QRP Labs Ultimate3 WSPR beacon back in the game

Last year saw my rather nifty Ulitmate3 WSPR beacon giving up the ghost after having been placed in it’s long awaited custom made housing. As to why it decided it didn’t want to work any more is anyone’s guess but my money is on a broken cable somewhere.

With that in mind it had been sat on my desk for the best part of 6 months until I had the time and the inclination to get it working again. Part of the problem may have been trying to cram too much inside the case. I had diligently designed and built a PSU to provide a dual voltage to supply the beacon and the SKM52 GPS module but in hindsight, when I get the relay-switched LPF board built I was going to be making life harder for myself by trying to pack everything into the diminutive case.

I invested in a regulated 5V external PSU and the new recommended SKM61 GPS module from QRPLabs.com

The advantage of the SKM61 is it runs off of 5V, directly from the beacon – a few less wires to worry about. So, duly armed with a soldering iron I set about rebuilding the various interconnects and redesigning my case layout.

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Ok, not very exciting I must admit but a bit more secure and screened than my last jury rigged setup.

The SKM61 fiited nicely onto a tiny off cut of veroboard and I added a set of connectors to allow easy changing or boxing up (if I get to it!)

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Now with the moment of truth upon us, it was time to power everything up

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Unfortunately the photo isn’t brilliant, as this time after a 5 minute wait, I was receiving a very nice heart beat sync pulse from the GPS showing that we had a GPS lock and location and time were being provided by the GPS satellites. A quick fumble through the menu system to change my callsign to my new one and we were off!

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Well, sort of. I was in the middle of the Solent! Now this caused a degree of head scratching as I sure as hell wasn’t maritime mobile and the flood defences around Portsea Island hadn’t sprung a leak as far as I was aware! After revisiting the settings in the beacon my only conclusion was that the latitude and longitude being provided by the GPS were off. My old friend Google didn’t provide any clues on this one so I posted a call for help on the QRPLabs forum.

Thankfully, someone who knows a lot more about this than me (aka the all round nice guy, Mr Hans “QRPLabs” Summers) came to the rescue. To quote the man verbatim

“WSPRnet is a bit strange. 

Yes, the WSPR protocol only sends the 4-character locator. If you switch on the extended WSPR protocol then it will send 6 characters but that takes two WSPR transmissions and there are other disadvantages too, so it is not a good idea really. 
However most stations in WSPRnet have 6-character locators, even though they are only transmitting 4-character locators. The reason for this is that WSPRnet stores the 5th and 6th characters internally in its database and adds them to the 4-character locator received over the air.
The exact circumstances of this are not very clear to me. But I know how you can make WSPRnet “know” your 5th and 6th character and put them on all the spots of your transmission, and on the map etc (so that you will be inside Portsmouth). Unfortunately it is NOT a matter of becoming a WSPRnet user (with username) and configuring your 5th and 6th character – that does not work, you still show up as 4-character. 
What you have to do is UPLOAD your own reception report. As soon as you upload a reception report (your reception of other people’s WSPR stations), declaring your 5th and 6th character, your 5th and 6th character are put in the database. You can do it by actually receiving WSPR stations in the proper WSPR program, and uploading the spots. But there’s another way too, that I know does work. If you look at the old DB page http://wsprnet.org/olddb notice on the top right side of the page, some fields for uploading your log. Here you type in a 6-char locator, and this is where WSPRnet gets the 5th and 6th character from, that it puts on your spots. You need to find an ALL_MEPT.txt file, you can google for it and download it. Then edit the file to have one date header and one single row, that can be a fake spot of yourself, e.g. at a time/freq you know you transmitted. Then upload that. It seems that WSPRnet doesn’t write this entry into the database, it recognises it is you spotting yourself and excludes it; but it DOES get the 5th and 6th locator characters into WSPRnet.”

 

So, in short because my last WSPRnet reports were under my old call sign 2E0DFU, M0XXF has no entries in the database. As such, until it does the 4-character locator will be used, placing me in the middle of the brine.

I had a rummage around for the ALL_MEPT.txt file inside the WSPR software installed on my laptop and couldn’t find it until I discovered that versions of WSPR over 2.0 name it ALL_WSPR.txt

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Now Hans had offered me a solution to my problem, but my old Stellar Labs receiver kit was sat on the desk making a forlorn face at me as it hadn’t been used since the end of last summer. With that in mind it took all of 3 minutes to plumb it into my laptop and fire it up. By changing my callsign details within WSPR to M0XXF, in under 4 minutes I had current database report entries listed under my new callsign and my location was safely back on dry land!

Everything is working nicely and my beacon has a nice metal enclosure to keep it safe. The next step will be to sort out a D-plug connector for the GPS antenna, an enclosure for the GPS module and build the relay switched LPF kit, but in the meantime I’ll just let it sit there happily doing its thing.

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Ultimate3 QRSS beacon case arrives

Hans Summers wasn’t lying when he said the delivery time on the bespoke case for the beacon kits was running at weeks/months.

Today the Postie duly delivered my long awaited case. The packaging looked like it had been through the wars and all bar three bubbles on the enclosed sheet of bubble wrap had burst but it was all in one piece.

All I can say is that it was worth the wait as it’s a really nicely produced item. As much as I was looking forward to making a case from whatever I could source, there’s no way on earth I could have made something of this quality.

A job for the cold winter months will be transplanting the kit into the box and finishing off the relay-switched LPF kit.

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Overnight results

It would be very easy to just publish page after page of maps with pins, demonstrating that the beacon is being heard.

While I’m still tweaking it I may well publish some more data to show any increase or decrease in range and activity as a result of modifications, so I can learn from my mistakes.

After leaving the beacon running overnight, the database at WSPRnet.org reveals the following.

 

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Which when you turn it into a map, looks like this

 

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K9AN is in Urbana, Illinois. That’s 4035 miles away!!

 

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First Contact (it’s actually a spot, but work with it!)

In 1992 the BBC science documentary series Horizon, ran an episode entitled “Molecules with Sunglasses”. It was a pretty hardcore theoretical science episode detailing the discovery by scientists of a third form of solid carbon eventually named as ‘buckminsterfullerene’.

One line in the episode, detailing how the 60 atoms of carbon were arranged in space, will stick with me forever. The commentator is telling how they were wrestling to understand the mathematics and physical form of the structure. In a discussion with a colleague, where some pretty high powered terms were being used, one turns to the other and says “basically Chuck, what you’ve got there is a soccer ball”.

It epitomises how, if you keep it simple, you can explain anything to anyone.

A follower of this blog has said “great pictures, but the theoretical stuff is way past me.” The fact he’s actually taking the time to read this warms the cockles greatly, so just before the reveal, let’s put what this is about in “soccer ball” terms.

WSPR (Weak Signal Propagation Reporting) is a form of data communication/transmission which sends 160 characters in slow audio tone bursts lasting exactly 2 minutes. The sending and receiving of these transmissions is time critical and is reliant on the transmitter and receiver both having a very accurate clock, otherwise they would be out of sync. The receiver would be sat there aimlessly waiting for transmissions that would be being broadcast when his/her receiver wasn’t listening. The computer I use to decode received WSPR signals, with the receiver I built a few months ago, synchronises it’s clock very regularly to a series of atomic clocks which form part of the internet NTP service.

The beacon I’ve just built utilises the time signals transmitted by the GPS satellites which orbit the earth to accurately set its clock, so the transmissions are in sync with those receiving WSPR transmissions regardless of where they live on the planet.

WSPR is neither a cypher nor an encryption as amateur radio can’t be used to send transmissions that are encrypted. Morse code, although a “code” can be viewed as a shorthand, where everyone has the ability to listen to what is being exchanged if they have the wherewithal to learn or decode the the series of dots and dashes. WSPR is the same in that anyone can listen and interpret the transmission.

Once the transmission has been received and interpreted  the spot is sent to the WSPR community at WSPRnet.org and appears within the database so people can track the propagation paths of their transmissions.

The data within the WSPR transmission contains information so that the receiver knows who sent it and from where, allowing the “spot” to be identied. The microprocessor inside the beacon packages that data up into the prerequisite format and then passes it to the transmitter side so it can be sent off into the ether, in my case via 7.5m of wire strung out of a bedroom window and down the garden to a fence post.

The transmission power output from this beacon, which is just a fraction bigger than a Swan Vesta match box, is 200mW (milli Watts).

A 60W domestic light bulb is 60,000 milli Watts; the beacon is transmitting with 0.33% of that power. Putting it another way, that’s 1/25th of the power which illuminates the number plate bulb on your car.

So with that in mind, I was quite impressed that within 20 minutes of attaching the beacon to my antenna, I got this.

That 200mW of power, which wouldn’t even make your number plate bulb glow faintly, is pushing that signal over 487 miles to Scotland, 498 miles to Switzerland and 506 miles to Germany!

There’s definite fine tuning needed, but I may well strut in a Bee Gee’s “Stayin’ Alive” fashion for a few minutes!

 

Ultimate3 Configuration & First Run

After reworking the GPS receiver I was pretty much ready to go.

Firstly many thanks to Dan Trugian (M0TGN) for his advice regarding the GPS board. I’ve used the 10uF and 1uF decoupling capacitor set up as per the datasheet. Dan advises that a simple 10nF ceramic capacitor across ground and Vcc does the job. Also, ensuring that the screen on the cable between the beacon and the GPS is connected to respective ground terminals on each is a good move. Cheers Dan for the help, much appreciated.

Dan maintains his own site which is well worth a visit http://www.m0tgn.com/

So with everything plumbed in on power up everything was looking good.

The menu system took a while to work through but is simple enough.

My current settings are below for reference

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Hitting run, resulted in an instant accurate clock and a pulsing heart icon, indicating that the GPS had achieved satellite lock and was sending data to the beacon.

The next nail biting 10 minutes were spent crouched over the tiny display watching in anticipation.

The >40 indicates the next transmission will occur at 40 mins past the hour, so just over 8 minutes to go.

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And it’s off!! The 8, 16, 46 increment shows how far through the transmission the beacon is. A WSPR transmission is 160 characters long and comprises 3 tones, indicated by the last digit on the bottom right.

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At the end of the transmission the beacon runs through it’s calibration cycle using GPS data and makes adjustments to the frequency and saves them to the on board EEPROM.

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It then drops back into it’s waiting state ready to transmit at the next pre-defined time slot.

SKM52 GPS board wiring diagram

The arrival of some capacitors from the lovely people at Spiratronics means that the GPS module is now complete with decoupling capacitors soldered to the board and ready to go.

It could have been made smaller but 4 holes on a piece of Veroboard isn’t a huge amount of space and as said before it’s no bigger than a stick of chewing gum, so I can live with it.

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I used tantalum bead capacitors to keep the size down on the board and to achieve the quoted 10uF and 1uF from the datasheet.

As promised I’ve included a wiring diagram for the board. It’s hardly rocket science in hind site, but you’ve got to start somewhere with things.

SKM52 wiring diagram 2

R1 = 10K  C1= 1uF tantalum bead  C2 = 10uF tantalum bead

http://spiratronics.com/