Interstellar signals might be intermittent for many reasons, such as targeted sequential transmissions, isotropic broadcasts that are not 'on' continuously or many other reasons. The time interval between such signals would be important, because searchers would need to observe for long enough to achieve an initial detection and possibly determine a period. This article suggests that: (1) the power requirements of interstellar transmissions could be reduced by orders of magnitude by strategies that would result in intermittent signals, (2) planetary rotation might constrain some transmissions to be intermittent and in some cases to have the period of the source planet, and (3) signals constrained by planetary rotation might often have a cadence in the range of 10–25 h, if the majority of planets in our Solar system are taken as a guide. Extended observations might be needed to detect intermittent signals and are rarely used in SETI but are feasible, and seem appropriate when observing large concentrations of stars or following up on good candidate signals.

中文翻译：

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SETI中的间歇性信号和行星日

由于许多原因，星际信号可能是间歇性的，例如有针对性的顺序传输、非连续“开启”的各向同性广播或许多其他原因。这些信号之间的时间间隔很重要，因为搜索者需要观察足够长的时间才能实现初始检测并可能确定一个周期。本文建议：（1）星际传输的功率需求可以通过会导致间歇信号的策略减少几个数量级，（2）行星旋转可能会限制某些传输是间歇性的，并且在某些情况下具有周期(3) 如果以我们太阳系中的大多数行星为指导，受行星自转约束的信号通常可能有 10-25 小时范围内的节奏。