Editing Anti-ballistic missile (section)

===Canada===
Other countries were also involved in early ABM research. A more advanced project was at [[DRE Valcartier|CARDE]] in Canada, which researched the main problems of ABM systems. A key problem with any radar system is that the signal is in the form of a cone, which spreads with distance from the transmitter. For long-distance interceptions like ABM systems, the inherent inaccuracy of the radar makes an interception difficult. CARDE considered using a [[terminal guidance]] system to address the accuracy concerns, and developed several advanced [[infrared]] detectors for this role. They also studied a number of missile airframe designs, a new and much more powerful solid rocket fuel, and numerous systems for testing it all. After a series of drastic budget reductions during the late 1950s the research ended. One offshoot of the project was [[Gerald Bull]]'s system for inexpensive high-speed testing, consisting of missile airframes shot from a [[sabot (firearms)|sabot]] round, which would later be the basis of [[Project HARP]]. Another was the [[CRV7]] and [[Black Brant (rocket)|Black Brant]] rockets, which used the new solid rocket fuel.