I need to know how to calculate the standard deviation of Treasury Bond/Sovereign Bond for one year period? i have followed below method: please verify the method that i followed or if not what wis best method?

MY Method

I took one year daily prices of the bond and calculated the daily return and used excel function of STDEV.P and calculated daily standard deviation and Used SQFT (250) function to annualized the standard deviation.

Does this method correct? do we need to take price movement instead of daily movement (return)?

Please advice me which method is suitable to the calculate standard deviation of Treasury Bond/Sovereign Bond

Personally, I would also calculate, using the same method of yours, the weekly, monthly, and even quarterly returns volatility. If the results differ drastically, then I would ask a specialist about what is the norm in this cases (not my field btw).