SSB generator using a modulated PLL (by PE1NNZ)

Guido PE1NNZ has been doing some very impressive work on direct SSB generation using a PLL and implemented it on a Raspberry Pi mini computer. I don't claim to understand a word of it (!) but this really is clever stuff. He tells me he has made several contacts on the 40m and 20m bands with his Raspberry Pi!

For your interest, here is more information about the SSB experiment: http://pe1nnz.nl.eu.org/2013/05/direct-ssb-generation-on-pll.html

73, Guido
PE1NNZ

To Argentina on 10m WSPR today

The 2W WSPR beacon was copied several times today in Argentina (LU8EX, 11208km) and by CX2ABP (11127km) a few days ago. 4X1RF seems to copy me most days. 10m seems to open mainly on the N-S paths although I did spot a DU station (Philippines) a few days ago.

This evening I have fired up the 472kHz WSPR kit into the earth electrodes. PA3ABK is coming through despite my high local noise level and 6 stations so far are copying my 1mW ERP signal. PA3ABK is the best DX report of my signal so far at 306km but the beacon has only been on for an hour so far.

WSPR - how long to get a decode?

A question for my esteemed readers please.

Using WSPR (WSPR2 that is) the transmission burst is nearly 2 minutes long, but I believe strong signals can be decoded when only a part of the burst is received. My question is, how short a burst can be decoded?  Presumably it depends on how strong the signal is.

LB9YE was coming through quite well this morning but there was no decode of a very strong (I assume MS) burst at 1048 which lasted about 30 seconds. Of course with MS there may also be some Doppler shift which can mess things up a bit.

If you know about WSPR and can help with the answer, I'd appreciate it. I am particularly curious to know how WSPR might do with short MS bursts which can be strong but only last a few seconds. It also begs another question: there is now a longer version of WSPR (WSPR15) with better decode S/N levels. I wonder if a shorter version of WSPR has been considered? Then again I think there may be better modes for MS.

Night watch on 10m

Overnight, I ran WSPR on 10m just for fun. Although my 2W wasn't spotted until 0600, a couple of Germans were spotted here around 0400 presumably by Es or MS. Without modes like WSPR such brief night time openings would go unnoticed.

One Laptop Per Child project

When I left paid work in 2008, the One Laptop Per Child project was in its infancy. At that time the idea of a low cost PC or netbook was not really on the horizon, although the Linux 7 inch Asus EEE PC was a sign of the future.  As far as I can tell, the availability of low cost netbooks and tablet PCs has rather overtaken this project: low cost computing is now available from many sources.

The idea of making low cost computing and internet access available to under-privileged children and others worldwide is a noble one and one I fully support: knowledge is power and knowledge and education are  rights for all citizens of the world.

However, there seems to be some doubt about the success of the OLPC project 5 years on. It was a "good idea" but maybe market forces overtook it?

One of the reasons I like QRP projects is because they have the potential to make useful radio technology accessible to all at low cost.  Like the OLPC project, my dream is a simple, low cost, easily reproducible, HF transceiver design that really can produce useful results. There is something beautiful is "elegant simplicity" don't you think?

The £20 decent HF transceiver thoughts

I never fail to be impressed by what other people know and that I don't.  Several people have responded to my post about the "£20 decent HF transceiver challenge" with ideas that use PICs and similar micro-controllers in novel ways to generate SSB signals. In all honesty I wouldn't have a clue about how to start doing this, so I am VERY impressed.

My own approach to the £20 transceiver would be very low tech indeed: not an IC in sight probably and certainly no processors. Having said that, I would be very interested to see how such novel approaches could help to realise a low cost decent HF transceiver. As an example of this look at the HF WSPR transmitters produced entirely using a Rasperry Pi PC.

One thing that life has taught me is that it is impossible to know about everything: some of us know lots about RF (I am only a surface scratcher) whereas others know lots about software or something else. Some very talented people have a wide span of knowledge.

We should be grateful for the unique knowledge WE have and gracefully accept that others know lots more than us about something else. It never does any good to be stressed about what we don't know. In my work days I always told my staff never to be afraid to ask the dumb questions as there are lots of others waiting for someone to ask them!

Incidentally I have done nothing yet towards this design. Weather has been too nice to be inside engineering, HI.

Solar activity - a second peak?

Looking at the sunspot and solar flux levels in the last month, it looks like we are seeing evidence of a second peak to cycle 24.  Whether it exceeds the peak of November 2011 remains to be seen.  As the slide down from the peak(s) is slower than the rise towards the peak(s), we can expect reasonable HF conditions for several more years yet before we return to the quiet years when activity on 12 and 10m is very low indeed.

10m WSPR

My 10m WSPR system has been running most of the day with powers between 500mW and 2W. The only reports were from 4X1RF at 3519km. Best DX station copied here was DU1MGA at 10710km.

One of the reasons I like WSPR is that you can do other things at the same time whilst checking on how propagation is changing.  I am really looking forward to running WSPR in the quiet sunspot years on 10m and expect far more openings that might be found by calling CQ on CW or SSB with 5W.

New QTH work

New QTH rear garden - with the "roof tile feature"!

The work on our new (to us) QTH in Burwell is progressing steadily and if things go to plan we should be in later this summer. Today I was at the new location sorting out the garden - as much as I could - in the beautiful sunshine. There is still a great deal of builders rubbish and mess around and it will be some months before the garden can be properly worked on: for example, we have a row of roof tiles neatly stacked down the middle of the rear lawn and the front of the house has a pile or 2 of sand and bricks! The drive has a skip in it which is rapidly filling with neighbours rubbish too.

I am still thinking about ideas for antennas. At least in the new QTH I will have a dedicated shack where I can both build and operate: in 37 years at the current QTH this has not been possible. Currently I have called off the plans for VHF/UHF SSB/CW/data operation as I don't think there will be enough activity.  So, an effective, neighbour friendly stealth antenna for the higher HF bands and 6m will be the immediate priority.  

ISWL

Back in the 1960s, when in its heyday, I was a keen member of the International Shortwave League (ISWL). In those days its membership was measured in thousands from all over the world.

A few years ago I rejoined and enjoyed the monthly magazine called Monitor. I contributed a few articles too. Sadly, membership has been declining steadily and now, I believe, the membership numbers fewer than 300 people. The club keeps going as a result of the dedicated hard work by its voluntary staff who put together the magazine each month.

This last year I have started to take the magazine as a .pdf copy. It really isn't the same as a paper magazine you can take to bed and flick through. I find the pdf version much less satisfying.

After some thought, I've decided not to renew my subs this time as it is surely now only a matter of time before the ISWL folds. It served its purpose in its day, but those days have passed. This last month a final coffin nail was the closure of the ISWL QSL bureau, one of the last to process broadcast QSLs as well as amateur ones.