According to the AD7760 data sheet，，
Combined with the relationship between signal to noise ratio and bit number，
By calculation, the AD7760 did not really reach 24 bits,I would like to know what circumstances can achieve 24 bits？Did i understand it?
The resolution would determine the precision of the ADC converts the analog signal into digital form and this is best measure with DC accuracy measurements like Differential Nonlinearity (DNL), Integral Nonlinearity. For the AD7760, as shown in table2 , the DL is guaranteed monotonic to 24 bits.
The AC accuracy or Dynamic measurements, is when using inputs to ADC are changing, like a sine wave for example. The SNR, SFDR, THD are measured, including in this measurement are the noise contributed from the part and the system as well. As you pointed out on the above formula, the N could mean Effective resolution, Effective number of bits and peak to peak resolution. This may sound very similar, but there are some differences. This is best explain on some articles in the web. You can refer to the link below.
Peak to peak resolution vs. Effective Resolution
Resolution vs ENOB
Currently I am using the AD7760 to complete a data acquisition，but the waveform is：
I do not know why the waveform is this shape？
Retrieving data ...