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fed138
(@fed138)
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Joined: 2 years ago
Posts: 11
25/04/2018 1:10 am  

I'm seeing a lot of artifacts across the band at 5.5GHz with no Amp and no LNA at the front end. Front end is terminated with 50ohm load.

Of particular interest is in the center of the band, this artifact is across the board on my device at different frequencies (see second image).

Is this the expected flatness from this device at 175mhz (I'm looking at the average)...


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fed138
(@fed138)
Active Member
Joined: 2 years ago
Posts: 11
25/04/2018 1:35 am  

I will note that there is a "hide rtbw noise" option that seems to remove all these artifacts. However, I have no idea what effect that has on the signal as there is no documentation around the function.

Could you please elaborate?

Also, there are still some occasional spikes around 5.5GHz.

This option seems to be incompatible with an external LNA UBBV2... Is it? Or is that surrounding rf noise leaking into the LNA even though I have a 50 ohm load attached?


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Moderator
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29/04/2018 7:27 pm  

Yes at 175MHz RTBW the noise floor will rise to the right/left corners and at the center since no filter is perfect... But as you have seen we offer a lot of functions to flatten this huge bandwidth.

How should an amplifier be "incompatible"? For sure this is simply a noise floor added by the amp.

Snip


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fed138
(@fed138)
Active Member
Joined: 2 years ago
Posts: 11
02/05/2018 12:20 am  

I agree - that was part of my confusion. An LNA is an LNA. I do not expect to see notches anywhere in the middle of the signal and a drop on the sides.

It is unclear that this is the noise floor as I would expect that noise floor from the amplifier to be wider band than this (there is nothing on the edges).

I have attached the LNA to a R&S FSQ analyzer and see none of these issues coming from the LNA. Given what I see on another spectrum analyzer I'm left with the question: what does hide rtbw noise do?


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Moderator
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06/05/2018 10:20 am  

As mentioned before its simply the filter (sensitivity) curve.

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