Category: RTL-SDR

New Cross Country Wireless HF Preselector

A new reasonably priced 5-band HF preselector has been released by the company Cross Country Wireless, and it looks perfect for use with SDRs. The price is $56.95 GBP, which right now is about $72 USD. They write:

This can be used to provide additional front end selectivity for HF and medium wave receivers protecting the receiver from strong out of band transmissions, wideband noise and other transmitters on multi-station field days.

As the sunspot cycle declines and more listening is done on the lower HF bands with long wire antennas and strong NVIS signals then the HF Preselector is an ideal accessory to aid receiver performance.

It is invaluable when using simple conventional superhet or SDR receivers such as RTL-SDR dongles with upconverters or SDRPlay with large HF antennas.

It is an ideal tool to reduce ADC overload on the Icom IC-7300 with the new second receiver socket modification kit.

It can also be used with other transceivers that have sockets for a separate receiver input and receive antenna output.

It also covers the medium wave broadcast band for MW DXers.

The Preselector is a passive high Q design that does not use an additional amplifier or require external power.

  • Frequency tuning range: 0.5 to 52 MHz in five bands
  • Input impedance: 50 ohms
  • Output impedance: 50 ohms
  • Bypass option on switch
  • Galvanic isolation between input and output
  • Insertion loss: 2 dB
  • Selectivity: See HP network analyser plots below
  • Connectors: BNC female (RF in 50 ohms), BNC female (RF out)
  • Tough polycarbonate case
  • CCW Z Match
    Overall dimensions: 125 mm (L) x 85 mm (W) x 55 mm (H)
  • Weight: 192 g
The Cross Country Wireless HF Preselecter
The Cross Country Wireless HF Preselector

A Tutorial on Using a Raspberry Pi Zero Wireless for ADS-B Flight Tracking

Allaboutcircuits.com contributing writer Mark Hughes has recently posted a tutorial that shows how to use an RTL-SDR dongle with a Raspberry Pi Zero Wireless to track aircraft with ADS-B. As a bonus he also shows how to program and wire up a 64×64 RGB matrix screen to display currently tracked flight numbers.

The Pi Zero is one of the cheapest single board computers available, costing only $5 USD, and the wireless model with WiFi connectivity only costs $10 USD. It is powerful enough with its 1 GHz CPU and 512 MB of RAM to run an RTL-SDR and run several non CPU intensive applications such as ADS-B decoding.

The tutorial starts from the beginning by installing a fresh Raspbian image onto the Pi Zero. He then goes on to show how to install the PiAware tracking and feeding software from flightaware.com. Later in the tutorial he also shows how to collect data straight from the flightaware.com API, and also how to build and control an RGB matrix which can display live flight numbers.

It also seems that FlightAware themselves have recently released PiAware 3.5, which now directly supports the Raspberry Pi Zero Wireless.

Track Overhead Flights with a Raspberry Pi Zero Wireless, a Software Defined Radio, and FlightAware

Using a HackRF as a Beacon Transmitter on a Drone for Antenna Calibration

Over on his Twitter feed Sylvain Azarian (@sylvain_azarian / F4GKR) has been tweeting about his new antenna calibration method which involves the use of a HackRF SDR and Raspberry Pi mounted on a drone.

The idea is to use the drone as a remote beacon which can move all around the antenna. As the drone flies around, the HackRF on the drone emits a data chirp containing GPS telemetry of the drones position. The receiver on the ground decodes this data and also determines the SNR of the received signal. By plotting the received SNR together with the drones GPS position, the radiation pattern of the antenna under test could be determined.

The software is called “RadiantBee” and is developed by both F4GKR and F5OEO. It is available over on GitHub. The flying hardware consists of a quadcopter, GPS, Raspberry Pi 3, HackRF, 10 GHz upconverter, band pass filter and horn antenna. The base station consists of an RTL-SDR dongle, 10 GHz downconverter, GPS and the antenna under test.

[Also seen on Hackaday]

The RadiantBee Quadcopter.
The RadiantBee Quadcopter

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.