Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

Questions tagged [noise]

Questions about noise in the sense of that inevitable component of any real signal. For questions about avoiding or eliminating interference from manmade sources, use [rfi] instead.

63 questions
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How can I calculate the effects of an LNA, antenna gain, etc. on noise performance?

There are many things I might do enable my station to hear weaker signals that would otherwise be buried in noise. Just a few possibilities: Install a nice LNA Increase antenna gain Reduce feedline losses Buy a better receiver Move to a quieter…
Phil Frost - W8II
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Is a vertical noisier than a dipole, and if so, why?

I've had people tell me, anecdotally, that a vertical is noisier than a dipole. Is this true, and if so, why? If it is true: Is this additional noise, such that SNR is degraded, or is the vertical just more sensitive overall, making noise and…
Phil Frost - W8II
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Is FM modulation still more resistant to noise when given the same bandwidth as an AM signal?

FM modulated radio is much more resistant to noise and can deliver better sound quality than AM radio. But FM signals also use more bandwidth than AM signals. In general a wider bandwidth signal is more resistant to noise / can send more data than a…
JanKanis
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High 40m noise floor during the evening but quiet in the afternoon

I've been dealing with S7 static on 40 meters ever since I got started a few weeks ago. It's so bad that I have to use my RF ATT so that the static is not deafening. I did some research about finding noise sources (mostly wall warts) and common…
user3191449
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Rolling QRM from 3000-10000 kHz - What Is It?

Video I was lucky to catch the QRM start this morning @ approximately 10 AM Pacific Standard time. It was wide, starting around 3000 kHz up to 10000 kHz. It starts fast then slows to a crawl. The noise has pronounced high/low bumps as you'll see in…
user11702
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Is 20m noisy, or do I have a lot of local interference?

I'm making my first ventures into HF with a Yaesu FT-450D and a homebrew 20 Meter inverted-V antenna a local ham helped me set up. I've noticed that the 20 Meterm band seems to have lots of background noise (QRN) everywhere in the band. The S-meter…
Adam KC0DAD
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What are these continuous sine wave tones I keep hearing?

I'm messing around on WebSDR and by just scanning through I sometimes come across these continuous tones in USB. One in particular was 28.800 MHz USB. I've picked them up on nearly every WebSDR unit I've used. This one in particular was the most…
user11031
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Noise & shielding, SDR Dongle

First, I'm very new to SDR. This may turn out to be really obvious. I just want to verify my thoughts before I spend more dollars. I have a USB dongle with the RT28xx in it. Works great. Side by side I have a 35 year old Azden 2 meter receiver. …
David Hoelzer
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If receive performance doesn't depend on SWR, then how can I tune my manual HF antenna tuner by band noise?

The popular question "What is the relationship between SWR and receive performance?" asks if a receiver with a well-matched antenna (low SWR) beats a receiver with a poorly-matched antenna, with everything else being equal. The consensus opinion…
rclocher3
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HF Noise Level S5 to S9+18

Since I got my HF radio a year and change ago, I've been able to hear very little except noise and the WWV time station on 10MHz. Noise seems to vary by band, but not how I'd expect: 80m: S7-S9 40m: S9+10-20 20m: S2 15m: S3 10m: S9 6m: S5 My setup…
William
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Does a low amount of atmospheric noise reliably indicate a lack of propagation?

We know that the primary source of interference at HF is atmospheric noise. Thus, all else being equal, the strength of heard noise is a fair indicator of RX system performance (such as in adjusting an antenna tuner for maximum noise while…
Kevin Reid AG6YO
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Why does my received power rise so much when I connect an antenna?

I am in early stages of making a narrow-band radio receiver (block diagram below). To give you an idea, I am using a simple CP-FSK based modulation scheme, and have achieved 5dB SNR with a Tx signal of -118 dBm on wires (feeding signal via an R&S…
Kraken
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What does a receiver's noise reduction function do?

Some receivers contain a noise reduction button or function. What does this noise reduction do? Is there more than one type of noise reduction? How does the circuit or software know what part of the signal to reduce as noise and what part to not…
hotpaw2
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Does a loop antenna have less susceptibility to atmospheric noise than an open ended antenna?

I always get the feeling that an antenna which has a loop for the driven element such as a folded dipole or quad will pick up less static or 'high impedance' noise than an antenna that has free ends such as a dipole or long wire. Noting that…
Andrew
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How do I have a full signal of noise on a handheld?

I'm new to ham (although I've had a license for a long time) and I'm having issues with receiving on a basic handheld. I have a cheap BaoFeng UV-82HP and I keep getting full signal noise at random times. I have gotten this on different channels in…
Eric Fossum
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