One of the common misconceptions I've seen when discussing naval SAMs is that all you need to guide a SARH missile is a target illuminator and if you have an active radar missile you don't even need that, just the launcher. There's a lot more to it than that. So I thought I'd post this article that explains the history and operation of the SM-2 and ESSM missile data links and how intimately integrated they are with the ship's radar and CMS. Just because a ship has a mk41 launcher doesn't mean you can launch any mk41 capable missile from it. This information is specific to those missiles, but it's important to understand that data links are crucial in almost all modern medium to long range SAMs. https://www.jhuapl.edu/techdigest/TD/td2804/Cole.pdf The Preplanned Product Improvement Link discussed is now called the Joint Universal Waveform Link (JUWL). This missile link is used by SPY-3 and APAR Blk 2.