A parametric procedure for k-stage radar detection realizing CFAR mode in conditions of clutter with unknown power is offered. This procedure uses an estimate of clutter intensity /spl sigma/ in a "sliding window" of size m for adaptation of (2k-1) thresholds taking into account (2k-1) scale factors. The important practical case of detection of a coherent pulse train with random initial phase on the background of non-correlated Gaussian clutter with unknown variance /spl sigma//sup 2/ is investigated in detail. It is shown that another realization of CFAR mode is possible in this case, namely the following. The estimate of clutter intensity normalizes the decision statistic, thus an adaptation of k-stage detector thresholds is not necessary and it becomes possible to compute the thresholds beforehand by the previously known method; and also there is no need to introduce scale factors which considerably simplifies threshold computation.