Shulchan Arukh Orach Chayim · Siman 588

English

Time for sounding the shofar, and regarding this there are 5 paragraphs. The time to sound the shofar is during the day, and not at night. The mitzvah is [binding] from the sunrise [netz hachamah, the sun is visible in the horizon] onwards. And if one sounded since dawn [when the sun has began to illuminate but is not yet visible] one has fulfilled the obligation. However, if one heard the shofar being sounded partly before dawn and partly after dawn, one has not fulfilled one's obligation. Rema: And if there was the shiur (minimal halachic amount) of tekiah blasts in that what he heard in the day, see what was explained in Siman 597 Paragraph 3.

English

If one heard 9 teki'ot during 9 hours in the day, one has fulfilled one's obligation. And this is true even if there were 9 different people [blowing], and one heard a teki'ah from one, and a tru'ah from another, and a teki'ah from another, one has fulfilled. And some say specifically when there was not a break between them with a sound of the shofar that was not fit for that set (of blasts).

English

3. If one hears 9 teki'ot from 9 different people which were sounding the shofar at the same time, one has not fulfilled one's obligation, since there is no simple sound before and after it. Rema: And if two are sounding as one all the order (of blasts), even if one is sounding with a biblical trumpet, one has fulfilled one's obligation as long as one's attention is turned to the shofar.

English

4. This one needed a simple blast at the beginning and this other needed a simple blast at the end, one teki'ah fulfills the obligation of them both.

English

5. If the holy day of Rosh Hashanah falls on Shabbat we do not sound the shofar. Rema: and it is even forbidden to handle a shofar, unless if needed for itself (i.e. in an allowed Shabbos act like to carry water) or it’s place (i.e. on a chair that one wants to sit).