Short Wave Listening (SWL): WebSDR

"WebSDRs" are Software-Defined Radios (SDRs) connected to the Web
and able to be controlled by a multitude of simultaneous users.

This is generally possible because many SDRs can receive large
amounts of bandwidth or radio spectrum all at once.  So when
user A is tuning to (listening to) such and such frequency
and user B is tuning to some other frequency, neither of these
users have actually caused the SDR to "re-tune" the frequency
it is tuned to.

Obligatory shitty ASCII diagram:

__________________________________________________________________________
|                     *                                                  | 
|                     *                                           *      | S
|                     *                           *               *      | i
|  *                  **           *              *               *      | g
|  *          *       **   *       *       *      *      *        *   *  | n
|  *          *       **   *       **      *      *      *   **   *   *  | a
|  *    **    *      ***   *      ****    ***    **      ** ***   *  *** | l
| ********************************************************************** |
|             A                 Frequency                B               |    A = User A tuned here
| 0 MHz               10 MHz                20 MHz                30 MHz |    B = User B tuned here
--------------------------------------------------------------------------
|        USB          |            USB           |         USB           | Computer
|                     |                          |                       | running
|   SDR with 10 MHz   |      SDR with 10 MHz     |    SDR with 10 MHz    | SDR software
|    of bandwidth     |       of bandwidth       |     of bandwidth      | and hosting
|                     |                          |                       | Web interface
--------------------------------------------------------------------------
|         |                         |                       |            |
|         |                         |                       |            |
|      ---------------------------------------------------------         |
|      |                     Antenna splitter                  |         |
|      ---------------------------------------------------------         |
|                                   |                                    |
|                                   |                                    |
|                           To receiving antenna                         |
--------------------------------------------------------------------------

This configuration presents itself as one big 30 MHz wide receiver to tens
or hundreds of simultaneous users.  30 MHz is enough to cover all of
Shortwave Radio and more.  It also includes all of the bands that Amateur
radio operators tend to refer to as "long-distance" bands, or those being
of beyond line-of-sight communications.

Typically, someone making their SDR setup available via the Web is going
to have an impressive antenna configuration for receiving signals from all
over.

Another interesting thing about combining the use of a radio receiver with
a large multi-user environment is that users can "tag" or bookmark
various frequencies of interest for others to check out later.

By far one of my favorite WebSDRs to tune into is the Amateur radio club
ETGD / PI4THT WebSDR, run by the faculty for Electrical Engineering,
Mathematics and Computer Science at the University of Twente in the Netherlands.

Here is a link to their WebSDR.  It claims to be the first-ever WebSDR
site and has been in nearly continuous operation since 2008:

https://websdr.ewi.utwente.nl:8901/

And here are a few other WebSDRs, located in the United States, that I
sometimes tune into:

http://websdr.lumpkinschools.com/
http://websdr.k3fef.com:8901/

CREATED 2023-04-03