Modulating neutrinos is easy. You just control the production rate. For example ramping a fission reactor up and down will create pulses of neutrinos (though it

Modulating neutrinos is easy. You just control the production rate. For example ramping a fission reactor up and down will create pulses of neutrinos (though it's not terribly efficient). For practical neutrino communications, you'd want to use a muon beam to generate your neutrinos. The neutrinos are emitted roughly in the same direction the muons were moving when they decay, so you can make a directional beam, and by controlling the number of muons decaying at any given point in time, either by directly controlling the number of muons or how much time dilation they experience in the beam, you can ramp up and down neutrino production.