A few days ago we posted about RpiTx, a piece of software that allows you to turn your Raspberry Pi into a multi purpose transmitter by modulating the output on one of the GPIO pins.
Now over on YouTube user HA7ILM has uploaded a video showing his related software qtcsdr. Qtcsdr runs on the Raspberry Pi and interfaces with an RTL-SDR dongle and RpiTx to create a simple transceiver radio. In the video HA7ILM shows the software in action by using a microphone and RTL-SDR plugged into the Raspberry Pi, and showing the microphone transmitting via RpiTx and being received via the RTL-SDR.
As always with this type of thing only transmit if you are licensed and take care with the transmitted distance and filter the antenna output when transmitting over a distance that is further than your room. Also regarding this, on the qtcsdr GitHub page the author mentions that a Raspberry Pi shield called the QRPi filter + amplifier is currently in development (white paper).
QTCSDR Control GUI
Testing qtcsdr: receiving the transmission with an RTL-SDR via attenuator
Previously we posted about the Raspberry Pi’s ability to modulate one of its pins to produce FM transmissions with PiFM. A developer (F5OEO) has recently expanded on this idea, and now the Raspberry Pi is capable of modulating and transmitting FM, AM, SSB, SSTV and FSQ signals anywhere between 130 kHz to 750 MHz.
To transmit with the Raspberry Pi all you need to do is plug in a wire antenna to Pin 12 (GPIO 18) on the GPIO port and run the PiTx software by piping in an audio file or image for SSTV.
Important Disclaimer: While the output power is very small, you should still take great care as the carrier is a square wave, and there is no filtering on the antenna output. So any transmissions will cause harmonics all across the spectrum – possibly interfering with life critical devices. A filter *must* be used if you actually plan on transmitting with any sort of range further than your room. The predecessor PiFM has been reported to have a range of 10cm without an antenna, so it may be best to not connect an antenna to the pin if just testing. With a simple wire antenna the range is increased to 100m which could affect your neighbours. There are also strict laws and licences governing transmitting in most countries so make sure you follow them carefully. In short, get your ham licence and understand what you are doing before transmitting with any sort of amplification/range.
PiTX transmitting SSTV and received in HDSDR. From PiTX’s author’s Twitter @F5OEOEvariste
Over on YouTube the author of PiTx has also uploaded a video showing a wireless doorbell being replayed with PiTx. On the video description he writes:
PiTx is a software which permit to transmit HF directly through a pin of Raspberry Pi GPIO. Unlike PiFM which transmit only in FM, PiTx is able to perform multi modulation (FM,AM,SSB,SSTV,FSQ) : it has an I/Q input to be agnostic. The demonstration here is done in several steps : – Record an I/Q file from a doorbell transmitter on 434MHZ (first part) – Playing it with the Raspberry Pi using Pitx on HF on same frequency – Listen to the doorbell receiver which recognize the signal
Conclusion : Pitx is now a real TRANSMIT SDR at very low cost. Be aware that it generate lot of harmonics and never compete with USRP or HackRF. Goal is to popularize the transmission as rtlsdr popularize the reception.
Recently RTL-SDR.com reader Slaven Krilic wrote in to use to announce his project called MNM4SDR which stands for Monitoring Network Manager for RTL-SDR. The software allows you to set up a remote Raspberry PI embedded computer with an RTL-SDR dongle attached and access it remotely through a Windows PC GUI.
Unlike other server software such as rtl_tcp, raw IQ data is not sent over the network. Instead audio is first compressed in lossless FLAC or OGG formats. This allows you to use much slower network or internet connections. The software also allows you to collected RF scans over a large bandwidth in a similar way to rtl_power.
The software works over an SSH connection and requires that you have RTL-SDR and VLC set up on your Rasperry Pi first.
The script can easily be run by first editing the script to specify the frequency, dongle number, gain, PPM offset and destination folder. It can then be run by calling is with the start time, date, length and output file name. He also writes that you must be careful to not record for too long as long IQ files can use up a lot of disk space. To overcome this he uses a networked attached storage (NAS) device which is similar to an external hard drive.
Over on the Raspberry Pi Reddit discussion board user spfoamer has posted about his Raspberry Pi + RTL-SDR based outdoor ADS-B receiver. ADS-B stands for Automatic Dependent Surveillance Broadcast and is a signal broadcast by aircraft that contains information about their locations. With a receiver like the RTL-SDR and correct software you can make an aircraft radar.
In his design the Raspberry Pi transmits location data back to a PC via an Ethernet cable. In addition the Raspberry Pi is also cleverly powered via power over Ethernet (POE) which uses unused wires in the Ethernet cable itself to carry the power. Since he uses a 12V power source, to obtain the needed 5V to power the Raspberry Pi spfoamer uses a UBEC (Universal Battery Elimination Circuit) which is an efficient device that converts voltages from up to 23V down to 5V. Additionally, he uses a 1/4 wave ground plane antenna and a 1090 MHz bandpass filter to eliminate out of band interference.
On the Pi itself he runs PiAware and contributes his data to the FlightAware network.
ADS-B with a Raspberry Pi, RTL-SDR, Bandpass Filter all powered via Ethernet cable.Close up of the inside of the box.
A new image for the Raspberry Pi containing RTL-SDR software has been made available by tech enthusiast Gareth Hayes. The image contains all the software and drivers needed to get started with the RTL-SDR or HackRF on a 512MB Raspberry Pi. It is very useful as compilation of large software like GNU Radio is slow and problematic on an embedded PC like the Raspberry Pi. The image contains the following software:
GNU Radio V3.7.5 built from source, including GNU Radio Companion
Adafruit has released a tutorial showing how to build a portable TFT screen based Raspberry Pi RTL-SDR spectrum analyzer that was inspired by the HackRF portapack. Construction of the project is very simple and the “FreqShow” python software is provided as a simple download that is ready to run once the RTL-SDR is installed on the Raspberry Pi.
The FreqShow software appears to be fully featured with the ability to change the center frequency, sample rate, and gain. It can show on the TFT screen the real time RF spectrum of the currently tuned area or it can be switched to show a waterfall of the spectrum as well. Below is a video of the finished project that shows the software in action.
“Freq Show” Software in action on a Raspberry Pi with TFT Screen
FlightAware is an online service providing real time flight tracking. The flights are primarily tracked by volunteers who run ADS-B decoding hardware which is networked through the internet to the FlightAware servers.
Now FlightAware have written in to RTL-SDR.com to let us know about their new PiAware software which enables a Raspberry Pi running dump1090 to contribute data to the FlightAware network. Dump1090 is a popular RTL-SDR compatible ADS-B decoder program for Linux systems.
A major perk for running their software and contributing data is that FlightAware will buy you a licensed copy of PlanePlotter.
The press release provided is quoted below.
If you are running an inexpensive Raspberry Pi ADS-B receiver with dump1090 then you can install the PiAware Package from FlightAware to freely view nearby flight traffic and transmit this data to FlightAware’s tracking network. Most aircraft within Europe by 2017 and USA by 2020 will be required to have ADS-B transmitters onboard.
FlightAware’s user-hosted worldwide ADS-B receiver network tracks about 90,000 unique aircraft per day and feeds this live data into the FlightAware website in combination with other public/private flight tracking data sources. FlightAware has over 500 user-hosted ADS-B sites online across 60 countries, with top contributors tracking over 10,000 aircraft per day. To see how ADS-B data is put to use, check out the FlightAware Live Map.
The PiAware installation process takes only a few minutes. If you don’t have PlanePlotter, you can download it and then send FlightAware your installation’s serial number and we’ll buy you a license. FlightAware will also give users a free Enterprise Account ($90/month value) in return for installing PiAware.
