Never thought about the AM bandwidth thing before that is interesting and seems obvious now (from Fourier Transform point of view)
Radios, how do they work? (2024)
11–20 of 72 posts
Re: Radios, how do they work? (2024)
#12Never thought about the AM bandwidth thing before that is interesting and seems obvious now (from Fourier Transform point of view)
Here's a video of AM modulation. SDR transmitter (running GNU Radio) connected to an SDR receiver.
Re: Radios, how do they work? (2024)
#13To get an idea about radios, I made a crystal radio when I was in 7th grade, I only had few components. The only component I had difficulty in getting was the crystal oscillator (I was living in a rural town). It was mind blowing when I first heard the audio through IEMs ! It felt magical that this contraption was working without any battery source.
The crystal radios I know don't have crystal oscillators - the word "crystal" refers to the diode.
Re: Radios, how do they work? (2024)
#14To get an idea about radios, I made a crystal radio when I was in 7th grade, I only had few components. The only component I had difficulty in getting was the crystal oscillator (I was living in a rural town). It was mind blowing when I first heard the audio through IEMs ! It felt magical that this contraption was working without any battery source.
You can use a germanium diode or even Shottky now instead of a “crystal”.
Such a simple radio can be a gateway drug to a very complex and deep hobby. In my case it went like that:
1. Built a simple radio
2. Could hardly hear anything, need to add an amplifier to it 3. Now it’s better but captures a lot of noise
4. Design a filter to select just that one station
5. Now I want to listen to more stations.
6. Ugh, you can’t design a good filter with variable frequency. Enter the superheterodyne world.
7. Now finally got something that resembles a tunable AM radio, but it kinda whistles / hums a lot. Ah, so the mirror image is a real thing?!
8. Need a higher IF to be able to better reject the image before the mixer. Ok, let’s make a double conversion superhet then.
9. Buy a set of ceramic filters and play with them to get the best selectivity.
10. Try to add more amplification only to learn if you go too far you get an oscillator instead of an amplifier.
11. The sound level is not stable. Add AGC.
12. Pick up some stations from 5000+ km away. Nice. But there is some weird distortion. Oh, I’ve been a culprit of frequency selective fading…
Fast forward and now I’m building a PLL synchronized AM product demodulator with a squaring loop for carrier recovery.
Fun. Lot of fun! Wholeheartedly recommend!
Re: Radios, how do they work? (2024)
#15[deleted]
Re: Radios, how do they work? (2024)
#16I've been studying for my amateur radio license recently, and this article is a great introduction to the basics. But really, if you want to get your hands dirty with some practical electronics, and also want to be able to communicate without relying much on nearby infrastructure, amateur radio is a great hobby.
Do yourself a favor and study for both your technician and general at the same time (I’m assuming you live in the US). HF is exponentially more fun than just VHF/UHF.
Re: Radios, how do they work? (2024)
#17I've been studying for my amateur radio license recently, and this article is a great introduction to the basics. But really, if you want to get your hands dirty with some practical electronics, and also want to be able to communicate without relying much on nearby infrastructure, amateur radio is a great hobby.
Do yourself a favor and study for both your technician and general at the same time (I’m assuming you live in the US). HF is exponentially more fun than just VHF/UHF.
it’s stuff like this that make me wish i lived in the US. i have to memorise a long questionnaire in german if i want to get my license
Re: Radios, how do they work? (2024)
#18Earlier quoted context omitted.
Do yourself a favor and study for both your technician and general at the same time (I’m assuming you live in the US). HF is exponentially more fun than just VHF/UHF.
it’s stuff like this that make me wish i lived in the US. i have to memorise a long questionnaire in german if i want to get my license
You can take your licence exam in any CEPT country and swap it (i.e. that countries licence) for a German one under reciprocal licencing agreements.
Re: Radios, how do they work? (2024)
#19I've been studying for my amateur radio license recently, and this article is a great introduction to the basics. But really, if you want to get your hands dirty with some practical electronics, and also want to be able to communicate without relying much on nearby infrastructure, amateur radio is a great hobby.
Do yourself a favor and study for both your technician and general at the same time (I’m assuming you live in the US). HF is exponentially more fun than just VHF/UHF.
[dead]
Re: Radios, how do they work? (2024)
#20This reminds me of a beautiful book written by Paul Nahin, 'The Science of Radio'.
Bought it but never read it - is it worth pushing through?