Just a remark about the delta markers. When you take a 'difference' in dB's between two values (ie a ratio) the unit disappears. Eg the 'difference' between 23 dBm and 13 dBm is 10 dB. Likewise the difference between -100 dBm/Hz and -120 dBm/Hz is 20 dB.
It seems the Rigol takes the ratio of the powers and then divides by the RBW. For example at 24:23 I read 0 dBm and -67 dBm. the ratio would be -67 dB. Dividing by the RBW results in -87 dB/Hz.
However in my view the only point where this would make sense is when the reference marker is at the peak (as in your case). For any other point except that special case the Siglent way (just dB) is more generic. For example if I would want to compare the noise floor at two points, supposing there is a -10 dB ratio between the two powers, I would rather read -10 dB, than -30 dB/Hz. This latter value would not make any sense to me.
That makes sense. But if you put the marker in noise mode it should know this and give you the correct units of measurement you expect IMO.
Errr....
This is good that there read: IMO.
7 points wink: User need know whhat he is doing. Equipment can not know.
Is it better that you do some day one "teaching hour" Video where you explain Normalization to 1Hz, dBc/Hz and then NOISE dBm/Hz and importantly if you use noise cursors for look noise level dBm normalised to 1Hz noise BW.
It is not at all simple game. If we take (sinusoidal type) peak dBm level what we look with 100Hz RBWa filter. We can normalize it to 1Hz RBWb same kind of signal using same kind of RBW shape factor just using 20dB subtract. (10 * log (RBWaHz/RBWbHz)
With random noise situation is bit different.
Random wideband noise have Gaussian distribution, but here with RBW filter noise have Rayleigh distribution.
Also just sidenote: Many times VideoAverage Detector can not measure signal peak level so using example two (noise mode) markers for different kind of signal comparing drops user to trap very easy.
How machine can know what signal is under your marker position. This is what user need know. And USER NEED do Right selections/settings. But this need knowledge.
Proper using SA's for measurements need knowledge about basic fundamentals -- and also user need know his equipment. Tjis is why old times you buy expensive tool HP give also free teaching and training courses some time times and in lab, only peoples who have get training for equipment have access to use it. Also there was available quite deep explanation about theory of operation.
In other way we need every day wonder what hell results user get and are these results valid or total bullshits what we then discuss about why my equipment display so strange things. But, of course this we need also and this is (mostly) useful for lot of peoples who are curious and always willing to learn more - and this is least one reason why I have been hobbyist with electronics over 50 years and never get enough.
Out from box and then wondering this and that and oh my god this value or that figure is strange or wrong or is my equipment broken.
We have seen it with all equipments, here and there and everywhere.
For todays SA's this AN-150 is nearly as Mandatory reading. (It also tell how Siglent works in principle)
And very importantly if you are bit new with SA's and/or worked lot of with analog sweeping SA's and full
digital IF Sweep/FFT SA is new for user.
Btw: Chapter 5 pages 46 - 54 explain these noise things.
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