20-11-2024, 10:48 AM
(This post was last modified: 20-11-2024, 10:48 AM by Mike Watterson.)
Also a peak reading or RMS AC meter will give a much higher reading than the level seen on a spectrum analyser with wide band noise.
There are two main kinds of spectrum analyser. The analogue kind is really a superhet radio with the local oscillator swept by the X timebase of the scope. A purely digital kind uses an ADC and DSP (FFT typically). Some are hybrids of the two approaches. At least with a digital display rather than CRT you don't have a problem with the slow sweeps needed for accurate views of filters. That's why most serious CRT based spectrum analysers used very expensive "storage" CRTs. My HP141T was nice with 4 plugins for HF to 10 GHz, but the input on those is easily damaged and the "wrong" settings can give misleading results. Sadly the IF or part of PSU or both died. The Rigol digital model had an initially harder to understand interface, but I've mostly mastered it now. I can go above the 1.5 GHz using various LNBs (MMDS, C Band, X Band, Ku Band and Ka Band), if I really it, but I don't now, though I also had a HP141T in work and needed up to 10.5 GHz
There are two main kinds of spectrum analyser. The analogue kind is really a superhet radio with the local oscillator swept by the X timebase of the scope. A purely digital kind uses an ADC and DSP (FFT typically). Some are hybrids of the two approaches. At least with a digital display rather than CRT you don't have a problem with the slow sweeps needed for accurate views of filters. That's why most serious CRT based spectrum analysers used very expensive "storage" CRTs. My HP141T was nice with 4 plugins for HF to 10 GHz, but the input on those is easily damaged and the "wrong" settings can give misleading results. Sadly the IF or part of PSU or both died. The Rigol digital model had an initially harder to understand interface, but I've mostly mastered it now. I can go above the 1.5 GHz using various LNBs (MMDS, C Band, X Band, Ku Band and Ka Band), if I really it, but I don't now, though I also had a HP141T in work and needed up to 10.5 GHz
