OWON Oscilloscopes

Owon Electronics and test equipments. Discussion area is now open!
It is currently Sat Jun 24, 2017 11:38 am

All times are UTC + 2 hours [ DST ]



Welcome
Welcome to owon

You are currently viewing our boards as a guest, which gives you limited access to view most discussions and access our other features. By joining our free community, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content, and access many other special features. In addition, registered members also see less advertisements. Registration is fast, simple, and absolutely free, so please, join our community today!


Post new topic Reply to topic  [ 8 posts ] 
Author Message
 Post subject: DVB-T USB dongle as cheap SDR radio. (RTL-SDR)
PostPosted: Tue Sep 17, 2013 12:52 am 
Offline
Site Admin

Joined: Wed May 16, 2012 7:54 am
Posts: 187
(First some words by finnish language)



Tulipa sitten hurahdettua kokeilemaan näitä USB TV tikkuja softaradiona.

Asiastahan on paljon tietoa saatavissa monista lähteistä.


Tikuista on myöskin suorastaan ns runsaudenpula.

Mutta, siinäpä se sitten onkin kun alkaa selvittää missä tikussa on sopivat sisuskalut. Kun tämä asia nousi taannoin esiin että määrättyjä tikkuja voi käyttää SDR radiona alkoi myös niiden myynti "kiinalaisilla toreilla" ja myös hinta alkoi nousta erityisesti niiden tikkujen osalta joissa vastaanotinpiirinä oli (ja on) Elonics E4000. Sitten Elonics loppui, koko firma taisi loppua. Noita E4000 vastaanottimen sisältäviä tikkuja saa edelleen (vanhaa varastoa) mutta nyt on myös oltava tarkkana jos haluaa nimenomaan sillä vastaanottimella koska kiinalaiset myy mitä tahansa jota joku ostaa ja lisäksi harhauttavat esim eBay:ssa ostajia kaikenlaisilla kiertoilmaisuilla. On E4000 soveltuvaa ja on yhteensopivaa jne.. Aitojen Elonics E4000 pohjalta tehdyt tikut alkavat kadota ja hintakin on jo jonkun aikaa noussut (koska a ne on hyviä ja b ne käyvät vähiin)

Ebayssa on myös tikkuja joissa tuotteen otsikossa tms lukee E4000 mutta sitten varsinaiseen tuotteen kuvaukseen ainakin joku tunnollisempi myyjä on lisännyt huomautuksen että "vastaanotinpiiri ei ole E4000" ja jokunen muu ei kerro ollenkaan. Kun kysyy mailitse asiaa, ei tule vastausta tai vastaus on että on "yhteensopiva".

No Elonics E4000 ohella muitakin vastaanotinpiirejä on.
Elonics E4000
Rafael R820T
Fitipower FC0012 ja FC0013
jne


Top
 Profile  
 
 Post subject: Re: DVB-T USB dongle as cheap SDR radio. (RTL-SDR)
PostPosted: Tue Sep 17, 2013 7:37 am 
Offline
Site Admin

Joined: Wed May 16, 2012 7:54 am
Posts: 187
Made some tests using DVB-T USB dongle where is Elonics E4000 tuner.

1. Terratek:....Elonics E4000+ Realtek RTL2832U (Elonics is stopped. Pity!) 54 - >2000MHz


Later:

2. Noname:.....Rafael R820T+ Realtek RTL2832U 24MHz - >1500MHz*
3. NotOnlyTv:..Fitipower FC0013+ Realtek RTL2832U 22MHz - ~1100MHz*
*some variations possible. Look later test results.




some preliminary pic-ups.

E4000 tuner (Terratek DVB-T dongle): Signal 146MHz AM 1kHz 50% modulation.
(With 50% modulation, sidebands level is -12dBc)
With signal level -139dBm 1kHz sidebands are just around noise level. (barely visible in spectrum waterfall) Carrier of course higher.
Note: signal levels just what read on the HP8657B display. Becouse dongle input impedance is "unknown" it need note. (some dongle specs tell 75ohm but "who knows" what is truth.)
Later some test images and more details and data over freq range.
Sensitivity over frequency range is very flat. It was real surprice, as also this sensitivity.
E4000 band is not continuous, there is gap between around 1100MHz - 1240.5MHz.

These dongles are cheap and fun step to play with Software Defined Radio and perhaps then later buy expensive good SDR like Perseus or something more.
Also RTL2832U can sample 2.4 (2.8-3.2MSa/s simultaneously I and Q)
It can record over 2MHz band in real time. If there is lot of trafic you can then later listen different frequencies.

In tests I have used SDRsharp software.
in old Thinkpad T43p (just barely can run this).
SDRsharp need powerful PC if want all run ok.

Primary signal source HP8657B.
All three tested DVB-TV dogles have modified before test. I did not use different antenna input connectors. For every dongle I solder BNC with short thin semirigid coaxial directly to PCB RF input. (same point where is original antenna connector)


Top
 Profile  
 
 Post subject: Re: DVB-T USB dongle as cheap SDR radio. (RTL-SDR)
PostPosted: Wed Sep 18, 2013 2:14 pm 
Offline
Site Admin

Joined: Wed May 16, 2012 7:54 am
Posts: 187
Some words about softwares and drivers for Windows XP (or later).

There can use several SDR softwares but in tests I have used SDR# also known as SDRsharp.

How to install.

Read this SDRSharp Quick Start manual.
For installing you need only carefully follow simple steps in paragraph "INSTALLING SDR#"


You need download these:

1.
Download SDR# (and plugins if want)
These can find here.
Download (if also want plugins) two packages:
SDR
SDR# Dev (Continuous Integration, Last Changed Rev: 1165 )

2.
SDR Plugins
SDR# RTLSDR Plugin (Continuous Integration, Last Changed Rev: 1165 )

3.
Then need Zadig (for USB drivers)
Download latest Zadig here (there is most new versions!)
Depending your windows
Zadig for Windows XP (5.14 MB)
or this
Zadig for Windows Vista or later (5.03 MB)


4.
And then download this RelWithDebInfo.zip from Osmocom


Top
 Profile  
 
 Post subject: Re: DVB-T USB dongle as cheap SDR radio. (RTL-SDR)
PostPosted: Fri Sep 20, 2013 12:08 pm 
Offline
Site Admin

Joined: Wed May 16, 2012 7:54 am
Posts: 187
First just one sample. Listening weather (Pirkkala ATIS) with poor 10cm antenna stick inside house.
Image


Then about sensitivity tests with DVB-T dongle using Elonics E4000 tuner ( and of course)RTL2832U.

Signal from HP8657B using 1m coaxial cable.
Every USB module was modified so that its original antenna connector is still on there but for test signal there is around 20cm teflon coaxial soldered directly to antenna connector joint on PCB. Other end have normal BNC F. (these was ready made cables)
If input is 50ohm or 75ohm I did not care.

For get later some comparable result between other dongles I find simplest possible method.
Signal from HP is 50% AM modulated. Audio frequency 1kHz.

Then I adjust signal level so that sidebands are just barely visible on the spectrum waterfall. It means that sidebands are around same level as noise.

In this case carrier is around 12dB over noise level (but visual accuracy is not very good becouse noise affect also so that carrier level is jumping. (of course) But I have watched this by eyes in live situation.
(50% AM modulation 1kHz sidebands levels are -12dBc)

NOTE: SDRsharp software level scale is only proportional but it do not tell anything about true level. But I have tested that scale itself is ok... 10dB is really one div in scale.


Image
In this picture can see carrier and then these barely visible + and - 1kHz sides.

In this case HP display level is -136dBm (note unknown real impedance)
It is 0.035uVrms if there is 50ohm impedance load)

Carrier is more than 10dB over noise. If I now rise 10db also sidebands are then around 10dB over noise. But test results numbers are so that sidebands are around same as noise level.
With every single test freq I find this same situation with level.
Later I show whole table with all test frequencies after edited it from test notes.


It is clear that this result is much better what I think before any tests.
But it means also that this need take care in receiver use. Becouse if you example listen 146MHz this tuner see all from 52MHz up to 2200MHz in its input gate! This amazing sensitivity can use only with very good front end filtering!

SDRsharp main (and meaningfull) settings can see in picture.
Selecting receiver samplerate also affect some amount. For some kind of middleway I select 1.4MSa/s for test. RTL AGC off, Tuner AGC off. Freq correction for around right frequency.
Receiver RF Gain setting maximum available.


Top
 Profile  
 
 Post subject: Re: DVB-T USB dongle as cheap SDR radio. (RTL-SDR)
PostPosted: Sat Sep 28, 2013 9:28 pm 
Offline
Site Admin

Joined: Wed May 16, 2012 7:54 am
Posts: 187
Of course SDRsharp (SDR#) is not only software for use.

One other and quite well made software is HDSDR.
HDSDR (former WinradHD) is an advanced version of Winrad.

Today there is also support for Realtek RTL2832U based USB DVB-T dongles. ( support for various hardware through Alberto's (I2PHD) ExtIO DLL interface )

You need HDSDR software
ExtIO DLL
Zadig (right version dependent your windows)


Top
 Profile  
 
 Post subject: Re: DVB-T USB dongle as cheap SDR radio. (RTL-SDR)
PostPosted: Mon Sep 30, 2013 7:20 pm 
Offline
Site Admin

Joined: Wed May 16, 2012 7:54 am
Posts: 187
Here table about "sensitivity".
Test method explained previously and there is also example picture where is 435MHz measured.

Here whole table. Every frequency measured visually using same level on the SDR# spectrum and waterfall display.

Image

Using (newest) HDSDR software give perhaps some small amount better result.Also HDSDR level scale can calibrate. But work with my computer using HDSDR (former Winrad) is painfull. It really want brute force from PC. My old IBM T4x series laptops do not have enough processing power.

Using these DVB-T dongles together with up converter is also nice.

I have tested with one up converter what have filters and mixer with 125MHz local. Example HF 0.3MHz - 30MHz ==> 125.3MHz - 155MHz. SDR# and HDSDR can of course display right tuning frequency when use this local freq as offset.

Here just small tiny examples with both softwares.
In examples there was only around 4m some kind of wire as "antenna" and mainly inside room. (also some amount different in both pictures)

19m band with HDSDR
Image
Note: Displayed "LO A (or B)" is frequency where is middle of received band. Up converter local 125.000MHz setting is in in other window where is some receiver settings.
15300kHz VOR Novosibirsk (chinese language program) Note Notch filter for reject some noise in LSB. USB was nearly impossible to listen due to some interference/noise.




19m band with SDR#
Image
Radio Taiwan (Transmitted from France)


Note that whole received RF band (in practice max 2.8MHz wide!) can also save and analyze all later. If there is 20 stations all giving ID same time.. you can later analyze them all. But it need enough hard disk.
Note that these dongles have 2x8bit ADC (I-Q). So of course they have limits and can not competite with Perseus or other this kind of receivers. But these dogles give lot of value for money.

It need remember that from antenna to tuner IC input whole band is totally open without any kind of filtering. from nearly zero to over 2GHz. Good reception need some front end filter. In other case noise level is terrible due to many strong signal sources from HF/VHF/UHF (FM/TV/mobile).

Perhaps also Elonics E4000 tuner is best supported in these softwares becouse whole story have started with this tuner. Also today there is available full datasheet for this tuner. But bad thing is that this Elonics is not anymore available exept from old stocks. There is also Rafael R820T and Fitipower FC0012-0013 tuners but.. number one is Elonics. Also it go clearly and well over 2GHz.


Top
 Profile  
 
 Post subject: Re: DVB-T USB dongle as cheap SDR radio. (RTL-SDR)
PostPosted: Thu Oct 03, 2013 12:07 am 
Offline
Site Admin

Joined: Wed May 16, 2012 7:54 am
Posts: 187
Some more tests.

Some tiny detail samples from tests.

First need agen note that DVB-T dongle input impedance is not 50ohm. So, these levels are not exactly right. Signal is connected directly with coaxial cable from HP to DVB-T dongle input without any extra matching or other things.
HDSDR software level scale is adjusted so that using -100dBm carrier level setting (for 50ohm load) on HP8657B also HDSDR software FFT show -100dBm.
(true level may diffe due to mismatch. Dongle specs say 75ohm but who knows how it is in real and over whole band up to 2.2GHz. (look previous tests over freq range)


Also not only single dongle. I have measured "lot" of same dongles - not any markable differencies. Also I have tested of course other frequencies. (yes I have tested also other DVB-T dongles with different tuners etc but it is other story)

But it need also note that I have selected one of best dongle model on the market what have real genuine Elonics E4000 tuner (and of course Realtek RTL2832U for sampling tuner outputs etc.) (These dongles are not cheapest possible what claims "E4000")

Software used in this part of test was HDSDR. (it have some advantages over SDR# hassle)

In RF FFT spectrum was used 1Hz resolution BW.

(note also small offset in tune. Becouse peak visibility is better when red line do not overlay it.)
50% Modulation depth was selected becouse sidebands levels are -12dBc. Most of pictures have 1kHz modulation freq.

In first picture modulation signals are 400Hz and 15Hz(!) for realize this 1Hz RBW.
HP8657B minimum output level is -143.5dBm.
Other pictures show also nicely how level scale is nearly perfect (note also HP specifications)

Original pictures are 1400x1050. I do not know where this have resized and now pictures quality is not at all original. (it have destroyed some details)
(EDIT: Oh well it was Photobucket "trick")


Image



Image



Image



Image



Image



Image



Image



Image


Top
 Profile  
 
 Post subject: Re: DVB-T USB dongle as cheap SDR radio. (RTL-SDR)
PostPosted: Sun Oct 27, 2013 4:55 pm 
Offline
Site Admin

Joined: Wed May 16, 2012 7:54 am
Posts: 187
I will continue updates here.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 8 posts ] 

All times are UTC + 2 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
 cron
Donate Now
Donate Now



Hosted by © 2017 FreeForums.org | Create a free forum | Powered by phpBB
About FreeForums | Legal | Advertise Here | Investors | Contact FreeForums.org
Report Violation

subSilver+ theme by Canver Software, sponsor Sanal Modifiye
suspicion-preferred