  We analyze radio continuum emission of early-type galaxies with dynamical
measurements of central super-massive black hole (SMBH) masses, and
well-characterized large-scale environments, but regardless on the exact level
of the nuclear activity. The 1.4 GHz radio fluxes collected with $\sim$arcmin
resolution for 62 nearby targets (distances $\lesssim$ 153 Mpc), correspond to
low and very low monochromatic luminosities $L_{\rm r} \sim 10^{35} - 10^{41}$
erg s$^{-1}$. We quantify possible correlations between the radio properties
with the main parameters of supermassive black holes, host galaxies, and hot
gaseous halos, finding a general bimodality in the radio luminosity
distribution, with the borderline between ``radio-bright'' and ``radio-dim''
populations $\log L_{\rm r} / L_{\rm Edd} \simeq -8.5$. We analyze the
far-infrared data for the targets, finding that all radio-bright sources, and
over a half of radio-dim ones, are over-luminous in radio with respect to the
far-infrared--radio correlation. High-resolution radio maps reveal that the
overwhelming majority of radio-dim sources are unresolved on arcsecond scale,
while the bulk of radio-bright sources display extended jets and lobes of low-
and intermediate-power radio galaxies; those jets dominate radio emission of
radio-bright objects. Regarding the origin of the radio emission of radio-dim
sources, we discuss the two main possibilities. One is the ADAF model, in which
the radio and the nuclear X-ray radiative outputs at very low accretion rates,
are both dominated by unresolved jets. The other possibility is that the
radio-dim sources, unlike the radio-bright ones, are characterized by low
values of SMBH spins, so that their radio emission is not related to the jets,
but instead is due to a combination of starforming processes and past nuclear
outbursts.
