X5-400M noise floor & Magnitude vs frequ graphs

[grprg]

Dear customer support,

Could you please answer the following questions related to the X5-400M:

a) Referring to a Magnitude vs frequency graph provided by the Binview application, could you confirm that your dB scale simply corresponds to 20Log(half amplitude of the A/D Input [V])?

b) If we consider the noise floor (no A/D input, no cables plugged to the card) of an Amplitude vs Time graph provided by the Binview application (see for example Graph A or Graph B of the attached document), could you explain why channel 0 and channel 1 do not have a similar level of tension output? We were expecting that the noise signal of channels 1 and 2 matches since the card is supposed to be factory calibrated. Moreover, we observed that sometimes, the noise signals of channels 1 and 2 were matching for some other X5-400M. Do we have to calibrate the offset of channel 1 and 2 in order that they match and correspond to a same noise floor?

c) Then, if we observe a Magnitude vs frequency graph of the noise floor signal of channels 1 or 2, we noticed that the choice of an internal or external clock do randomly affect the apparition of peaks arising from the noise floor (see for example graphs I-L). Sometimes, with internal clock, the noise floor has less peaks, and sometimes, at the opposite, the noise floor has less peaks with the external clock (we are always using the same external clock, same cables, very same configuration of the experiment, only the choice of the clock source in the software is modified). The same trend is observed for various frequencies, with, as always a smaller number of peaks arising from the noise floor for clock frequencies below 200MHz .
Please, could you keep an eye to the graphs in attachment and tell us if that are typical Amplitude vs time or typical Magnitude vs frequencies observed with your X5-400M.

Thanks a lot!

Thanks a lot!

[jherring]