The Miracle of Software Defined Radios... Yes a Mircale

I can tell you are not convinced...

5/14/2019 ~ New Found Capabilities.

Having spent a large part of my ham experience with self constructed rigs (now RADIG) often these were simple no frill radios and this worked FB for me. Plenty of contacts and of course the thrill of articulating "the rig on this end is homebrew". But they were just that, no frills; but good sounding.

Now with my new RADIG --wow lots of frills for about the cost of one of my older bare bones crystal filter rigs. Today I was listening to a 'big time 40M DXer" who must have some pretty elaborate antennas and some expensive hardware. This chap was simultaneously working VK's and ZS's (for those newly minted extra class licensees --that is Australia and South Africa). Then I listened closely to his signal -- I actually think he had RF in his audio. To assure myself that it was not my RADIG I tuned to other stations of the same signal strength and they were crisp and clear. So it was something on his signal and not my RADIG.

If you look in the photo below, right below the vertical line and in the row of buttons  on the first line are a couple of buttons I have never used before. 

Depressing one of the buttons lets you record the signal being heard and the 2nd button lets you play back the recording. Wow, I know those of you with some of the commercial rigs have (had) this capability and in  many cases this has been around for a very long time. But this is a first for me. But wait -- if you are in the playback mode -- and press the PTT -- the recording is automatically transmitted over the air. Now that is a first for me. Yes some of you have had this for a very long time.

But now this opens up the possibilities when some one is having a problem to assist them by letting them hear their transmitted signal. Think also --free software and a $150 RADIG, and a $35 computer.

I can just tell by listening to this big time ham he would discount the recording by saying "there is nothing wrong with my signal". But there was! 

Now I have the capability to record on the air signals and play them back. Oh another feature you can hear what is being transmitted from the recording --this is useful so you know when there is evidence of a particular event. You got to love this technology. 

This has been a bonus find with today's button pushing. Guess it is time I read the Quisk manual.


5/12/2019 ~ New Hardware.

Today (in between cooking my XYL a Special Mom's Day feast) I added a 7 inch HDMI to my Omnia/RPi3. Stunning is a good word and second word is small -- really small. The third word is RADIG (A Radio Rig).

So Get Cracking and dig out that old RPi2 -- it will work with Quisk. 

Pete N6QW
I need only look at the paltry amount of viewers of this blog to see that my SDR adventures are discordant with many who formerly looked at my ramblings. Guess what --I don't care and I will continue to discuss my SDR efforts.

There is a great suspicion that the lack of enthusiasm for taking on self-constructed SDR rigs (in defference to those who do not think it is true homebrew because you can't touch or feel every component) is based more on a lack of a willingness to go beyond a certain comfort zone. Or perhaps it is a life peppered with "I can't do that". Well you can.

Jokingly someone suggested I try for the Guinness Book of World Records given the number of homebrew traditional sideband transceivers I have built. You can read several notable ham publications to see published articles on these projects. So it is with an experience base in the analog world I challenged myself to move to what one friend calls "the dark side". It is only a dark side because some have not opened the door. In a few days Xenia will happen and a host of new SDR radios will be unveiled. True a FTdx -101D can be had for about $4K but you can build a self-constructed SDR for about $250. I have done it!

What has made it possible to move to SDR without having a PhD in Electronics is the ready availability of hardware like the Raspberry Pi3 for about $35. Add a 64 GB SD card and you have a computer that 10 years ago cost over a thousand -- I know because at one time I had a computer business. Incidentally I have taken the latest free operating system NOOBS 3.0 and loaded it on a PI2 built 5 years ago. The RPi is good enough that you can even watch Netflix on the little device. Yes I can do that on my smartphone but it sure didn't cost $35.

In one of those notable publications I produced several articles on SDR radios you can self construct and I think essentially the same outcome: glazed look and the feeling I can't do that. Well you can. Just get off the couch and get smart about SDR.

I hope to start a series that will take you through the detail of how to self construct your very own SDR "radig"  (that is a combo of the words radio and rig).

Start first by acquiring a Raspberry Pi3 and a minimum of 16 GB SD card. Get a 5 Volt 4 amp supply to mate with the RPi and you will also need a heat sink for the RPi. I had bought a plastic case for the RPi and after a couple of hours of digital operation on WSPR a small red thermometer showed up on my screen. Never saw that before --so I added a small fan on the case top and now all is "cool". I use a wireless keyboard/mouse (Logitech) as that takes up only one USB port and you will need a HDMI capable monitor. I got a Sceptre 16 inch for $60. This will get you started.

For software you will want NOOB3 and later you will need Quisk 4.1.15 and WSJTX 2.0. I have the quisk on my website and believe it or not --once you get the RPi3 working you can down load it from my website to your Pi. Today I hope to add the permanent version of WSJTX 2.0.1 so you can download that also. The WSJTX can self install right on your Pi from the download directory. 

So if you are not into SDR --stop reading the blog!

I can only say that it has been such an eye opening experience to literally have daily QSO's with Japan and be able to filter out the crud and crap so often present on a simple rig lacking digital signal processing. I have my screen set up to see about 100 kHz of spectrum -- it is easy for me to see whether the band is truly dead or chock full of signals. All this with a $35 computer.

Pete N6QW

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