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I want to see an AM carrier wave and the resulting encoded frequency and the DC (I think) out of the wave, the information getting to my earpiece.

What kind of Oscilloscope do I use for seeing the representation of radio waves? Do I need an analog or will digital work?

I have seen videos of digital, but they appear to be "slow," on the older Analog scopes, it is faster and seems more responsive. I'm not sure I care which one as long as it is not a struggle to see it. With digital, I am guessing I can capture the information and view it offline, which would be better for analysis, so I can understand.

For frequency, I mean a USA AM radio station, 535 - 1605kHz.

I'm sure after that I'd want to use it for non-RF things.

One thing I am interested in is a Crystal Radio, no battery, and a scope showing what is being received, if that is even possible.

I am not asking for a specific product recommendation.

I originally asked this, but I think I didn't ask the right question:

Can a USB Oscilloscope be used reliably and accurately for RF projects?

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  • \$\begingroup\$ I have seen videos of digital, but they appear to be "slow," on the older Analog scopes, it is faster and seems more responsive. I think that that is a generalization and at least for any modern scope simply untrue. My guess: the person showing the digital scope didn't (know how to) use it properly. The main advantage of a digital scope is that it can "freeze" a signal. That's useful for continuously changing signals like audio (and therefore also an AM radio signal). On an Analog scope you would be unable to look at details. But what do you want to see in the AM signal? \$\endgroup\$
    – Bimpelrekkie
    Commented Sep 27, 2018 at 14:04
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    \$\begingroup\$ On nearly any scope with sufficient bandwidth you can observe an AM radio signal. But really, there's not that much to see. For real RF you would need a spectrum analyzer (they're quite expensive). A scope is more for low frequency stuff, focusing your choice on viewing the AM signal is pointless if you ask me. Either get a good used analog scope to learn what you need or get one of the popular cheap digital scopes if you have the cash. A USB scope could be OK but the good ones cost nearly the same as a standalone model so not worth it in my opinion. \$\endgroup\$
    – Bimpelrekkie
    Commented Sep 27, 2018 at 14:10
  • \$\begingroup\$ Digital scope is slower comparing to the analog one for example in this case: If you want to observe 10 seconds of 1Hz wave signal on scope screen analog is much faster almost immediate. When you want to adjust time scale in such application the digital one will stuck all the time. \$\endgroup\$
    – floppy380
    Commented Sep 27, 2018 at 14:40
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    \$\begingroup\$ @user1234 Observing 10 seconds of waveform cannot take less than 10 seconds. \$\endgroup\$
    – Dmitry Grigoryev
    Commented Sep 27, 2018 at 19:27
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    \$\begingroup\$ I think @user1234's point is that the analog scope has very low latency regardless of timebase, which isn't true for all digital scopes. USB scopes in particular will have high latency. \$\endgroup\$
    – pjc50
    Commented Sep 28, 2018 at 10:08

2 Answers 2

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Your highest frequency of interest is 1.6 MHz. That is "low" for ordinary oscilloscopes. Just about any scope can go up to 10 MHz. There is really nothing here any regular oscilloscope can't do.

Analog scopes today are only for specialty niche applications. Yours isn't one of them. A digital scope will serve you better. The drawbacks you claim for digital scopes are nonsense, especially for this application.

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  • \$\begingroup\$ I was only looking at a YouTube video here and there. Good to know it is not universal. \$\endgroup\$
    – johnny
    Commented Sep 27, 2018 at 14:55
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    \$\begingroup\$ Learn about the scope's triggering: how to chose the Trigger Source, the DC/AC coupling of the trigger, the Trigger Level. Then bring in an AM signal, set the scope timebase on 10 uS per division ( to have about 10 cycles of AM per division), and adjust the Trigger Level. If you see nothing, some scopes has "AUTO" setting where no triggering is needed; try AUTO. And change the TimeBase to 20 or 50 or 100 uS per division, where you will see 1KHz of voice/music modulation across the entire (10?) horizontal divisions of the display. \$\endgroup\$
    – analogsystemsrf
    Commented Sep 27, 2018 at 17:39
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Just to cover the "digital scopes appear to be slow" part: the scopes may be very fast, but the visualisation is only as fast as the computer and the oscilloscope software can do. Modern computers are typically fast enough, but cheap scopes come with bad software which is either poorly written or tries to hide the lack of hardware features (like triggers) by processing tons of waveforms and only showing you the good ones.

Not surprisingly, the quality of the scope itself and the software that comes with it is correlated with price.

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