Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

Questions tagged [receiver]

Use this tag for questions about the theory and structure of receivers.

A radio receiver is an electronic device that receives radio waves and converts the information carried by them to a usable form, usually in the form of sounds, images or data.

The technology of detecting RF energy has progressed since it was first demonstrated at the end of the 19th Century. Moving from early crystal detectors through vacuum tubes (thermistors) to solid state transistors.

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How is the FM-signal demodulated in my receiver?

I've built a radio receiver and I'm wondering how the demodulation works here. I think it's done by T1 and T2 (I've used BC547 instead of BF494, they're quite similar), but I'd like to know more about it. Source:…
Superlimonade
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Optically clear RF shielding?

Is there a material suitable for use as RF shielding that would allow at least 50% light transmission in the visible range? Thinking about a sensitive light receiver.
Adam Davis
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Carrier wave timing

I'm not really too technical when it comes to radio, but I understand that in AM, a shortwave radio generates the carrier frequency so that it can mixed with the received station and then removed, leaving the signal which was modulated with the…
user9468
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FFT frequency shift corrupting phase

I have written a Software Defined Radio. I take I/Q audio into the computer at a 192K sample rate and perform a 4096 sample Complex FFT. I display the spectrum (PSD) to the user so they can pick the signal they want to listen to, and capture the…
Chris AC2CZ
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Crystal set as wireless earphone

Reading about a 'necklace' coil inducing a strong alternating audio current (using an LM386 f.i.) into a magnet inserted in the ear canal set me thinking. The problem is that the magnet has to be inserted in very close proximity to the eardrum, so…
Erik
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WWV interference all over the band!

I have a mid-era Hammarlund HQ-129-x. It sounds great if I don't count the motorboating. But the problem is in the middle bands. I got the radio way out of alignment, and managed (I think) to get the IF working. I receive strong stations (folded,…
Caoimhin
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How to identify a practical HF communication receiver?

I've recently purchased a Hallicrafters S-120 -- 4-tube superhet receiver from the 1960s, continuous tuning from 540 kHz to 30 MHz, bandspread control, and a regenerative IF that doubles as a BFO for SSB and CW reception. Someone before me appears…
Zeiss Ikon
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What's the use case behind long AGC constants?

So my shortwave radio has adjustable AGC constant with settings between 0.1 s to 8 s. I always find myself using the fastest AGC settings. Often, I experience 20-30 dB fades and if I use the slower AGC settings, what happens is that the station is…
AndrejaKo
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What is this sound on FM radio?

When tuned around 87.5-88 FM, a strange repetitive sound can be heard. The title 'Les Professionnels' from 'Air' start with this sound.
Orace
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Square wave vs. sine wave timing reference

Some RF receivers accept square wave clock reference (10MHz, 1pps, etc) and others accept sine wave. Most of the GPS do devices are outputting 10MHz sine wave timing signals. Are there practical or theoretical differences in the way these timing…
John Ellinwood
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How does a scanner work

I was reading What is the difference between radio scanner and receiver? and I saw that it said that the scanner continues on scanning after a radio transmission is over. If I find a frequency that I want to listen to, can I tell the scanner to stay…
Reid
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How can I listen to channels above 1710kHz?

I hear of channels at, for instance, 4625kHz and I want to check them out but the only radio I have is the one in my car which only goes up to 1710kHz. What kind of radio do I need to listen to channels above that? P.S. I know nothing about HAM…
marcus marcus
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Can my portable radio receive amateur radio?

http://memorex-ce.com/product/amfm-pocket-radio/ Yeah, I guess it's cheap and probably won't pick it up but...
Uknow23
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What is DMR and can I listen to it?

I saw here Table of broadcasting stations that there is a mode called DMR (under Atlanta Technical College). What is DMR and if I buy a scanner (I am thinking about the Icom IC-R6) could I listen to those stations?
Reid
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Any way to block one FM station

I live next to a 100 kW FM transmitter, 600 feet away transmitting on 103.7 MHz. It is south east and most other station I want to listen to are in other directions. This station comes though most of the FM band interfering with other stations. Is…
crip659
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