Radio History?

A little while after moving to this QTH I joined the local radio club. Always a good way of getting to know local radio amateurs in a new area and an opportunity to chat to like minded people and share knowledge. One evening I mentioned that I used a few SDR receivers in the shack. A number of the club members were not familiar with SDR and to cut a long story short I ended up offering to bring along a couple of my receivers and give a demonstration.
Whilst I was planning my demo I realised that as the club meetings are in the evenings and HF conditions have been very poor lately it was quite possible that we would have very little to listen to. Then it occurred to me- Most SDR software has a facility to record. Not simply to make an audio recording, although it can do that as well as required. The clever bit about recording from an SDR receiver is that you can also "record" a whole bandwidth of signals. In the case of my Elad SDR radio it can receive and record up to 6mhz of bandwidth. The picture below shows it receiving the full 6mhz using the SDR console v3 software.

Using this facility I was able to record part of the spectrum in the daytime, when the bands were busy and use this to demonstrate the SDR software and receivers.

The received part of the spectrum can be recorded onto a hard drive (or any other media). When played back you can tune through the spectrum (in the example above from around 11 to 17 mhz) using whatever mode you want.

In effect you have a snapshot of that bit of the HF spectrum which you can listen to as if you were sat at your receiver when the recording was taken.

This set me thinking, if only we had this technology years ago. Today we would be able to tune through the HF bands of the 40s,50's 60's as if we were there! 

I wonder if anyone is recording the bands on a large scale now. The downside of this is at the moment these recordings use a lot of space. The recording in my picture above was for a 10 minute recording of 6mhz of spectrum which used 7gb of storage. I reckon to record the whole 30mhz of LF/HF (if you had a receiver with such a wide bandwidth) for 24 hours would use in the region of 8.4 tb. If you were attempting to record for any length of time you would need a massive amount of storage. But just imagine if we were able to tune through the bands of yesteryear!........................................

QRT? Not Quite

I haven't posted here for quite a while. Its not that I have lost interest however the shack has largely been dismantled  and most of the antennas taken down as I am waiting to move house. Of course these things take time and even if all goes to plan it may be a few months before I am at my new QTH. In the meantime the only antenna still in use is my Wellbrook active receiving loop along with a couple of receivers in the shack. So for now I am almost totally an SWL. This would not be so bad if I didn't have a very bad noise problem here. I have been unable to trace this noise. It disappeared for a couple of months in the summer, but now its back. I don't think it comes from my neighbours properties as a while back we had a power cut in the street and checking with a battery powered receiver the noise was still there. The noise it at its worst below about 7 mhz, it wipes out parts of the medium wave, as well as the 160m and 80 metre bands and affects 40metres to a lesser extent.

Here's an example of the effect on medium wave.

I am just hoping my new QTH will be a bit quieter on HF!!

I still have 2 metres FM and HF on my Icom 706 in the car so can operate mobile however 2 metres in this area is a wasteland with very little activity. With the house move and the prospect of no antennas for a while I have even got involved in an area of radio that I had always been rather critical in the past- D-STAR. I will talk more about this in future blogs, it is a way of still getting some radio activity in at the moment but it is cheating and doesn't of course have the same magic at operating on HF!

I had a little time to play radio this weekend so managed to work a few special event stations that were running for the lighthouse weekend. Conditions were not  that good and the noise problem I still have here doesn't help but I managed a few. One surprise was working EI0LHL on 20 metres. I can't remember ever working an EI on 20 before, the skip isn't usually that short on that band.

The noise problem here is very strange. A few weeks back we had a power cut in this area. Listening around on a battery operated radio at that time showed the noise was still there. So my noise is not caused by a near neighbour with a PLT device as I had suspected. Stranger still about two weeks ago the noise disappeared. Sadly it is now back again but perhaps isn't quite as bad as it was but it still makes a mess of Top Band (160m) and Medium Wave.

Contest surprise

Tuning around the 10metre band I heard V55V/P in Namibia. A contest station they were easily the strongest signal on the band. A quick call resulted in a 59 (!) report and a new one in the log for me.

Radio Rally time again

Tomorrow I will be attending one of the few local radio rallies that are held these days. This one is at Neath, it should have been at a sports centre in nearby Port Talbot (The Afan Lido- pictured above) but sadly that venue was destroyed by fire earlier this year. The new venue was a last minute arrangement so it will be interesting to see what the new site will be like.
One I first became interested in Amateur Radio it seemed like there were radio rallies to attend almost every week. That's not the case today and those that are left are generally smaller events. Still it is nice to catch up with familiar faces and obtain those bits and pieces needed for the shack.Myself I am not intending to purchase much, but I do need a new logbook and some plugs and connectors.
The higher bands continue to prove interesting and most of my recent PSK activity has been either on 21 or 18 Mhz. I have heard a limited amount on 24Mhz, but as yet nothing on 10 metres. When I have had the opportunity to listen in the daytime I have also noticed that 40 metres seems very lively with stations from the UK and Europe boomimg in.