Saturday, 26 March 2016

Top Dogs Comparison Round 2

March 26, 2016

Update March 31: Corrected typos.

Please read the 5-dongle comparison review (link) before this post, or if you require additional information on choosing the best dongle out there.

Under review (again) are Nooelec's NESDR Mini 2 + in metal case ($24 plus shipping from manufacturer, link) and RTL-SDR.com's dongle ($25 plus shipping from manufacturer, link).
Stop straining your eyes, new NESDR Mini+ has the lowest noise floor.

As of now, these two RTL-SDR dongles are the best on the market.

Along with the arrival of a second dongle from RTL-SDR.com, I also received a NESDR Mini 2+ from Nooelec for testing.
I didn't know that an update has been done. I asked about the changes, as apart from two extra accessories, something was fishy with performance.
I got the following answer from Nooelec, copy-pasted here word-by-word:
"We have also upgraded the 3.3v power supply regulator to an RF-suitable LDO, and are using a shielded inductor instead of a standard wirewound to improve EMI rejection."

Now I know. The ARRL General Class Handbook costs $19.95, and strongly recommended.

 Disclaimer: Dongles tested are free review samples.

Noise floor:

Same dummy load, rtl_power, three 15-minute runs averaged. Same data for the upconverter range as for the noise floor on top of page.
New NESDR Mini+ had lowest figures ever tested of stock dongles.
1dB difference on the chart is possibly due to testing variation, such as the difference visible between RTL-SDR.com dongles is normal and expected.
Also please note that the chart does not represent ultimate reception performance, only the noise floor.
A lower noise floor is better; modding decreases noise floor, as does cooling, so noise floor measurements for the R820T used in the video below are included at the end of the post. Not here, because values are lower than the bottom of the chart :-)

Old versus new RTL.com dongle


No change in performance as far as I can see or hear, swapping dongles makes no difference in either received audio or visible waterfall.
In fact, only way to know which one I'm using is the absence of paint on the old one, a cosmetic shortcoming which has been rectified on the updated version.


Old versus new Nooelec NESDR Mini 2+


Visible and audible change in noise.

New NESDR Mini 2+ versus new RTL-SDR.com dongle


After a week's worth of listening,the same conclusion: by a tiny margin, the Nooelec dongle is a better performer, only this time with less noise.
In the video below, alternating dongles, starting with an RTL-SDR.com dongle, then the new Nooelec, then an old and modded R820T.
A very lightly modded R820T is included to demonstrate the difference between new vs old chipsets, and the effect of a few minutes of modifying the dongle (less noise overload).


Again, starting with RTL-SDR.com, then Nooelec, then modded R820T, then starting over. I'm trying to find the best Signal-to-Noise ratio with RTL-SDR.com's dongle, then swapping over to Nooelec, then swapping over to a R820T dongle.

At this performance level, choosing between the two top dongles is entirely due to personal preferences.

Pros for RTL-SDR.com dongle: $25, option to enable Bias-t, direct sampling pads, usable large antenna, SMA connection, looks cool.
Pros for Nooelec NESDR Mini+: $32, metal case is peerless, 2-year warranty, suction cup magnetic mount with nice antenna (great for traveling), easier to mod and cool.

Please do not make the mistake of choosing the dongle from Nooelec over RTL-SDR.com's offering, or the other way round: the performance difference with the upgrades is so small that whatever you see in the video could be down to atmospheric conditions, my inability to use SDR#, or the neighbor drying his hair.

Personally, I'd still buy the Nooelec, 'cause lower noise floor for modding is important, and still recommend RTL-SDR.com's dongle to anyone, primarily because a beginner will be better off with the usable huge antenna.

Effect of modding on noise floor


Like the image at the beginning and you thought -20 is good? Here's a 1-hour noise floor scan with the new dongles versus the R820T used in the video.
Cost? Zero. It's only a start, for details on how to do noise measurements, and overly obsessed instructions for an even lower noise floor, click below and get my book.
If $6 is too much, consider raising butterflies.



If you enjoyed this post, please order my RTL-SDR
Guide Book on Amazon Kindle.
Close to 200 pages of knowledge, information and diagrams for all levels of expertise.

Kindle is available for computers (Windows and Mac), and for smartphones and tablets (Android and Iphone, iPad and iPod touch).

If you're interested in the Raspberry Pi, my book details the ins and outs of setting up, using and enjoying the Pi 3 microcomputer.



















2 comments:

  1. Hello! According to http://www.nooelec.com/store/sdr/nesdr-mini-plus.html the nesdr mini+ has r820t chip. Could you please do the noise floor test with NooElec NESDR Mini 2+ too? Thanks!

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    Replies
    1. Thanks for pointing that out, I did the test with the NESDR Mini 2+ (R820T2 TCXO in a metal case)

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