5
votes
Digital transmission sounds
See SigiWiki:
This wiki is intended to help identify radio signals through example
sounds and waterfall images. Most signals are received and recorded
using a software defined radio such as the ...
4
votes
Accepted
Lowest noise MMIC for HF? (160-20M)
The ambient noise on HF is so high that such a low noise figure will not appreciably improve performance. On 20 meters, the minimum ambient noise temperature you will encounter is about $3 \times 10^6 ...
4
votes
What is unique about a Low Noise Amplifier (LNA)?
If I were to design an amplifier, I would always design an amplifier with low noise anyway.
Nope! For a power amplifier, you'd do a different tradeoff; the noise figure of that amplifier nearly doesn'...
- 13.5k
4
votes
Accepted
Is there a technical reason to sell an LNA without advertising its gain?
The gain becomes an issue only if its ridiculously low. The main purpose of an LNA is to lift the signal well above any noise of the following stages, and often that can be done with a gain of several ...
- 268
3
votes
Digital transmission sounds
Here's one from the designer of fldigi.
http://www.w1hkj.com/modes/index.htm
- 1,646
3
votes
Accepted
Is SSB and FM voice considered TDD or FDD (and what are TDD/FDD)?
TDD and FDD are two methods of achieving a two way path (duplex) between two communications nodes (i.e. transceivers). They are mainly of interest for cell phones and digital data devices (e.g. WiFi)....
- 46
3
votes
How much dB gain do you need from an LNA in front of an antenna for great low-signal reception from satellites in the 2m and 70cm bands?
An earlier Answer mentioned LNAs would be “of some use only if ... the noise power from the antenna is higher than the noise floor of your receiver” (quote). That statement appears in need of some ...
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3
votes
Accepted
How much dB gain do you need from an LNA in front of an antenna for great low-signal reception from satellites in the 2m and 70cm bands?
A LNA amplifies signal and noise. It is of some use only if:
the noise power from the antenna is higher than the noise floor of your receiver, and
the LNA has a lower noise floor.
Many VHF/UHF ...
3
votes
What would happen if the low noise amplifier (LNA) is saturated?
As the amplifier gets closer to saturation, its gain reduces. This is because during the portion of time the transistor is saturated, it is not able to output any other signal. The signal of interest ...
- 145
2
votes
What would happen if the low noise amplifier (LNA) is saturated?
You would see higher order mixing products at the output of the LNA. The closest to the SOI would be third order products. 2f2-f1 and f2-2f1, where f1 and f2 are the frequencies of the two input ...
- 21
2
votes
How can I improve my Es'Hail 2 reception?
20-25 meters of RG-6 coaxial cable has significant loss at 739 MHz.
RG-11 coax has significantly lower loss than RG-6. Unless there is an issue with your LNA, I expect that replacing the RG-6 with RG-...
- 7,545
2
votes
Replace directional antenna by fixed antenna
These specifications mean:
VHF yagi antenna
This tells you the general kind of antenna it is: a Yagi intended to operate at VHF: "very high frequency".
12dBic gain
This means that in the ...
2
votes
Accepted
Generally, what happens when you power a GPS antenna or other RF amplifier with a low voltage?
It's hard to say whether your active antenna would work properly if provided with 3.3 VDC instead of 5 VDC. I doubt that any damage would be done, but I'm not the engineer that designed the antenna. ...
- 8,922
1
vote
Use noise figure and gain to calculate weakest signal radio can receive?
Phil's answer is sound from a technical perspective since there is not sufficient data to fully answer the question.
From a more pragmatic perspective, if you wish to increase the 12 dB SINAD ...
- 18.2k
1
vote
Strange Noise Floor observed in UHF Band
300 kHz channel at 436 MHz sounds a lot like your spectrum analyzer might be seeing that are at twice the frequency – 872 MHz would be a typical 2G cellular network frequency, and 300 kHz might be ...
- 13.5k
1
vote
How to bypass LNA for TX in UHF Antenna?
If the antennas are cheap and easy to build, why not build two and use one for TX and one for RX, then use a common RF sense antenna switch such as MFJ-1707 to switch between the two. This allows you ...
- 221
1
vote
Replace directional antenna by fixed antenna
Whether you can use an omnidirectional antenna to replace a directional antenna depends entirely on
the minimum signal-to-noise ratio required by the receiver, and
the amount of noise arriving from ...
- 23.1k
1
vote
Antenna + LNA Design Questions
Is there any way to independently test the two parts of the circuit -- the antenna and the amplifier?
Perhaps use a 1 megaohm through-hole resistor to directly connect your RF source to the big "...
- 111
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