Figure 6-36.--Block diagram of linefinder operation.

save space, switching equipment is shared. The main

linefinder start signal to the linefinder. This signal

pieces of equipment used in linefinding are the line

causes the XY switch to step automatically in the X

circuit, the linefinder, and the allotter.

direction, searching for the level in the wirebank

where the calling line is located. The XX-X bank and

LINE CIRCUIT.-- Since the shared equipment

wipers serve to indicate the tens level (level 4 would

must be available to all line stations on an equal basis,

be the tens level for line 45) of the calling line. When

there must be a method of indicating that a line station

the XY switch reaches this level, it stops and starts

requires switching equipment. The line circuit

moving into the wire bank in the Y direction. When

performs this task by sending a signal to the switching

the proper line is located, it stops again and

equipment when a station wishes to originate a call

establishes the necessary connections so that the

(lifts the receiver from the cradle to operate the hook

calling station may control the connector with the dial

switch). There is one line circuit associated with each

line station in the system, arranged so that on an

and complete the call. A dial tone then informs the

incoming call to the station, the shared switching

calling party that the line has been found. The

equipment is not connected to the station.

linefinder remains connected to the line during the

entire call and is released when the calling party hangs

LINEFINDER.-- Figure 6-36 illustrates the

up the handset.

basic principles of linefinding. For the sake of

simplicity, the allotter is not shown. When the calling

Only one linefinder is shown in figure 6-36. When

party operates the hook switch by removing the

other calls are made simultaneously from other

handset from the cradle, the line circuit sends a

stations, additional linefinders must be available. The

Figure 6-36.--Block diagram of linefinder operation.

6-39