Tagged: remote

Cloud-SDR: A Tool for Remotely Accessing SDR’s like the RTL-SDR and Airspy

Cloud-SDR is a new tool currently in beta testing which enables remote streaming access of SDR receivers, such as the RTL-SDR and Airspy. In a way it is similar to rtl_tcp in that it allows IQ samples to be streamed over the network, however Cloud-SDR appears to be a much more developed solution that can support more SDR’s and has many more features, as well as better performance. Cloud-SDR is not free, and during these beta stages of release the pricing does not appear to be public. However they have licences for personal/hobbyist use, which we assume will be reasonably priced. 

In this interesting post they describe various solutions for remote SDR access, and show why their Cloud-SDR solution is useful.

They describe their software in the following blurb:

Cloud-SDR can collect real-time IQ complex samples from an SDR hardware device connected on one machine, stream the samples to a second machine for demodulation or analysis, then send the resulting stream to third machine for storage.

In standalone mode, Cloud-SDR can execute signal processing tasks described with embedded JavaScript DSP engine.

Because network bandwidth is limited compared to SDR receiving bandwidth, the core concept of Cloud-SDR is to move the processing along the cloud to where it is required or possible : the DSP chain is divided in sub-tasks that are spread between computers interconnected through Internet.

For example a “signal scanner” application can be programmed with a script and stored on the SDR server for execution. Only found signals will threshold stream transmission through the TCP/IP network. Remote Client will only receive the IQ stream if a signal is detected by the DSP task. In “cloud mode”, the same script can be broadcasted to several SDR nodes located at different places, enabling parrallel signal search.

Server software SDRNode receives IQ streams from the different SDR hardwares, extracts the different bands, processes them and transmits the RF data using compression algorithms to limit TCP/IP network bandwidth.


Currently the hardware supported includes:

  • RTL SDR dongles
  • Perseus SDR
  • BladeRF x40 or x120
  • HackRF
  • AirSpy
  • SDRPlay (under work)
  • USRP UHD (Pro version only)
  • LimeSDR (Pro version only)

On their site they have some tutorials uploaded already. One tutorial shows how to remotely listen to airport radio with a remote Airspy, and one shows how to set up a dual-RTLSDR remote access system. This allows two RTL-SDR’s to be used together, with one streaming directly from the antenna, and the second streaming via an upconverter.

Sharing Two RTL-SDR's with CloudSDR.
Sharing Two RTL-SDR’s with CloudSDR.

There are also several examples of the Cloud-SDR in action over on the authors YouTube channel.

Creating a wireless RTL-SDR server with a small OpenWRT WiFi Router

Over on his blog yo2ldk has been experimenting with creating a wireless RTL-SDR server by using a mini OpenWRT based WiFi router (page in Romanian, use Google Translate for English). The router he uses is the GL iNet 802.11n 150Mbps router, which is a mini WiFi router that only costs $27 USD and is about the same size as an RTL-SDR dongle. It is mainly intended for use with IoT devices, but it runs the Linux based OpenWRT firmware and has enough processing power and WiFi bandwidth to run an rtl_tcp server streaming at 2MSPS with no lag.

With an RTL-SDR connected and the router running rtl_tcp, the router can be placed anywhere there is power (yo2ldk uses a portable battery pack) to create a remote radio receiver with absolutely no coax cable losses. It’s WiFi range could be extended over long distances by using a directional Yagi antenna.

Using routers instead of mini computers like the recently released Raspberry Pi 3 may be a good option because they are very small, usually much cheaper, maybe be more power efficient, and may work better at transmitting the large amounts of data rtl_tcp requires.

In the future yo2ldk hopes to install everything into a shielded metal case, add an upconverter and also a solar panel for remote power.

YO2LDK's remote RTL-SDR set up.
YO2LDK’s remote RTL-SDR set up.

We note that if you have an old Android phone, then this could also potentially be used as a remote RTL-SDR server. To create an android RTL-SDR server simply download the Martin Marinov Android RTL2832U Driver from the Google play store. Find the IP address of your Android phone by going to Settings -> About Device -> Status -> IP Address. Then open the RTL2832U driver app and click on “Enable advanced mode (for debug & stream to PC)”. Initially the rtl_tcp string will have the code “-a”, simply change this to the IP address of your Android phone, for example “-a” and then click Start stream. Now on a remote PC connected to the same network open SDR# go to RTL-SDR (TCP) and type in the IP address of the phone and use the port number 14423. Click the play button and you should now be streaming your RTL-SDR data over WiFi.

New Raspberry PI Remote RTL-SDR GUI Software: MNM4SDR

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.

MNM4SDR: Monitoring Network Manager for RTL-SDR
MNM4SDR: Monitoring Network Manager for RTL-SDR

OpenWebRX: A Multi-User RTL-SDR Receiver with Web Interface

From Reddit we’ve learned of a new web based SDR receiver software for the RTL-SDR called OpenWebRX. This python based software allows you to run a web server that allows multiple users to connect to an RTL-SDR and listen to it through a web interface. The web interface also allows the RTL-SDR frequency and mode settings to be controlled. The software appears to still be in beta, so it may have some bugs.

The author has also written his BSc. thesis on this software and it is available for reading here. The thesis describes his software design and implementation as well as some SDR theory and may be useful to anyone wishing to implement similar SDR software.

OpenWebRX Web Interface.
OpenWebRX Web Interface.