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A great many moons ago, I spent a 24 hour period with a HAM radio connected to a PC, and listening to transmissions from a massive number of sources.

Some of the transmissions included Morse, RTTY, SSTV with some plain audio as well... on the PC, I could scroll through a large number of frequencies, looking for interesting signals to listen in to, and potentially 'decode' using the PC to display appropriate output. The software would decode the transmission live, if I had it set to the correct option.

What would I need to do this now? I'd obviously need some kind of antenna and a method of connection, but this is where my knowledge fails. I've done some googling, but not knowing much about current technology, I don't know what is relevant or not.

To be clear, I'm looking for a receive ONLY setup, with minimal financial outlay.

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  • $\begingroup$ Not quite a duplicate, but mostly answered in ham.stackexchange.com/questions/12073/… $\endgroup$ – Chris K8NVH Nov 26 '18 at 16:34
  • $\begingroup$ Thanks Chris, That duplicate isn't specific with examples... which i figured might happen with SE... as HW is often subjective/opinion based... I'm SE Veteran, just not this particular group. $\endgroup$ – Stese Nov 26 '18 at 16:38
  • $\begingroup$ I think i'm looking at something like a HACKRF or similar device EDIT... or not, thats more expensive than I figured. $\endgroup$ – Stese Nov 26 '18 at 16:39
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    $\begingroup$ They also encourage us to delete comments on occasion and make sure that information is updated in the questions and answers $\endgroup$ – Chris K8NVH Nov 26 '18 at 17:16
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A generic search term you might use is “Software Defined Radio” or SDR (a topic which covers much more than your specific question).

Equipment possibilities for your specific question includes SDR hardware that covers the frequency bands of interest and that can be connected to your PC via USB or Ethernet, SDR software compatible with the specific SDR hardware device, plus a suitable antenna.

There are many SDR hardware products and vendors that cover a wide spread of performance levels and price points, from RTL-SDR USB dongles (for on the order of a couple dozen USD), to high-end SDR boxes (that cost thousands). Which to choose depends on more specifics about your requirements (budget, frequency bands supported, sensitivity, bandwidth, broadcast and image rejection, software options, and etc.).

Using a cheap RTL-SDR USB stick on HF requires either one that supports Q mode direct sampling, or an additional upconverter box. (Note that when paying “as little as possible”, to some degree you get what you pay for in terms of signal reception.). Other less cheap but common USB connected SDR boxes might include Airspy HF+, SDRPlay, HackRF, LimeSDR, and others. High-end SDR units might include ones from Ettus Research. (Hopefully updates and any of my omissions will be added to the comments below).

You will also need SDR software running on your PC. Many of the SDR hardware choices support multiple software application options for the PC (or Mac, or Linux/Raspberry Pi/etc., even iPhone, iPad, and Android devices) that supports the operation you describe. Some of the SDR software applications are freeware or open source. Some are not.

Some amateur radio HF rigs also include built-in capability, or allow attaching panadapters, or allow connecting to PC software via USB or stereo sound card, which may support similar functionality.

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  • $\begingroup$ Looks like I have more googling to do, thank you! :) $\endgroup$ – Stese Nov 27 '18 at 8:20
  • $\begingroup$ There is so much variety, it is like a rabbit hole. Every time I google I end up more confused than when I started. I am hoping for an answer along the lines of "get this and this, it will get you started". $\endgroup$ – Chris K8NVH Nov 27 '18 at 12:06
  • $\begingroup$ I'd say all (not merely "some") HF rigs provide some mechanism for connecting a computer, via the data, speaker, or headphone connections. $\endgroup$ – Phil Frost - W8II Nov 27 '18 at 15:12
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I agree with hotpaw2 but there's an even cheaper solution. You can also use the many different webSDR's that are around the world. With those you only need an internet connection. These are some places to start:

Google will give you a ton of extra possibilities.

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  • $\begingroup$ but I don't want to stop you from experimenting with radios and antennas! It's a wonderful hobby (and pretty addictive) $\endgroup$ – ON5MF Jurgen Nov 27 '18 at 9:37
  • $\begingroup$ No, thats great. I 'found' the Chilterns NDB in the UK once by listening on my car radio... i'm curious what else can be 'heard' $\endgroup$ – Stese Nov 27 '18 at 9:42
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Other answers here cover SDR well, but software defined radio with dedicated SDR hardware is not the only way to do radio things with a computer. You can also take nearly any radio with a speaker output (ham radio or not) and use an audio cable to connect the radio's speaker out to your computer's sound card line in. Many software packages (example: FLdigi, freedv) can then view the audio and decode digital modes. This could potentially cost no more than just the audio cable if you have an existing radio.

If you want to transmit as well, it may be a bit more complicated. If your radio has a line in, it's easy, just connect a wire from your computer's speaker out to the radio's line in, and make sure that all operating system events are set to not emit sound (which might accidentally go over the radio).

If your radio only has a microphone in, you will need something (like a rigblaster) to convert the computer's speaker out into the radio's microphone in, matching impedance and voltage levels.

For either receive or transmit, you you may want to also control the radio from the computer. (Software /controlled/ radio) Many modern ham radios have a serial port on them; higher end ham radios may actually have a USB port or ethernet port which might include both control and audio. Older radios may have a radio specific accessory port that includes serial and audio lines that can be split out to the correct connectors for your computer. (I've built several of these for different radios after buying the necessary plugs for the radio.)

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