Web based Transceiver
“Remote SDR” is a web application allowing to remotely control an amateur radio transceiver between 1 MHz and 6 GHZ. Its first application was the duplex control of a station allowing links to the geostationary satellite QO-100 / Es’Hail 2.
Remote SDR version 5.0 is available on Github.
New features as :
- New SDRs processed:
- SDR Play RSP1, RSP1A,
- MSI.SDR
- Sharing the receiver between multiple users
- https protocol (port 443) grouping all communications
Listen to QO-100 live with Remote SDR
Characteristics
Receiver
- SDR in reception:
- RTL-SDR (example: NESDR SMArt from Nooelec) or,
- HackRF One or,
- Adalm-Pluto
- RSP1, RSP1A
- MSI SDR
- Frequency: 1 MHz to 6 GHz (depending on the chosen SDR)
- Spectral band processed: 2 MHz on 2048 points (depending on the chosen SDR)
- Audio: 1 channel
- Demodulation: NBFM, WBFM, AM, SSB or CW
- RTTY decoder
- Automatic band scan
- Equalizer on the audio channel
- Notch filter
- Noise filter
Transmitter
- Hardware:
- HackRF One or,
- Adalm-Pluto (common with the receiver) or,
- NBFM VHF / UHF SA818 module from G-NiceRF
- Frequency: 1 MHz to 6 GHz (depending on the chosen SDR)
- Power: 1 dBm to 30 dBm (depending on the chosen SDR)
- Audio: 1 channel
- Modulation: NBFM, SSB or CW
- RTTY encoder
- Transmitter modulation compressor
- Audio equalizer
- CTCSS encoder
- DTMF encoder
- 1750 Hz encoder
- Programmable frequency offset for relays
- Automatic CW Manipulator (Iambic A and Iambic B)
Radio processing
- Hardware:
- Orange Pi Zero 2 , or
- Raspberry Pi 4B (2 GB)
- Software:
- Operating System: Armbian / Debian Bullseye
- Web server: Node JS /Express
- Signal processing: GNU Radio 3.9
- Remote SDR (version v3 minimum)
- Html
- Javascript
- Python 3
- Chrome, Edge or Chromium web browser. Don’t use Firefox.
- Network interface: wired Ethernet or WIFI
- Interfacing with Gpredict to compensate the Doppler of low orbit satellites
- Interfacing with GS-232 type rotator
- Display and Audio: WEB page on PC, tablet or smartphone
Configurations
COMPACT CONFIGURATION with an ADALM-PLUTO – Rasperry Pi 4 – ETHERNET

Avantages | Disadvantages |
– Well-known RPI4 – Wifi or Ethernet – 12 bits of Pluto dynamic | – poor stability in frequency of the Adalm-Pluto |
May require the addition of an external oscillator and the extension of the Adalm-Pluto band.
COMPACT CONFIGURATION with an ADALM-PLUTO – Opi Zero 2 – Wifi

Avantages | Disadvantages |
– optimized for cost – Wifi or Ethernet – 12 bits of Pluto dynamic | – poor stability in frequency of the Adalm-Pluto |
May require the addition of an external oscillator and the extension of the Adalm-Pluto band.
Mixed Configuration HackRF – RTL-SDR – Orange Pi Zero 2

In degraded mode, it is possible to extend reception in the 0.5 MHz – 30 MHz band with an RTL-SDR V3.
Avantages | Disadvantages |
– optimized for cost – good frequency stability of the TX if a TCXO mounted on the HackRF One | – different frequency coverage of RX and TX – RX frequency stability depends on the chosen RTL-SDR model – 8 bits of SDR dynamic |
Mixed Configuration HackRF – RTL-SDR – Raspberry Pi 4

In degraded mode, it is possible to extend reception in the 0.5 MHz – 30 MHz band with an RTL-SDR V3.
Avantages | Disadvantages |
– Well-known RPI4 – good frequency stability of the TX if a TCXO mounted on the HackRF One | – different frequency coverage of RX and TX – RX frequency stability depends on the chosen RTL-SDR model – 8 bits of SDR dynamic |
Configuration 2 Hack RF One

Avantages | Disadvantages |
– Well-known RPI4 – good frequency stability of the TX and RX if a TCXO mounted on the HackRF One or shared between them – large frequency coverage | – 8 bits of SDR dynamic |
Configurations RTL-SDR and SA818


Avantages | Disadvantages |
– cost around 100 € – power 1w HF | – VHF 2m and/or UHF 70cm only – only NBFM transmission, no SSB |
Details on the one band transceiver here.
Details on the two bands transceiver here.
These configurations make it possible to locate the HF part near the antennas, which is essential for links above GHz. In the transmission chain, amplifiers must be added to bring the HF signal to the desired level as well as filtering to ensure that unwanted lines are not emitted. The SDR of the reception chain can be either an HackRF One, an RTL-SDR or a Pluto depending on the frequency band you want to cover. Not all RTL-SDR models cover the same band. The transmission reception is carried out in full-duplex which is essential during satellite connection to hear the return of its own signal.
As of today (October 2021), the Raspberry Pi 4B (2 GB) is a good solution, but there are supply difficulties. The “Orange Pi” are processors similar to the Raspberry Pi running under the Armbian or Debian Operating System. In 2020 I used the Orange Pi One Plus, now in 2021 the Orange Pi Zero 2 also offers a 64-bit / 4-core processor, but also an ethernet or wifi connection. They serve as a web server and perform radio signal processing.
Example Transceiver QO-100

Example UHF Transceiver – Wifi – Orange PI Zero 2
New configuration with the Orange Pi Zero 2 which allows communication via WIFI. No more wired Ethernet link, only 220v near the transmitter / receiver.

Note that you need a USB Hub between the Pluto and the Orange PI One Plus (not for the Orange Pi Zero 2). This corresponds to a system bug.
Code Source et Image
The source code and the image for Orange Pi and Raspberry Pi 4B are available on Github https://github.com/F1ATB/Remote-SDR .
Updates
Since version 5.0, it is possible to update, online,Remote SDR to the last version. Go to the “Tools” page and click on :
Look for updates / Recherche des mises à jour
Key points of Remote SDR
In addition to being able to locate the HF treatment near the antennas, other points should be noted such as:
Data rate reduction
An SDR like the Pluto requests 1.4 M samples / s (minimum) * 2 Bytes (16 bits) * 2 channels (I and Q) = 5.6 M Bytes / s for reception. It is the same for the emission. Which gives us more than 10M bytes / second.
With Remote SDR, output on Ethernet or WiFi requires:
- 10 k samples / s * 2 bytes for the audio in reception
- 10.24 k sample / s * 2 bytes for the received spectrum
- 10 k sample / s * 2 bytes for transmit audio
We are at less than 100 k bytes / s by adding the control data.
There is therefore a reduction of approximately 100 in the communication speed required, which facilitates remote control via internet / ethernet without loss of quality through data compression.
The mini remote computer

Indeed, we have a remote computer which has a GPIO to which it is possible to add functions. For example, controlling an antenna rotor, measuring electrical voltages, temperatures, etc., … It is possible to access the system via the web (Apache server), in SSH to launch an application in terminal mode, or in graphical mode by the desktop and VNC.
Posts Remote-SDR
- Remote SDR V5 -Raspberry 4B or Orange Pi Image Installation
- Remote SDR v5 – Manual Installation
- Remote SDR v5
- QO-100 Live
- RTTY
- Troubleshooting
- QO-100 Transceiver
- SSTV
- WSJT-X – FT8
- Omnirig – Remote SDR
- Communication Ports
- Tone generators
- Setting of GPIO outputs
- Band Scanning
- Gains and Dynamics
- Frequencies Management
- Launch of Remote SDR
- CPU Cooling
- Web GUI
- Microphone and signal processing authorization
- Configurations
- Characteristics
- Introduction to Remote SDR
- Remote SDR – Audio Channels
- CW with Remote SDR
- Rotary Knob and Morse Manipulator for Remote SDR
- VHF and UHF NBFM Transceiver
- Remote SDR v4
- Gpredict — Remote SDR
- Remote SDR V4 – Raspberry Pi 4B or Orange Pi Zero 2 image installation
- Remote SDR v4 – Manual Installation
- SA818 – RTL-SDR
- Remote SDR – Examples of realization
- Transmit over QO-100 satellite with a Smartphone
- Remote SDR V2 – Software Architecture
- Remote SDR V1- Purchase
- Remote SDR V1 – Man Machine Interface
- Remote SDR V1 – Signal Processing
- Web Client to GNU Radio
- GNU Radio to Web client
- Remote SSB Transmitter
- Remote SSB Receiver
- GPIO on Orange PI One Plus H6
- TCXO installation on HackRF
- Q0-100 Transceiver with 2 SDR – Remote SDR V1