Have you heard of an SDR?
SDR stands for Software Defined Radio. The unit itself is basically a small box, and is typically no bigger than two decks of cards. Inside are the electronic concepts that you’d see in old radios but in a SDR, these are implemented by using software to receive radio waves. All you really need is an antenna which can be as basic as a hunk of wire and sometimes a personal computer and power supply. Everything is relatively inexpensive I think.
Of course, better antennas will receive weaker signals on all bands. Usually, since SDRs are wide band, this means that they can receive signals of all types and frequencies from 1 kilohertz to 1 Gigahertz. Which is huge spectrum of broadcast signals. And yes, this usually means AM or FM based frequencies such as “regular commercial” broadcasting, as well as: amateur/ham radio, aircraft, public service. SDRs really are quite amazing devices.
Folks that have SDRs can stream their reception on personal SDR websites., setting up their software so that it receives exactly what they want for their website. For instance, some people will limit their SDRs to receiving only commercial FM Broadcasting signals. Others I’ve come across are strictly aircraft listening frequencies. Keep in mind that they just receive what they can based on their antenna and locality. I suppose that’s part of the fun of trying out different SDR websites, since you can visit SDR websites all over the world.
Listener
If you’re a listener, you simply locate one of the SDRs based on location (see map link) and interest from one of several websites. Clicking on a map location will bring up the actual software and at that point you are in control of the receiver. You’re able to enter tune, enter frequencies, select the band mode (AM, FM, SSB, etc.) adjust the audio levels and, if that’s not enough: Visualize and locate broadcasts using a band spectrograph. Happy listening.
SDR Map Example: https://rx-tx.info/map-sdr-points
Web Broadcaster/Listener
If you are interested in having your own SDR, there is no license required since you are just listening. When it comes down to the actual SDR receiver, there are many different types and on the web it can be downright confusing. But the two that stick out that I’ve researched are: KiwiSDR and RSPDX from SDRPlay (UK). Both are available online, but the latter can be bought locally at many amateur/ham radio stores. Setting one up is pretty straight forward.
For example, the RSPDX unit covers the largest range of frequencies, and is practically plug and play. All you have to do is hook it up to a computer, supply an antenna, load the software and then connect via a web browser from anywhere in the world. Setting up either of these as an online accessible receiver doesn’t use a lot of bandwidth. Usually when set up for general public web browsing, they’re on 24/7 for the general public. However, you can restrict who can browse your SDR. Of course the RSPDX hooked to a laptop can be used to completely offline.
Here’s a short list of the differences between the units
KiwiSDR
– doesn’t require a laptop
– basically has a small computer (daughter board) and OS as part of the package
– can be used remotely by itself
– only an Ethernet wired connection is required. Currently Wi-Fi internet connection is not supported.
– requires a small external power supply. Similar to what you charge your cell phone with.
– typically will not receive FM broadcast band or the VHF/UHF public service frequencies such as aircraft, fire or police bands
– will receive the AM broadcast band, amateur radio, all frequencies within the LW, MW and HF bands.
– probably the best receiver in terms of sensitivity
– as far as I know, only sold online, somewhat proprietary, but a very strong user group of enthusiasts. Dedicated software that is very creative and thorough. Somewhat cryptic though.
SDRPlay RSPDX
– requires a laptop or other computer
– simply hooks into any USB port on a computer
– doesn’t require an external power supply since it gets its power through the USB port
– the computer you hook it to will be your operational point for the SDR receiver. You’ll download and install the software for the SDR operation on that computer. I believe that there are Windows, Mac and Linux based app software available from the company’s website
– computer requires an Ethernet wired connection or Wi-Fi
– can be used totally offline independently of an internet connection after the software has been downloaded
– the largest receiving range which includes AM broadcast band, amateur radio band, HF bands for amateur radio, VHF and UHF bands for public service, aircraft, fire and police
– currently has the best instructions and not as cryptic since it’s more public-based rather than enthusiast
