Tagged: airspy

Frugal Radio: Review of our RTL-SDR Blog L-Band Patch Antenna

Over on YouTube Rob from Frugal Radio has uploaded a video reviewing our new L-Band Patch antenna which we released for sale late last month. The patch is currently on a release sale for US$44.95 including free standard airmail shipping to most countries. We will be ending the sale this Wednesday at which point the price will go to US$49.95, still with free standard airmail shipping to most countries. The patch can be purchased from our web store at www.rtl-sdr.com/store.

In the video Rob demonstrates the patch receiving Inmarsat signals strongly, and decodes a few AERO signals using JAERO. He shows that the patch works on any RTL-SDR with bias tee capability as well as an Airspy Mini. Lastly he compares the unit against the SDR-Kits patch.

We note that we are also supplying a kit for a giveaway to Frugal Radio subscribers that we will announce in an upcoming video coming out a few days time.

RTL-SDR updated L-band patch antenna review - perfect for your SDR radio!

UPDATE: Giveaway information now available in the latest video below.

RTL-SDR L-Band Patch Antenna Giveaway

SDR# Updated: Improved Performance and Better RTL-SDR Compatibility

SDR# (SDRSharp) is one of the most popular free software defined radio programs available with RTL-SDR support. Recently it has been updated to version 1811 and the new version brings improved performance and also improves RTL-SDR compatibility with some systems. The changelog reads:

Date:   Mon Mar 29 15:03:09 2021 +0200
Commit: d5cb6c3

More DSP optimizations;
Many fixes for RTL dongles (mainly workraounds for old libs);
Revert to libusb for backward compatibility;
Revert to portaudio 2016 for backward compatibility;
Code cleanup.

@lambdaprog (the SDR# programmer) has also tweeted showing how well SDR# can run on a 10 year old i7 4700 laptop with the new performance improvements. With a huge 160 MSPS baseband IQ file, the software is seen to be using very minimal CPU. 

GNU Radio Amateur Radio Meeting: A Look at Project 25 (P25) Digital Radio

Over on their YouTube channel GNU Radio have uploaded a recent talk by Aaron Rossetto titled "A Look at Project 25 (P25) Digital Radio". The talk explains the North American public safety P25 system in great depth, and is a good watch for anyone looking into details on how the system works in a deeply technical way. He later shows some examples of his P25 decoding and recording setup. Slides can be found here, and the video is posted below.

Agenda: In this presentation, I will introduce Project 25 digital radio, with a strong emphasis on its use in North American public safety trunked radio systems, and to describe experiments monitoring and decoding P25 traffic using GNU Radio code.

  • What is Project 25?
  • A brief introduction to trunked radio
  • Diving into the P25 protocol
    • Modulation
    • Packet framing and encapsulation
    • Packet types
  • GNU Radio and P25 decoding experiments

GNU Radio Amateur Radio Meeting

Building an 11.2 GHz Radio Telescope with an Airspy and 1.2m TV Satellite Dish

In the past we've posted several times about how 1.42 GHz Hydrogen Line amateur radio telescopes used with RTL-SDRs or other SDRs for Hydrogen line observations of the galaxy. Recently Hackaday ran a post highlighting a project from "PhysicsOpenLab" describing an 11.2 GHz radio telescope that uses an Airspy SDR as the receiver.

Celestial bodies emit radio waves all across the radio spectrum and typically observations can be made anywhere between 20 MHz to 20 GHz. Choosing an optimal frequency it is a tradeoff between antenna size, directivity and avoiding man made noise. For these reasons, observations at 10-12 GHz are most suitable for amateur radio telescopes.

The posts by PhysicsOpenLab are split into two. The first post highlights the hardware used which includes a 1.2m prime focus dish, and 11.2 GHz TV LNB, a wideband amplifier, a SAW filter, a bias tee, and the Airspy SDR. The LNB converts the 11.2 GHz signal down to 1.4 GHz which can be received by the Airspy. Once at 1.4 GHz it's possible then to use existing commercial filters and amplifiers designed for Hydrogen line observations.

The second post explains the GNU Radio based software implementation and the mathematical equations required to understand the gathered data. Finally in this post they also graph some results gathered during a solar and lunar transit.

Finally they note that even a 1.2m dish is quite small for a radio telescopic, but it may be possible to detect the emissions from the Milky Way and other celestial radio sources such as nebulae like Cassiopeia A, Taurus A and Cygnus A a radio galaxy.

A 11.2 GHz 1.2m Amateur Radio Telescope with GNU Radio and Airspy

New SDR# User Guide Available

Paolo Romani IZ1MLL has recently created a SDR# users guide document which comprehensively explains all the features and settings available in the program. SDR# (aka SDRSharp) from Airpsy.com is designed for Airspy SDRs, however it is one of the most popular SDR receiver programs used with RTL-SDRs as well.

Paolo's guide appears to build on our own guide at www.rtl-sdr.com/sdrsharp, providing new information and updates since many changes and new features have been released in SDR# since we wrote that guide a few years ago.

The guide can be found on the airspy.com/download page and is available in English, Italian and Spanish.

SDRSharp Guide

Tech Minds tests out the YouLoop HF Passive Loop Antenna

Over on YouTube Tech Minds has uploaded a new video where he unboxes and tests a YouLoop HF Passive Loop Antenna with his Airspy. The YouLoop design is also known as a Möbius loop, or noise cancelling passive loop "NCPL". The passive nature of the antenna means that highly sensitive radios will work best with it, however limited results may still be obtained with other radios. The advantages are extremely low levels of interference pickup and high portability.

In the video Tech Minds explains the specifications of the antenna before demonstrating the antenna receiving the HF bands with an Airspy + SpyVerter. He also tests the loop on VHF, demonstrating its ability to receive a distant 2M beacon.

We note that we sell official YouLoop antennas on our store for $34.95 including free shipping to most countries.

YouLoop HF Passive Loop Antenna

DSDPlusUI Now Available as a Plugin for SDR#

At the beginning of 2020 Annunaki (@StupotSinders) released his third party user interface for DSDPlus. DSDPlus is a digital speech decoder capable of decoding protocols such as P25 P1, DMR, NXDN and more with an SDR such as the RTL-SDR. As it is a command line tool, it can be a little daunting for some users, which is where the GUI comes in handy.

Recently Annunaki has released an SDR# plugin version of DSDPlusUI. This makes it so you can visualize the digital voice signals at the same time as controlling and decoding with DSDPlus. The plugin is available on the DSDPlusUI website at dsdplusui.com. To use it you will need to be using SDR# 1777 or later.

DSDPlusUI as a plugin for SDR#

Airspy Black Friday Deals Now Active

Airspy have released their black Friday 2020 deals today with 30% off. Back in 2019 we saw that the black friday deals were the best time to purchase an Airspy and we don't expect pricing to get cheaper than this. Links to their distributors can be found on airspy.com.

Airspy sell a range of software defined radios. The HF+ Discovery is one of the best (if not the best) low cost HF SDRs we've ever tested, and the Airspy Mini and R2 are good wide band VHF/UHF radios that are a step up from RTL-SDRs. The SpyVerter is a good upconverter that is also compatible with RTL-SDRs, and can be used with the bias tee on the RTL-SDR Blog V3.

The sale brings the pricing down to the following prices in USD (plus shipping costs):

Airspy HF+ Discovery: $169 $118.30
Airspy Mini: $99 $69.30
Airspy R2: $169 $118.30
SpyVerter R2: $49 $34.30

Frugal Radio has also uploaded a short video regarding the sale.