Category: Mobile

QuestaSDR: New RTL-SDR Software for Android

Last year we posted about QuestaSDR, which is a simple SDR multi-mode GUI that is compatible with the RTL-SDR. Since then QuestaSDR has evolved, and is now available on Android devices as well. It looks to be a nice alternative to RF Analyzer and SDR Touch which are the most popular RTL-SDR Android apps. The description of Android QuestaSDR reads:

QuestaSDR - powerful and flexible, cross-platform Software Defined Radio Application (SDR). Built-in scheduler architecture provides integrate plugins, plugins kits and multi - UI. Typical applications are DXing, Ham Radio, Radio Astronomy and Spectrum analysis.

Support Hardware:
- RTLSDR Dongle

Main features:
- Dark, Ligth, Universal, Material application style
- Many spectrum settings (FFT size, waterfall FPS and color theme)
- AM/SSB/NFM/WFM demodulator
- RDS decoder
- Record AF file
- Frequency bookmarks
- Web remote
- Supported IF-adapter, upconverter, downconverter hardware
- Rig samplerate, frequency, level and iq disbalance calibrate

To start using QuestaSDR, you will need:
- RTL-SDR dongle
- USB OTG Cable - used to connect a RTLSDR to your Android device.

Connect the USB dongle to the USB-OTG, then insert the free end of the cable into the USB port of your Android device and launch the QuestaSDR! Now you can listen to live frequency range shortwave, VHF, UHF.

Feedback and bug reports are always welcome.

Please note that I am not responsible for any legal issues caused by the use of this application. Be responsible and familiarize yourself with local laws before using.

QuestaSDR - New RTL-SDR Compatible Android App
QuestaSDR - New RTL-SDR Compatible Android App

New Apple iOS (iPhone/iPad) RTL-SDR rtl_tcp Client App in Beta Testing

Over on our forums poster hotpaw2 has released news about his new RTL-SDR app for iOS (iPhones/iPads). If we're not mistaken, this will be the first app that enables RTL-SDR usage on iOS. However, as iOS devices don't allow RTL-SDRs (or any arbitrary USB device) to connect directly to devices, you still need to use a Raspberry Pi or other network connected computing device as an rtl_tcp server. So the RTL-SDR does not plug directly into the iOS device. Currently he is looking for beta testers to help test a pre-release of the software. Hotpaw2 writes:

Hi. A first version of my iOS SDR app is nearing completion. So I'm interested finding a few users who would like to beta test a pre-release of the app, and provide some feedback. The beta test requirements are having a 64-bit iOS device (iPhone or iPad) running iOS 11.2.x or newer, having Apple's TestFlight app installed, having a Mac, PC, Raspberry Pi (or other Linux box) that already has rtl_tcp installed and ready to run. (And an RTL-SDR obviously.) The rtl_tcp server must be on a fast WiFi network reachable by your iOS device. Note that iOS TestFlight app distributions do have an expiration date.

iOS does not recognize arbitrary USB devices such as an RTL-SDR. This is even true when using Apple's Lightning Camera Connection kit to provide an iPhone with a wired USB port. So an adapter must be used. I use a headless Raspberry Pi 3 running rtl_tcp as the USB adapter to provide raw IQ samples from the RTL-SDR to the iOS app. A Raspberry Pi Zero W would also work. I then connect to the server either over WiFi, or via wired ethernet. 

This iOS SDR app is fairly simple. I've been experimenting with developing low-level DSP code in Swift. So this SDR app was written from scratch in the Swift programming language. Because the app is targeted for the iOS App store, it uses none of the existing SDR C++ code base. 

The app currently demodulates AM, N-FM, and mono W-FM. It also displays a spectrum and rudimentary waterfall, and allows one to swipe-to-tune. There are not a lot of controls, as screen real-estate on an iPhone is quite limited. But I can walk around the house and, from my iPhone, monitor if my RTL-SDR or AirSpy HF+ are picking up any interesting signals.

Contact info for beta testing can be found here: http://www.hotpaw.com/rhn/hotpaw/ 

Source code to librtlsdr and rtl_tcp can be found in many repositories on github, but zero support for finding or installing such, and/or setting up your Raspberry Pi, will be provided by me.

Screenshot of the RTL-SDR iOS app
Screenshot of the RTL-SDR iOS app

 

A Portable SDR Transceiver with LimeSDR Mini, Android Phone and QRadioLink

QRadioLink is a Linux and Android compatible radio app that can run on smartphones. It can be used to receive and transmit digital radio signals with a compatible SDR such as an RTL-SDR (RX only), or a LimeSDR Mini (TX and RX). The following video by Adrian M shows QRadioLink running on an Android phone with a LimeSDR Mini connected to it. An external battery pack is also connected to maintain power levels over a longer time.

In the video Adrian shows how this combination can be used as a fully portable radio transceiver. The video first shows him receiving broadcast FM, digital amateur radio voice (Codec2 & Opus is supported), narrowband FM and SSB signals. Later in the video he transmits a digital voice signal using the microphone on his Android phone. He notes that an external amplifier would still be needed if you wanted more transmission power.

 

Building your Own Cell Phone Network with a Raspberry Pi and BladeRF

As part of their senior project Matthew May & Brendan Harlow of Champlain College worked on a project that involved creating their own software defined radio based portable cell phone network. If you're interested their setup is nicely documented on their project page. Basically it consists of a bladeRF software defined radio and Raspberry Pi running the YateBTS base station software. This is nothing new in terms of work done before, but the clear documentation makes it a good starting point for anyone looking at building their own SDR based cell basestation. 

A custom cell basestation may be useful for those in remote areas without commercial cell phone reception, during disasters or even just to create a type of secondary network in your home.

[Also seen on Hackaday and Motherboard]

A cell phone connected to their custom network
A cell phone connected to their custom network

Aerial TV: Android RTL-SDR DVB-T Decoder Officially Released

Last month we posted about Aerial TV, a new Android based DVB-T decoder that works with RTL-SDR dongles. Back then the app was still in beta testing and had a few operational bugs. Now the Aerial TV app has been officially released.

UPDATE: Due to Google policies Aerial TV has been removed from the Google Play Store. It is claimed that Aerial TV could be used for copyright violation. It is now available on the Amazon store. Official information will always be available on the new official website at aerialtv.eu

The app is based on the new Android DVB-T driver for RTL2832U devices which is written by Martin Marinov who is also the programmer of Aerial TV. The DVB-T driver is open source, and currently supports RTL2832U devices with the R820T, E4000, R828D, FC0012 and FC0013 tuner chips. Of note is that the R828D also has DVB-T2 support.

Aerial TV is free to download and test, but requires a $7.99 licence to use for more than 30 minutes. To use it you will need an OTG (On-the-go) cable adapter and an RTL-SDR dongle with antenna.

Just watch TV – no data plan or wifi connection required. Aerial TV works by picking up digital TV channels off the air with a regular TV antenna.

You will need a low cost USB TV tuner. You can grab one online for less than €10. Make sure to get an RTL2832 tuner. When it arrives, just connect the provided antenna and start watching. You may need a USB OTG cable to plug the tuner in your Android device. USB OTG cables are inexpensive and easy to find.

Note that your Android device must support USB OTG. If unsure, do a quick search online or consult your Android device manual. Also check that there is DVB-T/DVB-T2 service in your local area by doing a quick search online. Signal needs to be strong enough for Aerial TV to pick it up. For best results use an outdoor aerial.

You get free unlimited access to radio forever. You also get to watch all TV channels and experience all features of Aerial TV during the trial period for free. After the trial period ends you can make a one-off purchase and watch as much TV as you want. Remember: you can keep listening to radio even if the trial has ended!

Q: How do I find a supported dongle?
A: All major RTL2832 (rtl-sdr) dongles are supported. These dongles can be easily purchased online. Just type in “RTL2832” or “RTL2832U” in the search box of your favourite online store.

Q: What tuner do I need to watch DVB-T2?
A: If your country has DVB-T2 broadcasts (such as Freeview HD in UK) you will need a DVB-T2 compatible receiver dongle such as R828D in order to watch DVB-T2 with Aerial TV.

Aerial TV Screenshot
Aerial TV Screenshot

Aerial TV: An Android DVB-T Decoder for the RTL-SDR

On the Google Play store a new RTL-SDR compatible app called ‘Aerial TV’ has been released (in beta) by Martin Marinov. Aerial TV allows you to watch DVB-T HD TV on your android device, with an RTL-SDR connected to it via USB OTG cable. Martin is also the author of the popular SDR Touch Android program and the RTL2832U Android driver port. 

The new software requires a different DVB-T driver app to be installed first, which is also provided by Martin. This is because the RTL-SDR needs to be operated in a mode different to the way that the SDR drivers use it in. Martin has also open sourced his Android DVB-T driver and it is available on GitHub.

Aerial TV is currently free on the Google Play store, but looks like it may eventually have some in-app purchases. Also, it is currently marked as ‘Unreleased’ on Google Play, which is essentially a beta version, so you might expect there to be some bugs.

Aerial TV Screenshot
Aerial TV Screenshot

Over on YouTube user GiamMa-based researchers SDR R&D IoT has uploaded a video showing Aerial TV scanning for TV channels, and then eventually playing some video.

Building an RTL-SDR “Moto Mod”

One nice feature of modern Motorola smartphones is that some models can accept ‘mods’, which are essentially phone cases that snap onto the back of the phone and interface via some exposed data pins. Some examples include a snap on speaker, projector, battery pack and zoom lens. Currently Moto Mods and Indiegogo are running a promotional campaign that gives developers a chance to pitch new Moto Mod ideas to Motorola, and if successful be partnered with Motorola and receive funding to complete and sell the hardware.

Vaclav Bouse is one developer who has been working on an RTL-SDR based Moto Mod. The idea is to integrate RTL-SDR hardware into the Moto Mod phone case form factor and possibly even add transceiver capabilities via an AX5043 transceiver chip. The hardware is still in the very early concept and design phases, and Vaclav is seeking donations on Indiegogo to help fund the development of a prototype (note that donating will not get you the final product). As it will be an RTL-SDR, it should be compatible with all Android RTL-SDR software, such as SDR Touch.

The hardware is also related to his other Moto Mod campaign idea which is a universal remote control.

The Moto Mod RTL-SDR Concept
The Moto Mod RTL-SDR Concept

Camp++ YouTube Talk: GSM Signal Sniffing for Everyone with GR-GSM and Multi-RTL

Over on YouTube the channel Budapest Hackerspace has recently uploaded a talk by Piotr Krysik which was given during the August 2016 Camp++ 0x7e0 information security conference. The talk is titled: “GSM signal sniffing for everyone with gr-gsm and Multi-RTL by Piotr Krysik” and talks about using the gr-gsm software and RTL-SDR dongles to sniff the GSM mobile phone network. Also, a tool developed by Piotr called multi-rtl which allows the proper synchronization of multiple RTL-SDR dongles in order to cover the large gap between the GSM uplink and downlink frequencies is discussed.

The talk explains a bit about how GSM works, and then goes on to talk about the gr-gsm and multi-rtl software. The talk blurb reads:

Gr-gsm is a set of tools for receiving GSM transmissions, which works with any software radio hardware capable of receiving GSM signal. Together with widely available RTL2832 based TV dongles, that are popularly used as low cost software radio receivers (known as RTL-SDR), it enables everyone to receive and study protocols used in GSM’s mobile radio interface.

Ability to receive signals spread over wide frequency range exceeding single RTL-SDR receiver’s bandwidth (~2.4MHz) was available exclusively for the owners of more capable and more expensive SDR devices. With introduction of Multi-RTL project by the author of the talk, this limit was overcome through synchronization of multiple RTL-SDR receivers in time domain, that doesn’t require complicated hardware modifications. With Muli-RTL it is possible to receive for example uplink and downlink of GSM900 transmissions, that are separated by 45MHz.

Speaker will present origins of both of the projects, together with description of their inner workings, examples of applications and plans for the future.

The talk slides can be downloaded here.