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Introducing rx-tx.info
Go to Map of SDR Receivers…https://rx-tx.info/map-sdr-points is a free, online, searchable map of live and available Web SDR Receivers from across the world.
Online Map of WebSDR Receivers. NB: this is just an image; for the interactive map, visit: https://rx-tx.info/map-sdr-points
Go to Map of SDR Receivers…Unlike the standard “go-to” website WebSDR.org, rx-tx.info displays each known and alive WebSDR on a global map, allowing you to find a websdr by its location, by the frequencies/bands the websdr supports, and by the SDR type.
This is useful when you’re seeking a WebSDR that is in a very specific area for for a specific purpose.
For example: POTA (Parks on the Air). You might be hunting POTA activators and may want to find a websdr that might hear a transmission by it being located in a particular area of the world (hint: because of how RF transmissions propagate, a websdr in the same county/state as the POTA Activator may not receive the transmission).
Reducing QTH/RX White Noise with SDR
| ☠️ | Update: since publishing this post, the Whiteley WebSDR Receiver (http://garths.zapto.org:8074/) has gone off-line. |
Our weekly open club net uses the repeater GB3CW. Sometimes, our home location (QTH) may be generating significant white noise, making listening to others’ transmissions on the net difficult. Yet, even with such QRM ongoing during the net, our colleagues tell us that our transmissions are strong and audible.
We can use a WebSDR in a kind of “split” situation. Picking one that’s close to the repeater, we can eliminate the RX noise by:
- listening to the net using a WebSDR local to the net, and
- transmitting to the net using our transceiver.
We might have to mute the WebSDR when we transmit (to avoid hearing our own voice being echoed back a fraction of a second after transmission), which is simple enough using the WebSDR’s controls.
Tip: For the 2m Open Club Net, the WebSDR located near Whiteley/Wickham has an ideal 2m receiver.
Other Uses
- Testing the audio quality, or the reach of our transmissions. For example, using a WebSDR that’s located close to us to listen to our VHF/2m transmissions or using one that’s located much farther away from us (eg using Hack Green from a Portsmouth QTH) to listen to our HF transmissions. We can record our transmissions to learn how others may be hearing us.
- Monitoring Amateur Radio Bands. Amateur radio operators frequently use WebSDRs to track activity around the world on various bands, including the HF, VHF, and UHF bands. For example, you can tune into the 2m band (145 MHz) and listen for local or international transmissions, even if your own radio equipment lacks the reach or sensitivity. This allows operators to verify propagation conditions or simply listen in on conversations across different regions.
- Signal Propagation Research. By observing how signals behave on different frequencies and at various times of the day, WebSDRs are invaluable for studying signal propagation. Researchers and amateur operators alike can track how ionospheric conditions impact long-range communications, particularly on HF bands, making WebSDRs a helpful tool for learning about radio wave behaviour without needing expensive equipment.
- Receiving Utility and Commercial Signals. WebSDRs allow users to receive various non-amateur signals such as aviation, maritime, and emergency services transmissions, depending on the band and frequency. This enables enthusiasts to listen to weather stations, air traffic control communications, or shipping routes from remote locations, providing insight into real-time operations that are typically difficult to access.
- Remote Antenna Testing. WebSDRs offer an easy way for radio enthusiasts to test and verify the performance of their antennas by listening to their own transmitted signals on different SDRs around the world. This helps in determining how well the antenna is working in real-world conditions and fine-tuning its orientation and tuning to optimize transmission range.
- Learning and Experimentation. For newcomers to radio, WebSDRs offer a hands-on way to explore the radio spectrum and understand how different frequencies are used for various communication types. From listening to broadcast stations to scanning for weak signals on ham radio bands, it provides an accessible platform to experiment with radio listening without needing a dedicated receiver or license.
Each of these uses makes WebSDRs a flexible and valuable tool for both hobbyists and professionals interested in exploring the radio spectrum.
Other WebSDR Resources
Here are five useful websites for accessing WebSDRs and related resources:
- WebSDR.org – this is the primary directory for WebSDR servers worldwide. The site lists SDRs that allow users to tune into various frequencies, with a wide range of amateur radio, HF, VHF, and UHF bands available. It’s a go-to hub for finding operational WebSDRs located in different countries.
- SDR.hu – another extensive directory of public SDR receivers, SDR.hu allows users to access KiwiSDR and other software-defined radios. It offers an easy-to-navigate interface, filters for different receiver types, and provides a map to locate SDRs near you.
- KiwiSDR Network – KiwiSDR Network focuses specifically on KiwiSDR devices. It features a global list of KiwiSDR receivers, which are popular for their high-frequency (HF) capabilities. The site is useful for exploring long-distance, lower-band frequencies like shortwave, maritime, and aviation bands.
- OpenWebRX – OpenWebRX is an open-source platform that hosts a directory of SDR servers running the OpenWebRX software. It provides access to receivers across different regions and allows users to listen to a variety of bands and modes. It’s ideal for those interested in a community-based SDR project.
- SdrSpace – SDRSpace offers a collection of WebSDR and KiwiSDR receivers, along with articles and resources for setting up your own SDR. This site provides an organized list of available radios and also supports real-time browsing of HF/VHF/UHF bands.
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