Electronics > Metrology

Solartron 7061 noise

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With increasing numbers of SMPS and PV systems in the grid the mains frequency may show more jitter / variations than in the old times when the supply came mainly from large classical generators. So the PLL may have more difficult conditions than at design time.

To get reduche the effect of wavefrom distorions / higher frequency noise on the main waveform, one could consider a little filtering for the mains signal pic off.

For the PLL it may be worth looking at the VCO control voltage an look if there are some dominant frequencies. Ideally this would not be the case, but a poorly tuned loop filter can show some amplifications / tendency for ringing.

The alternative to a PLL is to have a stable crstal clock and accept a lettle less mains hum suppresion.

When I adjusted the VCO on my unit I used a Keysight 53230A in trend chart mode, this way I was able to observe the PLL trying to lock by "sweeping" the frequency. So the frequency I adjusted the VCO to is not neccessarily 49.152MHz, but close enough to get the PLL to lock.



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