Sotagoat app on iOS – workaround for “alert” time error

The SOTAGOAT app is a well presented and popular app for iOS and works well on my iPhone 5s and the iPad.

Its features include displays for alerts and spots, just like the sotawatch.org website, configuration options allowing you to choose between UTC and local time for displays and posts, an option to produce a goat bleat when each new spot is received from sotawatch, a filter option to specify which modes you want to be informed about and the time periods in which you want the notifications and bleats to occur. It uses an internal list of summits which can be updated from a sotawatch site and can display a list of summits near to your current location, which it gets from the GPS info in the phone or tablet.

However, the current (2016) version of the app has an error in the time calculations for new alerts. Sotawatch uses UTC dates and times. I have sotagoat set to display and post in UTC.  But the times posted and seen on sotawatch were always incorrect and I observed that they were incorrect by the UTC offset. The app was adding my UTC offset to the UTC times I wanted and then posting the adjusted time to sotawatch.  I have found the error can be worked around by adjusting the alert time as follows.

When posting an alert I subtract my UTC offset from the alert time.

For example to post an alert for 2300 UTC I subtract 11 hours (in DST periods) or 10 hours (in standard time) and post the alert for the adjusted time, namely 1200 UTC.

This is easy for UTC times after 1100 but for earlier times, the date must be adjusted back too. It’s simple arithmetic you can do in your head. For say 0400, subtract 11 hours: I do that by one of these two methods:

  • First subtracting 4 hours to get back to 0000, then subtracting the remaining 7 hours (because 4+7=11) from 2400 to get 1700.
  • Add 24 hours to 0400 (2800) and subtract 11 hours from that (1700).

In each case, because the time is in the previous day, subtract one day from the date too.

What if I was in a time zone that is behind UTC instead of ahead?

I don’t know whether the software error treats both time offsets similarly. It is possible that it is correct for negative offsets.

The error has been notified to the author of the software but as it can take a while for new versions to be released via the iTunes Store, I will use this workaround until it is fixed. The utility of the application is too good in all other ways to stop using it.

SOTA QSO Party 22nd October 2016 at Bobbara hill

My station setup for this event was later than planned.  My original summit was to be VK2/ST-042 and to get access a phone call to the owner of the access road is usually all that’s required.  However after two phone calls getting a voicemail response and no callback, I decided to go to Bobbara Hill, just west of Binalong, although that required a longer walk time as well as an extra 20 minutes of travel time.
Once I left the car, opened and closed the gate and starting to walk along the track leading to the hilltop, I was surprised by the wind strength even on the valley floor.  As I climbed further I found the wind was even stronger on the hilltop.
I started setting up in the eastern side of the hill which happily allowed me to avoid the wind, but when I lifted the antenna pole up into the wind it was being blown around so vigorously in the turbulence that I decided it had no chance of surviving in that position and I moved everything further around to the east side of the mountain.  More delay.
Finally I got on the band and called cq on cw, then worked 12 contacts, many being S2S.  I tuned around for ssb activators but apart from Don M0HCU didn’t hear many.  I did call some but lost out to Europeans.  Looked for Ed DD8LP lower in the band where he was spotted but nothing there.  Twice the pole collapsed mid-contact.  Very difficult especially on a slope and in that wind.
I forgot to spot myself but while the contacts are coming you don’t need more qrm.  I have a 250 hz filter in the 703 but that wasn’t narrow enough to sort through the signals at one stage.  Have to say my sending was affected by the unseasonably cold temperatures, not sure exactly what the temp was, but less than 10C, possibly down to 6C or so by the time I finished.  Others were making mistakes too.
Found the tablet was ok for logging but on cw it is tricky to log an incoming call as it happens.  Pencil and paper are easier for that…
Bobbara Hill looking west
Bobbara Hill looking west
Bobbara Hill SOTA setup
Bobbara Hill SOTA setup
I worked 12 contacts, DL3TU, VK4BJS, HB9FVF, OK2PDT, DL3HXX, DL4CW, HB9DQM, OE5AUL, CT7AGR, HB9AFI, JP3DGT and M1EYP just after sunset. Thanks to all.
The surprise was to finally work Tom M1EYP as my last contact and then I looked up and realised the light was fading fast so I packed up.  Walking back down the hill, I was in near darkness as I approached the car half an hour later.
The next morning I received an email from CT7AGR, Portugal, a very nice message thanking me for the contact.  I was just relieved to make the 12 contacts I did including 8 as Summit to Summit (s2s).
 Update: received another email re the S2S contacts.  S2S are the most desirable of all the sota contacts.

Using the Wifi hotspot from an iphone for the android tablet

I was having some trouble getting reliable linking to provide the android tablet (a Lenovo Tab3/7) with internet access while on hilltops or in parks.

A bit of research found a lot of wave-away-the-problems type of solutions, which didn’t solve it at all.

Finally I discovered a comment about the type of hotspot that the iphone actually provides.  It is not an infrastructure type but an adhoc hotspot.  And more to the point, it does not advertise it continuously.  It only advertises the hotspot for a limited time after being enabled, or after you visit the Personal Hotspot option in the Settings menu.

After some experimentation I now find that the tablet happily links to the iphone every time, provided I go to the Settings > Personal Hotspot item in the iphone and then wait about 10 seconds.  Nothing else needs to be done, provided the wifi password has been set in the tablet.

The other solution I have used from some hilltops is to take a personal hotspot device with me.  As my phone provider uses a provider that does not have as good coverage as Telstra, this provides my tablet with excellent network coverage from places without any service on the other network.

Here’s a pic of the hotspot lashed to a tree on the Boboyan Range summit, 40 km south of Canberra.

 

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Telstra hotspot, tree mount variety.

VK1DA in England at SOTA summit G/NP-028

During our trip to England in June 2016 I planned to activate several SOTA summits.

Having arranged to activate several hills in the Peak District I thought this would be a simple matter of driving to my contact’s house, collecting him there and proceeding to the parking area at the base of the hill, then executing the well rehearsed process of activating a summit. This was not to be and I wasn’t able to carry out that plan. But with only a few days left in my England visit, I thought there may be another opportunity coming up when we were staying at Leeds. I asked Mike 2E0YYY, with whom I had talked from Australia on dozens of occasions in the past few years, for advice on which summits would be achievable for someone with somewhat limited mobility. He immediately offered not only advice on the summit but said he would drive up to Leeds and activate the summit with me. An offer I could not refuse.

Mike duly collected me on the morning of 20/6 and we headed out past Bradford, through a hundred small villages and through lanes narrow enough to be converted into wind tunnels for aircraft experimentation, passing within millimetres of other vehicles and I was reminded of how good it was to have someone else doing the driving.

Arriving at the car park at the approximate activation time, I had poor phone coverage and could not update my alert. Mike cheerfully said, no problem, we’ll be there soon. Walking up the stone pathway in my rainproof pants and jacket, I could only hope the weather stayed fine enough to setup and operate for a while. Mike said the light rain we were walking in was nothing to the tropical rainfall he had driven through that morning. I hoped it had gone in another direction.

Onsite at the trig we set up my 10m Dxwire pole and my home made linked dipole on 20m. I decided to use my FT817 given how much effort it was to bring the radio and other gear. The pole was guyed using the guying ring made for me by my good friend Adan VK1FJAW in Canberra, on his 3D printer.

Starting on CW mode with the 5w from the 817 I made the first four contacts in relatively slow conditions with only a few callers each time I called CQ or QRZ? But after the fourth or fifth contact, more and more callers came back, so I eventually had about 20 contacts on CW without having to move frequency or do anything heroic. Several S2S contacts were included, so nice to work people like HB9BCB and others with big signals in Europe instead of hearing the somewhat weaker signals from the other side of the globe.

Andrew VK1DA (L) and Mike 2E0YYY (R) at NP028
Andrew VK1DA (L) and Mike 2E0YYY (R) at G/NP-028

After making another bunch of contacts on 20m SSB we decided to try 40m. We made a few contacts there but generally it was not as productive as 20m. My morse paddle cable seemed to be intermittent and would only work correctly with the paddle placed on top of the radio.  I was unsure whether it would last the distance if I continued on CW.  I had intended to operate on CW on at least 20 and 40m, and had also taken a 6m antenna to try that band. Given the occasional short distance contact on 20m it seemed there was some sporadic E occurring and I may have had some fun on 6m. However at that stage I was happy enough to have activated the summit successfully and I did not want to risk stressing my sore foot. So the 6m band was never attempted.

In summary, I am very grateful to Mike 2E0YYY for going to so much effort to help me activate in England. It was very good to make contacts with some of the SOTA crowd that I had worked many times from home in Australia.  Amateur Radio again shows itself to be a magic ingredient for a tourist.

Preventing the “power spike”

This problem was discussed on the moon-net list in May-June 2016.  I thought it was worth documenting what is going on with many radios that produce a “power spike”.

The problem is that the gain of the amplifier chain (from say, final mixer to output) will vary from rig to rig, also the drive level will vary. Therefore the actual gain required of the amplifier chain varies from rig to rig, purely due to component variations and even due to alignment settings, which are probably done fairly quickly at the factory.

The use of ALC to control the gain of the amplifier chain is a typical and common approach taken by manufacturers. It is a technique that does not work very well for modes other than FM and where external amplifiers are used, where the output power required is less than the maximum rated power of the radio (actually, less than about 1.5 X the rated power).

Other manufacturers also have these problems. They address them in different ways.

In one example, the Yaesu FT8*7 series, there are two controls for each band set (HF, VHF low, VHF high and UHF), being drive gain and output power limit.

Another example is Icom’s IC910 where I understand that the power level control has a dual action, one is to reduce the amplifier gain and the other is to change the output power limit level. So it achieves the same kind of result as the Yaesu 8*7 series, and should result in no power spike when first transmitting.

In any radio, if the driver gain is too high, the output power may momentarily exceed the preset level intended from the radio and set by the power level preset feeding the ALC circuit. The time constant of the ALC circuit determines the attack and delay times but cannot prevent the power level rising above the preset value, momentarily, and that’s all we need to exceed the limits of a solid state amplifier device.

So in the 8*7 series you can set the gain level appropriately so that the radio cannot output any more than your chosen power level, and it is a matter of alignment procedure to adjust output limit and stage gain appropriately to get the result you want. They do (cleverly) offer three power levels and you can set the gain and the output power limit for each power level.

For a radio capable of 100w output it is never going to be enough to set the output limit (driving the ALC) to (say) the 25w level. As already stated, that will still result in a power spike while the ALC sets the output level to what the user requires (via the output power control). It is more obvious and easiest to see in the constant carrier modes like fm and CW.

If the drive level is sufficient to allow the power amp chain to produce 100w, then the initial output (on say CW mode) will be 100w, and if you have set the output limit to 25w, feedback via the ALC circuit will reduce the power to 25w. But the initial spike will always be there. It may only last a few milliseconds, but with solid state circuits it is not a matter of heat or averages, it is whether the input voltage exceeds the correct level at all, for even the first sine wave at 144 MHz, ie. for 1/144 microseconds.

What produces the spike? There is enough drive to the final amplifier for 100w. The output limit setting may be set for a lower power level, if so the ALC line is used to send a gain control voltage back to the gain controlled stage(s).

To make it impossible for a power spike to be produced, the drive level has to be reduced. We need to limit the drive to the power amplifier chain to whatever is needed to produce the nominal power level, whatever it is, 1w, 25 or 75. This could be done in several ways.

The first and typical way to reduce the drive level, when using audio source and ssb mode, as for WSJT and other AFSK type modes, is to reduce the audio level going into the radio.  This would work, but if the reduction in drive required is significant (more than say, 10 db) that decreases the signal level without reducing the level of noise and other inevitable spurious signals, including the suppressed carrier of the ssb signal.  Eg a carrier suppression level of 45 db may be specified by the manufacturer, referenced to its performance at full rated power.  By using the audio drive to reduce total output we are accepting that the suppressed carrier can remain at its current level, and that may be ok for some radios.

The second method of reducing the output is to use a high power attenuator between the radio and the external amplifier.  This attenuator would be in that circuit on receive mode too.  For EME use many operators using the separate receiver antenna input to the receiver, or use another receiver anyway.  But the impact of the attenuator on receive mode is another factor to consider.

Other options include:

  • Modify the radio’s internal gain in the transmitter chain, preferably in the section amplifying at the transmitting frequency.  Depending on the design of the radio, there may be a point where the final mixer output is fed to the amplifier chain, which would be a good place to insert a suitable attenuator.
  • Insert a voltage on the ALC line, setting the gain of the transmitter to the highest it is allowed to be – reducing the output level to the highest it can be to safely drive the external amplifier.
  • Bypass amplifier stages.

Some types of mods would render the radio incapable of higher power output, so would need to be reversed when moving the radio on to another purpose. Whatever method is chosen, it must prevent the drive chain from producing enough power to drive the output stage to full power.

Importantly, it should be done in a way that is absolutely foolproof.  A casual mistake by the operator that destroys the external amplifier is something to prevent entirely.

The metering on the radio would be meaningless if some of these options were taken.  Separate methods of metering the drive level and adjusting for best operation would be required.

This is not a plug and play application. We are using a radio in a way that is outside its designed purpose.

The inability of the TS2000 (or other radio) to be used without modification for lower power purposes is no reflection of its suitability for other purposes. All commercial radios are built for the most common use by the majority of buyers. When we apply these general purpose radios to special uses such as for EME amplifier drivers, we cannot really be surprised that they are not ideal for EME drivers “out of the box”.

Wyong Field day and three SOTA activations

The Wyong field day is a major hamfest held at Wyong every February, with equipment exhibition and sales, a flea market for used equipment sales, a seminar room and supported by food and refreshments.

I have visited this event every year of the last 10 and have usually looked at the new equipment, passed through the flea market, sometimes buying something unique and desirable (such as the 3 element 6m yagi I bought one year)  but mostly just catching up with friends who I often see only at this event.  Some I never hear on the radio these days but they turn up at Wyong in February.

Having decided in advance to activate several summits on the way to Wyong, Andrew VK1AD (ex VK1NAM) and I set out from Yass at about 9am and reached the parking area in the vicinity of VK2/SY-002 Riley’s mountain at about 12:30, having stopped for coffee on the Hume Highway.

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Sign at the start of the walk up to Riley’s Mtn

The walk from the carpark to the summit was signposted as 2.6km each way or 5.2 km for the round trip.  The track through the forest was in good condition and the forest was green and healthy, with chirping birds the only sound breaking the peace apart from the noise of our boots on the gravel and dirt track.  After about 30-40 mins steady walk we found a sign pointing left labelled “Riley’s Lookout”.  Taking the side path we were soon standing high above the Nepean River enjoying the view of the forest and river.

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Nepean river and Blue Mtns National Park

Considering where to set up our radio gear to activate this rather nice location, we decided to walk the 50m or so back to the main track and set up there, using the sign as a support for the antenna pole.  In no time we had the antenna up in the air, the radio connected to the antenna and power and the microphone and key paddle plugged in.

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Equipment and operator at the lookout sign on Riley’s Mtn

We posted spots on SOTAWATCH  to be sure chasers and other activators looking out for S2S contacts knew we were on the air and where to find our signals.  A good session of contacts ensued with reasonable signals into Victoria, Queensland and South Australia, as well as some closer contacts in various parts of New South Wales.

One of the contacts made was with Marek OK1BIL/VK2 who was operating  at Mt Alexandra with Compton, VK2HRX.  We met Marek at Wyong the next day and had a good chat with him.

Leaving Riley’s mountain after about an hour of operation, we headed northwards to the Great Western Highway and then towards Sydney, onto the Newcastle freeway and eventually turned off the highway near Ourimba, to reach Mt Elliott VK2/HU-093.  Again this was a very pleasant and easy place to operate from, with picnic tables, expanses of grass inviting sevevral poles supporting antennas.  Here we used a 20m quarter wave vertical on one pole and a linked dipole on the other.  On 20m we made a few CW contacts into Europe and some into other parts of Australia.  Conditions were not good enough on 20m to make long distance SSB/voice contacts.

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One of the picnic tables at Mt Elliott was pressed into service as an operating desk
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Andrew VK1AD operating on 40m

Shortly before sundown we closed down and made our way to Wyong where we had booked accomodation for the night (two months earlier, or more).  We had a meal and some cool drinks at Panarotti’s at Tuggerah Westfield.

In the morning I woke early and decided to observe the International Space Station’s pass which was almost directly overhead.   I lost sight of it to the northeast when it was over New Caledonia according to the tracker.   It was brighter than most other things in the sky apart from the moon.

At the Field Day there was a good collection of second hand goods for sale in the flea market, some new items but it was strangely quiet in the corner where one of the larger traders usually is found.   At the VHF seminar, some discussion about the rules for VHF/UHF contests prompted me to make some unplanned comments about operating practices in these events, specifically about the practice of callinq CQ, making all contacts and listening all on 144.150, which many field and home stations appear to do.  A straw poll of those present revealed that while a number of people operated in that event, only a small number of them had made contacts into VK1, only 250km away from the Sydney area.  I suggested that this was due to being stuck on the calling frequency and it would help everyone to make more contacts, make more points in the contest and increase activity if they could move to other parts of the band during these events.  Let’s see whether a direct appeal to the operators has the desired effect.  I wish the contest rules did not specify a calling frequency.

We departed Wyong at about 12 noon and headed homeward. After a lunch break at Pheasants Nest we continued to the turnoff for Mt Wanganderry, VK2/IL-003.  Setting up there we were able to make contacts on 40m using SSB and CW, we did try 20m without any success.  This was a new summit for us both.

The antenna and shelter at Mt Wanganderry
The antenna and shelter at Mt Wanganderry
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Using the sun shelter at Mt Wanganderry

Mt Alexandra VK2/IL-005 on 6 Feb 2016

Although I had operated from this site in June 2015 for the VHF field day (and the 6m contacts counted towards the SOTA 6m/10m challenge) I was hoping to increase my “unique callsigns worked” count by operating from this site.  It has a good lookout towards the Sydney area and on a clear day you could probably see the big smoke, if that makes any sense.

So I took my IC703 for its 10w of power on 10m, and the FT817 with its 5w on 6m.  The antennas were a vertical half wave on each band.  The 6m antenna was in the form of a coaxial dipole with the lower end terminated by a resonant choke in the feedline, sometimes called a flowerpot vertical after the mounting method chosen by one of the people popularising the design.  (VK2ZOI)

The 10m antenna was lent to me by Andrew VK1AD, who had two similar versions.  It is a half wave fed by a tapped quarter wave coaxial line, usually called a J pole.  The tap point is at a position where a good match is found to 50 ohms, and the top end of the quarter wave is a reasonable match to the bottom end of the half wave.  This arrangement works fine for low power.

Matt VK1MA had been onsite during the morning and was just packing up when I arrived. We chatted about conditions and how the bands were working, then Matt headed off to his next summit which was Mt Gibraltar on the other side of Mittagong.

So at about 2:30pm I started operating at the Katoomba lookout point on Mt Alexandra.  With several 6m and 10m contacts made during the afternoon it was productive if a bit slow. One of my strategies for finding new contacts was to call on 52.525 FM which has some following in Sydney. I did make one contact that way, but probably did not have enough signal level for the average mobile in Sydney.  Calls via the 6m repeater seeking simplex contacts got no replies. 

On the ssb end of the band, there were several responses to my CQ calls on 50.150 which is supposed to be the calling frequency within VK.  I did call cq on 50.110 and got one reply, and we moved up the band a bit to leave the calling frequency clear.  

On 10m FM I did hear  a Japanese station but my 10w was not making the grade back to him.  The most fruitful mode was ssb on 10m, where I did work several vk4s as well as some Sydney area stations. 

Operating at the picnic table on Mt Alexandra
Operating at the picnic table on Mt Alexandra
I had arranged with my wife to meet her in the car park at about 6pm.  So at about 5:30 I started to roll up cables and put the gear into the backpack.

Walking down a steep section of the track back to the car, I managed to put both feet onto slippery surfaces at the same time, resulting in a probably very funny sight, with me falling backwards onto my backpack, and in the process flinging my hands out and back, to “break my fall”.  That was not a good move.  It didn’t break my fall but came close to breaking a bone.  My right wrist was in some pain and I sat on the ground for a minute or so before I could get up and resume walking.  

I had fractured the radius bone in my right arm, quite close to the wrist.  I ended up being treated by the emergency ward of the hospital the next day, then discharged with my arm in a cast and 6 weeks of relative inactivity ahead.

I can only think about the many times I have been much further from my car or another driver, yet have climbed up and down rocky paths and gravel roads without any mishap.  But any of those places could have produced a similar result.  A sobering thought.

The result of  a few seconds of inattention
The result of a few seconds of inattention

So that ended my activations in the 6m/10m challenge a week earlier than I had expected.

I am now temporarily writing (and sending morse) with my left hand.  My handwriting is not pretty (and my morse is tentative and slow).  I count myself lucky though – this could have been worse.  But my wrist will mend and I will have the use of it again.  Incidents like this make you appreciate having two arms and hands.

Amateur Radio, Computing and other activities of Andrew VK1DA/VK2UH