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Author Topic: DVB-T Stick as SDR  (Read 102917 times)
KA4POL
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Posts: 1907




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« on: April 25, 2012, 11:16:10 AM »

Similar to the well known Funcube a simple USB DVB-T receiver can be used as SDR. It must contain either the E4000 or the RTL2832U chip. Software can be WinRad or HDSDR for example. See http://www.youtube.com/watch?v=-Fh4EB0sX2w
This is a simple and really inexpensive solution but nice for experimenting.
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KE5JPP
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« Reply #1 on: April 25, 2012, 04:06:32 PM »

Similar to the well known Funcube a simple USB DVB-T receiver can be used as SDR. It must contain either the E4000 or the RTL2832U chip. Software can be WinRad or HDSDR for example. See http://www.youtube.com/watch?v=-Fh4EB0sX2w
This is a simple and really inexpensive solution but nice for experimenting.

"The RTL2832U outputs 8-bit I/Q-samples, and the highest theoretically possible sample-rate is 3.2 MS/s, however, the highest sample-rate without lost samples that has been tested so far is 2.8 MS/s. The frequency range is highly dependent of the used tuner, dongles that use the Elonics E4000 offer the widest possible range (64 - 1700 MHz)."

8 bit samples is going to severely limit dynamic range even with process gain.  It is not going to be much more than a toy.

Gene
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KA4POL
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« Reply #2 on: April 25, 2012, 09:50:47 PM »

Funcube uses the E4000. At a cost of about 20$ you can't expect a perfect SDR from a DVB-T stick.
A compatibility listing can be found here: http://www.reddit.com/r/RTLSDR/comments/s6ddo/rtlsdr_compatibility_list_v2_work_in_progress/
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KE5JPP
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« Reply #3 on: April 26, 2012, 05:24:08 AM »

Funcube uses the E4000. At a cost of about 20$ you can't expect a perfect SDR from a DVB-T stick.
A compatibility listing can be found here: http://www.reddit.com/r/RTLSDR/comments/s6ddo/rtlsdr_compatibility_list_v2_work_in_progress/

I am sure it is fun to play with and for that price for the hardware its not bad.  But people should be aware that 8 bit samples are really going to limit the dynamic range of this receiver.  It may be OK for DVB-T where the signals are strong you don't need great dynamic range, but for general purpose receiving use it will disappoint.

For informational purposes, those  in the USA who might think they can pick up and demodulate digital TV on one of these devices, the DVB-T system is not used in the USA.

Gene
« Last Edit: April 26, 2012, 05:27:09 AM by KE5JPP » Logged
KA4POL
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Posts: 1907




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« Reply #4 on: April 26, 2012, 08:31:01 AM »

For those traveling to Europe, however, the main use of those sticks is to receive terrestrial video. There is no more analog TV available. And, by the way, beginning on April 30th even Satellite TV will be purely digital in Europe.
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W0ARN
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« Reply #5 on: August 16, 2012, 02:58:33 PM »

There's lots of free software to use with this ultra-cheap SDR dongle with more coming daily.  Many people are playing with it in a number of very interesting comm. (not necessary amateur comm.) projects, so I wouldn't overlook this off if you're into comm. generically.  Free software + ultra cheap hardware + computer you already have = something fun to play with:

Search youtube.com for RTL2832 and you'll find 112 videos.  Here are a few:

$20 ultra-cheap Software Defined Radio with RTL2832 DVB-T USB stick

https://www.youtube.com/watch?v=Z0hEquzLsWU

RTL-SDR APCO Project 25 (P25) receiver (DVB-T)

http://dangerousprototypes.com/2012/04/06/rtl-sdr-apco-project-25-p25-receiver/

World's cheapest INMARSAT reception system using DVB-T USB dongle (RTL SDR)

https://www.youtube.com/watch?v=zuyHpx1tnWI

World's cheapest aviation RADAR Mode S ADS-B receiver: AvMap + $20 RTL2832 Dongle

https://www.youtube.com/watch?v=bKzii5K3AqA

RTL2832 SDR + WRPLUS : WFM test

https://www.youtube.com/watch?v=BX9cLj1nMjQ

Google Group Ultra Cheap SDR:

https://groups.google.com/forum/#!forum/ultra-cheap-sdr
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N9RO
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« Reply #6 on: August 16, 2012, 09:41:14 PM »

I have a Funcube and performance radio's these are NOT.  For playing around with they are cheap and fun.  I quickly glued together some apps, thru up a CMS system and uploaded the recorded Funcube GUI to the web site so some of the local repeater owners could go to the web and see their signal (for entertainment purposes).  The legacy hams at this point in time would probably have no use for these but for low cost experimenting they are fine.

Tim
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Real techies don't use knobs.
KA4POL
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Posts: 1907




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« Reply #7 on: December 15, 2012, 12:41:31 AM »

There is a detailed description in QST 01/2013. It even includes a proposal for an up-converter. Seems interesting for those inclined to experiment and DIY.
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WD5GWY
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Posts: 390




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« Reply #8 on: December 15, 2012, 10:03:28 AM »

Looks like a fun and cheap setup to play with. And I am very tempted to order
one. Plus that would give me a reason to get back into programming again!
C# is not one of my favorite languages, (love VB.net) but, I can do some things
with it.
  I read the article in QST and found it quite interesting.
Guess, I'll have to go and spend some money now!!   Grin
james
WD5GWY
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N3DT
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Posts: 448




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« Reply #9 on: December 15, 2012, 12:43:47 PM »

So the limitation is the 8 bit sample rate.  Exactly what does that mean to my analog brain?  As a disappointment, in what area?  For $20 and some time spent playing is it worth it or is it just going to be like the old original 2fer's, or worse.
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WD5GWY
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Posts: 390




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« Reply #10 on: December 15, 2012, 03:06:16 PM »

So the limitation is the 8 bit sample rate.  Exactly what does that mean to my analog brain?  As a disappointment, in what area?  For $20 and some time spent playing is it worth it or is it just going to be like the old original 2fer's, or worse.

The sampling rate has to do with the Analog to Digital converter(s) and Digital to Analog converters in a device. Here are a couple of articles from Wikipedia that might help:

http://en.wikipedia.org/wiki/Analog-to-digital_converter#Sampling_rate
And here is one that lists various SDR radio's specs along with their sampling rates:

http://en.wikipedia.org/wiki/List_of_software-defined_radios

 In the above list, the DVB-T dongle from RealTec, seems to sample  from 1 Mhz to
3 Mhz. But, tends to not be reliable at the top end. Still, for $20 or so, that is not too
shabby! And building an upconverter for HF reception is cheap as well. If you get QST
read the January 2013 issue and there is a good article there covering this pretty well.
james
WD5GWY
 
 
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N3DT
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Posts: 448




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« Reply #11 on: December 15, 2012, 06:03:10 PM »

I read the qst article, that's why I'm here.  But it sounds like the guy is listening to P25 stuff, which is cool and way more than anything I have available otherwise.  But what is it like on ssb and cw, or even AM?

I got involved in the P25 with the Motorola Astro radios before I quit work, but our agency was encrypted and I know this thing is not going to do that, but it would be nice to hear the P25 local stuff.

It might be a worthwhile project for the bad winter days when I can't get outside and I'm sure any decent SDR would be at least 10 times that price, no?
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WD5GWY
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Posts: 390




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« Reply #12 on: December 15, 2012, 06:53:07 PM »

Do a search on YouTube for "DVB-T" and you'll find a ton of
videos showing AM, FM, SSB and other modes using the DVB-T
dongle with and without, an HF up-converter. The audio on most
of the videos is not great. But, then again, they are probably recorded
with cellphone cameras that have pretty poor microphones.
There is even a few demos of HF being tuned in without using an up-converter.
But,image rejection is poor. There is a company on Amazon.com that sells
the DVB-T dongles and also  sells an HF up-converter. For less than $90 total,
you can get an entire setup if you don't want to build your own converter.
james
WD5GWY
 
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KA4POL
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Posts: 1907




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« Reply #13 on: December 15, 2012, 10:02:16 PM »

So the limitation is the 8 bit sample rate.  Exactly what does that mean to my analog brain?  As a disappointment, in what area?  For $20 and some time spent playing is it worth it or is it just going to be like the old original 2fer's, or worse.
You are combining two things, the sample rate and the the data bit length.
The sampling rate determines how often a data conversion takes place. This usually limits the upper frequency (Nyquist Criterion). You need at least two samples to read a signal. This means at a sampling rate of 125 MHz you can read signals up to 62.5 MHz.
The dynamic range can roughly be calculated by multiplying the bit length by 6: 8 bit times 6 is 48 dB. This is not much but good in relation to the cost.The dynamic range can be regarded as the ratio between the highest number and the smallest number that it can represent expressed as a dB value.
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KE5JPP
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« Reply #14 on: December 16, 2012, 07:28:32 AM »

So the limitation is the 8 bit sample rate.  Exactly what does that mean to my analog brain?  As a disappointment, in what area?  For $20 and some time spent playing is it worth it or is it just going to be like the old original 2fer's, or worse.

It is something to play with, but you'll soon grow tired of the poor dynamic range and the image problems.

Gene
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