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Remote SDR v5

Web based Transceiver

“Remote SDR” or “SDR Distant” 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 Firefox web browser
  • 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
Remote SDR – Adalm-Pluto – Raspberry 4
AvantagesDisadvantages
– 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
Remote SDR – 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
RTL-SDR – HackRF One – 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
Remote SDR – HackRF One and 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
Remote SDR – 2 HackRF One – Raspberry Pi 4B
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
VHF or UHF NBFM Transceiver
VHF and UHF NBFM Transceiver
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

F1ATB QO-100 Transceiver since May 2020

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.

Experimental 432 MHz (70 cm) transceiver

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 .

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

Raspberry 4
Orange Pi zero 2

Here is the detailed procedure to install Remote SDR in version 5, on a Raspberry Pi 4B with at least 2 GB of memory or an Orange Pi Zero 2. The latest images written for an SD card of 16 GB or more are available on Github.

Installing the image

  • Upload the image corresponding to your card on Github
    https://github.com/F1ATB/Remote-SDR/releases
  • Unzip the image
  • Burn the image to a minimum 16GB micro SD card with PC software like Win32diskmanager
  • Connect an SDR Pluto or HackRF One and RTL-SDR or SDR Play
  • Connect the Raspberry/Orange to the local ethernet network
  • Power on the Raspberry/Orange
  • Go to your box to find the IP address that has been assigned to the Raspberry/Orange Pi
  • All Remote SDR source codes are in /remsdr folder

Hardware Configuration

Only one Raspberry PI 4 is necessary with an Adalm-Pluto or a HackRF in transmission and an RTL-SDR in reception.

Rpi4 – Pluto
Rpi4 – HackRF – RTL-SDR
Deux Orange Pi Zero 2

Since version 2.5 of Remote SDR, it is possible to connect 2 HackRF One to a single Raspberry.

Configuration de F1ATB adaptée à QO-100 avec 2 HackRF One

Other SDRs such as RSP1 or RSP1A are also treated.

RSP1A

Launching Remote SDR

You launch the application on the address of the receiver. You need a recent browser like Chrome, Edge or Firefox.

http://<ip of the Rasperry Pi>

Note that all exchanges (video, audio) from version 5, are done in https on the usual port 443.

In parallel, it is possible to interface with Gpredict via port 8006 for the receiver and 8007 for the transmitter.
It is also possible to connect via VSPE with standard Omnirig interfaces.

Access is via the secure https protocol in order to be able to access the microphone and some signal processing functions of the browser. When you first connect, you will get a security alert message because of a self-signed security certificate and not certified by an accredited organization..

Ne vous inquiétez pas et cliquez sur paramètres avancés.

Alert message that will be adapted to your IP address

Main Pages

Welcome Page
Transceiver
Settings page

The Settings page allows you to define the parameters of your transceiver. You must enter an access key (1234 by default) to be able to modify them. It is important to define the model of the connected SDR.

Similarly, you must enter the access key to be able to transmit.

PILOT

It is possible to share the receiver between several users. But only one person can drive the audio channel fader. It is entitled to green light on “SDR RX Pilot”. The other people connected are red.

The system owner can force his pilot position. To define yourself as the owner, you must enter in the “Settings” page an access key identical to that of the AccessKey.txt file in the /remsdr folder. By default “1234”, but it is recommended to customize it.

SDR Rapid Test

You can do a quick test to verify that the connected SDR(s) are visible to the Raspberry/Orange Pi. Go to the Tools page and click on “List USB devices”.

Tools page

Reset Old Configurations

Tools page

It is not impossible that an old configuration disturbs the first start of Remote SDR V5. In this case, perform a “Reset” of the settings saved locally in your browser.

System Setup Customization

You can, but do not have to, customize the installation of the system on your Raspberry/Orange Pi. The image on Github is configured in English language, US keyboard and GMT time. Access the Raspberry (user pi, password: remsdr) or the Orange Pi (user root, password: remsdr) by ssh and type:

raspi-config ou armbian-config

In the ‘Location’ section you can enter your preferences.

You can also access the Raspberry/Orange Pi in graphical mode using the VNC chrome extension or a dedicated application.
user: root for the Orange Pi and port 5901
password: remsdr

All source files are in the /remsdr folder.

Cooling

If you use your Remote SDR application intensely, consider putting a heatsink on the CPU. The charging rate is significant: around 60%.

Do not view Remote SDR on a monitor connected to the Raspberry/Orange and running in the web browser. If this is possible, the computational load will be too great and this will result in audio dropouts and CPU overheating.

Security

I recommend that you install a safety device on the power supply of the amplifiers as described here.