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--- projekte:sdr_rx [2025/03/13 10:49] – Gian Piero de Medici
+++ projekte:sdr_rx [2025/03/13 11:12] (aktuell) – [Some additional Resources:] Gian Piero de Medici
@@ Zeile 1: / Zeile 1: @@
-====== SDR Web-based Shared Access Receiver (RX) ======
-===== You may already have noticed that... =====
-...we have SDR receiving (RX) capability set up.
-  * For educational purposes: for example when holding courses or open-door days and projects.
-  * For test purposes: for example to test our RF transmissions (TX).
-The SDR receiving end of our shack is composed of 1 receiver.
-Our "Kiwi", for High Frequencies i.e. Short Wave, a KiWi SDR v.1.
-Work is in progress to add VHF:
-Our "Berry SiDeR", for VHF, with a single RTL-SDR attached to a Raspberry Pi (4 Model B) running OpenWebRX, is under construction.
-Frequency ranges
-  * KiwiSDR: 10 kHz to 30 MHz (VLF-HF spectrum) - with optimal range limited to between 1.6 MHz and 56 MHz due to the Diplexer (see below).
-  *
-  * RTL-SDR: 24 MHz - 1766 MHz (HF-VHF-UHF spectrum) - with optimal range between 76 MHz 470 MHz due to the Diplexer (see below).
-Both connected to the same antenna through a diplexer (which on it's way per mail).
-The concept is "Web-based Shared access":
-  * "Web-based": users do not need to install anything on their PC, all that's required is an HTML5 capable browser.
-  *
-  * "Shared access": Multiple users can use the same receiver at the same time, and can listen to different frequencies and modes.
-The number of concurrent users are restricted on OpenWebRX, typically to five or six for a single 2 MHz RTL-SDR.
-OpenWebRX is a python based software that allows to run a web server to which multiple users can connect to the RTL-SDR and listen to it through a web interface.
-Short Waves (HF) and Medium Waves (AM) can already be listened to by accessing:
-https://sdr.chaospott.de/
-http://kiwisdr.local:8073/
-Wavelengths of ten meters to one meter (VHF) can be listened to by accessing:
-(Under construction - http://openwebrx)
-===== About the Antenna =====
-Since 2024 a "Mini Whip Active Antenna".
-Planned to be replaced with an Eggbeater antenna in 2025, which has a lower noise floor compared to the Mini Whip, it is located on the side of the building, it's best exposition is along the North South axis.
-The Eggbeater Satellite Antenna has a Ground Plane and is resonant on 70 cm.
-We have tested it and has proven itself to be a great omnidirectional base station antenna receiving antenna for all Amateur Radio, Broadcast bands and many services.
-The ground plane elements under the Eggbeater increases the overall upward gain of the antenna, useful for hearing Satellites and the International Space Station.
-===== About the Diplexer =====
-DIAMOND MX-62M Diplexer for the ranges between 1.6 MHz and 56 MHz, and between 76MHz and 470 MHz.
-Allows to connect one antenna to two receivers.
-The diplexer limits the optimal ranges of the SDRs to an overall smaller bandwidth,
-this limitation can be overcome by bypassing the diplexer for the required time, at the cost of using one SDR at a time.
-===== About the KiWi SDR SW HF Receiver =====
-It comes with a GPS Antenna for precise timing.
-The KiwiSDR is a software-defined radio that attaches to a Seeed BeagleBone Green (BBG) embedded computer.
-It is a standalone device that allows access through LAN and optionally through the Internet.
-===== About the OpenWebRX SW running on Raspberry Pi =====
-OpenWebRX is a multi-user SDR receiver that can be operated from any web browser without the need for any additional client software.
-Requires a computer, an SDR device and network access.
-OpenWebRX is designed for public shared access.
-OpenWebRX
-https://www.openwebrx.de/
-Images from
-https://www.openwebrx.de/download/rpi.php
-===== Some additional Resources: =====
-OpenWebRX: A Multi-User RTL-SDR Receiver with Web Interface
-https://www.rtl-sdr.com/openwebrx-an-multi-user-rtl-sdr-receiver-with-web-interface/
-https://www.openwebrx.de/about.php
-A list of currently active WebSDR servers is on
-http://www.websdr.org/
-===== Future developments =====
-A project for future development could be to design and make a home brew Diplexer with wider bandwidths.

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