&gt; what if there is already a scheduled item? in this case i must schedule<br />&gt; the frequency change item before any other item. also the frame number<br />&gt; of frequency change may be more than 255 frames ahead.<br /><br />Feel free to extend the scheduler to fit your needs.<br /><br /><br />&gt; my suggestion: because hopping sequence is a function of time, the<br />&gt; starting time should also be included in this function (rfch.c).<br /><br />The only function in rfch.c returns the parameter for a given time.<br />It does _NOT_ and should _NOT_ make any change to the parameter itself.<br />That&#39;s left up to the caller because we need to call that function several time.<br /><br />If you want to introduce some call that configure the channel and make changes and stuff, put it into another function and make sure it&#39;s called when required.<br /><br />    Sylvain