Browse Prior Art Database

Transmission Line Multiplexor

IP.com Disclosure Number: IPCOM000075954D
Original Publication Date: 1971-Dec-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Hippert, RO: AUTHOR [+3]

Abstract

Described is a switching technique for mutliplexing a number of transmission lines into a single receiver. Data from keyable entry units, not shown, is bipolar in form and swings approximately plus or minus four volts around ground. A typical signal is illustrated in Fig. 2. It is possible to attach any number of keyable entry units to a single receiver.

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Transmission Line Multiplexor

Described is a switching technique for mutliplexing a number of transmission lines into a single receiver. Data from keyable entry units, not shown, is bipolar in form and swings approximately plus or minus four volts around ground. A typical signal is illustrated in Fig. 2. It is possible to attach any number of keyable entry units to a single receiver.

In order to select one of the key entry units, a six-volt signal is applied to the selected point V1 - V4 illustrated in Fig. 1. Thus, if V1 is brought to six volts and all of the others are at ground, the gates of silicon-controlled rectifier SCR1 and SCR2 will be forward biased with respect to the cathodes. Due to a +5 volt center tap on the transformer, all of the other SCR's will have a reverse gate to cathode voltage applied thereto. The states described above are from a DC standpoint and do not take into account AC signals on the selected or unselected lines. Assuming that the data is as shown in Fig. 2 and appears on the selected transmission line XMTR, AC ground will now be at +5 volts DC. With a positive pulse on the line at A'0 - B'0, SCR1 will now conduct, since the positive voltage from the anode to the cathode will forward bias the diode. D2 will also be forward biased to complete the termination. D1 and SCR2 will not be conducting. The voltage A - B will now be that of A'0 - B'0 minus the loss of the transmission line and the forward diode drops of SCR1 and D2. From the above, it can be seen that when a negative pulse occurs A'0 - B'0, SCR2 and D1 are the conducting diodes and SCR1 and D2 are tu...