells you almost all you need to know to run it.

One of the things the documentation doesn't tell you is that AX25-SCS uses the default Windows sound card. For testing, I had to make the sound card used by my Elecraft K3 the default. This is not convenient, as it robs my computer of the ability to play sound through the speakers (and risks broadcasting Windows sounds and web audio over the airwaves) so sadly I am unable to make permanent use of it.

The documentation also doesn't advise you to select "Cancel APRS-SCS support" when you first run it. If you don't, nothing will appear in the window until an APRS client connects to it, making you think that the program just isn't working.

For HF use you need to select 300baud from the menu, as 1200baud is the default. You also need to select Enable SCS TX to allow transmission. It would be a bit of an annoyance that you have to do this every time you start the program as the settings are not remembered.

Once the receiver is tuned in - AX25-SCS uses the KAM standard 1600 / 1800Hz tones for HF - and the sound levels adjusted so that packets are being decoded, you can close and then restart the program this time choosing "Enable APRS-SCS support" from the initial dialog. After that, start APRSIS32 and create a KISS TNC RF port at address port 4000. When APRSIS32 connects, the display should appear on the AX25-SCS window as it did before and this time any packets received should be displayed in APRSIS32 as well. Beacons and messages sent from APRSIS32 should result in audio being generated by the sound card modem for transmission.

For transmit, APRS-SCS requires the transceiver to use VOX. This is not a problem with my K3 which supports VOX via the rear audio connections and which allows the delay to be adjusted down to a very short interval, but it would make the program unusable with other transceivers like the FT-817 which don't.

I tried running APRS-SCS and AGWPE Pro in parallel to see which was the better decoder but it was difficult to do a fair trial as APRS-SCS needs a lower level of audio input so the signal level was either too high for one program or too low for the other. As far as I could tell, APRS-SCS appeared more tolerant of off-frequency signals but less sensitive to weak ones than AGWPE Pro. This is also the verdict of Chris, G4HYG.

I would be willing to give APRS-SCS more of a try, but the inability to specify which sound card to use makes that impractical. It's a pity that APRS-SCS is not open source so that someone could fix that and the other minor niggles, because it is a nice program that is quite easy to set up and use with APRSIS32.

Tuesday, August 17, 2010

Nice Nagoya

As regular readers may recall, I have a pathological hatred of SMA connectors when used as antenna connectors for hand-held radios, which has become even more entrenched since I had the centre pin of the TH-F7E stock antenna break off in the adapter I use for testing such antennas on my antenna analyzer. I now have an SMA to BNC adapter permanently installed on my VX-8GR. The picture on the right shows my latest adapter which is anodized black and looks like an integral part of the radio. The previous one I used was gold plated with a knurled body and whilst it worked perfectly and provided a robust fitting for the BNC antennas it looked a bit ugly.

If you never change the antenna on your HT then one of these adapters isn't necessary, but SMA connectors were never designed for multiple connections and disconnections (in one email group I saw someone state they were rated for 100 disconnections) so if you want to change between a short stubby antenna for inconspicuous local use and one with more gain the BNC adapter is the way to go.

All of my BNC whips are 2m antennas, which is fine most of the time as almost all my operating is done on 2m, but there are rare occasions when I might want to use 70cm and removing the BNC adapter in order to attach the stock antenna kind of defeats the object of it. So I ordered from eBay a Nagoya NA-701 antenna which is a short dual band whip similar in size to the ones supplied with amateur dual band handhelds but with a BNC connector.

I tried it out on my antenna analyzer and it showed a nice sharp SWR curve with the minimum around 147MHz. It could be better, but it's closer than some stock antennas I've tested. I couldn't check it on 70cm as my antenna analyzer doesn't go up that high.

I need to devise way to make comparative tests of all these HT antennas, because asking for signal reports or seeing if you can hit a repeater is a pretty crude measure of performance that won't reveal small differences. This little antenna doesn't perform as well as a six inch monoband helical on 2m, nor a quarter wave telescopic, but that is only to be expected. The beauty of the BNC adapter is that if you need a gain antenna you can easily whack on something like my 5/8 wave Black Whip, which you certainly couldn't use with a standard SMA connector.

Mystery beacon

For the last three hours or so I've been driven mad by an APRS beacon on 2m that I can't decode and which is not being gated to the internet by Richard MM1BHO's gateway. The amount of activity on VHF APRS round here is so low that I normally leave the receiver audio on so that I can hear whether anyone is about. The signal I'm hearing is quite solid, obviously from a fixed station or a stationary mobile, and though it isn't massively strong - just about making 1 bar on the Kenwood's signal strength meter - it sounds fully quieting and as good as other signals I hear which are decoded.

I tried both wide and narrow FM modes and when that didn't help I switched the antenna over to the FT-817 so I could try the AGWPE sound card decoder. I even tried plugging the antenna into the VX-8GR to see if that could decode it, but no joy. Listening to the sound of the beacon compared to the sound of my VX-8GR's beacon, the one I can't decode is quite a bit louder. I think it might be over-deviated.

So on the off-chance that someone trying APRS round here might read my blog, I thought I'd publish this posting. If it's you, try turning the audio into the transmitter down and you might get gated.

Is it just my computer, or has Jeff KE9V's blog site gone QRT? His last posting in the Blogger "Reading List" feed was to do with the controversy over the Ground Zero mosque, but when I click through the page has gone, as has his entire site except for one placeholder page. I don't know what Jeff had to say on the subject or whether it had anything to do with his site now being down.

Monday, August 16, 2010

Another great cockup

Another weekend of glorious weather. I decided to make an early start on Sunday and try a slightly more ambitious Wainwrights On The Air (WOTA) activation than normal. The plan was to walk over Barrow and Outerside and, if my legs still had enough energy left in them, Causey Pike. Though a much easier walk than those undertaken by Phil, G4OBK, I haven't done much hill walking since getting married nearly 8 years ago and am not as fit as I used to be. This would be the longest walk I'd done for a long time.

I set off in the warm sunshine at about 9.30 and after about 15 minutes heard "CQ WOTA" from Phil who had arrived on the summit of Dodd, the other side of Bassenthwaite Lake. I was afraid I might have missed him while I was on the road. His expected arrival had been an hour earlier and I'd waited to try to catch him from the home station. But the day was warming up and he might have had a change of plan so I decided I couldn't wait any longer. Dodd was a new summit worked for me so I was glad to have caught him. It also meant that Phil's effort hadn't been in vain because Dodd is a difficult hill to get contacts on.

The path I was taking passed along the flank of Barrow. To reach the summit I would have to backtrack on a higher path. On the map it didn't look far but in reality it looked quite a long walk so I decided to get Barrow on the way back and started the climb to Outerside. It was a pleasant and not difficult climb, but sweaty work in the growing heat. Eventually I reached the top (first picture) from where I made several contacts on 2m using the telescopic 5/8 wave antenna, including another with Phil G4OBK/P who had by now reached Carl Side.

I was not inclined to hang around on the summit which was plagued with flying ants - as were all the Lakeland summits judging by the comments of other hill-toppers. I descended the other side of the hill and made my way back to the main path from where I saw a track up the side of Causey Pike which looked like a shortcut. I crossed the path and made my way to the track, where I sat down and ate my packed lunch as there were no insects in that area.

Causey Pike is a narrow ridge with several undulations along its length. In fact I seem to remember one walkers guide I read a few years ago referring to it as Causey Pikes. My Ordnance Survey map shows it as a long, narrow island surrounded by the 2,000 foot contour (it's an old map, made before they went metric.) I have walked along it several times over the years since I first came to the area but I had never given much thought to exactly which of the undulations was the actual summit was because at the time it didn't matter.

The shortcut looked too short to reach 2,000 feet. I set off, and after about 15 minutes reached the crest. From there it didn't look like 2,000 feet either. To my left, after a few more feet of climbing, was a small plateau which was followed by a sharp descent into the valley. To my right, the crest of the ridge rose steadily for what looked like another 400 or 500 feet. "The summit must be up that way" I thought, so I turned right and off I went. On the way I stopped to work Ian, 2E0EDX/P on Brim Fell, for another summit that I wouldn't have worked from home.

Eventually I arrived at the highest point which was surmounted by a rough stone cairn. I started to call "CQ WOTA" and made several contacts from what I described as the summit of Causey Pike, including one with Colin, 2E0XSD whom I asked to check whether my position was showing on He confirmed that it was, and the details tallied with what my VX-8GR GPS was showing.

I started to make my way off the fell on my way home by the main footpath when I was called by Phil, G4OBK, to pass on a message that Colin didn't think I was on Causey Pike when I made the contacts. Since Colin sometimes has a bit of fun at my expense due to an error I made during an earlier activation the thought crossed my mind that he was having a wind-up. Shortly after that I received an APRS message from Colin which stated that I was on Scar Crags, not Causey Pike. I had never heard of Scar Crags but I knew that there was another hill nearby called something Crags (having checked it is Ard Crags) so I thought that perhaps the position of the labels on the map may have caused Colin to mistake my position and decided to carry on descending.

While all this was going on I was watching a couple of mountain bikers zooming down a zig-zag path that had been made on the side of the fell named Sail opposite where I was standing. This unsightly path has been made because the number of boots (and presumably tyres) ascending and descending the fell had destroyed the original path and made it dangerous. Britain is an overcrowded island and the number of visitors, particularly in recent years as more people take holidays at home, is literally causing the hills to wear out!

Further down the path back to the car the surface had been repaired by tipping truckloads of small rocks into the channel caused by thousands of boots, so that instead of a gentle walk down I had to pick my way from rock to rock like on a rocky beach. Not a particularly welcome activity for legs that were becoming tired. The battery of my VX-8GR finally expired during a contact with a SOTA summiteer in Northumberland whose call I heard on the walk down, so there being no point in taking the loop over Barrow I walked straight back to the car and came home.

Back home, examination of my position report on showed that Colin had been right. I had indeed been on Scar Crags when making my "Causey Pike" contacts.

I had never heard of Scar Crags before and was completely unaware that it was the name of a Wainwright summit. However, had I stopped and looked at the map at the time it is unlikely that it would have convinced me that Colin was right. In this small grab from the online version of the map Scar Crags is shown at the bottom of the crags, which would suggest to me that it was the name of the cliffs and not of the actual summit. And the plateau that I now think may have been Causey Pike did not seem as prominent as the contours on the map make it look. Perhaps all the millions of boots have worn it flat, too. Only seeing my GPS position on the map and looking at Wainwright's book made me realize that this was another great cockup (as distinct from Great Cockup.)

It's rather embarrassing to make such a public mistake, as well as frustrating to have missed the opportunity to activate the real Causey Pike. I will just have to try again one day. And next time, perhaps I'll also activate Barrow.

Saturday, August 14, 2010

Inconvenient spurious

During the middle of the day here 30m becomes virtually dead and there is nothing to see on HF APRS. I decided to try some digital modes. After a quick tune around I couldn't hear any digital apart from PSK. These days, if there's propagation there is PSK activity.

I had quick listen on 15m and even spotted a couple of stations to PSK Reporter, but signals were really weak so I dropped down to 17m. On 17m I have to use the MFJ magnetic loop, which I needed to re-tune from 30m. As I did so I was startled by a loud buzz from the Kenwood TM-D710 on the VHF APRS channel. I turned the volume down, suspecting a spurious but not knowing if it was the fault of the K3 or the Kenwood.

I made several European contacts using PSK31 before lunch including Veljo, ES0OU on Saaremaa Island, which is IOTA EU-034. None of my contacts wanted chat, though you have to realize that English is not the first language for any of these stations, if they speak it at all. I suppose here in Europe we have to be thankful for macros.

After lunch I walked into town with Olga. On my return the receiver was still on 17m and had spotted a long list of stations to PSK Reporter. KU1T, Zibi from Glengary, WV (pictured above) was one of those spotted. I waited and eventually saw his trace appear on the screen. I gave him a call and he replied. Copy was in and out of QSB so it was one of those contacts where a conversation would not have been possible. KComm told me this was my first USA contact on 17m.

Later, a few seconds with the calculator revealed the reason for the strong interference with the VHF APRS frequency. 18.100MHz, the carrier frequency used when operating in the 17m PSK31 band segment, is exactly one eighth of 144.800MHz!

Rough justice

Some UK readers may already know of the case of Carl Johnson, M3VWP, who was prosecuted for driving without due care and attention, found guilty, fined and received three points on his driving license for operating his 2m mobile rig whilst driving.

In the UK it is, quite rightly, illegal to use a mobile phone whilst driving - though you can see this law being flouted every day of the week. There is, however, an exemption for the use of two-way radio, which applies to ham radio mobile operation. You could argue - and personally I would argue - that if it's dangerous to use a mobile phone then it is no less dangerous to use a ham radio. But that's beside the point. It is not illegal to use a ham radio whilst driving and unless he was actually driving dangerously as a result, M3VWP should never have been prosecuted for it.

Nevertheless, he was, and when summoned to court he decided to represent himself. Despite the existence of many holes in the prosecution's case - according to his letter in Practical Wireless, Carl was stationary at traffic lights when spotted by the officer, who after an hour at the roadside apparently admitted he didn't know the relevant law himself - M3VWP was found guilty. He decided not to appeal.

Of course, it's just my opinion, and I know only what I have read, but I feel sure that if M3VWP had been professionally represented in court, or had appealed, he would probably have got off. A good solicitor might have got the point across that the law against using mobile phones did not apply in this case and that Carl could hardly have "not been in proper control of his vehicle" as he was stationary when spotted by the police.

Unfortunately in the UK only the very poor or the very rich have access to justice. If you're poor, you receive legal aid, but if you have any means at all you have to pay the exorbitant legal fees yourself, and only the very wealthy can afford to take such a hit to their bank balance. One can only feel sorry for M3VWP for being convicted when he did nothing wrong. It seems that it doesn't matter what the law says, if the police think you've broken it then that's it.

Radio amateurs in the UK take note. Operating your radio whilst mobile could cost you a hefty fine and even, if you already have some points, lose you your driving license.

Friday, August 13, 2010

No improvement

I know that one of the purposes of my website is meant to be to demonstrate that you can play ham radio even if you can't have outside antennas. But sometimes the frustrations of not quite being able to achieve what you want to make become almost too much.

On Tuesday I replaced my home made ribbon cable Slim Jim 2m antenna with a commercial dual band colinear from Moonraker. I wasn't sure the home made antenna was working as well as it possibly could. Originally I planned to replace the Slim Jim with a single band 5/8 wave Sirio, but after a month waiting for Radioworld to deliver it I cancelled the order and gave up. Then I got the Kenwood TM-D710 which is a dual band transceiver, so I decided I should have a dual band antenna to give me the option of running a public Echolink node on 70cm.

During the last few days I have been searching for signs of improvement in my 2m receive capability, but the signs haven't been good. I'm hearing a frustrating number of APRS "braaps" that are just not strong enough to decode.

The antenna certainly works. I'm getting almost end-stop signals from the repeaters GB3DG and GB3LA, whilst GB3AS is about S5 with a bit of noise on it. I have had a couple of solid contacts using the antenna but nothing to form a basis for comparison until today, when Noel G4PEW drove past.

On the left of the screengrab you can see his track on Monday, when I was still using the Slim Jim. On the right you can see today's track, received using the new antenna. It's a lot shorter. I certainly heard a lot of packets after the last one shown by the grey blob, but none were strong enough to decode.

If only I could have the antenna outside the attic, up above the apex of the roof, I'm sure that extra little bit of height would make all the difference.

Wednesday, August 11, 2010


I happened to visit the web site of Andy, GD0TEP this afternoon and noticed that he had a link to a page of scanned images of his QSL collection. These are not your average QSL cards, but ones containing images of attractive young ladies wearing little or no clothing in some quite delightful poses. If you are a red blooded male then these are sure to bring a smile to your face and get your pulse racing!

I believe that some people may be offended by such images (though I can't imagine why, as the naked human body is surely one of the more attractive of nature's creations) but to avoid any surprises this link will take you to the warning page Andy has created. From there, click on the link to enjoy his collection!

Highest activation?

Steve WG0AT, Rich, AC7MA and Guy, N7UN recently returned from their expedition to activate Huron Peak in the Sawatch Range in Colorado, USA, for Summits On The Air (SOTA). Together with their "sherpa" goats Rooster and Peanut, they took a GPS-equipped Yaesu VX-8R so people could track their progress.

You can see a slide show of the expedition here.

I rather like the idea of using goats to carry the heavy equipment but I think you'd get some funny looks in the hills around here. This has made me wonder what has been the highest SOTA activation to date. Has anyone activated Mount Everest yet? I bet that would create a pile-up!

Logging assistant

When you are out in the field, especially on a windy hilltop, logging the contacts you make can be a bit difficult. One hand holding the radio or microphone leaves only one hand free to hold down the log book and write in it. If you're using a hand-held and standing up to get the maximum height gain, it's even more awkward.

A few weeks ago I hit on the idea of using a personal digital voice recorder. Initial researches suggested that they were a bit expensive - many models sell for around £70 or more. But diligent searching on eBay revealed that it was possible to buy them for much less than this.

The one I got is an Olympus VN-100 Digital Voice Recorder and cost £15.99 including free postage. It was described as "refurbished to new condition by Olympus." This might be an indicator of a product that tends to fail and has a high number of warranty returns. However, this particular one was indistinguishable from new, works fine and is simple to use. It isn't the colour I'd have picked if I had a choice, but price and functionality were the principal considerations.

I don't know what the differences are between the VN-100 and the more expensive models apart from colour, probably storage capacity. However this model has capacity for more than 13 hours of recording - more than adequate for my purposes.

I find the VN-100 easy to operate with the hand that isn't holding the radio. You just press one button to start recording and another to stop. A bar meter shows the level of the audio input. You can either say the callsign, time and whatever else you are interested in logging, or just point the device at the radio and make an off-air recording. At home it could be a handy shack tool for recording unusual DX contacts.

The only problem I found is that the voice recorder is just as sensitive to wind noise as the microphone in the radio. More than once I have returned home to find a recording was unintelligible. However, mishaps like this can probably be avoided with practise.

I'm finding my digital voice recorder to be an indispensable companion on portable outings. It's also handy for jotting down ideas for blog posts that occur whilst you're out and about!

Tuesday, August 10, 2010

APRS for Blackberry

Hot off the press. An APRS client for Blackberry smartphones is being developed. More information about it can be found here.

Internet killed the radio chat

The unwillingness of many hams to chat or ragchew on the air is becoming a frequently raised topic on blogs and forums. One QRP blogger recently complained after one of his CQs received a "599 TU OM" type of reply.

It's sad but, I think the disappearance of the ragchewer is inevitable. Thirty five years ago when I was first licensed, if I wanted advice on something I was doing I would call CQ and hope someone knowledgeable would reply. Much of what I learned about radio after getting my ticket I learned from on the air conversations. Today I would go on the internet where I can find out much more, much faster.

In the late 1980s I added my first modem to my home computer and discovered bulletin boards - the forerunner of today's internet. There I could chat with fellow computer enthusiasts without any of the aggravations of QRM, QRN and QSB that afflicted ham radio communications. My ham radio usage fell right off to the extent that I eventually sold my gear and let my license lapse for several years.

Whilst playing with radio is fun, especially if you like building electronic things or are interested in propagation, the internet is a much better system for finding like-minded people to chat with and provides more reliable ways to communicate with them. We're all guilty! Every mailing list or forum thread and every blog post with its follow-on comments is a conversation that once upon a time might have been conducted on the air. The internet has changed ham radio and there is nothing anyone can do about it.

That isn't to say there is no point to ham radio any more. But the point is increasingly about how far (or where) your radio signals reach, not what you actually say. Contesting and award chasing with their "599 TU" exchanges are popular like never before. And there is lots of interest in modes like WSPR and QRSS beaconing that allow you to see how far your transmissions go without the bother of having to contact somebody and receive a report from them.

The art of on the air conversation is dying out. The reluctance of digital mode users to venture beyond sending their pre-prepared macros is one example of this. Making a ham radio contact no longer requires an exchange of personal information, you simply need to receive enough of someone's signal for it to be identifiable as theirs. And digital modes have been developed that facilitate the exchange of just this minimum information.

The popularity of the JT65A mode on HF can be explained by the fact that it allows people to make "contacts" without having to speak or type anything, because the exchanges are all coded into the software. VHF enthusiasts now work each other using weak signal digital modes whilst they are in constant contact, not using radio, but via ON4KST Chat, an internet chat channel. When you need to keep in contact, it seems, radio is too unreliable. The same appears to be true for DX Cluster spots. How many people still receive them using packet radio?

The ham bands are becoming no more than a playground for those in which the unpredictable vagaries of propagation provide the key element that makes their activities a challenging and absorbing pastime. But as a serious communications medium, unless you're half way up a mountain or in the middle of Africa where the internet and cellular networks aren't available, radio is becoming somewhat redundant.

If you want to talk to somebody about your favourite ham radio topic why worry whether the propagation gods are feeling kind to you when you could just start a thread on Yahoo Groups or or go on Echolink?

New digital mode for LF

A new narrow band digital mode optimized for MF and LF (160m and down) has just been released. Developed by Con, ZL2AFP the new mode is called CMSK.

(Image removed per author request)

CMSK uses Minimum Shift Keying (MSK). This is similar to Phase Shift Keying (PSK) but the frequency is shifted smoothly, achieving a 180 degree phase shift within one bit period, with the result that no amplitude variations occur, so the transmit amplifier need not be linear.

The mode has been designed specifically for use on the lower frequencies which provide good phase stability on received signals and low Doppler shift but can suffer from a high level of impulse interference. Four variants are available, ranging from CMSK8 which has a 12.5Hz bandwidth and supports a typing speed of 3.75wpm to CMSK125 which requires 200Hz and gives a typing speed of 60wpm. The default mode is CMSK63 which uses a 100Hz bandwidth and supports typing at up to 30wpm.

The software can be downloaded from Murray Greenman ZL1BPU's website.

Look, no antenna

If you are frustrated by the inability to put up as good an antenna as you would like, take a look at the experiments being conducted by Roger, G3XBM, using an antenna made in the ground using 20m spaced earth electrodes. The results are quite amazing.

Unfortunately many of us in the UK cursed with antenna restrictions also have postage stamp sized plots where achieving 20m separation would involve having one electrode in next-door-but-one's garden. But if your only problem is awkward neighbours, not the size of your plot, this might be something to try.

Monday, August 09, 2010

R is for Readability

A couple of times I have been told by a station I was in contact with that my signal was "Radio Five". I was a bit offended. As a classical music lover I would have preferred to have been "Radio 3", or at least "Radio 4" which is the BBC's highbrow channel with news, arts and current affairs programming. But joking apart, what were they trying to tell me?

I don't want to sound like one of those curmudgeonly old farts who believe that it would have been better if newly licensed hams had never been born in the first place. I'm well aware of how such an attitude can, and has, put off newcomers to the hobby, and don't wish to discourage someone who might just have plucked up the courage to make their first QSOs by telling them they are doing it wrong. At the same time, I'm afraid that if one does nothing, says nothing, these nonsensical phrases will slip into common usage like a virus as others hear them on the air and think that's what they are supposed to say too.

So let's set things straight. The only "Radio" you need to mention during a contact is the make and model of the box you are talking to me with. If you are giving me a report on how well you are receiving my signal then the term is READABILITY.

Pileup on the fells

The hills are alive with the sound of "CQ SOTA" and "CQ WOTA". These two adventure radio programmes are becoming so popular that anyone trying to make contacts from a hilltop this last weekend on 2m FM had trouble finding a clear frequency. The sight of radio amateurs on mountain summits is becoming so commonplace that soon it will be the ones without radios getting the funny looks.

On Sunday morning Olga said to me "You should go for a walk". Needing no further encouragement, I tossed the VX-8GR and a few bits and pieces into my rucksack and off I went. I parked at Thornthwaite near the old Swan Hotel and made my way up through the forestry roads to the minor summit of Barf. I didn't go up by the direct path from opposite the Swan as it is very steep and slippery - I came down that way once a few years ago and it was enough for me.

On the way up I had a contact with top Wainwrights activator Phil, G4OBK/P on the summit of Brandreth. Phil is well on his way to completing the challenge of activating all 214 Wainwright summits in the English Lake District within two years and reached the half way mark this weekend. Visit Phil's Wainwrights blog if you get a chance.

Shortly after contacting Phil I saw two ospreys circling over Bassenthwaite Lake and calling to each other with their high-pitched cry. I stopped and took the picture shown above of the view towards Keswick. About ten minutes later a small red deer came out of the forest about 100m ahead of me and trotted into the distance. Perfect!

It was cool but humid, but the misty weather creates a special atmosphere in the forest that is very pleasant. However once on the top of Barf a drying breeze was experienced. I made another contact with Phil, who was now en route for Great Gable, so he could tick Barf off on his "worked" list, and made another contact with Geoff GM4WHA. I also received an APRS message from Colin 2E0XSD, who unfortunately couldn't hear me direct due to the amount of rock between us.

I then set off for the higher summit of Lords Seat, which I reached in about half an hour, where I stopped and had my lunch. By then Phil had reached Great Gable so we had a summit-to-summit contact. I made numerous other contacts, including Geoff and Colin and a couple people on SOTA summits outside the Lake District. I received a lot of comments about wind noise in the microphone, despite trying to shield the radio with both hands. The VX-8GR is the only one of my 2m hand-helds not to have a speaker mic, due to the fact that the only option is the expensive original Yaesu version. I should probably carry the VX-8GR just for the APRS and take the Motorola GP300 for voice contacts.

Simon, M3IWN/P called CQ from the top of Scafell Pike in the Lake District, which is England's highest mountain. He was doing a SOTA activation and had a beam antenna with him. On a clear day I could probably see his summit from where I was, but he had so many callers that after 10 minutes of trying he still hadn't heard me. I decided to move to another frequency and make some contacts of my own, checking back on Simon's frequency now and again until eventually he got my call and we had a contact. At the time I worked him Simon had filled two and a half log pages with contacts including several summit to summits.

The QRM up there had to be heard to be believed. I was only using a 2m helical. The VX-8GR receiver tends to die in the presence of strong signals and I have heard strange things when using anything better than the stock antenna. Another reason for taking the Motorola, which has a better receiver. First, though, I will need to reprogram it to cover 145.300MHz, the frequency Phil likes to use on his activations.

Over the weekend I think something like 20 Wainwright summits were activated by around half a dozen different operators. Scafell Pike was actually activated twice on Sunday! Later in the afternoon after Simon had left I saw a spot had been posted for another station on the same summit.

I returned to the car via the forestry roads for a very pleasant walk with a lot of radio fun as well. If you want to join in, come to the English Lake District on a summer weekend - you won't regret it!

Saturday, August 07, 2010

Making HF APRS MOR robust

I was surfing around looking at information about robust digital modes, as you do, and stumbled across something called the WINMOR Sound Card TNC. WINMOR is a free, open and documented protocol intended for reliable HF data communications. Originally developed as a low cost alternative to Pactor for emergency communications systems such as Winlink, it has been made available as a virtual TNC for other developers to incorporate in their products. I started to wonder if this is the solution people are looking for to make APRS over HF more reliable, rather than trying to use digital modes such as PSK63 or GMSK that weren't designed for this type of application, as is being tried by G4HYG in APRS Messenger.

The documentation for the software is somewhat over my head, but from what I can deduce the Sound Card TNC (shown above) does not provide an interface like a regular packet TNC. However there is a module called BPQ32 that appears (from the description) to implement a TNC-like interface. I've probably misunderstood something - in which case hopefully someone will point this out to me - but it doesn't seem beyond the bounds of possibility to connect an APRS client like APRSISCE to this TNC and then you would be able to send APRS using the reliable WINMOR protocol with forward error correction (FEC).

The only problem would be finding a place to operate, since SCS's proprietary Robust Packet protocol seems to have already established itself below the FSK300 APRS channel on 30m.

In the air

I haven't had time since I got back from holiday to read every post of every blog that I follow, but I was glad that I caught the post about HFDL in Adam, M6RDP's blog.

 HFDL stands for High Frequency Data Link. It is also known as HF ACARS, which gives the game away as to what it is about, for ACARS stands for Aircraft Communications Addressing and Reporting System. In other words, it's like APRS but for aircraft.

HFDL uses a proprietary protocol. Transmissions use USB with a symbol speed of 1800 baud. The modulation is 2-PSK, 4-PSK or 8-PSK with effective bit rates of 300, 600, 1200 or 1800 bits/sec. Aircraft log on to a ground station, of which there are currently 17 located around the world, each of which receives on several different and unique frequencies. The ground station assigns the aircraft a sequence ID number which is used in subsequent communications with it. HFDL is used by over 1200 aircraft operated by more than 60 airlines and allows pilots to always be able to communicate with the ground, no matter where they are located.

I downloaded the PC-HFDL software from the author G4GUO's web page which unfortunately contains no information about the program itself. I also downloaded and installed Google Earth which is used to display the positions of the aircraft. I tuned my receiver to the frequency 6532kHz mentioned by Adam, which is one of the frequencies used by the ground station at Shannon. After a minute or so I received a loud signal that was obviously a burst of quite rapidly modulated data.

After a few minutes of head scratching when the program did not decode anything I found that it apparently sets the input level from the sound card to zero at start-up. PC-HFDL is "shareware" and this is presumably one of the annoyances authors of such programs put in to encourage users to pay up. It is more likely to encourage me to uninstall the software, but that's another subject.

Once the program is receiving the audio from the radio, each burst results in a decoded message being displayed by the PC-HFDL program, while the aircraft position is plotted on Google Earth. You can see the results of about 10 minutes of listening on the 6532kHz frequency in the screen grab.

After 10 minutes or so of receiving the program shuts down, another limitation of using it without purchasing a registration. But 10 minutes is probably enough for most people to realize that, whilst the technology is interesting, as a pastime it would quickly get boring. Perhaps it would be possible to receive signals from more distant aircraft, but that's about it. There's a lot more happening on HF APRS, plus as a licensed amateur you can actively participate.

It doesn't appear to be possible to submit position reports from PC-HFDL to a site like (which I discovered from a comment to Adam's post) which aggregates aircraft positions received by amateur enthusiasts to display a real-time radar map of all the commercial aircraft in Europe. Those position reports are sent using ADS-B (Automatic Dependent Surveillance - Broadcast) which uses a frequency of 978MHz and requires a dedicated receiver costing around £500.

Friday, August 06, 2010

The most valuable ham homepage?

Dan, KB6NU, often claims that he has the #1 ham radio blog because it tops the Google search results for "ham radio blog". Today he posted a review of the top ham radio blogs according to Google. I was disappointed to find that mine wasn't even mentioned.

I ran the search myself and found that Dan's blog came third, while G4ILO's Shack came right after it. I guess Dan didn't mention it because the result wasn't a blog. Curiously, my actual blog doesn't appear as a search result in its own right at all, at least I hadn't seen it by the time I got bored paging through the results. Google moves in mysterious ways. I wish I understood it, especially as my entire living depends on the fact that I own a website that ranks #1 for several quite profitable key phrases. The fact that this is completely out of my control gives me sleepless nights sometimes.

While I was trying various searches to see if my blog appeared I stumbled across a site called Biznut, which values G4ILO's Shack at £23,517.27 - considerably more than the value of the contents of my actual shack! I don't know how Biznut comes to that conclusion, but if anyone wants to pay me that they are welcome to the site. I'll even knock off the £17.27!

VX-8GR in Prague

As regular readers will have realized from my previous post, I have been on holiday in Prague, capital of the Czech Republic. I won't bore you with details of where I went or what I did, though I have made a few comments about the holiday over on my other blog. So I will just describe my ham radio experiences over there.

Prague is quite a hilly city. The picture above was taken from the Botanical Gardens to the north of the city, looking towards the famous Zizkov TV Tower. This building, looking from a distance like an Atlas rocket waiting to take an Apollo mission to the Moon, is widely regarded as the ugliest building in Prague. But from a radio point of view it would be a good QTH. I quite like it. Apparently you can go up it to see the view, but that is something we have yet to do.

I took with me on my travels my Yaesu VX-8GR dual band APRS hand-held. Due to the language difficulty (I don't speak Czech) I didn't anticipate having many contacts with locals but I could see from that there was quite a lot of APRS activity in the city and I was interested to experience it first hand. I was not disappointed.

From the moment the VX-8GR was first switched on the APRS channel on 144.800MHz began receiving packets. The station list, able to hold the 50 most recently received APRS packets, filled up in about ten minutes. I was receiving position reports from fixed stations and mobiles, not only in the Czech Republic but also sometimes from Germany, Poland and Austria. I also received local weather reports, including the position of lightning strikes over a more than 300km radius and weather bulletins sent out by OK1COM. Coming from West Cumbria where you can often go a whole day without receiving anything on VHF it was quite a revelation.

I sent a greeting using APRS to Colin, 2E0XSD. By checking I discovered that he received it, but I didn't receive any of the acks his client sent back, nor his reply. It appears that no-one sets up their gateways to gate messages and acks for locally heard stations from the internet to RF, so the much-vaunted APRS messaging capability is essentially useless except between stations in direct radio contact.

Later in my stay I did have a messaging QSO with OK1RQ on foot in Prague with a Kenwood hand-held. Unfortunately he was busy so I never got to meet him or any other local hams. I also received greetings via APRS from a couple of other local stations.

We needed to make some local phone calls so I purchased a pre-paid SIM card from O2 for my smartphone. This included 3G data so I was able to try the APRSISCE client from Prague. I had several messaging conversations over the internet with Lynn, KJ4ERJ, the program's author. We also had our first voice QSO via OK0BNA, the Prague repeater, which Lynn was able to access through Echolink as it is connected to OK1OGA-L. I monitored OK0BNA on many evenings and heard only two other contacts take place on it. I did not hear any other FM contacts on either 2m or 70cm the whole time I was in Prague.

APRS works well in Prague because there is a network of several digipeaters and gateways within a radius of a few kilometres of the centre. The apartment where we were staying was just a few hundred metres from the QTH of OK1ALX who runs a digipeater and Igate, so most of the APRS signals I heard on my VX-8GR inside the apartment with the stock rubber duck were S9+.

The map on the right shows the tracks of some of our outings in the seven days before our return, tracked using the VX-8GR. Although reportedly stores position reports for a year, it doesn't appear to be possible to display tracks for specific periods retrospectively, and as I didn't have a computer with me (this was supposed to be a holiday) I couldn't capture my tracks at the time. But you can see at the top one day's walk in the Botanical Gardens, at the bottom a walk around Vysehrad, and in the middle a circular walk we made into the city centre and back along the river one evening.

Tracking an outing from start to finish wasn't very convenient, or even possible, because the GPS wouldn't pick up a fix inside the apartment and I couldn't be bothered to stand around for 3 or 4 minutes on the street outside waiting for it to get a fix before we started. Hence the big jumps from where we were staying to where we started walking.

We were on foot or using public transport and you would lose a fix whenever you got on the metro or a tram or went inside a building, and then have to wait to regain a fix when you came out. It was too much hassle. But when we were planning to just walk, it was interesting to see where my beacons were picked up, both from higher ground and from street level within the city.

I didn't use the Windows Mobile client for tracking much at all (apart for one short evening stroll along by the river) because using the GPS reduced the phone's battery life to an unacceptable couple of hours. However I was impressed by the battery endurance of the VX-8GR. After reducing the beacon frequency to no more than one every two minutes and using the 2.5W power setting, it lasted all day with enough power left for a couple of hours receiving in the evening. This is particularly noteworthy considering that the power saver was disabled (as it needs to be for APRS usage) and the receiver was constantly receiving and displaying APRS data. If only the GPS was quicker at finding its position after switch-on it would be just about perfect.

Like most hams, I guess, I always keep an eye open for antennas wherever I'm travelling. Antenna-spotting in Prague is quite difficult as every building has comprehensive lightning protection consisting of tall lightning conductors looking like VHF collinears, usually connected together along the ridge of the roof. I have never seen this anywhere else.

Close to where we were staying, in a street called Vysehradska, I noticed a shop window displaying a few old radios, some vacuum tubes, what looked like a tube tester and some other electronic bits and pieces. On the roof of the building next door I spotted an MFJ multiband HF vertical antenna. I was sure that the owner of the shop must be a ham, so we decided to go in and introduce ourselves.

Inside, the place looked more like somebody's untidy workshop than a shop. There were three elderly gentlemen, one of whom was presumably the owner. Another was leafing through a dog-eared book while the third was inspecting a vintage broadcast radio he had taken down from a shelf. They looked at us expectantly. I said "ham radio?", anticipating that someone would understand at least that English phrase, but was met with blank stares and something we couldn't understand in Czech.

Older people in the Czech Republic speak Russian, a legacy of the Russian occupation, so Olga then explained in Russian that I was a ham radio enthusiast and was interested in what they had in the shop. No-one introduced themselves as a licensed amateur, however. Instead, they told us that it was not a ham radio shop, but that there was one a few blocks away. Unfortunately Czech street names are confusing to non-native speakers, even to Olga. We didn't find it. Perhaps we will on our next visit.