Consider a terminal connected to the Network at the Network Termination Point , NTP. [terminal]---+---[ line ]---[exchange] NTP What is the Zc of the Terminal? What is the Zc of the Exchange? What is the Z looking into the line towards the Exchange at the NTP? What is the Z looking into the line towards the Terminal at the Exchange? The NTP is nominally 2km from the Exchange.
What is the TransHybrid loss caused by different line lengths? 2x2 matrix model being simulated:- [V] = [ Line(length) ] [ nominal exchange input impedance is 300 ohm + 1000 ohm || 220 nF ] [v] [I] [i] Use Shunt Termination when you need Io =0 and Vo != 0Trans Hybrid loss - E/M,dB: all: A = E/M , M=1, V=0 B = E/V , M=0, V = 1.0 C = I/M , M=1, V=0 D = I/V , M=0, V = 1.0
Use Series Termination when you need Vo =0 and Io != 0
Hybrid | line | seriesTermination
Calculate Mic to ear gains.
/* This models the hybrid inputing 4 wire to 2 wire [ M ] = [ ] [V] see paper on loudness ratings [ E ] [ ] [I] */ M, E near Phone m, e far phoneComplex Z //Th SIN has //The terminal Figure 1: Terminal Complex Impedance Network = 370+ 620//310nf
//The nominal exchange input impedance is 300 ohm + 1000 ohm || 220 nF (see Figure 2) at NTP.
//The NTP is nominally 2km from the Exchange. // The Balance impedance for the exchange is not published. we need to plot what we present. we want E/M where M is 4 wire Vout, E = 4 wire Vin
--[line]--[OC term]--[short] V near Voltage,I near Current v far voltage, i far current //The terminal Figure 1: Terminal Complex Impedance Network = 370+ 620//310nf var z_complex_z = z_abc(370, 620, 310.0e-9 , freq[c] ); //The nominal exchange input impedance is 300 Ù + 1000 Ù || 220 nF (see Figure 2). var z_complex_znom = z_abc(300.0, 1000.0, 220.0e-9 , freq[c] ); w =freq[c]*2*pi; rar=1.0;rai=0.0; rbr=0.0;rbi=0.0; rcr=0.0;rci=0.0; rdr=1.0;rdi=0.0; /* This models the hybrid inputing 4 wire to 2 wire [ M ] = [ ] [V] see paper on loudness ratings [ E ] [ ] [I] convert(); /* We want E/M , use convert() to get [E] = [ a b ] [M] [I] [ c d ] [V] V is a function of M, so append series Zterm and this allows us to short V */ // The Balance impedance for the exchange is not published twoto4(z_complex_z.r,z_complex_z.i, z_complex_znom.r,z_complex_znom.i ); /* lines */ lines( ll_ ); //Add series Termination so that output can be short circuited. // add Term Z = 370+ 620//310nf // add exchange Z = 300+ 1000//220nf // if we want Zin add Zexch if ( term ==0 ){ multz(( z_complex_z.r, z_complex_z.i ) } else { multz( z_complex_znom.r, z_complex_znom.i ) } convert(); /* We want E/M , used convert() to get [E] = [ a b ] [M] [I] [ c d ] [V] output is short circuited to allow V=0 so E = a M */