Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

Questions tagged [snr]

Signal to Noise Ratio - any questions about improving or detecting an SNR or lowering your noise floor.

This tag is for any question about detecting the Signal to Noise Ratio of a given signal, improving the SNR of a transmitter or amplifier, lowering your receiver's noise floor, or anything else to do with extracting a signal from noise.

12 questions
31
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6 answers

Can I reduce RFI/noise at the antenna?

Recently, the power was out in my neighborhood for an extended period of time. I fired up my HF rig using battery power and was amazed at the lack of noise across the HF bands. When the power grid came back online, the noise returned. The…
The Driver
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13
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3 answers

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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9
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1 answer

Digital-mode signal reports

When operating analog voice, we give a qualitative (or possibly just arbitrary) signal report, 'scoring' the signal either out of a maximum 'five by five', or a maximum '599'. How do you report the quality of the received signal when using digital…
Dan KD2EE
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6
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1 answer

SNR measurement for a BPSK/QPSK signal

I have created a software (gnuradio) that performs modulation/demodulation and supports a number of modulation schemes and error correcting codes. I'm in the process of evaluating the BER vs SNR for this software by using a secondary…
Moses Browne Mwakyanjala
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5
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3 answers

How big is a decibel?

Say I've calculated that my feedline losses are 3dB, or I'm considering an antenna with 10dB gain, or trying to decide between a transmitter with 10dBm output power versus 16dBm (6dB difference). I understand a decibel is a degree of change in…
Phil Frost - W8II
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4
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2 answers

Use noise figure and gain to calculate weakest signal radio can receive?

An FM radio receiver, using a 1 kHz tone at 3 kHz deviation has a 12 dB SINAD (Signal To Noise and Distortion) of -116 dBm. I would like to increase the 12 dB SINAD sensitivity of the receiver to at least -121 dBm to increase the weak signal…
Skyler 440
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4
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1 answer

Is the error rate for QPSK31 in a white noise channel worse than BPSK31?

I've read in a couple sources that in a channel consisting of only additive white Gaussian noise (AWGN), at low SNR, QPSK31 is actually worse than BPSK31. http://www.arrl.org/psk31-spec, probably copied verbatim from…
Phil Frost - W8II
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3
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2 answers

Link margin calculations with two antennas and two low noise preamplifiers

Background - UHF - 434-438MHz Two identical crossed Yagi's mounted on rotator. Currently, I have a low noise preamplifier after combining cables from the two antennas (T connector + matching stub). I'm considering adding two separate identical low…
user80551
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3
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3 answers

Are there any terrestrial timecode signals receivable in Boston Massachusetts?

I'm looking for any timecode station (like WWV/B, CHU, etc.) with an SNR > 0 dB that I should be able to receive in Boston Mass. WWVB at 60 kHz has a phase modulation that one can apparently receive on the east coast, but the signal is borderline…
Martin Klingensmith
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2
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1 answer

Preferred signal report format for Digital Voice?

When using FreeDV or other digital voice modes, what's the preferred signal report? The software has a single SNR number, but that fluctuates quickly. Since it's a digital mode, you either get the transmission, or you don't, so the RSQ system…
scruss
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2
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1 answer

FSK real world application BER

I have designed a receiver for FSK reception in 434 MHz ISM band. For this I used USRP1 and GNU Radio. Now, I would like to measure performances of my receiver. For this purposes I did following: I transmit over cable using signal generator a bunch…
Nexy_sm
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What is the point of using LNA if the SDR can increase the gain itself

Usually there is a LNA next to antenna, while SDR devices also have gain setting so we can increase the gain. As i know LNAs are amplifying all signals with same gain (Am I right?) So i wonder what is the point of LNA here? if the SDR device can…
Ariyan
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