  Freire et al. (2009, MNRAS, 396, 1764) have put forward a technique for
timing the double pulsar system PSR J0737-3039A/B (hereafter A and B,
respectively). Their technique can be used to determine the sense of rotation
of A relative to its orbital plane. In this paper, we present another technique
with the same purpose. Two well-known periods, the sidereal day and solar day,
are often used to define the spin period of the earth. Their difference is
caused by a kinematic effect which correlated with earth's rotation and
revolution. We think that this kinematic effect should exist in the double
pulsar system and can be used to determine the sense of rotation of the
pulsars. Commonly, B's modulation frequency is considered to be equal to A's
rotation frequency, because B's signal is modulated by A's energy flux. When
the kinematic effect is considered, B's modulation frequency will be, similar
to the solar day and sidereal day, a little higher or lower than A's rotation
frequency. If this frequency offset can be found, A's rotation sense will be
determined and the position of the lighthouse model will be consolidated.
