I looked into signal glossary, all not random event signals cost 30 for all levels, so it may be better to send signals that caused something to happen when downloaded even on 0 level to get more points. Also, it is better to not send out signals only if they are less than 0,5 MB instead of 1 MB, because most signals that are more than 0,5 MB still cost same amount of points, and all signals that are less than 0,5 MB cost 0 for all levels