# Questions tagged [noisefloor]

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### Noise floor of an unmatched resistive network thru PSD calculations

I am modeling the PSD of various loads to calculate noise floors. I have various load terminations from 25 ohms to 250 ohms. Per Johnson-Nyquist, the noise floor on a resistor when load and source are ...
• 21
1k views

### Calculate receiver dynamic range (understanding the effect of FFT processing gain)

I'm attempting calculate the dynamic range of a receiver. That is, the ratio between the maximum and minimum detectable powers at the reception antenna. The receiver is composed of (in order) an ...
• 1,063
1 vote
161 views

### Do parallel LNAs at 90-degrees to eachother reduce the noise floor more than side-by-side?

Wiring amplifiers in parallel in a summing configuration improves the signal to noise ratio because amplifier noise in each LNA is uncorrulated. However, external noise sources will still be a factor ...
• 2,200
438 views

### How does wiring two LNAs in parallel affect charactaristic impedance?

It appears that wiring amplifiers in parallel improves the signal to noise ratio. I thought I would experiment with two SAV-541+ LNAs in parallel and see how they perform: How does wiring an LNA in ...
• 2,200
287 views

### Understanding Noise Figure of LNA (HP 461A amplifier)

I have recently got a HP 461A linear amplifier (from the 60's) which works from 1Khz to 150Mhz. I have checked that: it's input gives a SWR <1.1 across all spectrum (i.e., the input impedance is ...
• 53
1 vote
264 views

### Noise Floor of ADC using PWELCH

While using MATLAB's Pwelch function, I am not able to match the noise floor of the "Modelled" ADC to (Delta)^2/6 {1 sided Spectrum}. ...
60 views

### Amplifying noise floor

Let's say you have -120Db noise floor on an amplifier circuit. You feed this noise into an ideal noiseless amplifier with an Av=25. What is the new noise floor? Proper equation?
• 1
130 views

### How to derive receiver noise figure/input noise floor

When calculating the noise figure for a receiver, assuming the IF bandwidth is narrower than the input RF bandwidth, do you use the narrower IF bandwidth to derive the receiver noise figure? Also, ...
95 views

### Noise when Charger Connected [closed]

I have a handheld rechargeable Measuring Instrument. When I use it normally, without charger connected, readings on screen are stable. But when I connect the charger into it (It's a 5V USB charger) ...
• 483
1k views

### calculating the RMS noise of an accelerometer

I would like to measure the noise density (microg/sqrt(Hz)) of an accelerometer and then compare the measured one with the typical value in the datasheet. I know the sensitivity and the sampling ...
66 views

### Can signal arrival times be a function of receiver bandwidth?

Lets assume that the speed of light is exactly $3\!\left(\!10^{8}\!\right)\text{meters}/\text{second}$. Suppose we have a transmitter on the surface of the earth emitting a signal at 1000 MHz and ...
• 103
1 vote
124 views

### Noise vs Signal

All, I have created a photo-diode amplifier(2 stage) which allows me to set a gain from 2 to 551 (v/v) [4.6 to ~55dB] in 64 steps. The gain is achieved using pre-calculated resistance to provide non-...
• 425
266 views

### Measuring band-limited noise coming from an amplifier

I have a strain gauge amplifier and from my analysis, it will produce a low level of white noise above approximately 1kHz i.e. the power spectral density is flat above 1kHz. If I measure the output ...
• 465k
6k views

### How to calculate RMS of total noise from digital Oscilloscope (FFT)?

Only the red channel is in consideration. The yellow curve is not relevant, which is only another channel of the oscilloscope. The image above was captured from a digital oscilloscope. The vertical ...
• 1,622
3k views

### Very low noise high pass filter design

We are trying to design a high pass filter, which mainly goals are: very low noise. Low noise is the first concern. suppresses 1kHz by around 50dB and passes 2kHz. Gets rid of DC Dont care on other ...
• 1,622