Video: Introduction to $20 Software Defined Radio...

[w2aew]

...using USB DVB-T dongle tuner and free software...

[PA0PBZ]

I just started to play with one of those RTL dongles in combination with gnuradio and grc (gnuradio-companion).
You've probably come across it already, it is very nice to put some graphical blocks on screen like the dongle source, a filter, a fm demodulator and a sound sink (output), connect them together and have your radio built in like 5 minutes 

Now playing around with psk detectors and stuff like that, just to learn how these things work and look at some on-air signals and try to decode. It's another aspect of the hobby where there is again so much to learn!

[accesscontrolforum]

I just bought one off amazon based on your video. Thanks!

[Alex Eisenhut]

20$? Am I made of money?

http://www.ebay.com/itm/181350890744?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[w2aew]

20$? Am I made of money?

http://www.ebay.com/itm/181350890744?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Ok, two for $20, including shipping...

[miguelvp]

Now you need $45 for the upconverter:
http://www.nooelec.com/store/ham-it-up.html

and $20 more for the enclosure:
http://www.nooelec.com/store/sdr/sdr-accessories/extruded-aluminum-enclosure-kit-for-ham-it-up.html

[w2aew]

Now you need $45 for the upconverter:
http://www.nooelec.com/store/ham-it-up.html

and $20 more for the enclosure:
http://www.nooelec.com/store/sdr/sdr-accessories/extruded-aluminum-enclosure-kit-for-ham-it-up.html

You can build one with a simple diode ring mixer or NE602 plus an oscillator for the LO. Add a couple of passive filters for preselection and IF and LO filtering for best performance.

[tcekolin]

There is an android version of sdrsharp which works fairly well. Free for basic use, pay for some features such as saving the audio and using the waterfall for more than a couple of seconds. You need an on the go adapter to connect the dongle to the phone. This works fine on my LG G2 phone, but a buddy has another LG phone that doesn't seem to be able to use the RTL driver.

My only wish is that i could rig something up so that I could power the phone and dongle from the car usb while using the dongle on my phone. If anyone has any ideas on how to do that I'd be very interested!

73 - Tony, AK4ZF

[EEVblog]

Silicon Chip have a nice looking USB SDR based project coming up. I got some of this on video from Electronex that I just reminded myself I haven't posted yet...

[urlkrueger]

So W2AEW says build a frontend yourself.  That's exactly my goal.  A half century ago I would read construction articles on HAM radios, make up parts lists, fill out order forms and then decide I didn't have enough money.  Really I just knew it would never work.  Fear of failure reigned supreme!

But now I'm on my way.  As a learning tool I have put together a couple of crude crystal oscillators and a diode ring mixer and I get out something like a mixed signal with all kinds of frequencies in it and it sort of looks like the signal in the W2EAW video.  Hurray, it works!

However, with one oscillator running at 4.2MHz as my RF and the other at 2.4MHz as my LO I expected to be able to see something at 1.8MHz ( 4.2 - 2.4 ) and maybe something at 6.6MHz ( 4.2 + 2.4 ) but at the IF output of the mixer I see a strong 2.1MHz varying at a 350KHz rate.   I haven't figured out how this comes to be yet, but that's the whole point of the exercise.  More mental work to be done yet.

What was really cool was that when I hooked up various high pass / low pass RC filters to the output of the mixer I could actually see the attenuation of the various frequencies in the mixed signal as expected.  Theory comes to life!

Anyway, a big thanks to Dave and Alan for leading me along on this adventure.

earl...

[dannyf]

A couple extensions of this:

1) it can be used as a spectrometer.

2) you can extend the low-end coverage: the low-end usually stops at 60Mhz (some lower than that), missing the broadcast bands. A mixer can be built easily to remap that to a band that is covered by the sdr. You can then use offset tuning to receive those lower bands.

It is the best value in the radio land.

I use SDR# with it.

[w2aew]

Here's the followup video showing a simple diode ring mixer being used to upconvert some ham radio transmissions (on 7MHz, 40m) an some shortwave broadcast (11-12MHz, 25m) signals so that they could be listened to using the RTL-SDR:

Oh, and if you search (not very hard either), you can find these RTL-SDR USB dongles for less than $10 US...

[EEVblog]

About 7:45 in
]https://www.youtube.com/watch?v=adSk6suM29E

[RobertoLG]

dunno, maybe of interest to somebody?

http://websdr.ewi.utwente.nl:8901/

[Tac Eht Xilef]

Silicon Chip have a nice looking USB SDR based project coming up. I got some of this on video from Electronex that I just reminded myself I haven't posted yet...

That one in the Electronex video is one they published a few months ago, isn't it?

(Just looked it up - yeah, Oct/Nov 2013).