{"id":2223,"date":"2019-12-01T00:00:53","date_gmt":"2019-11-30T15:00:53","guid":{"rendered":"https:\/\/micronix-jp.com\/?p=2223"},"modified":"2023-03-25T09:16:13","modified_gmt":"2023-03-25T00:16:13","slug":"relation_speana_att_eg","status":"publish","type":"post","link":"https:\/\/micronix-jp.com\/english\/note\/application\/relation_speana_att_eg.html","title":{"rendered":"Relation between noise floor of spectrum analyzer and internal ATT"},"content":{"rendered":"

\nThis note explains the relationship between the noise floor of the spectrum analyzer and the internal attenuator (ATT).\n<\/p>\n\n\n

Application<\/h2>\n

The figure below shows a simplified block diagram of the spectrum analyzer. If a signal exceeding the appropriate level is applied to the mixer input, harmonic distortion and spurious will occur due to saturation, and correct measurement will not be possible.
\nTo prevent this, an internal ATT is inserted before the mixer.<\/p>\n

\n

Simplified block diagram<\/p>\n

\"Simplified<\/p>\n<\/div>\n

The following shows the result of measuring the noise floor with no RF signal input and changing the internal ATT of the spectrum analyzer.
\n(In the MSA series, the internal ATT value is automatically set according to the reference level setting value.
\nRefer to \u201cRelation between reference level and ATT \/ AMP\u201d in the instruction manual.) <\/p>\n\n