if ($t >= $dxchan->{pc50_t} + $DXProt::pc50_interval) {
$dxchan->send(pc50(scalar DXChannel::get_all_users));
$dxchan->{pc50_t} = $t;
if ($t >= $dxchan->{pc50_t} + $DXProt::pc50_interval) {
$dxchan->send(pc50(scalar DXChannel::get_all_users));
$dxchan->{pc50_t} = $t;