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!........................................

A new receiver

I have owned the Cross Country Wireless SDR 4+  SDR receiver for a couple of years now. I wasn't sure how I would get on with an SDR, as it turned out I have really taken to it. I am probably more active as an SWL than I am as a transmitting radio amateur but since having the SDR in the shack my Kenwood R1000 and R5000 traditional analogue receivers have been hardly used. there is a link on this blog to a short review of the SDR4+and I will soon be updating it with my views of the receiver two years on, but basically I have been really pleased with it. It is still in almost daily use and coupled with my elderly Windows XP laptop acting as a server works well remotely.
One of the big plus points of the SDR is than I can control it remotely over the internet using my compact Acer Netbook computer and I have had a lot of fun doing this. I suppose the next step would normally be an SDR transceiver like the flex radio but for my ham radio activities I still prefer the traditional "knobs and buttons" approach of my rigs.

However on the receiver side, early in December I ordered  a Elad FDM S2 direct sampling SDR.
This receiver covers from 9khz up to 160mhz and comes with its own bespoke software. Due to a stock shortage the receiver was not delivered until 24th December, this meant that with the Christmas festivities and visiting family  I have not had much time to use the receiver until the last week or so.

Here it is sitting on top of the SDR4+. Although  almost the same width the Elad is only half the depth. Its facilities are more complex than the SDR4+ and the software takes some getting used to although I can also use third party software such as the "SDR Radio"  package which I am more familiar with. First impressions of this receiver are excellent, although it is more demanding of the PC hardware. My main machine here in the shack is a dual core processor with 4Mb of Ram but struggles with the receiver on some of the wider bandwidth settings-possible an upgrade of the shack PC will be required.
I have no doubt I will be posting more about the Elad as I get to know it better.

Just prior to the Christmas break a fault developed with my main station antenna the Western HF10 doublet. I checked all the obvious things, the coax cable was OK, no breaks in the Ribbon cable feeder (which seems to be the antennas only weak point-it is otherwise extremely well made), The antenna element itself was checked for continuity as were the loading coils. All seemed ok but the antenna would not tune on 80 metres. As I was short of time I have taken the antenna down and replaced it with a half size G5RV for now. I will give the balun connections on the HF 10 a good clean up and replace the ribbon feeder and hope that will cure the problem. I am keen to get it back up in the air as I have found it to be an excellent antenna.

Some Progress

A little while back I posted about the problems I had with remote operation of my CCW SDR4+ SDR receiver.
Originally I had set the receiver up on my main PC, running windows 7 and I (and others) were able to access it over the internet using the SDR-Radio software. All was well until a problem with Win 7 on the PC meant I had to reinstall the OS, after that whatever I tried I could not get the remote access to work. After many fruitless hours I pretty much gave up.

Yesterday I dug out an old Windows XP laptop I have. After a bit of tweaking, to my surprise I was able to connect the SDR receiver to it and operate it remotely

The important part of the screenshot above is the little "OK"  near the bottom of the left hand section. That means the SDR server program is accessible online. I don't think I can use the laptop as a permanent solution. Whilst I am happy enough to leave PC in the shack running for a day or two am I a bit concerned that a laptop would overheat. Maybe I am over cautious? In any event I have at least proved that my router is ok and the settings I am using in the SDR software are correct. Clearly something in my Windows PC is blocking access. Finding out what is the difficulty.

DVB Dongle

I have been reading quite a bit lately both on the Web and in the various radio magazines about the use of cheap USB digital TV dongles as VHF/UHF SDR receivers. Whilst browsing Amazon the other week, looking for a birthday gift I noticed that they had suitable USB dongles for around £11. At this price I could not resist. Well the TV dongle arrived yesterday. After a few false starts I have managed to get it to work with the "SDR Sharp" software. So far I am just using the tiny vertical antenna that came with it but I have managed to receive some local FM broadcast stations. I have an antenna adaptor lead for the dongle so will see if I can sort out a better antenna. For the very modest cost it has to be worth experimenting with this little unit.

Shortwave Listening.

I managed to do quite a bit of shortwave listening over the past weekend and have been putting my new SDR4+ receiver through its paces. Rather than clog up this post with my ramblings about my new toy you can click here to find out a bit more about it.
Suffice it to say I am rather impressed with this little rig!

Christmas is coming.....

Well in my shack anyway! An early Christmas present in the form of an SDR shortwave radio. This is the Cross Country Wireless SDR4+ which I received last week.

It covers from around 900Khz to 30 Mhz and so far I am very impressed. In the main I have been using the SDR-Radio Software to control the radio.

I have even managed to set the radio up so I can remotely tune and listen to it over the internet. If you visit SDRSPACE.COM and down load the software you will see a number of receivers that you can remotely use. Mine isnt on 24/7 at the moment though.

I will write further on the SDR4+ soon but for now I am enjoying tuning the bands with it.

Battling with SDR

I thought I had the answer to my problems with the Elektor SDR yesterday. The Winrad software would not run under Win 7 properly and my base Unit XP machine seems just to slow to cope. As a last resort I dug out my seldom used Win XP laptop, Installed Winrad, hooked up my external soundcard and............It worked! But hold on, the audio is a bit distorted, and now the machine wants to switch off. Guess what? My laptops power supply has died! Oh well, I have ordered a replacement so hopefully I will soon have the loaned SDR receiver in operation. Watch this space!

Computer woes

In earlier entries I have mentioned the Softrock SDR receivers which I have been loaned and have been playing around with.These little receivers are single band, fixed frequency affairs. Basically you just feed their output into your computer soundcard, chose one of the many SDR software packages and away you go.
My local amateur friend who loaned me the softrock has recently purchased a Flex Radio HF transceiver. I called around to see it in his shack last week and had a quick tune around and it looks an impressive piece of kit. He is still learning how to use it and this is where I think the SDR rigs fall down at the moment. They are nowhere near "Plug and Play". Now thats fine in itself as part of the hobby is about learning and self improvement. The problem here thogh is you don't need to learn about radio its computer knowledge that counts. Knowing which operating system will or wont work with your software, installing USB drivers, dealing with incompatible soundcards, not your usual radio related problems.
I have been dealing with some of this myself this week. My friend having purchased the new rig offered me the loan of his Elektor Hf receiver. Covering up to 30 mhz this little receiver is an interesting device but:


The best way to control it is to use the "Winrad" software to which a file can be added that allows it to fully control the Elektor receiver. The problem is however that my main PC uses Windows 7. Windows 7 doesn't like Winrad- it says it is incompatible. Now Windows 7 isn't telling the full truth as I did have the little SDR working well for about 10 minutes or so before Winrad and Windows 7 disagreed and the PC locked up. Now of course Windows 7 won't even open Winrad, or if it does the software instantly locks and cannot be closed!

This isn't too bad a problem because I have an older PC here, which I use for HF data work that runs Windows XP. The only thing now is it is a slow machine 1.3Ghz CPU and 512Mb of memory, it doesn't seem to want to run Winrad. I am going to try to remove as much unnecessary software as I can from this machine and see if I can get it to work but this may take some time.

My point is this, no doubt many SDR transceivers offer superb facilities. But this morning I was able to pop into my shack- I had a few free minutes and take a quick listen on the bands. I turned on my 20 odd year old Kenwood R5000 receiver. I didn't have to wait for it to boot up, it didn't need to recognise a soundcard or any drivers- it was on- instantly and ready for use! What's more, when I was finished it switched off just as easily. As well as this it doesn't have any noisy monitors or peripherals that cause hash on the HF bands. At the moment I am not sure that there are any SDR radios that rival it!

First Steps in SDR

I mentioned in an earlier entry how a local amateur friend had purchased an Elektor, general coverage SDR receiver board. After some initial problems , he is up and running with it and it sounds like quite a promising piece of kit.
In the meantime he has loaned me a Softrock receiver board which he built some time ago.
The Softrock is a crystal controlled receiver. This one covers both 40 and eight metres.  But only a portion of those bands. With my sound card I get a 96khz section of both bands (largely the CW section).You may not be able to tell from the pic but it is very small in size with lots of tiny components on the board. I wouldn't fancy my chances at building one!

Initial impressions of using the Softrock is that I have a lot to learn! In addition to your receiver and antenna your results are also affected by the quality and type of the sound card you use. The SDR software seems quite confusing to someone like me who is used to turning knobs and pressing buttons. In any event I have the receiver up and running. I have decided to use the Winrad software with this board, after having compared a few programs including the "Power SDR" program pictured.

Revisiting DRM

Today the amateur bands didn't seem in very good shape, but I had some radio time. I fired up my old Kenwood R1000 receiver, dug out an old usb external soundcard and did some listening to DRM shortwave broadcasts once I has loaded the DRM "Dream" software onto my main PC.

There are still quite a few DRM broadcasts to be found, I received DRM for four or five different broadcasters today. The sound obtained from DRM is at its worst similar to perhaps mono sound via the internet and at best almost as good as an FM stereo broadcast. The problem is though that you need a very strong signal S9+20Db at minimum to get a readable signal from DRM, or at least that is the case using my elderly modified receiver.

This has brought me round to thinking about SDR radios. I mentioned in an earlier entry how a local amateur friend recently purchased a flex radio transceiver. I have briefly seen it in operation and the receive side sounded very good, with its filtering and good interference rejection. Of course such a device is very expensive and personally I would rather my main equipment is capable of being manually operated, I don't want to have to always have my PC running. An SDR receiver sounds appealing, particularly as I still do quite a bit of shortwave listening but again this is a very expensive proposition. So when another local amateur told me of the Elektor SDR radio which he was buying I was very interested. The Elektor is basically a populated board with all components installed  but no casing. My amateur friend has just received his and is in the proccess of setting it up and testing it out. When it is up and running I am hoping to see it in action. if it is any good it will be very tempting at the asking price when you compare it to the other SDRs on the market.