Late last year the ThumbNet team announced their custom RTL-SDR dongle which they named the “Nongles N3”. This is a standard R820T2 RTL-SDR, but with some interesting additional features. Some of the changes they made include:
Shielding can on the PCB
Thick rugged metal case
External 5V power input
Low noise PCB design
As explained in our previous reviews (prototype review, production review) the N3 is a rugged dongle, probably best suited to applications where the SDR could take a beating. The F-Type connector is also preferred by some people as it is fairly commonly used on TV equipment in most parts of the world. Shielding against local strong signals is also excellent due to its double shielding with a shielding can on the PCB and with the metal case.
Probably the most defining feature other than its ruggedness and low noise floor is that it can be optionally powered by 5V external power. So it could be used at the end of a very long active USB cable, with power provided locally. Or if very low power noise is desired, a linear power supply could be used.
We now have these N3 dongles available for purchase in our store. Please note that this is a commission sale, so the N3 will actually be shipped by the Nongles team in the USA once a week. The current price of the Nongles N3 is $33.5 USD + $4.5USD shipping in the USA, or $10 USD shipping worldwide.
Back when it was released in November we posted an initial unboxing and initial first impressions review of the ThumbNet N3 RTL-SDR dongle. In this post we continue that review and post a few more in depth results.
The ThumbNet N3 is the latest iteration of ThumbNet redesigned RTL-SDR dongles. It’s main features include a shielded PCB, metal enclosure, F-type connector, Mini-USB connector, all linear power supplies and an external power mode. It is designed specifically to be used in the ThumbNet system, but because they need to order the units in bulk they sell the excess off to other users too on their new site Nongles.com. The N3’s list of features is shown below.
Full backward compatibility with existing RTL-SDR dongles and software
High stability TCXO (+/-0.5ppm) (ensuring rock-solid stability from start-up and over a wide range of temperatures)
Standard R820T2 + RTL2832U (plus 24C02 EEPROM) chipset
Improved/enhanced decoupling. (Common-mode choke on USB port)
Low-noise, linear only power regulation (separate 1.2v and 3.3v regulators)
External DC (+5v, 450mA) supply connector
Mini-USB connection (allows easy separation of the RF unit from the noisy PC)
F type RF connector (very common and compatible with existing ThumbNet tracking stations)
Large (6x4cm) contiguous ground-plane (for better thermal dissipation)
Static drain-away resistor on the RF input (1K to ground)
All unnecessary parts (IR receiver, high-current LED etc.) eliminated to reduce parts count and noise
Circuit board can be mounted into a common 1455 case
ThumbNet/ThumbSat is a company that hopes to help experimenters get mini satellites into orbit starting from $20k USD. The ThumbNet project aims to provide hundreds of schools and educational institutions with RTL-SDR based satellite receivers in the hope that they will use them as an educational resource, and at the same time help set up a worldwide monitoring network, so that the live data from the launched satellites is always available to the satellite experimenters.
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 (Nongles.com) and us at RTL-SDR.com. 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 reddit.com/r/rtlsdr 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.
The latest RTL-SDR receiver from Thumbnet, the Thumbnet N3 is now shipping out. Back in October we received a sample of one of their prototypes and found it to have a very low noise floor since they have replaced the 1.2v switching regulator with a linear regulator.
ThumbNet is a company that is hoping to provide low cost satellite deployments, and make use of volunteers around the world with RTL-SDR’s to help track them. The RTL-SDR’s and antenna kits are provided to schools and educational institutions for free by ThumbNet, in exchange for students setting up and monitoring a satellite tracking station.
In their release email they wrote:
ThumbNet would like to send a very large “Thank You!!” to all of you who have supported us by purchasing one of our surplus N3 SDR receivers, and we wanted to take a second and let you know that we’re excited to announce that the N3’s have left the factory and will begin shipping.
The support has been tremendous and we have a backlog of many hundreds of receivers to get out. We will be working extremely hard, over the coming days to get them all delivered as quickly as possible (Orders will be shipped in the order they were received.).
Earlier this month Akos from the RTLSDR4Everyone blog reviewed a prototype of the latest ThumbNet N3 RTL-SDR. In this post we will also give a quick review of a prototype of their new unit which was kindly provided to us by ThumbNet. ThumbNet is a company that is hoping to provide low cost satellite deployments, and make use of volunteers around the world with RTL-SDR’s to help track them. The RTL-SDR’s and antenna kits are provided to schools and educational institutions for free by ThumbNet, in exchange for students setting up and monitoring a satellite tracking station.
To help with the needs of their project they have designed and manufactured the ThumbNet N3, which is a redesigned RTL-SDR dongle. As they must order in bulk, they are also selling surplus units to the RTL-SDR community with the hope that any profits will help fundraise for other related projects.
The ThumbNet N3 is a redesigned RTL-SDR with a focus on lowering the noise floor and spurs for optimal reception of their satellites. The N3 uses a 0.5 PPM TCXO for low frequency drift and a common mode USB choke for reduced USB noise. The PCB size is also increased allowing for better thermal dissipation. Since F-type is more common in the areas they intend to donate the units to, an F-type antenna connector is used on the dongle. A full list of the changes and improvements they’ve made can be found on their N3 details page.
One way in which they have reduced the noise is by disabling the internal switching voltage regulator within the dongle, and instead using a linear regulator. Linear regulators are much quieter than their switching counterparts, however they do draw significantly more power. The N3 draws 450mA of current, wheras a standard RTL-SDR draws closer to 270mA. Since many USB ports have a 500 mA limit this gets close to problematic to run directly from the USB port. To get around this, the N3 has an external power port, so it can be powered by an AC->DC power pack (like what you use for charging your phone), or more ideally with a quieter linear power supply or batteries. This has the added advantage of avoiding noisy USB power lines.
Review & Testing
The N3 feels very sturdy, and all the connectors are mounted strongly and are unlikely to break off. The top of the receiver shows the power port, the USB port, the shielding can and the F-type connector. The USB connector uses the older depreciated “USB mini” standard (which is different to USB micro found on most phones).
The bottom shows a few components as well as the two linear regulators. In order to power the unit we used an AC to DC 5V power supply (normally used for mobile phone charging) which we soldered on to the bottom of the PCB. Ideally we’d use a battery or linear power supply, but we’ll test that later with the actual production unit.
The standard N3 unit comes with no enclosure or RFI shielding cans (these are paid add-ons). Our prototype unit came with a shielding can covering the components which was enough to block most interfering signals. We did not see many unwanted signals being received with the antenna unplugged which is a good sign that the shielding can is doing its job.
We gave the unit a quick test on a noise floor scan. The results show that the noise floor has been significantly reduced. The clock spurs are still there but they are reduced in strength vs the standard RTL-SDR.
On L-band at around 1.5 GHz the standard RTL-SDR dongles tend to fail at receiving after they heat up a little. The ThumbNet N3 showed no problems in this region, probably thanks to its larger PCB with better heat dissipation.
Once the production model is released we intend to do a more in depth review, but as it stands right now the N3 is looking very good especially for those who use RTL-SDR’s in monitoring applications that can benefit from very low noise floors, or for those who like the idea of being able to externally power the unit.
The ThumbNet N3 can be bought from their store. It costs $25.75 (with no shielding can), $27.75 (with shielding can), $31.50 (with aluminum case and no shielding can) or $33.50 (with aluminum case and shielding can) + $4.50 worldwide shipping. ThumbNet write that initial demand for the N3 unit has been high, so if you are interested in the unit, you need to order early to ensure that you can get one. They are due to ship out by the end of October. We’ve received a note that the delivery date is rescheduled for no later than November 11.
Also in a recent email from ThumbNet they wrote:
First of all, let me thank you from the whole team, for your support of ThumbNet and helping to promote STEM education around the globe with your purchase. We have sold more of the surplus N3’s than we expected to at this point, so if you have friends that are hesitant, tell them that time is running out! 🙂
Secondly, I wanted to take a moment to update you on the status.
The production run testing of the N3 was completed on time, but testing found three small improvements we could put into effect immediately, to produce a better receiver. Those changes have been submitted to the manufacturer and we are currently waiting for a revised ship date.
We still anticipate that the N3 will ship in the month of October, but I will send a follow up email with a more accurate schedule, when I get one in a day or two, from the manufacturer.
I thank you all for your understanding and patience. All of our testing so far indicates that the N3 is performing very well, and we hope you’ll agree it was worth the wait, when it arrives.
A few weeks ago we posted about ThumbNets announcement of their new N3 RTL-SDR dongles. The main theme of their new dongles is lower noise as can be seen by their decision to disable the on board switch mode power supply and add an external power port for powering the dongle from a clean power supply.
Akos from the RTLSDR4Everyone blog received a prototype sample of the N3 for an initial review. In his review he shows some close up shots of the N3 PCB, and does a quick test on receiving some signals. His screenshots show that the noise floor is indeed very low, and that many noisy spurs are eliminated or at least significantly reduced.
Once ThumbNet release their actual commercial units we intend to produce our own review as well.
ThumbSat is a company hoping to enable experimenters to get low cost mini satellites into orbit for about $20k. To support the need for global RX of these satellites they have the ThumbNet project which utilizes RTL-SDR dongles as the receiver. They aim to provide schools and eligible volunteers around the world with free RX hardware to receive and record the data coming from these satellites.
ThumbSat is a company that aims to help experimenters design and launch experiments on their mini satellites (10x smaller than a regular cubesat with most of the same functionality) into orbit. They write that for about $20k they will fully design a satellite based experiment and launch it into orbit – all you need to do is provide the orbital experiment that you would like done.
To aide with the reception, they also have the ThumbNet project which aims to setup a network of satellite receivers around the world. They do this by providing school students around the world with low cost satellite receivers. The satellite receivers consist of modified/upgraded RTL-SDR dongles and satellite antennas.
Today the ThumbNet project announced the latest iteration of their RTL-SDR dongle, called the ThumbNet N3 SDR Receiver. This receiver has some interesting design changes when compared to any other dongle that we’ve seen so far. The biggest change appears to be that this dongle uses an external power port for power. They also replaced the 1.2V switching regulator with a 1.2V linear regulator for lower noise operation. This is useful because switching regulators can cause noise, whilst linear regulators are much cleaner. However, using a linear regulator increases the power consumption significantly, and the new dongle draws 450mA of current (vs 250-280 mA on standard or our V3 dongles), meaning that some USB ports may be unable to power the device unless the external power supply port is used.
The other interesting change is that they have changed the PCB form factor, and it can now fit into a common 1455 aluminum case. Also, similarly to our V3 RTL-SDR dongles, they have decided to add a common mode choke to the USB lines, which significantly reduces USB noise. To add ESD protection they also added a static bleed resistor. Finally, like their previous receivers they continue to use a F-type RF connector and a TCXO for frequency stability.
The price is $25.75 each plus flat rate global shipping of $4.50 and the receivers are expected to ship in mid-October. While we have not yet tested this model, it looks to be like a good receiver for those who need very low noise, or external power options.
The next Generation, ThumbNet N3 is designed from the ground up to be as simple to use as older generation dongles, but with powerful hardware features for advanced hobbyists and experimenters.
We removed all of the excess components that were sources of noise or interference in other dongles, and optimized the circuit for simplicity, sensitivity and selectability. Then we added a port to use a cable with the extremely common mini-USB connection so that the N3 is less prone to noise from the host computer than a traditional dongle. Finally, the use of standard Surface Mount 0603 or larger components makes it simple for testing or modification.
We built them for our own use, then decided to offer them to everyone.
A quick list of the features of the N3:
– Full backward compatibility with existing RTL-SDR dongles and software – High stability TCXO (+/-0.5ppm) (ensuring rock-solid stability from start-up and over a wide range of temperatures) – Standard R820T2 + RTL2832U (plus 24C02 EEPROM) chipset – Improved/enhanced decoupling. (Common-mode choke on USB port) – Low-noise, linear only power regulation (separate 1.2v and 3.3v regulators) – External DC (+5v, 450mA) supply connector – Mini-USB connection (allows easy separation of the RF unit from the noisy PC) – F type RF connector (very common and compatible with existing ThumbNet tracking stations) – Large (6x4cm) contiguous ground-plane (for better thermal dissipation) – Static drain-away resistor on the RF input (1K to ground) – All unnecessary parts (IR receiver, high-current LED etc.) eliminated to reduce parts count and noise – Circuit board can be mounted into a common 1455 case
Ideal for experimentation:
– Can be connected to an external power supply for very clean power – All of the important tracks are visible on the top side of the board for easy access – All of the RF parts are on the top of the board (only regulators and decouplers on the back) – Logical, simple layout using 0603 (or larger) SMT parts – IF port break in connector (between front end and IF/USB chip) provided
While not required for operation, the N3 receiver is designed to be able to utilize a clean source of power from an external 5v power supply, instead of using the noisy power line coming from the computer’s USB port. This gives a tremendous advantage to the purist or experimenter who wants to utilize power from the N3 to power any external experiments. (When the external power supply is active, no power is drawn from the USB port to power the N3.)
PLEASE NOTE: The N3 draws approximately 450mA of current and care should be taken, even when using a powered USB hub, as it could possibly exceed the current limit of the USB port.
The ThumbNet project is a project that is aiming to provide low cost satellite receivers to students and any other interested communities in order to promote worldwide education in science, technology and engineering.
In addition to ThumbNet, there is also the ThumbSat project which hopes to launch it’s own satellites sometime next year. However, at the moment the focus is on ThumbNet where the team are currently building their ground station network by supplying customized RTL-SDR dongles to schools and interested communities all around the world for free.
Once the satellites are launched the receive stations will be used to download data from the ThumbSat satellites, creating a large network of receivers. To raise the incentive for participation, in the future they also hope to provide a small amount of money to each actively participating school or organisation. They write that the RTL-SDR’s could also be used for receiving other educational signals such as communications from the ISS. More information about the project can be found on their website www.thumbsat.com, and in this white paper (pdf).
As generic RTL-SDR dongles were not up to their specifications they decided to develop their own. Their RTL-SDR receivers are custom made to have a 1 PPM accuracy Temperature Controlled Oscillator (TCXO), a R820T2 tuner chip and a F-Type connector. The Type-F connector was chosen as they found that it was the most commonly found connector around the world and would be the easiest for students in remote areas to have access to.
If you are interested in getting one of these dongles and you meet their criteria (school or similar), you can either ask to participate in the ThumbNet program for free, or alternatively if you just want a dongle for your own use you can buy one through us. We have decided to help with the ThumbSat project by helping them advertise and sell off some of their surplus units through our blog.
In their official blurb ThumbSat writes:
Scoutek LTD, in the United Kingdom and ThumbSat Inc, in the United States are proud to have partnered together to provide an opportunity for schools and educational groups around the globe to promote radio science, technology, engineering and mathematics to their students and attempt to influence the next generation of scientists and engineers. By donating small radio kits to each school or educational group, the project has already begun making a positive change in the lives of hundreds of students.
ThumbSat has been working with schools and educational groups around the globe and to date, more than 20 groups have committed to volunteering where students and staff members will operate the satellite monitoring stations as part of their science courses! As a few examples, stations are being operated in diverse areas the Cook Islands, Christmas Island, Singapore, Ecuador, Tanzania and Botswana. One individual in Micronesia was operating the station by himself at 12 years old!
ThumbNet is open to anyone who is interested in participating and has a desire to setup and operate a small ground based radio listening station. No permits or licenses are required, since there is no transmission of any sort and no permanently installed antenna systems.
ThumbSat and Scoutek encourage education for everyone and is looking for anyone young, old, educated or uneducated, individuals or groups to participate.