Finding Cheap Pre-Designed PCBs for SDR Projects

Recently RTL-SDR.com reader Neil KM4PHK wrote in to us to let us know that he’s been having a good time searching for SDR related PCB’s over on OSH Park. OSH Park is a company that allows you to upload and share a PCB, and then have it cheaply printed and sent to you for construction.

Some useful RTL-SDR related PCBs we found searching through their shared projects include PCB’s for a SAW filter, a PSA4-5043+ based LNA, an MGA-53543 based LNA, a lowpass or bandpass filter, an FM trap, an ADS-B filter with LNA and a bias tee. More projects can be found by searching the shared projects page for strings like “SDR, LNA, Filter, Bias Tee, ADS-B”. Neil also writes that although some projects don’t have instructions on their OSH Park page, usually searching Google will reveal them.

An example PCB for an LNA that can be found on OSH Park.
An example PCB for an LNA that can be found on OSH Park.
Tweet10
Share
Reddit
Vote
Email
10 Shares

Setting up a Raspberry Pi Based AIS Receiver with an RTL-SDR

Over on YouTube user Tobias Härling has uploaded a video showing how he used a Raspberry Pi and RTL-SDR dongle to set up an AIS receiver. AIS stands for Automatic Identification System and is a radio system similar to ADS-B which allows you to create a radar-like system for boats. For Windows we have a tutorial on AIS reception here.

In his setup he uses rtl_ais and the kplex software and shows how to install everything from scratch. He also shows how to set the system up so that decoding automatically starts up and begins outputing NMEA data through the network when the Raspberry Pi is powered on. This way an a device like an iPad could be used to run OpenCPN to view the plotted ships.

$50 Raspberry Pi AIS-Receiver - How to

Tweet19
Share
Reddit
Vote
Email
19 Shares

Partial Discharge Detection using an RTL-SDR

Partial discharge is the situation in which electricity arcs through an insulating dielectric material when high voltages above the rated voltages for the insulator are applied. Continued partial discharge can cause the insulator to eventually be destroyed and fail, potentially causing catastrophic failure.

Recently a technical academic paper by H Mohamed et al. was released and titled “Partial Discharge Detection Using Low Cost RTL-SDR Model for Wideband Spectrum Sensing”. In the paper they investigate using the RTL-SDR as a low cost means for partial discharge detection in equipment such as power generators, motors, gas insulated switchgear, and power grid equipment for the purpose of improving the future electrical smart grid.

Partial discharge can be detected using a spectrum analyzer to monitor the spectrum for noise signatures associated with a discharge. Using a program written in MATLAB to make the RTL-SDR act as a spectrum analyser they show that the measured spectrum can be used to detect when partial discharge is occurring and that the results are similar to a more expensive spectrum analyzer.

Lab set up for using an RTL-SDR to detect partial discharge.
Lab set up for using an RTL-SDR to detect partial discharge.
Tweet11
Share
Reddit
Vote
Email
11 Shares

Review: FlightAware ADS-B RTL-SDR + LNA Positioning

Recently FlightAware released a new RTL-SDR dongle sold at zero profit at $16.95 USD. It’s main feature is that it comes with an ADS-B optimized low noise amplifier (LNA) built directly into the dongle. FlightAware.com is a flight tracking service that aims to track aircraft via many volunteer ADS-B contributors around the world who use low cost receivers such as the RTL-SDR. In this post we will review their new dongle and hopefully at the same time provide some basic insights to LNA positioning theory to show in what situations this dongle will work well.

FlightAware Dongle Outside
FlightAware Dongle Outside

A good LNA has a low noise figure and a high IIP3 value. Here is what these things mean.

Continue reading →

Tweet11
Share
Reddit
Vote
Email
11 Shares

AISRec Updated to Version 2.1

AISRec is an RTL-SDR (and now Airspy) compatible AIS (automatic identification system) dual channel decoder. AIS is an acronym for Automatic Identification System and is a system used by ships to broadcast position and vessel information. By monitoring AIS transmissions with the RTL-SDR we can build a boat radar system.

Last time we tried AISRec we found its performance to be very good, with it decoding more messages than other software we tried. The new version includes the following updates:

  • Added auto detection of devices when devices are plugged in.
  • Added the support for airspy. Allow selection of devices by serial number for rtlsdr dongles.
  • Added AISRec core 3.0. The new core is 2x faster than AISRec core 2.0.
  • Added one embedded multi-user TCP server. Any client works with AISRec should implement auto reconnection.
  • Added auto display of local IP for the TCP server.
  • Added one output to one serial port.
  • Added interactive changes of gain parameters for devices.
  • A few changes on GUI.
  • Added an icon for GUI. Users should reset the windows icon buffer to allow the display of the new icon.

In addition, while AISRec hopes to be commercial software one day, at the moment they are currently offering free registration. See their FAQ for information on registering for free.

AISRec running with OpenCPN.
AISRec running with OpenCPN.
Tweet12
Share
Reddit
Vote
Email
12 Shares

Receiving Differential GPS Beacons with a HackRF

Differential GPS (DGPS) are signals that exist between 285 – 325 kHz and are used to enhance the accuracy of GPS receivers. The system can improve GPS accuracy from 15m down to 10cm in some cases. It works using a network of ground stations at a very accurate known location that continuously measure the GPS error they receive. They then broadcast this error to DGPS capable receivers. The receiver can then use this error knowledge to correct their own readings.

With an VLF capable radio these DGPS beacons can be received and decoded on your PC. Over on swling.com guest poster Mario has submitted a post showing that these DGPS beacons can be received with a HackRF SDR and the MultiPSK software. The HackRF is a $299 SDR that can tune down to VLF (at reduced sensitivity). We note that the same or better results could also be achieved with a HackRF or RTL-SDR with upconverter.

DGPS received with a HackRF
DGPS received with a HackRF
Tweet20
Share
Reddit
Vote
Email
20 Shares

Using an RTL-SDR on a high powered rocket to capture GPS data

Over on the SDRGPS blog Philip Hahn and fellow aerospace engineer Paul Breed have been working together to try and use an RTL-SDR to help get accurate GPS data for tracking small high powered rockets. They write that their end goal is to be able to “track high power rockets in high acceleration / speed / altitude environments”.

In their latest attempt they launched a rocket with an RTL-SDR on board with it capturing GPS data to be later processed with GNSS-SDR. The goal was to get a GPS fix throughout the flight. Unfortunately they found that a good fix was only obtained while the rocket was on the ground, and not much data was obtained while it was in the air. They write that they suspect that the fault lies in the vibration in the rocket which can affect the frequency stability of the crystal oscillator, or in the GPS satellite tracking loop algorithm.

They still hope to be able to get some usable information from the flight by trying other algorithms on the data, but they are also seeking advice from anyone who might know how to help them, so please contact them if you know anything that may help.

If you are interested in this, then see our previous post about how Philip showed us how to use an RTL-SDR to receive and plot GPS data.

RTL-SDR + GPS antenna plus an Intel NUC computing platform.
RTL-SDR in aluminum case + GPS antenna + an Intel compute stick and IMU.
The rocket carrying the RTL-SDR.
The rocket carrying the RTL-SDR.

Tweet13
Share
Reddit
Vote
Email
13 Shares

RTLSDR4Everyone: The best RTL-SDR setup for $60

Over on his blog RTLSDR4Everyone author Akos has uploaded a new post showing what he believes is the best possible RTL-SDR set up that you can get for under $60. Akos writes that the best combination of components is one of our RTL-SDR Blog dongles (back in stock in a couple of weeks!) with bias tee combined with an LNA4ALL low noise amplifier. The LNA4ALL is a ~$30 USD LNA based on the Minicrcuits PSA4-5043+ component and is sold by Adam 9A4QV who also sells other products such as RF filters.

Akos reminds us that the LNA4ALL can actually be bought from Adam with the bias tee enabled already which saves you from the difficulty of needing to source the required inductor and perform surface mount soldering. The post also explains why  you might want to use an LNA in the first place and how to enable the bias tee on our RTL-SDR.com dongles.

RTL-SDR.com dongle + an LNA4ALL
RTL-SDR.com dongle + an LNA4ALL powered with the bias tee
Tweet12
Share
Reddit
Vote
Email
12 Shares