Category: Applications

Tech Minds: Testing an RTL-SDR Wideband Scanner with WebUI

Over on YouTube Matt from the Tech Minds YouTube channel has put up a video demonstrating an open source program released on GitHub called "RTL SDR Scanner", or "rtl-sdr-scanner-cpp". This program is compatible with RTL-SDR and HackRF software defined radios, and allows users to record multiple analogue FM audio channels within the active bandwidth simultaneously. 

To get a wider bandwidth, you can use a HackRF as your SDR, or you can also use multiple RTL-SDR dongles, or a device like the KrakenSDR which has multiple RTL-SDRs built into it. Alternatively, you can also have the software scan a much larger swath of bandwidth, however this could result in some transmissions being missed. 

The audio is recorded as a wav file, and can be accessed through a web UI. We note that currently only FM recordings are supported but AM may be supported in the future.

RTL SDR Scanner - FULL Bandwidth Recording With WEB UI

SARCTRAC Mk3b: A $290 Satellite Antenna Rotator

In January we posted about the AntRunner, which is a $325 (incl. shipping) satellite antenna rotator shipped from China. Recently we've come across another low cost satellite rotator from Australia called the "SARCTRAC Mk3b" which was developed as part of a school amateur radio educational program. This rotator fully assembled comes in at AU$400 + AU$50 worldwide shipping (US$290 + US$40 = US$330), making it's price comparable with the AntRunner. SARCTRAC can be purchased from the sarcnet products page. Currently only the fully built unit is available, but in the future they plan to offer a cheaper kit option.

We're yet to test the SARCTRAC Mk3b, but based on an overall review of it's advertising, it appears that the SARCTRAC has some superior specifications and a superior design when compared to the AntRunner.

Unlike the AntRunner, SARCTRAC comes with all its components enclosed in a waterproof IP65 rated enclosure. Its design also makes use of a 3D position sensor with magnetometer, allowing the unit to know its orientation at all times, meaning that it should be able to automatically position itself from startup. The design also makes use of DC motors with a built in worm gear drive, so the the motors back driving is not possible. 

The system is controlled via a built in Raspberry Pi 3B+ and can communicate with the controlling PC via WiFi. Raspberry Pi's have stable WiFi connections, so we shouldn't see the connection problems that we had with the ESP32 based AntRunner.

Just like the AntRunner, SARCTRAC is only a lightweight rotator with torque specs of 50kg.cm static and 25kg.cm dynamic. So it should be able to handle counterbalanced Yagi beams, and lightweight dish antennas.

The SARCTRAC Mk3b. An Australian designed and made light duty antenna rotator.
The SARCTRAC Mk3b. An Australian designed and made light duty antenna rotator.
SARCTRAC Mk3 Satellite Antenna Rotator Controller and TRACker

Using a PlutoSDR as a Monopulse Tracker

Over on YouTube Jon Kraft has been uploading videos explaining some interesting beamforming experiments he's been doing with his PlutoSDR. One experiment shows how to create a DIY monopulse tracker, which is a type of radio direction finding technique.

The PlutoSDR has two RX ports and two TX ports, and in this experiment he uses two directional antennas for the RX and one monopole antenna for the TX. Part 1 of this series explains standard phased array beam forming, and part 2 moves on to explain monopulse with adaptive tracking.

If you were interested in this, check out Jon's other videos on his channel. A recent video explains how time delays work in digital beamforming.

Build Your Own Phased Array Beamformer

Monopulse Tracking with a Low Cost Pluto SDR

Tech Minds: Demonstrating RTL_433 Running on ESP32 Devices

Earlier in the month we posted about how rtl_433 has been ported to ESP32 devices that are combined with CC1101 or SC127X transceiver chips, such as the low cost LILYGO LoRa 32 boards available on Aliexpress.

Over on YouTube Matt from the Tech Minds channel has uploaded a video showing how to set up rtl_433 on an ESP32 device, and how to set it up with a home automation service like Home Assistant, Node Red or OpenHAB via an MQTT broker.

RTL 433 ON ESP32 DEVICE - MQTT HOME ASSISTANT

AirNav Systems Launch AIS Aggregator ShipXplorer.com

AirNav Systems are behind the RadarBox ADS-B tracking aggregator, one of several companies that use data obtained by volunteers running RTL-SDR dongles to collect ADS-B flight data from all over the world.

Recently they've launched a new project called ShipXplorer.com which is a marine AIS aggregation service. Like RadarBox, ShipXplorer relies on volunteers running receiver stations all around the world. AIS is an acronym for 'Automatic Identification System', and in a similar way to ADS-B on aircraft, AIS allows the real time tracking of marine vessel positions. 

To help enthusiasts with AIS reception, AirNav have also launched an AIS optimized RTL-SDR dongle. At the moment we're not exactly sure how this dongle works, as it advertises NMEA output with no add-on programs required. So this may imply it has some onboard processing. But reviews imply that it is just an RTL-SDR dongle with TCXO. We are currently inquiring with AirNav Systems. UPDATE: We have clarified with AirNav and confirmed that the dongle is an RTL-SDR dongle with AIS modifications (LNA & TCXO). There is no onboard processing and the advertising text was an error. 

AirNav Systems write:

Some great news on a new product we've been developing for the last year and that's just been released.
 
As you know our company has been in the industry for over 20 years, offering innovative and unique flight (RadarBox) tracking solutions. We supply multi-million USD companies with reliable/accurate worldwide real-time flight information and the RadarBox.com portal has now over 1.3 million accounts registered.

I'm reaching out to you to introduce you to AirNav System's ship tracker, ShipXplorer.com, which we launched a few months ago 
 
About ShipXplorer.com:
ShipXplorer is a vessel tracking website that tracks global vessel movements in real time. ShipXplorer was developed to cater to the increasing navigational and tracking challenges faced by the maritime industry. In addition to offering professional maritime tracking solutions, the platform is also available for public use, with features and services specially developed for the burgeoning maritime enthusiast and vessel spotting community.
 
ShipXplorer.com
ShipXplorer.com Screenshot
ShipXplorer Screenshot
ShipXplorer Screenshot
ShipXplorer.com Screenshot
ShipXplorer.com Screenshot
In addition to our recently launched ship tracking portal, we have a variety of AIS hardware, such as dongles and AIS antennas. 
 
ShipXplorer AIS Dongle:
This high-performance dual channel AIS USB Receiver decodes AIS transmissions and enables the reception of AIS messages and data directly onto devices such as a Raspberry Pi or Laptop.
ShipXplorer AIS Optimized RTL-SDR Dongle
ShipXplorer AIS Optimized RTL-SDR Dongle

ShipXplorer AIS Antenna:
ShipXplorer's omnidirectional AIS Antenna is optimized for long-range, dual channel (Channel A and B) 162 MHz VHF reception. It also ships with a 30 ft cable (SMA connector). Meant for outdoor use, this antenna is built with a fiberglass & aluminum alloy and can weather prolonged exposure to the elements.

ShipXplorer AIS Antenna
ShipXplorer AIS Antenna
ShipXplorer Sea Range AIS Receiver:
SeaRange is ShipXplorer's newest 162 MHz, dual channel, AIS receiver. This brand-new model includes an added filter and an inbuilt amplifier designed to optimize AIS reception on both 162.025 MHz & 161.975 MHz frequencies.
And we are currently working on expanding our AIS coverage globally. 
ShipXplorer Sea Range AIS Receiver
ShipXplorer Sea Range AIS Receiver
ShipXplorer website: https://www.shipxplorer.com

ShipXplorer hardware: https://www.shipxplorer.com/store

 
Sharing AIS Data with ShipXplorer: 
 
And recently, we've also introduced the possibility of sharing AIS data with us using the AIS Dispatcher:
 
Some of the benefits feeders receive for sharing data with ShipXplorer include: 
  1. Free Business Account Access (benefit from all possible website features for free, while sharing data with ShipXplorer) 
  2. Dedicated Whatsapp, Facebook & Telegram Groups
  3. Access to ShipXplorer' MyStation page where users can monitor all traffic received by their own units.

rtl_433 ported to ESP32 microcontrollers with CC1101 or SX127X Transceiver Chips

Receiving wireless sensors operating in the unlicensed ISM band has been made almost universal with rtl_433 and RTL-SDRs. However, recently rtl_433 has been ported over for use on ESP32 microcontrollers that are combined with CC1101 or SC127X transceiver chips.

PCB boards that combine these two chips can be found cheaply on Aliexpress as LoRa boards, under the name "LILYGO LoRa 32". If you are unaware, ESP32 chips cheaply combine a WiFi and Bluetooth modem with a microcontroller that is capable of hosting a webserver. CC1101 and SC127X are low cost low power hardware transceiver chips made for IOT devices. We've posted about LILYGO boards in the past as they've been used with interesting projects such as Meshtastic, and for weather balloon tracking.

This project could be useful for home automation as a module has been made available for openMQTTGateway. Instead of dedicating a more powerful Raspberry Pi and RTL-SDR, you can now dedicate a much cheaper and much lower power device to the task. 

[Also seen on Hackaday.]

RTL_433 running on a LILYGO LoRa V2 Board
RTL_433 running on a LILYGO LoRa V2 Board

YouTube Satellite Decoding Series

Over on YouTube @dereksgc has been putting together a comprehensive video series on weather, amateur and other satellite reception. His series starts with receiving images from NOAA APT satellites, then Meteor M2, as then goes on to talk about low cost V-Dipole satellite antennas, how satellite dishes work, and recently how to use Ku-band LNBs with a satellite dish.

If you're getting started with RTL-SDR and satellite reception, this video series may be a good introduction for you.

SIGpi: A Signal Intelligence Focused Linux “Go-Kit”

Thank you to Joe NE2Z for sharing his Linux distribution called SIGpi. SIGpi is an installable Linux distribution for Ubuntu and Raspberry Pi 3/4 that focuses on providing multiple open source SDR programs that can be used for signal intelligence. Support for RTL-SDR and other SDRs is included.

The distro is actually created via a bash script that installs all the programs automatically on a fresh OS install. It also provides a system for easily upgrading software as developers work on them.

For a full list of the software that comes with SIGpi check out their Wiki.

SIGpi is a "go-kit" for Signal Intelligence (SIGINT) enthusiasts with emphasis on capabilities in the VHF, UHF, and SHF spectrum. For completeness, HF spectrum related software is included for optional install. This (bash) shell script builds SIGINT tools on the following platforms:

  • Raspberry Pi4 4GB RAM or Raspberry Pi 400 with 32GB microSD card running Raspberry Pi OS Full (64-bit)
  • Ubuntu 22.04 LTS on arm64 and amd64

A headless server only install (Node Install) can be performed on Raspberry Pi3 B+ with 32GB microSD card running Raspberry Pi OS Full (64-bit)

A possible hardware setup with SIGpi
A possible hardware setup with SIGpi