Thursday, 26 September 2013

Suddenly, best-ever beacon dx

Last weekend I saw my new Arduino Sudden Tx Shield and the DDS Shield sitting on the bench and an idea struck me - I'd work up a beacon which combined some of the flexibility of my multi-mode beacon with the simplicity of the Arduino beacon.

I took the code I'd developed for the Kanga enhanced VFO system and hacked it to make a beacon capable of sending QRSS FSK-CW, QRQ CW and WSPR.

 Here's the set-up on the bench...

I had arranged for the software to use VFO A of the Kanga Enhanced VFO for the CW transmissions and VFO B for WSPR.

Here's the screen in close-up during the "Rx" phase between transmissions...

Notice the band display at lower right - not only could I adjust the frequency of the transmissions (to fit between other signals showing on the grabbers) but also I could change bands at will (as you'll see later in this post). Here's the display in transmit mode - in this case I'm sending the usual QRSS FSK-CW as you see at the top of the screen...

I started on 40m in the evening of 23 September and immediately got some decent reports on WSPR and QRSS - here's the overnight performance from 23 - 24 September...

Gratifying and consistent with the sort of results I'd obtained before with other beacon systems (Blogs passim) here at m0xpd (although I'd never before been spotted in Bermuda - thanks John, vp9ni !)

 I decided to exercise the flexibility of my new system and switched to 30m for the night from 24 to 25 September and was rewarded by my best-ever beacon performance...

I was so excited by the journey to Oz that it took me a while to notice that Dick, vk7dik, is actually further away in Tasmania. Brilliant.

Also the little beacon had bagged some nice new reports from Greenland and the Canaries (where I've never "been" before). Note further how Chris, 4x1rf (who has received my beacon signals before) spotted this new system's output in Haifa on both 30 and 40m - thanks Chris!

After that exhilarating performance, the next day (today) was a wash-out.

Changes in propagation conditions are seen by the sudden-ness (pun intended) of the "cut-on" as reception wakes up - as seen in this example at pa1gsj...

I also noticed a slight droop in the frequency during the course of reception at the same grabber - a rough "guesstimate" of the gradient suggests the VFO is drooping by about 0.8 Hz/minute (during the transmit phase) in this application...

This is interesting, as its the first shred of non-ideal behaviour I've seen in the DDS module - perhaps it doesn't like sitting close to the 2N3866 sweating away on the nearby Tx shield.

All-in-all a really pleasing result.

Now for the good news - I'm going to be making the beacon software freely available for you to download and use as part of the supporting materials for the joint Kanga / m0xpd projects.

It will be a great application for the DDS Shield and (once we get round to completing it) the Sudden Tx Shield.

Watch this space.

...-.- de m0xpd

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