Tagged: rtl-sdr

Building a 3D Printed LHCP Helical L-Band Feed for Inmarsat, AERO and HRPT

Thanks to Manuel a.k.a. Tysonpower for submitting his latest YouTube video tutorial about building an 1550 MHz L-band LHCP helical antenna for receiving satellite signals such as Inmarsat, AERO and HRPT.

Manuel's design is based on a 3D printed part which is used to accurately form the helical winding. The winding then mounts onto an aluminum plate and a satellite dish arm using a custom 3D printed adapter for the dish arm. In the video he uses the helical feed with an 80cm satellite dish and a standard 40mm LNB mount on the dish arm. Attached to the feed are two LNAs in series which help to lower the noise figure and reduce losses in the coax cable.

With this setup he writes that he was able to get very good AERO and Outernet reception from Alphasat (25E geostationary). He also writes that he's had good results using it for HRPT reception as well.

The 3D printing STL files and list of parts required are available on Thingiverse, and the companion video is shown below. Note that the video is narrated in German, but English subtitles are available.

[EN subs] LHCP Helix L-Band Feed - 3D Druck für eine genaue Helix

Manuel's L-Band Helical Feed
Manuel's L-Band Helical Feed

QrssPiG: Decoding QRSS on a Raspberry Pi with an RTL-SDR

QRSS is a ham communications mode that is essentially just very slow CW (morse code), with each dash/dot being broadcast for a number of seconds. With QRSS instead of audibly decoding the morse code signal, it is decoded visually via a spectrum display (or automatically by software). It is designed to be a QRP mode, which means that hams transmitting QRSS can be heard all over the world even though very low transmit power is used. 

QrssPiG is a QRSS grabber program that runs headless on a Raspberry Pi and can interface with an RTL-SDR. It automatically generates the waterfall graphs of received QRSS images, and supports uploading them via SCP or FTP. The software can also run with a HackRF, or via audio piping from another SDR or standard hardware radio.

Recently on Twitter @ON4CDJ has been trying QrssPiG with an RTL-SDR V3 and has been having good results.

Testing Public Airspy HF+ SpyServers over the Internet

SpyServer is a streaming server for SDR# which allows you to use Airspy and RTL-SDR radios remotely over a network connection. There is now a list of publicly available SpyServers that you can connect to over on the airspy.com website.

The servers that are currently online include some streaming from Airspy HF+ devices, which is the hotly anticipated but as of yet unreleased HF receiver from Airspy. Over the last few months and weeks a number of prototype devices went out to testers and programmers and some have now put them online with a SpyServer. There are also some Airspy One/Mini and RTL-SDR devices available for streaming too.

To connect to one of the servers simply download the latest version of SDR# from airspy.com, and then in SDR# select SpyServer from the Source menu. Enter the URL from the list into the box and press the play button up the top. Note that you must ensure that there are no spaces after entering the URL in SDR#.

Most servers are locked to a particular frequency band, but some allow for free tuning. But if more than one person is connected to the server free tuning will be locked until there is only one person connected again. Currently streaming from most servers seems smooth, but it's possible that some may struggle if many users are connected at once.

If you want to set up your own SpyServer then we recently put up a tutorial which is available here.

The current list of SpyServers
The current list of SpyServers

Alternative streaming SDR lists for other non-Airspy SDR hardware include sdr.hu and websdr.org, but those stream compressed audio instead of IQ data.

Outernet Dreamcatcher Setup with ADS-B dump1090 and PiAware Tutorial

The Outernet Dreamcatcher is a single board PC with a built in RTL-SDR. It has a TCXO and two SMA ports, one being amplified and filtered for L-band applications and the other being a regular port for all other applications.

With built in computing hardware the Dreamcatcher can be used as a standalone unit for various applications. As the Dreamcatcher is now on sale we've decided to create a brief tutorial that shows how to set one up as a cheap ADS-B aircraft radar receiver, and also how to set it up as a PiAware feeder. PiAware is software that allows you to feed FlightAware.com which is an ADS-B aggregatpr.

Any simple SMA antenna can be used, like our Dipole kit, an old RTL-SDR whip antenna, or even a short piece of wire.

We also have a previous review of the Dreamcatcher available here. In the past the main problem with the $59 USD Dreamcatcher was that you could get a more powerful Raspberry Pi 3 and RTL-SDR dongle for a similar price. But now at the sale price of $39 USD the Dreamcatcher is definitely a great deal.

Note that we'd recommend NOT purchasing the Dreamcatcher specifically for the Outernet data signal as we're unsure exactly how long that signal will continue to be broadcasting for. 

The Outernet Dreamcatcher
The Outernet Dreamcatcher

What follows below is a tutorial that shows how to set up a Dreamcatcher. The tutorial installs dump1090 at the same time, but afterwards could be used for a number of other applications.

Continue reading →

Adam Tests his UP-64 Upconverter with an RTL-SDR

Over on YouTube Adam 9A4QV has uploaded a video of him testing out his 'UP-64' upconverter together with an RTL-SDR. An upconverter moves low frequencies 'up' into a higher frequency. This is useful for HF reception, as normal reception on an RTL-SDR starts at about 24 MHz (without using direct sampling mode).

Adam previously manufactured and sold his UP-100 upconverter, which was an upconverter of his own design that utilized a 100 MHz oscillator. These days it has been accepted that using an upconversion frequency that avoids the broadcast FM band is generally better as it avoids the interference that can come from very strong FM signals. The 64 MHz oscillator on the UP-64 avoids the broadcast FM band for the most part unlike the older UP-100.

RTL-SDR + UP-64 test on 14MHz

QRadioLink Development Webpage Now Up

Back in September we posted [1, 2] about the QRadioLink software which is an RTL-SDR compatible digital amateur radio voice decoder and encoder program for Linux and Android (with chroot). It supports modern digital voice codecs like Codec2 and Opus. It is capable of being used with multiple SDRs, and can be used for transmitting digital voice too if you have a transmit capable SDR.

Andrian the developer recently wrote in to let us know that QRadioLink now has a website at qradiolink.org that you can follow for updates about its development. The website also explains some of the features of the software, and lists possible performance values of digital voice. The features include:

  • Receives and transmits analog voice, digital voice, low resolution video, text, IP protocol.
  • Narrow band modem with Codec2 or wideband modem and Opus.
  • Digital Modems: BPSKQPSK2FSK4FSK
  • Modes: narrow FM, SSB, digital voice, digital video, digital data
  • Formats: Codec2 700B, Codec2 1400, Opus 10 kbit/s
  • Video formats: JPEG
  • Supported hardware: Ettus USRP, RTL-SDR, HackRF, BladeRF and in general all devices supported by gr-osmosdr

Typical Receiver performance is given in the following table, with all values being measured on an R820T RTL-SDR.

Mode Condition Sensitivity (dBm)
Codec2 700B 20 db SINAD -115
Codec2 1400 20 db SINAD -112
Opus 20 db SINAD -102
Narrow FM 12 db SINAD -118

In the future Adrian hopes to expand the software to include features like VOIP integration, SSB transceiver, DTMF & CTCSS encoder/decoders, multi-channel RX, HD video, remote control and a GUI improvement.

QRadioLink Main Page

RTL-SDR Blog V3 Units back in stock at Amazon

This is just an announcement post to say that the RTL-SDR Blog V3 is now back in stock at Amazon USA and should be ready for shipping from there soon.

These include our bundle that comes with the new multipurpose dipole antenna kit for $25.95 USD. Please go to rtl-sdr.com/DIPOLE for further information about the new dipole kit.

Click here to visit our store for the links

Our RTL-SDR Blog V3 with Multipurpose Dipole Kit.
Our RTL-SDR Blog V3 with Multipurpose Dipole Kit.

Outernet Dreamcatcher Sale is a Steal: $39 USD RTL-SDR + Computing Board All-In-One

The Outernet Dreamcatcher has recently gone on sale and is now only $39 USD. Previously it was priced at $79 and $59 USD. The Dreamcatcher is an RTL-SDR and computing board all built onto the same PCB. It has two SMA inputs - one is an L-band filtered and amplified input and the other is a standard wideband port good for all frequencies covered by a standard R820T2 RTL-SDR. For $39 it appears that you get the board itself, and a WiFi dongle, but no antennas, cables or SD cards are supplied with the unit.

In you are interested in the Dreamcatcher then back in June we posted a comprehensive review of it as well as their ceramic L-band patch antenna. Since then we've found that the Dreamcatcher has become much more stable and is very useful for applications like setting up a dedicated ADS-B receiver/feeder. At this price the Dreamcatcher is even better value than using a Raspberry Pi 3 plus external RTL-SDR dongle which can end up costing over $60 USD.

According to Outernet stocks appear to be fairly limited so this price probably won't last for too long.

Note: We'd advise not purchasing this for use with the Outernet data signal as we're unsure if that signal is going to last for much longer. Purchase it as a general purpose radio/computer instead.

The Outernet Dreamcatcher Board
The Outernet Dreamcatcher Board