AmateurRadio.com

A week ago I received a Yaesu VX-8GR VHF/UHF APRS hand held transceiver with GPS. The transceiver performs as expected except in one extremely annoying respect – its GPS takes a very long time to get an initial fix on its position after switching on the radio. It cannot get a fix from inside the shack at all. By contrast, my HTC smartphone will get a fix in a couple of minutes whilst sitting in its charger cradle on the shack desk. Or at least, it did.

This morning I noticed on aprs.fi that the last reported position of my smartphone, G4ILO-10, was somewhere in Somerset. I started the APRSISCE application with the intent of “bringing it back home” by sending a position report with the correct location. But after ten minutes the phone had not managed to get a fix.

I switched off all my radio equipment in case one of them was an interference source, and rebooted the phone, and eventually after several more minutes it obtained an accurate fix. I am beginning to suspect that something is interfering with GPS reception in the area of my house.

If you Google “GPS interference” you will find links to numerous articles and research papers raising concerns about what is apparently an increasingly common problem. One article states that a directional television receiving antenna widely available in the consumer market contains an amplifier which can emit spurious radiation in the GPS L1 frequency band with sufficient power to interfere with GPS reception at distances of 200 meters or more. Other potential interference sources include spurious outputs from TV transmitters.

Another website states that “We are seeing increasing evidence of GPS interference and also apparent erratic behaviour (e.g. mis-reported location)” and provides a form for reporting cases of interference. This page provides links to two reports on the issue which unfortunately require registration in order to access them.

Have other amateur GPS users experienced difficulty in receiving the satellites or an increase in inaccurate position reports? For many GPS applications the effects of this could have rather greater impact than a radio ham’s inability to report his position to aprs.fi. Perhaps the US administration was rather hasty in its decision to decommission Loran.

There was recently a change of crew at the International Space Station and one result of that has been the reappearance after a long absence of the packet radio digipeater on 145.825MHz. When the Space Station passes over you can receive some very strong signals from it. I have decoded APRS beacons on a VX-8 handheld standing on a window sill inside the shack. But it is even better to use the main station, then you can see the positions of the stations you received on a map.

When using the ISS you need to use different settings to what you would use for terrestrial APRS. Digipeating, if enabled, must be turned off. You want to be connected to APRS-IS so you can gate received packets to the internet, but you don’t want to send anything received from the internet out to the ISS. You probably don’t want to display data from the internet on the map, to leave it clear to show those stations received by the radio. If you want to transmit through the ISS yourself you must also change the APRS path to “ARISS”.

After thinking that we really need an ISS option in APRSISCE/32 for this it occurred to me that all I needed to do was make a copy of the program in a new folder, then I could change the settings however I wanted without affecting the copy I use for terrestrial APRS. It worked fine. It was fun to see the stations heard via the satellite show up on the map, although when the map is zoomed out to cover such a large area the icons are hard to see. It was also amusing to see that the icon for the ISS’s own beacon was a bicycle. Perhaps someone should tell NASA!

After several abortive attempts to get my own beacon digipeated by the Space Station I set the transceiver to Narrow FM and got through on the first attempt using just 10W to my 300ohm ribbon cable Slim Jim in the attic. The proof is in the map of stations heard through the ISS at ariss.net.

Not a very useful activity perhaps, but fun to try.

A recent addition to the G4ILO shack is a new Yaesu VX-8G hand held transceiver. In case you are thinking that I need professional help over my addiction to hand held radios you may be right – however a week or so ago I received an email from someone who has a collection of 150!

Long-time followers of my blog may recall that less than a year ago I bought a Yaesu VX-8E APRS transceiver with GPS. However I found that the usefulness of APRS was limited by the lack of digipeaters and internet gateways in this part of the world. I decided to use a smartphone based APRS client, APRSISCE instead and sold the VX-8E shortly afterwards.

Using the cellular network instead of amateur radio has its advantages but it eliminates the interest of seeing how far a little 2m RF can go. Interest in APRS has increased in this area over the last few months so I decided to give RF another go. In the meantime, Yaesu brought out an improved version of the original VX-8R called the VX-8DR and a lower cost version called the VX-8G. So I didn’t regret my decision to sell the VX-8R as it allowed me to acquire the updated version.

One of the things I really disliked about the VX-8R was the clunky way the GPS attached externally to the radio (and the absurdly expensive fixing bracket.) The VX-8R (and the updated DR) has a number of other features that I never used and didn’t need in an HT: 50MHz coverage (including AM), short wave receive (which was useless anyway without an external wire antenna), a barometer/altimeter and a temperature sensor. Nor did I care that it was submersible. I did lose a brand new HT in the Solway several years ago, but as I didn’t immediately notice it had fallen off my belt I never found it again.

The VX-8G lacks these unwanted features and can be set to vibrate when you receive an APRS text message – a new way to get a thrill out of amateur radio! More importantly it has the GPS built into the radio which makes for a much neater package. It costs about the same as a VX-8DR without the GPS option.

The VX-8G is not available yet in the UK so I purchased it from Solid Radio, an eBay trader based in Hong Kong. This was the most expensive thing I have ever bought from a Far Eastern trader and I felt like I was taking a bit of a gamble, but the radio arrived in just over a week and with no unpleasant surprise on delivery.

The VX-8G looks very similar to its older brother but is a little slimmer and lighter. I seem to remember that the body of the VX-8R was metal, or else it had a substantial chassis that added to the weight. With the standard battery installed the VX-8G is noticeably lighter than my Kenwood TH-F7E.

The Yaesu’s GPS takes much longer than the one in my hTC smartphone to acquire a signal. In fact after waiting several minutes on first turning on the radio I started to worry that the GPS wasn’t working so I stood it out in the garden on a table where it eventually established its position. On subsequent occasions it has still taken a few minutes to fix its position which is a bit annoying.

Operationally the radio appears to be the same as the VX-8R and the menus are very similar. One of the new features is SmartBeaconing which varies the frequency of position reports according to your speed and whether you have changed direction. There are different settings for this depending on whether you are walking, cycling or driving. The original model would only send position reports on a fixed time interval. Once I had enabled SmartBeaconing it sent a very accurate track of my walk.

It is too early to say with any precision what battery life is like but initial impressions are that with the GPS enabled it is pretty poor – a criticism that unfortunately is also true of the smartphone. I used to have a navigational GPS called an iFinder GO2 which ran for about 18 hours on two AA batteries so low current consumption GPS devices do exist – why doesn’t Yaesu use them? In the VX-8 radios when you use APRS the problem of short battery life is compounded by the need to disable the power saver (which causes the receiver to listen in short bursts rather than all the time) so you don’t miss the start of a beacon or message sent by another station. The VX-8G uses the same batteries as the VX-8R and DR models so a higher capacity pack available, but it is quite expensive.

I am pleased with the VX-8G so far and am looking forward to discovering where I can be tracked from. I think APRS holds some of the same fascination as WSPR on the HF bands in that it is interesting and sometimes surprising to see how far your low powered signals can travel.

I don’t know when the VX-8G will be introduced in the UK or what its UK retail price will be but I expect it will still be quite an expensive radio. A pity, as I think the cost puts a lot of people off discovering APRS for themselves.

I have just added a new article to my website:
APRS – Putting ham radio on the map.

It’s quite a long article, but do read it if you have the time. I hope that it will explain what APRS is for to the many people who don’t seem to understand, and even more I hope it will encourage more people to try it.

If you like the article and think that it will help to spread the word about APRS, please post links to it anywhere you think would be appropriate.

Linux users now have an alternative APRS client to Xastir. It’s called APRSIS32 for Win32. I have discovered that Lynn KD4ERJ’s Windows APRS client runs almost perfectly under the Linux OS using wine, the Windows compatibility layer.

It’s pretty easy to get APRSIS32 going. Just download the Win32 version from the APRSISCE Yahoo group, save it into a folder somewhere under .wine/drive_C and run it. The program will start downloading maps so you can zoom in and set your home location. The only problem is, you can’t see them. By default the maps are displayed semi-transparent and it appears that wine doesn’t support transparency. So you will need to keep hitting the right arrow key which increases the opacity until the maps are 100% opaque, when they should appear. Check the APRSISCE/32 documentation wiki for more information.

There are a few screen redraw issues and the automatic updater always seems to fail, but these are minor issues. APRSIS32 uses code common with the APRSISCE version that runs on Windows CE mobile phones. These use a pretty small subset of the features available to current Windows software so by happy accident the program avoids doing things that wine doesn’t support which prevent more complex programs like Ham Radio Deluxe from working.

I haven’t tried the program with a GPS or a TNC as I don’t have them, but since these are just standard serial connections which are certainly possible under wine that is unlikely to be a problem. Lynn seems pretty keen to tackle the problems that I have discovered. In the meantime, the program still seems to work pretty well, so if you use Linux and are interested in APRS why not give APRSIS32 a try?

I wish Murphy, the patron saint of things that don’t work, would leave me alone. It’s a bit frustrating reading on other blogs that someone spent a weekend and ended up with some perfect working piece of gear while I spent several hours just trying to get a computer to talk to a radio.

Although APRSIS32 now supports transmit and receive using AGW Packet Engine which can use a soundcard as a modem I have never decoded a single packet, nor have my beacons been reported as heard by anybody. I started to wonder whether my cheap USB dongle – one of those things about the size of your thumb with a USB plug on one side and two 3.5mm stereo jacks on the other, that cost next to nothing – was up to the job. It had worked acceptably well for Echolink, but although my braaaps sounded to me like packet, they might not sound enough like packet to someone else’s decoder.

My computer’s on-board soundcard is in use by my K3 so there was no point in trying that. But I did have another slightly better USB audio dongle being used for PC sound, so I decided to swap them over. I removed the cheaper dongle in order to better access the audio sockets and when I replaced it I received a message from Windows that “One of the USB devices attached to the computer has malfunctioned” and it disappeared from the system.
Giving up on computer sound for the moment I proceeded to try to test APRS packet transmission using the other dongle. But although I was receiving audio OK and keying the transmitter I was not transmitting any audio!

I fished the interface out from behind the rigs – a trying task ever since I installed the new shelving – in order to test it with my netbook and FT-817. It worked perfectly with Fldigi. Perhaps a bad connection? Back in position connecting the Icom to the shack computer and still no transmit audio, even though I could plug the computer speakers into the headphone output and hear the braaps being generated by the software!

Eventually it finally dawned on me that the AGWPE soundcard software only generates audio on the left channel. My radio interface was wired to the right channel! The cheapo USB audio dongle (that was now malfunctioning) presumably had a mono output so I was getting audio on both channels. The better one was generating proper stereo so there was no output on the channel I was using. D’oh!!

Fixing this ought to have been simple. Just open up the interface and switch the wires so the one from the left channel provides the input instead of the right one. But of course, it wasn’t. Even though the cable from the stereo jacks used in this interface had no less than four insulated wires within the screening, only one was connected to anything – the tip (right channel) of the plug. The ring was unconnected. So I had to take another audio patch lead, cut it in half, and use that to make new audio cables for the interface using the left hand channel.

Finally, it appears to be working, though I have still to decode an APRS packet. But now I have no computer audio because the other USB dongle is still broken and the connecting cable was cut in half to get the interface working. I came this –><-- close to saying "the hell with all this" and ordering a Signalink USB interface this morning.

Kudos to Lynn KJ4ERJ, developer of the brilliant APRS client APRSISCE. Yesterday he read my comment that the program doesn’t support transmit through the soundcard based AGWPE software yet, and today it does! So now my APRS beacons are braaping out over the Cumbrian airwaves.

I have noticed a bit more APRS activity round here in the last few weeks. Today I noticed another new station mobiling around the north-east of the county – G7NZR. The info for this station showed that he was actually using DPRS, the digital version of APRS, and was being gatewayed through MB6CA. This is a D-Star simplex node set up by G7NZR. Its coverage map shows that MB6CA can’t be heard in Cockermouth or Workington, so for the time being at least West Cumbria is still a D-Star free zone.

When I looked at the MB6CA coverage map I was reminded of a map I saw some years ago showing the spread of grey squirrels across the county. Overseas readers may not know that the grey squirrel is an illegal immigrant – from the US, no less – and it has been gradually wiping out our indigenous red squirrels, so that there are now only a few pockets of them left.

Will D-Star be the grey squirrel to analogue FM’s red, gradually increasing its territory as more and more people are persuaded to make the switch, until Icom ends up with a virtual monopoly over the VHF and UHF bands?