But when the congregation is to be gathered together,.... At the door of the tabernacle of the congregation, and not to move in separate camps or bodies one after another:
you shall blow, but you shall not sound an alarm; blow with an even and uninterrupted sound, and not with a broken and quavering one; by which the congregation and camps were distinguished from one another, the same certain sound being given to each constantly, whereby they knew which were called to motion: see 1-Corinthians 14:8; according to Ben Gersom blowing was a voice drawn out, and joined or continued; an alarm, a voice not joined, but broken.

But to call the congregation together they were to blow, not to sound an alarm. תּקע signifies blowing in short, sharp tones. הריע = תּרוּעה תּקע, blowing in a continued peal.