Few things that make chance of detection low 1 Primitive species uses primitive methods, another more advanced species would use a new form of transmission/det

Few things that make chance of detection low 1 Primitive species uses primitive methods, another more advanced species would use a new form of transmission/detection to contact equivalent advanced species. 2 the window of a species transmitting could be in hundreds of years at any point of the billions of years the universe a has existed and we have to also be at that same window.