SDR (was citlivost autoradia ??)

[Naprstek, Jiri]

>> nie celkom :-) ako som v predoslom maile pisal. Povedzme 80Msps
>> prevodnik ma sirku analogoveho pasma povedzme 500MHz. To znamena
>> ze mozes samplovat signal az do 500MHz rychlostou do 80Msps.
>> Spejbl & Hurvinek ti to podrzia :-)
>
>Aha, rozumim. Pripada mi to tedy trochu zmatene nazvane (asi jako
>Wekovi), protoze 500MHz je v tomto pripade "nejvyssi pripustna
>frekvence", kdezto sirka pasma zpracovatelneho signalu je pak
><=40MHz. 

No, ze sirka zpracovatelneho signalu je <=40MHz neni tak docela presne, pokud je ten signal periodicky (tedy, pokud je odchylka mezi periodami pod rozliseni casove i napetove kvantizace prevodniku), lze signal samplovat opakovane s postupne fazove posunutym samplovanim a zmerit si 500MHz sinusovku i 80MHz prevodnikem.

Ma to spoustu nebezpeci prave kolem te "periodicnosti" signalu, nicmene se to pouziva(lo) prave tam, kde byl pomaly prevodnik a rychly stabilni signal. (napriklad je to take duvod, proc nektere starsi HP osciloskopy dokazou pekne lhat :-))

J.N.

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