  We have investigated the charge ordering phase of the quasi one dimensional
quantum antiferromagnet (TMTTF)$_2X$ ($X=$ SbF$_6$, AsF$_6$ and PF$_6$) using
high fields/frequencies electron paramagnetic resonance. In addition to the
uniform displacement of the counter anions involved in the charge order phase,
we report the existence of a superlattice between the spin chains in the
direction $c$, caused by the space modulation of the charge order. When the
field is high enough, the magnetic decoupling of the spin chains allows us to
estimate the interaction between the chains, $J_c<1$~mK, three orders of
magnitude lower than expected from the mean field theory.
