“What now, inventor boy?” his copilot asked. “Don’t you ever give that brain of yours a rest?”
“Oh, hi, Bud!” Tom looked around absent-mindedly. “I’m just trying to figure out a way to crack the Brungarians’ antisonar system.”
“Good night!” Bud sank down on a lab stool.
136 THE ELECTRONIC HYDROLUNG
“You’ve come up with a way to make our own subs undetectable. Isn’t that enough?”
Tom shook his head. “Not if we want to keep track of those sneaks. And I think I see a way to do it.”
“How?”
“So far, I have been thinking about refining our own search sonar.” Tom explained that the new system he had in mind would send out a complex pulse-that is, an underwater sound wave with many harmonics instead of a single tone, sharp-peaked sound impulse.
“This will make it less likely that their antidetection gear will absorb all of it,”
Tom went on. “What’s not absorbed will return as an echo. I’m also going to modify our receivers. But I’ve still not worked that out.”
Bud nodded, his forehead puckered in a look of concentration. “So-?”
“So our sonar picks up all that hash, and by means of a computer setup filters out the sub’s real echo from the shadow reflections.”
“Hey! Sounds pretty cute,” Bud said.
Tom broke into a dry chuckle. “Right-if I can do it.” After that job, Tom added, he hoped to adapt his own antidetection methods to make hydrolung wearers safe from underwater detection. “And if the Jupiter prober hasn’t been found by that time, Bud, I’m going to request the Navy to let us take over the search alone.”