For the PC. As of now, I just need to analyze radio waves for demonstrations in my trig class (FM vs. AM) and I’m trying to take up ham radio as a hobby so something that can analyze that incoming signal would be good.
I’m assuming the signal would come through the mic or USB port.
Have you tried Vernier’s Logger Pro?
Radio waves are fairly high in frequency and are well above the frequency range of your mic input. There are oscilloscope programs that use your sound card’s input but they are restricted to audio frequencies. If you just want to demonstrate AM vs. FM they’ll work, though you’ll have to find audio examples of each.
You can buy external oscilloscopes that hook up to your USB port. The higher the frequency the higher the cost, generally speaking. Note that most oscilloscopes these days are digital, and they advertise the sampling frequency, not the highest frequency that they can handle. A 100 MHz oscilloscope will have a 100 MHz sampling rate, which means it’s not going to be of much use for anything above 10 MHz (well below the FM radio band).
Also note that radio signals are pretty weak, unless you happen to be fairly close to the radio transmitter. Just sticking an antenna on the front of an oscilloscope and hoping for the best probably isn’t going to yield useful results.
My personal recommendation for a cheap scope is the DSO Nano from Seed Studio, which is a tiny little pocket sized scope. It’s less than a hundred bucks and has a good sampling rate. On the negative side, it ships from China (not obvious when you buy it) and its interface is extremely unintuitive. It won’t display on a PC, but you can take screen captures and download them to your PC using USB. I have no affiliation at all with this company other than I bought one and I’m fairly happy with it. It won’t replace a proper high frequency Tektronics scope though.
ETA:
Here’s a sound card scope. I haven’t used this one, but I believe it is free for non-commercial use. Note that a sound card scope will not be able to handle DC signals and will be limited to about 20Hz to 20 kHz.
Also note that your average oscilloscope can’t be “tuned” to look at a specific signal. They display whatever is there. So you can’t really expect to pick up something that’s being broadcast without some filtering. (Think in terms of a microphone - they don’t just pick up the person speaking…they also pick up all the background noise in the area.) The typical use for ran oscilloscope is to attach a probe to a physical wire or point on a board, and to monitor that specific signal.
In the RF world, there are specialized signal monitors that help solve this. They tend to be pricey.
When you say you want to analyze radio waves - are you generating them for the purpose and then going to analyze them? Or something else?
I have had good success with this handheld oscilloscope - it comes with hardware and software for around $250
If you do can live without the RF frequencies, then this oneand the ones like that on Amazon maybe good choices too.
Just to clarify, I will be using a radio receiver and running the output to the oscilloscope. My grandfather did that. Does that change anything?
That means you just need to look at “Audio” frequencies, so a sound-card input ‘scope should work for you.
Which output? The audio output? The intermediate-frequency RF output from the tuner?
If you are just looking at the audio output from a radio receiver (I’m assuming that’s what the OP’s second post meant), then you can just use a sound card oscilloscope. However, the demodulation is already done by the radio receiver, so you can’t demonstrate AM vs. FM using this method.
Nope. I want to look at the modulated signal.
The only way to do that would be to find a radio receiver that gives you access to the IF frequency, and then you can look at that with a 'scope.
Looking at the direct RF, you’d have your signal plus every other radio station and non-resistor spark plug in town. You need a first stage to selectively filter just the narrow band of freqencies you’re interested in for that station, then look at that. The IF of a radio is pretty much that, at a lower frequency, but most radios don’t give you easy access to it.
Then how did my grandfather run his AM/FM radio into an old oscilloscope and showed both the amplitude and frequency modulation (not at the same time of course) coming from the radio?