As part of our quest to understand the pulsar radio emission
mechanism, we have undertaken a program to study pulsar signals with
the highest possible time resolution. The so-called "giant pulses"
from the Crab Nebula pulsar are particularly suitable for this work
because they are strong enough to yield good signal to noise ratios at
high enough frequencies to avoid the distortion caused by interstellar
scattering.
I will review the properties of the "giant pulses" and then discuss
our recent results, where we have found that both the time and
frequency signatures of the Crab pulsar's interpulse are distinctly
different from those of the main pulse. Giant main pulses can
occasionally be resolved into short-lived, relatively narrow-band
nanoshots. We believe these nanoshots are produced by soliton
collapse in strong plasma turbulence. Giant interpulses are very
different. Their dynamic spectrum contains narrow, microsecond-long
emission bands. We have detected these proportionately spaced bands
from 4.5 to 10.5 GHz. The bands cannot easily be explained by any
current theory of pulsar radio emission; we speculate on possible new
models.