SDR USB DVB-T RTL-2832U Lowest 'Noise Floor' Shootout

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VK6DVR
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SDR USB DVB-T RTL-2832U Lowest 'Noise Floor' Shootout

Post by VK6DVR » Tue Aug 12, 2014 7:53 pm

The 'Noise Floor' on some of the cheaper DVB-T dongles is pretty dismal, but I think I've seen somewhere where dongles with a much better 'Noise Floor' can be purchased, hopefully from AU-OZ with a faster delivery time than from our 'trusty' CN suppliers.

Is there anyone out there who has either performed their own tests, or knows the best DVB-T dongle to choose that has a good 'Noise Floor' specification?

Here is where I'm starting from:
http://www.google.com.au/#q=RTL-2832U+L ... r+Shootout

It's my son's 46th birthday coming up and my 10-yo grandson and he are both into flying RC model aircraft two or three mornings a week in Brisbane and I've found some nice software that does a neat 3D 360° graph of a field-strength survey of his and other RC gear, that also lets them choose a clear frequency to fly on.

The implications of using the same techniques on the ham bands would well and truly solve many a ham's headaches when trying to locate the source of RFI or other forms of EMR.

So, I'll be investing in a couple of these better units in order to reduce any frustration and headaches from using something not quite up to par.

I've already played and had fun with a couple of different models and found a few issues that deserve more research into getting the best 'bang-for-buck'.

If anyone else is contemplating playing SDR's with these devices, here's a tip on extra cables you'll find that you'll need to get going;

For Android tablet users, make sure you get a microUSB plug to stdUSB socket adapter cable to plug your dongle onto.

You'll also need an appropriate microCOAX plug to BNC, Nseries or UHF socket adapter cable, depending on your favourite choice. Typically, the socket on the USB DVB-T dongle is a tiny MCXseries socket.

On some DVB-T sticks you might find the larger, older Belling-Lee Pal (IEC) 75Ω TV socket, but I'm not too sure whether or not these adopt the RTL-2832U chipset.

Here are some links to resources when playing with these DVB-T devices:

RTLSDR Scanner Now Supports GPS for Signal Strength Mapping - rtl-sdr.com
http://www.rtl-sdr.com/rtlsdr-scanner-n ... h-mapping/
Image
RTLSDR Scanner | A cross platform Python frequency scanning GUI for rtl-sdr:
http://sourceforge.net/projects/rtlsdrscanner/

I found the above, when I visited this site...
rtl-sdr.com - RTL-SDR (RTL2832U) and Software Defined Radio:
http://www.rtl-sdr.com/

There's a Category set aside, just for us guys 'Amateur Radio Archives - rtl-sdr.com':
http://www.rtl-sdr.com/category/amateur-radio/

There's a tip at rtl-sdr.com about buying a suitable device, bit not focussed enough on 'Noise Floor' specs.
http://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/

Breaking News as of 08-Aug-2014
XiOne - The portable Software Defined Radio - SDR | Indiegogo Funding Project:
https://www.indiegogo.com/projects/xion ... -radio-sdr

Cheers & 73's Danny VK6DVR.
Danny Robinson, VK6DVR

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Re: SDR USB DVB-T RTL-2832U Lowest 'Noise Floor' Shootout

Post by VK5TM » Wed Aug 13, 2014 2:20 pm

I did see somewhere that shielding part of the dongle internally helped with noise. Think it was the input section.

Thought I had bookmarked the page, but can't find it at the moment.

Another improvement is to mount the dongle inside a metal enclosure.

As for E4000 versus 820T, the 820T is supposed to be the better of the two, besides which, I believe there are few, if not no E4000 types available for sale any more.

I have one of each but not really had any time to play with them.
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Re: SDR USB DVB-T RTL-2832U Lowest 'Noise Floor' Shootout

Post by VK2MUS » Wed Aug 13, 2014 10:56 pm

I have the NooElec NESDR Nano SDR & DVB-T USB Stick (R820T) which is connected at present to a mfj1796 using the 2m stub - there is a distinct difference in noise levels depending on how close it is to the computers in the shack - currently it sits on a 3m extension well above the computers.

I also have another that is connected to the Ham It Up v1.2 - RF Up-converter, the up-converter is enclosed in metal case but the same rules apply as the usb unit as above -

The WWV 10MHz and 15MHz signal are clear on this unit ( if the bands are open of course)and were used to calibrate the up converter. Have also picked up jt65 on 20m and decode it via Jt65-HF

ON the supplied antenna ADS-B is quite workable in my rural location.

If you are thinking of purchasing the NooElec units buy then direct from their site it is cheaper then Ebay or Amazon

I have tried the following software
SDR Sharp
SDR Console
HDSDR
I use HDSDR more then the other two . I use RTL1090 ADS-B Decoder for the ADS-B decoding

John
From the Hill in Muswellbrook. VK2MUS
Occupation: Amplitude Modulator :om:

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Re: SDR USB DVB-T RTL-2832U Lowest 'Noise Floor' Shootout

Post by VK5TM » Fri Aug 22, 2014 5:42 pm

I found the page about noise and shielding of the cheap SDR dongles.
About a third of the way down the page:

http://g8jnj.webs.com/currentprojects.htm
Attachments
SDR Dongle - MARTIN - G8JNJ.pdf
To save hunting thru the page. Here is the relevent part as a pdf
(2.8 MiB) Downloaded 471 times
Last edited by VK5TM on Fri Aug 22, 2014 6:13 pm, edited 1 time in total.
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Re: SDR USB DVB-T RTL-2832U Lowest 'Noise Floor' Shootout

Post by VK3ZAZ » Fri Aug 22, 2014 5:49 pm

Mine has to be at least 1 meter from PC to avoid degrading performance.
they are heaps of crap.
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Re: SDR USB DVB-T RTL-2832U Lowest 'Noise Floor' Shootout

Post by VK2AVR » Sat Aug 23, 2014 11:04 am

VK3ZAZ wrote:Mine has to be at least 1 meter from PC to avoid degrading performance.
they are heaps of crap.
I don't understand the negativity in this forum sometimes. These DVB-T dongles cost $20, they are practically free.. somebody even wrote some clever software to make them do something they're not intended to do and gave that software away to the community and you are STILL whining.

Go buy a USRP or FlexRadio, please. Maybe spending $1-2k on a radio will let you see these cheap and cheerful dongles in a more flattering light.

As for these dongles, we tested some at a club meeting and found they were sensitive to -110dBm to -115dBm depending on model. Not amazing, but plenty good enough for casual use.. if you stick them on a decent antenna you'll still hear a lot of stuff. If you used a Minikits PGA-103 as a pre-amp (cheap+good kit) then it would overcome the relatively low sensitivity.
Geoff
VK2AVR

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