Tagged: rtl-sdr

A Warning for R820T2 RTL-SDR Purchases on eBay/Aliexpress etc

Just a brief warning for those purchasing the generic dongles on eBay and Aliexpress. We’ve recently heard of a number of customers having ordered generic dongles advertised as having R820T or R820T2 chips, but receiving dongles with FC0012 chips inside instead.

The R820T2 is capable of tuning from around 24 MHz to 1766 MHz, whereas the FC0012 can only tune between 22 – 948 MHz. Compared, the R820T2 is definitely the better chip.

This scam is probably happening because the price of the FC0012 is less than the R820T/2. So these sellers may be trying to cut costs and simply hoping that no one will notice the chip change since both chips are RTL-SDR compatible in the drivers. You can check what tuner chip you have either with rtl_test, or simply by reading the markings on the chip itself.

In addition we have also recently seen several scammer bots on eBay pop up who are selling our own RTL-SDR Blog V3 dongles at very low prices. These sellers are typically automated bots that mass copy popular listings, and undercut their price hoping to grab a few fake sales before disappearing. They usually have zero feedback, or a small amount of feedback from purchases made from the account, and they price the product extremely low, typically even below the manufacturing cost. Most likely you will never see a product from them and they will simply disappear from eBay after a few days. This has already happened to one scam seller that we have been tracking, although before they disappeared they had already made 80+ fake sales.

FlightAware Prostick Plus Now Available in our Store

The FlightAware ProStick Plus is an modified RTL-SDR designed specifically for ADS-B reception. Its main defining feature is that it has a built in low noise figure LNA, and a 1090 MHz SAW filter. The LNA reduces the noise figure of the RTL-SDR, improving ADS-B reception and thus increasing the number of messages received and the receivable range of aircraft. The SAW filter helps remove out of band signals which can cause the RTL-SDR to overload if they are particularly strong. The Prostick Plus also comes with a TCXO, and SMA connector.

If you are mainly interested in ADS-B reception, or are looking to set up an ADS-B station then the Prostick Plus is one of the best choices you can make. See our previous review here.

We are now reselling some of FlightAware’s Prostick Plus dongles in our store now. They cost $24.95 USD including free shipping worldwide. We intend to sell them mainly to customers outside of the USA, as FlightAware already sell them officially on Amazon, but we offer free shipping anywhere in the world.

Click here to visit our store

The Pro Stick Plus RTL-SDR based ADS-B Receiver from FlightAware.
The Pro Stick Plus RTL-SDR based ADS-B Receiver from FlightAware.

SDRSharp SpyServer Now Supports the RTL-SDR

About a month ago the Airspy and SDRSharp development team released their new ‘SpyServer’ software. SpyServer is a streaming server for Airspy devices, which allows them to be used over a network connection. It is somewhat similar to rtl_tcp which is familiar to RTL-SDR users, although unlike rtl_tcp, SpyServer uses a multiclient architecture which allows several clients to connect to the server at the same time with each being able to choose individual bandwidth settings.

Today SpyServer was updated (changelog), and it now also supports the RTL-SDR dongle. The software can be found in the latest version of SDR# from www.airspy.com. The Airspy download contains the SpyServer for Windows and Linux, and the Raspberry Pi and Odroid server is available here.

To use SpyServer with the RTL-SDR you’ll first need to edit the “spyserver.config” file which is in the SDR# folder. Open this file with a text editor like Notepad, and set the “device_type” to “RTL-SDR”. Now you can run spyserver.exe on your server and it will use your RTL-SDR. Multiple dongles can be used by editing the “device_serial” string in the config file. Next on the client PC run the latest version of SDR#, and choose the Source as “Spy Server”. Here you can enter your networked PC’s IP address to connect to it.

We tested the updated SpyServer with an RTL-SDR dongle and it worked perfectly. On an 802.11n WiFi connection we were able to stream up to 1 MSPS without problems. 2 MSPS was a bit jittery, but on an Ethernet or 802.11ac WiFi connection it should work with no problems. We also tested connecting two PC’s to a single SpyServer and both were able to run at the same time without trouble. The client which connects first gets to keep control of the center frequency and gain, whilst the second client has those options locked.

SpySever Running with an RTL-SDR Dongle.
SpySever Running with an RTL-SDR Dongle.

A New Meteor M LRPT Image Decoder for Windows, Linux, MacOS and Raspberry Pi

Thanks to twitter user @LinuxSocist for submitting a link to this new Meteor M weather satellite LRPT decoder called ‘meteor_decoder’ which can be run on both Linux and Windows. Pre-built binary of the software for Windows, Linux Raspberry Pi and MacOS are available at orbides.org.

This software decoder appears to be an excellent choice for those people who want to perform their reception and decoding of Meteor M satellites all in Linux. Previously as explained in this previous post, you were able to receive the QPSK data in Linux with an RTL-SDR and a GNU Radio program, but then you’d still need to boot into Windows or run Wine to run LRPTofflinedecoder in order to generate the image. Now it appears that the image generation can be performed natively in Linux too with meteor_decoder. This help with creating portable automated Raspberry Pi based Meteor M decoder servers.

Meteor M is a class of Russian weather satellites that transmit live weather images of the earth as they pass over your location. They are somewhat similar to the NOAA satellites, although the Meteor satellites transmit higher quality images via a digital LRPT signal, rather than the analog APT signals used by NOAA. With an RTL-SDR, an appropriate antenna and decoding software they can easily be received.

An Example LRPT Image Received with an RTL-SDR from the Meteor-2 M2.
An Example LRPT Image Received with an RTL-SDR from the Meteor M-N2 Satellite.

Amateur Pulsar Observations with an RTL-SDR

Back in September 2015 we made a posted that discussed how some amateur radio astronomers have been using RTL-SDR’s for detecting pulsars. A pulsar is a rotating neutron star that emits a beam of electromagnetic radiation. If this beam points towards the earth, it can then be observed with a large dish antenna and a radio, like the RTL-SDR.

In their work they showed how they were able to detect and measure the rotational period of the Vela pulsar, one of the strongest and easiest to receive pulsars. They also noted how using several RTL-SDR dongles could reduce the required satellite dish size.

Recently we came across Hannes Fasching (OE5JFL)’s work where he shows that he has detected 15 pulsars so far using RTL-SDR dongles. His detection system specs include:

Antenna: 7.3m homemade offset dish, OE5JFL tracking system
Feeds: 70cm (424 MHz) dual-dipole with solid reflector, 23cm (1294 MHz) RA3AQ horn
Preamplifiers: 23cm cavity MGF4919, 70cm 2SK571 (30 years old!)
Line Amplifier: PGA103+
Interdigital filter: designed with VK3UM software, 70cm 4-pole, 23cm 3-pole
Receiver: RTL-SDR (error <1ppm), 2 MHz bandwidth
Software: IW5BHY, Presto, Tempo, Murmur

Furthermore, from looking at the Neutron Star Group website, it seems that the majority of amateur radio astronomers interested in pulsar detection are currently using RTL-SDR dongles as the receiver. Some of them have access to very large 25m dishes, but some like IW5BHY, IK5VLS and I0NAA use smaller 2.5m – 5m dishes which can fit into a backyard.

If you are interested in getting into amateur pulsar detection, check out the Neutron Star Group website as they have several resources available for learning.

OE5JFL's 7.3m pulsar detection dish with an RTL-SDR receiver.
OE5JFL’s 7.3m pulsar detection dish with an RTL-SDR receiver.

Some Tests on our BCAM and BCFM Filters

Over on YouTube user ElPaso TubeAmps has uploaded a video showing his tests on our broadcast AM (BCAM) high pass and broadcast FM (BCFM) band stop filters. These two filters are designed to block broadcast radio signals which in some locations can be extremely strong. If they are very strong then they can overload your SDR which causes very poor performance, even on other frequencies.

Some possible solutions for reducing overloading include:

  1. Attenuation – reduce all the strength of ALL signals coming in.
  2. Increase SDR dynamic range – purchase a higher end SDR with more ADC bits as these can handle strong and weak signals coming in together much better.
  3. Filtering – reduce the signal strength on the problematic frequencies that are causing overload, or only allow your frequency of interest to pass.
  4. Antenna tuning – use a narrowband, directional and/or differently polarized antenna which reduces the unwanted signal’s strength.

In the video he uses his signal generator and a spectrum analyzer to analyze the output of the filters. His results closely match our VNA results which are posted on the BCFM and BCAM filter product release posts.

RTL-SDR 88-108 MHz Bandstop Filter & 2.6 MHz HPF Broadcast AM Filter Measurements

YouTube Tutorial on Setting up a Soft66IP RTL-SDR

Over on YouTube user Danny Shortwave And Radio DX has uploaded a video showing an overview and tutorial about setting up the Soft66IP RTL-SDR. The Soft66IP is a custom RTL-SDR that is made in Japan by JA7TDO. It is an RTL-SDR with upconverter and LNA built into a box together with an embedded computing platform. We’re not sure what the computing platform is, but it is likely to be something similar to a Raspberry Pi. The computing platform is then used to run an rtl_tcp server, and so via a network cable or WiFi connection the device can be accessed by a remote PC.

On the video Danny gives an overview on what the Soft66IP is, and what features it has. Then later in the tutorial he shows how to SSH into the Linux server on the Soft66IP, set it up for your local network, and then later how to connect to it from a remote PC.

How to setup Soft66IP for your Local Area Network with SDRSharper

New Outernet Hardware “Dreamcatcher”: An RTL-SDR with Embedded Computing Hardware

Over on the Outernet forums Outernet CEO Syed has just released pictures of the latest upcoming Outernet receiver called “Dreamcatcher”. The new receiver is an RTL-SDR, LNA, filter, and embedded Linux capable computing hardware all on board a single PCB. The full specs are pasted below:

  • L-band SAW filter (1525 – 1559 MHz)
  • Two-stage L-band LNA with 34dB gain
  • 0.5 PPM TCXO
  • RF bypass for tuning from 24 – 1600 MHz – use as a regular RTL-SDR!
  • USB ports
  • GPIO forest
  • UARTs, I2C, SPI headers (unpopulated) for driving external hardware
  • Two microSD card holders – for boot and storage!
  • 1 GHz CPU
  • 256 MB RAM Now 512 MB RAM
  • USB wifi dongle (not shown) – STA+ AP mode capable!
  • Lots of LEDs! and Switches!
  • microUSB OTG
  • microUSB power port
  • Audio In/Out
  • Speaker with 1.4 W integrated audio amplifier
  • Fully mainline (4.10) Kernel and (2017.01) Uboot support!
    *** JST battery is being removed

On the Roadmap:

  • armbian/debian support

This is a fully-integrated SDR receiver – RF frontend, SDR, Compute, Wifi – Everything!

Outernet is an L-band satellite service that aims to be a download only “library in the sky”. Currently they are broadcasting from Inmarsat and Alphasat geostationary satellites which can be received from almost anywhere in the world. We have a tutorial on receiving and decoding their signal here. Every day almost 20 MB of data is sent down, and this includes data like news, weather forecasts, APRS, wikipedia articles, books and more. In the future you will be able to pay to upload private files or messages. This could be useful for sending messages to people isolated from cell phone reception, or for operating remote hardware.

Previously Outernet sold a DIY version of their receiver which included an RTL-SDR V3 or E4000 dongle, LNA+filter, a C.H.I.P embedded computer, and a patch antenna. Recently they have changed to their custom RTL-SDR hardware which is called the “SDRx”. The SDRx includes the RTL-SDR, LNA and filter on a single PCB. Over time it seems that they are moving in the direction of integration of all components onto a single PCB and this can be seen in the Dreamcatcher which now also includes the computing hardware. This is especially good news as the $9 C.H.I.P computing hardware has been almost impossible to acquire since its release.

The Dreamcatcher looks to be also not just useful for Outernet, but also for general projects that can be done on embedded hardware as there is a port which bypasses the L-Band filter.

Back in 2014 we posted about the XiOne. This was also to be an RTL-SDR and computing hardware built onto the same PCB. It would have been controlled via a WiFi connection and apps on a smart phone/tablet. Unfortunately the XiOne Indiegogo crowdfunding campaign never reached its target so the project faded away. The Dreamcatcher is somewhat similar in that both are RTL-SDRs with onboard computing hardware and WiFi connectivity.

The Dreamcatcher is not yet for sale, but it is currently under production. From the looks of the discussion on the forums, it looks like it will sell for $149 USD. Outernet have said that they are sending us a review sample, so keep an eye out for the review in the coming weeks.

The Outernet Dreamcatcher: RTL-SDR + LNA + Filter + Computing Hardware on a single PCB.
The Outernet Dreamcatcher: RTL-SDR + LNA + Filter + Computing Hardware on a single PCB.