Marker path finding arrangement including immediate ring

Claim 1

In a telephone system; marker apparatus to select paths and establish connections between a first set of terminals and a second set of terminals through a first plurality of switching stages via a plurality of intermediate junctors and a second plurality of switching stages arranged in tandem between terminals of the first set and terminals of the second set, each of said stages comprising a plurality of relays arranged in coordinate arrays, at the coordinate points of each of said arrays, each relay having a normally open set of its own contacts connected in series with its hold winding, there being links interconnecting adjacent stages, a hold conductor interconnecting the series combination of the hold winding and normally open contacts of a relay in each of the adjacent stages, busy links have the hold path contacts closed at each end and having holding current flowing through the hold windings so that a given potential appears on the hold conductor; a plurality of ringing generators, interrupter means having a first means for applying pulses of operating potentials in a time displaced relationship to said plurality of ringing generators; said plurality of intermediate junctors divided into a plurality of groups, each of said plurality of groups of intermediate junctors having connected thereto one of said plurality of ringing generators; said marker apparatus comprising an arrangement for selecting a group of possIble links via said second plurality of switching stages for a given connection of said second set of terminals to said intermediate junctors and for connecting the hold conductors thereof to individual inputs of a detecting arrangement, first means in the detecting arrangement to distinguish between the circuit conditions on an idle link and the said potential on a busy link conductor, a plurality of combinational logic gates, a second means in said interrupting means for applying to said logic gates pulses preceding the corresponding pulses from said first means, only said logic gates operated responsive to a nonbusy condition of the links in a path from a terminal for said given connection to available junctors that have a pulse from said second means to apply a test potential to said intermediate junctor group corresponding to said ringing generator, means in said junctors effective in an idle condition thereof to pass said test potential through to a test terminal, said marker apparatus further comprising a second arrangement for selecting a group of possible links via said first plurality of switching stages for a given connection and for connecting the hold conductors thereof and said junctor test terminals to individual inputs of a detecting arrangement, means in the detecting arrangement to distinguish between the circuit condition on an idle link and the said potential on a busy link hold conductor, a route selector comprising a scanning arrangement having counting means and coincidence checking means, with connections from the counting means and the detecting arrangement to the coincidence checking means, means to produce a path-found signal from the coincidence checking means responsive to the counting means being in a position corresponding to a path via idle links and an available intermediate junctor as indicated by the presence of a test potential on said test terminal.