ThumbNet N3 Unboxing and SDR Lego

A few days ago we received a production sample of the new ThumbNet N3 receiver. Our sample came with the works, which includes the green aluminum enclosure and shielding can soldered on over the PCB. This full set costs $33.50 USD + $4.50 USD international shipping, but there are cheaper options if you do not want the aluminum case or the RFI shield.

We’ve only had a brief time to play around with it so far, but it’s performance seems very similar to the prototype unit that they sent us earlier. We intend to give the N3 a longer review next week but our first impressions are favorable. In this post we’ll simply unbox the unit, show some photos and give it a quick turn on test.

The N3 comes in a protective cardboard box with the N3 and Thumbnet/Nongles logo on it. Inside sits the ThumbNet N3 unit itself, and there is a power plug terminal block adapter located on the bottom of the box. Excluding the F-type connector, the ThumbNet unit has dimensions of 6.2 cm x 4 cm x 2.1 cm, and weighs 58g. The green enclosure is strong and rugged.

Unlike the prototype they sent, this unit can run direct from USB power alone. We saw that it draws about 400 mA of power, and we had no trouble running it from our 1A capable USB ports. Of course one of the main advantages to the N3 is the ability to power it with a low noise external power supply, and we will be testing that in the next review.

Nongles SDR Lego

ThumbNet have also announced their new sister site, On this site they intend to soon begin selling something called “Nongles” which is a mashup of “NOt a dONGLE”. Nongles are an idea that can be best described as a type of “SDR Lego”, and we think will be very interesting to people interested in experimenting with different SDR set ups and for use in education. Nongles will be based on the RTL-SDR design, but they are going to be split the RTL-SDR up into several discrete PCB modules/blocks such as:

  • R820T2 Module
  • RTL2832U Module
  • Experimenter Module
  • External Clock Module
  • LNA
  • Bias Tee
  • Signal Amplifier
  • 50 – 75 Ohm Transformer
  • Filter blocks such as SAW/FM Bandstop/High Pass/Low Pass and other DIY kits

Obviously you’ll at least need the R820T2 and RTL2832U blocks to have a working system. Then the other blocks can then be added in as needed. The Nongles are not ready for sale yet so keep an eye on their website for news of their release.

Radio For Everyone: An Easy Homemade Outernet Antenna, More FlightAware Pro Stick Plus Results

Akos from the radio for everyone blog (formerly known as the rtlsdr4everyone blog) has uploaded two new posts. On the first post he shows some further tests on the new FlightAware Prostick plus. The Prostick is an RTL-SDR that contains a built in LNA and the Prostick plus adds an additional SAW filter on the stick. For him the Prostick Plus works significantly better than the regular Protstick + external FA cavity filter and also gets about twice the ADS-B reception reports as our V3 which does not use an additional internal LNA. Next week we hope to release our own review of the Prostick Plus, and we’ll hopefully be able to show and explain why some people see better performance with the plus and why some instead see degraded performance.

In his second post Akos shows a tutorial on building an easy helical antenna for Outernet reception. The antenna is constructed from readily available household materials such as a soda bottle, coax cable, electrical tape and a cookie tin. With the cookie tin used he was able to get a SNR reading between 7 – 9 dB, which is pretty good considering that only 3 dB is required for Outernet decoding to work.

Outernet hardware plus the homemade helical antenna made by Akos.
Outernet hardware plus the homemade helical antenna made by Akos.

Some More Reviews of the SDRplay RSP2

Two days ago the RSP2 was released for sale as we released a review of a pre-production unit that they sent us. Since then there have been some more review that have come out from other users who had a review unit. have released a good review of the RSP2 along with a video. The author writes how he’s impressed with the additional shielding, the software switchable antennas and the bias tee. Like in our review he also tested the RSP2 bias tee with the Outernet LNA and found good results. He notes that the RSP1 and RSP2 are very similar in terms of RF performance, but writes that he noticed times when the RSP2 seemed to be more sensitive or exhibit a lower noise floor than the RSP1.

On YouTube user reviews the RSP2 and also has a live Skype interview with Jon the head of marketing at SDRplay. Jon gives a good overview of the new features and some applications that they could be used for.

Over on Paul Jones also reviewed his RSP2. He was very impressed with the performance of the Hi-Z port, the performance of the BCFM notch filters and the stability of the TCXO.

The author of has also released his review and he too was impressed by the improvements.

On a related note the RSP1 is now for sale for black friday at HamRadioOutlet for only $119.95 USD.

SDRPlay RSP2 Release Announcement and Review

Today SDRplay have just released their newest software defined radio – the Radio Spectrum Processor 2 (RSP2) which is the successor of the RSP1. The RSP2 costs $169.95 USD, and the older RSP1 is still for sale at $129.95 USD. There is also the “RSP2pro” model which is an RSP2 in a metal enclosure, and this sells for $192.95 USD.

The RSP2 has nearly the same base specifications as the RSP1 (12 bit ADC, 10 MHz bandwidth, 10 kHz – 2 GHz range), but now comes with additional features and enhancements such as a software switchable BCFM and BCAM notch filter, TCXO, multiple antenna ports, HF optimized Hi-Z antenna port, clock in and out ports, better shielding and can also now tune down to 1 kHz.

It is available for purchase at (Worldwide), (USA) and ML&S (UK).

The announcement reads:

SDRplay Limited has today announced the launch of a second Software Defined Radio product – the RSP2.

Building on the popularity of our first product, the RSP1, we have now launched the RSP2. The RSP2 delivers a significant number of additional features which result in a higher spec for specialist amateur radio users as well as benefits for additional scientific, educational and industrial SDR applications.

Here are the main additional features of the RSP2:

  • 10 built in front-end pre-selection filters, with substantially enhanced selectivity
  • Frequency coverage extended down to 1 KHz
  • Software selectable variable gain Low Noise Preamplifier
  • 2 x SMA Software Selectable 50Ω RF ports (1.5 MHz – 2 GHz)
  • 1 x High Impedance RF port (1 kHz – 30 MHz)
  • Built in software selectable MW /FM notch filters
  • Highly stable 0.5PPM TCXO trimmable to 0.01PPM
  • 24MHz Reference clock input / output connections
  • 4.7V Bias-T option (on one of the software selectable antenna inputs)
  • RF screening within a strong plastic case for the standard RSP2
  • A Rugged metal box version – the ‘RSP2pro’

When used together SDRplay’s own SDRuno software, the RSP2 becomes a high performance SDR platform. The benefits of using the RSP2 with SDRuno include:

  • Highly integrated native support for the RSP2 professional grade software based upon class leading ‘Studio 1’, free of charge
  • Calibrated S-Meter including support for IARU S-Meter Standard
  • Calibrated RF Power Meter with in excess of 100 dB of usable range
  • Best in class audio quality

Currently the RSP2 requires the use of SDRuno software, but in the coming weeks we plan to provide support for HDSDR, Gnu Radio, CubicSDR and we are working with Simon Brown to get support within SDR Console.

We believe that the RSP1 will continue to prove very popular as the lowest cost 12-bit SDR for general applications such as Short Wave Listening or for use as a panadapter and we pleased that we can now offer more choice to the growing community of RSP users.

The RSP2 is expected to retail at approximately £130 (excluding taxes) or $169 (excluding taxes)

For more information visit our website on

The new RSP2
The new RSP2

The table below shows a comparison of the RSP1, RSP2 and RSP2pro. A datasheet can be found on SDRplay’s new RSP2 webpage.

Differences between the RSP1, RSP2 and RSP2pro.
Differences between the RSP1, RSP2 and RSP2pro.

SDRplay RSP2 Review

Two other reviews have already come out, one from and one from

Thanks to the generosity of the SDRplay team we were fortunate enough to receive an early pre-production review model of the standard (not pro) RSP2 unit. The unit arrived a few days ago, and here we give it an initial review. In a previous review we did a comparison of the Airspy SDR, SDRplay RSP1 and HackRF. We found that the RSP1 and Airspy had similar overall performance, but that the Airspy would be better for those people who needed high dynamic range performance in strong signal environments, and that the SDRplay RSP1 would be best for people who wanted a low cost all-in-one unit with performance better than an RTL-SDR. 

The Inside

We decided to take a look inside and see how much the PCB has changed from the RSP1 to the RSP2. Judging from the two photos we can see that there is quite a significant increase in the number of components used. What was once a sparse PCB is now populated much more heavily with additional filter banks and several new switches. However, the core design of the RSP2 remains similar to the RSP1. The RSP2 uses the same Mirics MSi001 tuner chip and MSi2500 ADC chips.

The standard plastic enclosure is also now spray painted on the inside with conductive metal paint which helps by acting as a Faraday cage. This prevents interference from getting through and should be almost as good as a metal enclosure.

The conductive paint seems to be working well, as in our tests the RSP2 does not receive any signals with the antenna disconnected, whereas the RSP1 does weakly receive some very strong pager signals.

Conductive paint on the plastic case inside.
Conductive paint on the plastic case inside.

Continue reading for the rest of our review

Continue reading

The 2016 /r/rtlsdr Reddit Giveaway

The mods of the /r/RTL-SDR community on the Reddit discussion platform are currently hosting an RTL-SDR themed giveaway. The prizes up for grabs include units which have been donated from ThumbNet ( and us at The prizes also include several donated home brew projects including filters and downconverters. See the table at the end of this post for the full prize list.

To enter all you need to do is write a comment on the competition thread at and mention what you like about SDR and what you hope to do with a prize if you win. While you’re at it we strongly suggest subscribing to /r/rtlsdr if you haven’t already as that is one of the the largest and most active communities of rtlsdr users on the web.

The competition closes on December 3rd and only one entry per household is allowed.

Place Prizes Description
1st-2nd 2 ThumbNet – N3 SDR RECEIVER
3rd-5th 3 RTL-SDR Blog V3 Dongle + Antenna Kit
6th-7th 2 $25 ThumbNet – Gift Certificate
8th-11th 4 Blog V3 Dongle Only
12th 1 PA0RDT Mini-Whip Antenna
13th-14th 2 Blog Broadcast FM Filter
15th-16th 2 Up to ~4.5GHz Microwave Downconverter
17th 1 70cm HamSat / 433 Combline BPF
18th-20th 3 Choice of Custom Made 5 Pole HF BPF/LPF/HPF

Two Videos That Show How To Set Up An Outernet Receiver

Outernet is a relatively new satellite based file delivery service which can be received with an RTL-SDR dongle. They continuously send out useful data like weather reports, news, APRS data as well as files like Wikipeda pages, images, videos and books. Previously we posted a tutorial that shows how to set up an Outernet receiver here.

If you instead prefer video tutorials, then two YouTube channels have uploaded Outernet set up tutorials. The first tutorial is by MKme Lab. In this video they set up Outernet using a Raspberry Pi and a Lipo battery for portable operation. Once setup he shows the Outernet browser and weather app in action.

The second video is by John’s DIY Playground and is similar, but goes a bit deeper into setting up the software on the Raspberry Pi and shows how to point the patch antenna towards the satellite.

An RTL-SDR Receiver App Written in Swift for MacOS

Over on YouTube user GetOffMyHack has uploaded a video that shows his development of a Mac based general purpose tuning app for the RTL-SDR, which was written in the Swift programming language. Swift is a programming language which is designed for creating apps for a wide range of smart Apple devices.

GetOffMyHack’s program currently has a spectrum and waterfall view, can tune to any frequency, demodulate NFM and AM, and it also has a built in CTCSS decoder. At the moment the software and code is unreleased, but he writes that in the future the code will be released and made open source once he reaches the next version in the development cycle. Keep an eye on his YouTube channel for any updates.

A Portable RTL-SDR Project

Frequent reader Rodolfo recently wrote in to us wanting to share a portable RTL-SDR set up that he has produced. From the supplied photo the portable unit looks very robust and really well built. We hope that it will give inspiration to others wanting to make portable units as well. Rodolfo wrote:

Last year, a friend of mine in the telecommunication services industry, was talking to me regarding some kind of sporadic interferences he was getting in their devices, and asked if I can do something about it. I spend some days trying to figure a way to help him, as it was (and is) a good friend of mine. I seat in my library at home, and start to scratch some designs, based in article published in 6 October 2014: “RASPBERRY PI RTL-SDR SPECTRUM ANALYSER SCANNER”. Some weeks later, I get the designs and get a good cup of coffee with him. After the second cup,  and I get a “go” sign, and so it born a portable spectrum capture that I called “sapinho”, as my youngest son nickname. Just “for the record”, “sapinho” in Portuguese means a little frog – you can jump from place to place to scan the RF band.

So, the device is very simple, the great problem was  finding the most small configuration possible, to meet the portable specifications:

  • Raspberry pi ver. B;
  • NooElec RTL Receiver;
  • “FreqShow” python software.
  • A pair of LM2596 DC-DC;
  • 3.5 ‘’ TFT LCD Touch Screen for Raspberry Pi;
  • 6VDc battery;
  • Cable;
  • Expandable antenna;
  • Enthusiasm.

Trying to get the most of it, I put a wifi dongle, so that he can connect to a nearby hotspot, or get a “had oc” connection for remote control. There is a plug for charging the batteries, and two red leds (one for the charging , and the other for operation status).  All of it was install in a 100 x 300 x 100 (mm) portable aluminum box.

Portable RTL-SDR Unit
Portable RTL-SDR Unit