AmateurRadio.com

The webmaster of Summits On The Air kindly gave me permission to access the SOTA Spots RSS feed from the Wainwrights On The Air website so that spots for SOTA summits that are also Wainwright summits can automagically appear in the WOTA system. I started work on that the day before yesterday. I also noticed that APRS objects for the position of Mads, M/LA1TPA/P, were not appearing because the length of his call exceeded the maximum length of an APRS object name. I implemented a fix for that by lopping off the /P if the name would exceed 9 characters. Yesterday morning I did not receive any SOTA alerts over APRS at all so I wondered if I had broken something.

It didn’t help that I had trouble accessing aprs.fi to see whether the APRS spots were getting out. That might have given me a clue as to where the problem lay. As it was, it took quite a lot of time before I realized that the problem was my internet connection. Although the ADSL was up and working, I was having trouble connecting to various sites including the APRS-IS Tier 2 servers and packets were being lost along the way.

This forced me to address another problem. Currently all the APRS packets are sent by the WOTA website calling a file on a web server running on a network attached storage (NAS) backup device running in G4ILO’s shack which is actually a little Linux computer that runs Apache. This server hosts the script that sends the packet to the APRS network. I had tried running the script on the WOTA web server itself but it hadn’t worked and I didn’t know why so I decided to go for the path of least resistance since life is too short for making computers work the way I want them to.

Apart from the problem of connectivity with this solution there is also one of continuity. I don’t like to run computers 24/7 because it adds a significant amount to an electricity bill that is already high due to the fact that there are two people using even more computers and equipment home all day. Also, Olga is not happy about leaving any equipment running when we go away. Whilst it is unlikely that anyone will activate summits in the middle of the night they are certainly going to do so while we are on holiday. So I really need to send the APRS alerts entirely from the web server.

After another couple of hours of getting nowhere I filed a support ticket with the web hos. They replied that they block port 8080 which is the one used to post APRS packets to the network using HTTP. When you are paying $8 a month for web hosting there is a limit to the amount of help you can expect particularly when it comes to changing the configuration of the server (which no doubt hosts hundreds of sites) just for my convenience. The last reply said “please try now” but I did and it still didn’t work. So it looks as if I might have to live with having APRS spot functionality that goes QRT when we are on holiday.

Meanwhile I am waiting for someone to activate a SOTA summit in the Lake District so I can see whether my script to check the SOTA spots RSS file is doing what it supposed to.

A few weeks ago the European Union’s Frequency Management Working Group agreed a harmonized specification for Citizens’ Band Radio across Europe to include AM, FM and SSB modes. It will now go to public consultation before being passed to national governments to become law. However Ofcom, the radio regulatory authority in the UK, is expected to live up to its nickname of Notcom by saying “no” to allowing AM and SSB, claiming there is a potential for harmful interference to other services. How absurd!

Now some readers may be wondering why a ham radio blog is concerning itself with whether CB users should be allowed to use the AM and SSB modes. After all, if they want to use those modes they could just get a ham radio license, surely? The test is so easy even a child could pass it, and many do. So what’s to complain about?

But that isn’t the point. The point is this is one more example of how we in Britain always seem to get the mucky end of the stick when it comes to European legislation. We’re told we can’t opt out of European human rights law that seems to attach more importance to the rights of criminals, rapists, murderers and paedophiles than their victims. But when it comes to something as unimportant as giving a few hobbyists the right to use the same modes as their counterparts across the North Sea, opt out we can. Are we in Europe or aren’t we?

If allowing CBers the use of AM and SSB isn’t a problem for the rest of Europe then it isn’t going to be a problem in the UK. If there was “a potential for harmful interference to other services” then that would surely have been proven by now, since there are plenty of people illegally using SSB on 27MHz already. How many people have been caught and prosecuted for using SSB on 27MHz? Hint: it’s a very round number. And if there is a risk of harmful interference to other services from allowing people to use 12W of SSB on 27MHz, why is there no risk from allowing hams to use 400W a few hundred kHz higher?

There is no sound basis for preventing British CBers from enjoying the same frequencies and modes as their counterparts in the rest of Europe, just as there is no sound basis for restricting the use by British radio amateurs of digipeaters and internet connected nodes. It is about time we had a more open regulatory system in this country so that radio users cannot be denied something for false or risible reasons.

Here’s a question for you software experts out there. Do you know of a free, simple, no-frills sound recorder application that can record audio from any sound card?

Windows Sound Recorder has the simplicity I need, but it can only record from the default recording device. If I want to record from the radio I have to change the default input device to whatever sound card is attached to that radio. This usually results in hours of head-scratching later on after I forget to switch the default sound card back.

Audacity is the sound recorder application most people recommend. It is free, and it can record from any sound card, but the user interface is so complicated I can’t figure out how to use it.

So I have decided to ask you, my readers. I imagine this is something that many hams have tried to do. What do you use?

On Thursday I wrote about how my WX-1 APRS weather station was not being received by my TH-D72 and the PIC TNC because the baud rate was slightly fast, and of my unsuccessful attempt to fix it. Glenn W9IQ offered to take a look at the PIC source code and see if there was an easy fix. I sent him a link to the code and a day later I got a reply back. Glenn’s suggestion solved the problem perfectly. But he didn’t just tell me what to change, he explained what the code did and how it worked. I thought that his explanation would be of interest to anyone trying to understand how packet tones are generated using a PIC, so with his permission I am copying it here.

“The baud rate is determined by an interrupt service routine. The interrupt is driven by Timer 0 (TMR0) that is configured to use the instruction clock as its input (frequency of Y1 divided by 4). The input of TMR0 is also initialized to have a divide by 32 prescaler (the code comment says 16 but that is wrong). So at this point the timer is being driven by the frequency of Y1 divided by 128 or (20 MHz / 128) =  156.25 kHZ or a period of 6.4 uS.

Now the math and routines get a little more complicated. The interrupt is serviced by the code in the “packet” file. This code sets the TMR0 count to start at a value of 127. This TMR0 count will tick up one count every 6.2 uS (the clock from the output of the prescaler). When the timer count rolls over from 255 to 0, the interrupt is triggered.

At first glance, it would appear that this would generate an interrupt every 129 counts or 825.6 uS (6.4 uS * 129). That would seem to put the interrupt at roughly 1211 Hertz ( 1/825.6 uS). But this is not correct due to the way the author wrote the interrupt routine plus a small nuance of how a PIC handles the reset of the prescaled interrupt timer.

The interrupt service routine in “packet” executes 6 instructions before resetting the interrupt timer to a value of 127. Each instruction takes 4 clock cycles so this adds another 1.2 uS to the time between interrupts. In addition, when the prescaled interrupt timer register is written, there are another 4 instruction cycles of delay before the timer starts to run again. This is another 0.8 uS added to the interrupt time. So we now have an interrupt cycle of 825.6 uS + 1.2 uS + 0.8 uS totaling 827.6 uS or 1208 Hz. I believe this is what you measured as the current baud rate from your board.

Improving this is fairly straight forward. The interrupt goal is 1200 Hz or 833.3 uS. If we change the TMR0 count to 126 instead of 127, this will add another 6.4 uS to the interrupt period. This would give us 827.6 uS + 6.4 uS = 834 uS. Then if we eliminate one instruction in the interrupt routine, we eliminate a 0.2 uS delay for a total interrupt time of 834 uS – 0.2 uS = 833.8 uS or 1199.3 Hz.

This change is effected in the code located in the “packet” file. Look for the following code fragment:

Change this code fragment to read like this:

Recompile everything and reload the processor and you should see the baud rate drop as described.”

When I ran the modified code the baud rate dropped from 1207/8 baud to 1198/9 baud which is pretty much just as Glenn predicted. The weather station is now being received by the Kenwood TH-D72 as well as my other APRS radios. It can also now be received using the PIC TNC though the level of the receiver audio is critical and unfortunately not the same as that needed to decode the VX-8R. I think that is because the maximum deviation I can get out of the Radiometrix transmitter module is a bit on the low side.

I had an anxious couple of minutes when I found that although the D72 was decoding the packets it was rejecting them as invalid. This turned out to be because the position co-ordinates had a lower case n for North and w for west: In my haste to see what effect the changed code had I had entered the settings carelessly, though the other radios didn’t seem to mind. That was soon fixed.

The WX-1 weather station is now back in position beaconing the temperature, humidity and pressure as G4ILO-5. I would like once again to express my thanks to Glenn W9IQ for acting in the finest spirit of ham radio and helping me out with this.

Today Geoff GM4WHA became the first Wainwrights On The Air (WOTA) chaser to claim a certificate. He worked me on Longlands Fell (LDW-179) thereby completing Wainwright’s Northern Fells having made contacts with stations operating from each of the fells in that book.

Noticing that a few chasers were just a few fells short of completing a book, I suggested in the WOTA forum that chasers should post the fells they need, which might motivate some activators to go out and activate them. Geoff duly posted, and Longlands Fell was one of the ones he needed. As it is only about 20 minutes drive from here and an easy walk, I thought it would be a good idea to blow away the cobwebs of more than two months of slothful inactivity by activating it. So I did.

Despite an early start (for me) I was lucky to find a place to park at Longlands near the Uldale Common track. The ascent is quite easy up a grass path, but due to the long period of inactivity (and having put on a couple of kilos since Christmas) I had to stop for a breather rather a lot. The photo shows the view from the top with the summit cairn in the foreground, Over Water in the middle distance and the often visited summit of Binsey (LDW-190) in the background. What it doesn’t show was the bitingly cold strong wind which numbed my fingers and made it too difficult to use the 5/8 telescopic antenna.

Despite using a 7in. helical antenna (which tests have shown to perform comparably to a 19in. quarter wave whip and much better than the dummy load supplied with the handheld rig) I made 9 contacts from the summit including the all-important one with Geoff, which is good going from such a summit which is well screened to the south.

I have probably said this too often, but WOTA keeps on getting more and more popular. I’m hearing new chasers all the time – the latest recruit is Steve, M6CDX – and even people who originally said they were getting too decrepit to climb the fells have been heard operating from some of the lower ones. So far this year I have worked 50 different summits and made 72 WOTA contacts from home, not far short of my total for the whole of 2010, and we’re only a bit over half way through the second month. I’m sure others have also noticed the greatly increased activity.

There is great camaraderie among all the participants, too, many of whom feel like old friends even though most of us have never met. I think it is fair to say that the success of WOTA has exceeded my wildest expectations. Combining two of my favourite activities – walking in our wonderful mountains and making contacts on the radio – it doesn’t get much better than this!

I like to think APRS is a haven from the aggravation often found on the rest of the bands, but unfortunately we have our problems too. This afternoon an APRS message appeared on my screen from G1ZRN-10 that clearly had been addressed to ALL.

It obviously wasn’t intended for me personally. I don’t gate from one band to another. In fact at the weekend I leave my HF IGate receive-only because I don’t want to add to the mayhem. But there is a lot of traffic gated from VHF to HF by stations in the south of France. It serves no useful purpose for me in the UK to receive information about French repeaters or French radio club meetings nor is there any point in gating position beacons from French VHF stations on to 30m. But what can you do?

I don’t think getting your blood pressure up and acting like a band policeman will solve the problem. Unfortunately the language barrier doesn’t help here. Because of that there are no common forums where European APRS users meet, where an approach could be worked out. A direct approach to the offenders would need to be made by a native speaker who could gauge the individual’s attitude, find out why they are doing this, and tactfully dissuade them from it. Blunt emails in capitals and in English could easily have the opposite of the desired effect.

I think it is one of those things we just have to live with. Actually I’m not sure the effect is really that bad. I’m running just 10W to a magnetic loop in the attic and my beacons are reliably gated throughout most of the day by stations in Germany. When European HF mobiles are about I often gate them, so the network still works. But it would be nice to have a blacklist function in my IGate software so that I can refuse to pass traffic for the offending stations. If everyone did that, it might get them to mend their ways or get off the air.

Some folks have set up an alternative APRS network on 20 metres called Net14. I don’t think that’s the answer. Sure, you get away from the idiotic VHF to HF gateways, but you get away from all the other activity too. I tried it a couple of times and it was even more boring than VHF is here most of the time.

If anyone has any serious suggestions as to how to solve the problem of cross-band gating on 30m I’d be glad to hear them. Or even non-serious ones. Right, I’m off to bid for a GPS-guided missile on eBay!

What is it about ham radio that encourages boorish behaviour? Or is it just the internet? Whenever you post in any forum or specialist group suggesting that something about a particular radio is not a very good design and could be improved you will usually get several responses that amount to “I don’t think there is anything wrong, so there can’t be anything wrong.” If you attempt to defend your statement you will eventually end up on the receiving end of insults. Yahoo groups are aptly named it seems.

If you want a VHF radio that can be used simultaneously as an APRS gateway and for voice there aren’t a lot of choices. The Kenwood TM-D710 is really the only option given that Yaesu’s FTM-350 doesn’t have an accessible TNC. Like most radios capable of 50W output the TM-D710 has a fan. Unfortunately Kenwood’s fan logic is dumb. The fan comes on the instant the transmitter starts, no matter how long you transmit for or what the power level, and runs for about two minutes. This means that it runs for two minutes out of ten, triggered by my one second five watt APRS beacons. This is completely unnecessary as no significant heat is generated by such a short transmission. The noise is an annoyance – it’s significantly louder than the computer, or my K3’s fans – but more importantly this must also reduce the working life of the fan unnecessarily. One day the fan will fail when it is needed because of all the times it ran when it wasn’t.

When somebody complained in the Kenwood D710 group about the fan noise because he was using the D710 in his quiet living room, I agreed, saying it was just cheapskate engineering for Kenwood not to have incorporated a thermostatic fan controller. This upset the yahoos. I was told that it was better for the fan to run than for it not to run, that if there was a bad antenna mismatch the fan running in those first few seconds could save the PA transistors, that it was necessary for the fan to run all the time because some users install the radios in tight spaces in vehicles where the temperature reaches over 100 degrees F, that group members had equipment with other fans that were even noisier, and so on. None of which, if true, actually invalidated the argument that a thermostatically controlled fan would be an improvement over the present dumb logic. It was just “It isn’t a problem for me, therefore there is no problem.”

It was also suggested that a thermostatic control would add $10 to $40 to the cost of the radio. I’m not an electronics engineer but I doubt that it would add more than a couple of dollars to the manufacturing cost, which would not make a significant difference to the retail price given these aren’t cheap radios to begin with. Even my power supply, which cost a third the price of the Kenwood, has a thermostatically controlled fan. If Diamond could fit one without making the price of the product uncompetitive I’m sure Kenwood could have done.

Sadly, online groups have ceased to be a place where you can intelligently discuss the strengths and weaknesses of various products due to the activities of the yahoos who will brook no criticism of the thing they have purchased. I could regale you with another recent encounter, this time on the Elecraft reflector, over the stupidity of having the K3 change mode to the one last used on a band when a program sends a change frequency command, overriding the mode set by the program so you may end up in USB in the CW part of the band or vice versa. Needless to say, the Elecraft Way is The One True Way and it is the developers who won’t modify their programs that are wrong, even though by making this one change Elecraft could enable the K3 to work properly with N3FJP and several other programs whose developers won’t change them just to suit Elecraft. In fairness I should point out that Elecraft didn’t refuse to make the suggested change (they didn’t respond to the thread) it was the fanboys who defended the status quo as usual.

Frankly I’m getting tired of engaging with hams over any subject at the moment. So I have decided to unsubscribe from the majority of ham radio groups and will restrict myself to posting my thoughts here in future. I’m sure that will please many people who don’t like seeing points of view they don’t agree with. Commenters to my blog are welcome to disagree, as long as they do so intelligently and politely. Boorish comments that amount to “I don’t agree, therefore you’re wrong” without providing any supporting evidence as to why I might be wrong will be unceremoniously deleted.