Krohn-Hite Function Generator (Model 2400)

ECE 351 ELECTROMAGNETICS

EXPERIMENT EM1

CROSSTALK IN WIRES

OBJECTIVE: The purpose of this experiment is to demonstrate the phenomena of crosstalk in wires and the effect that various wiring schemes have on crosstalk.

EQUIPMENT: Oscilloscope Krohn-Hite Function Generator (Model 2400) Connectors and Clip Leads Four Cable Assemblies

I. EQUIPMENT SETUP A. INITIAL SETTING ON OSCILLOSCOPE Select a Dual Trace CH 1 : Amplitude setting at 1 V/div. Ensure AC is selected. CH 2 : Amplitude setting at 10 mV/div. Ensure AC is selected.

A TRIGGER: COUPLING: AC SOURCE: CH 1 To lock onto the signal, adjust SLOPE and/or LEVEL.

B. FUNCTION GENERATOR MULTIPLIER (Hz) 10 K WAVEFORM Sinusoid D.C. OFFSET Off (by pushing knob in) AMPLITUDE Minimum FREQUENCY Minimum MODE (on right side) CONT

II. PROCEDURE A. CROSSTALK IN CABLE ASSEMBLY 1 (Non-twisted, separate ground).

1. Connect the test leads to cable assembly 1 as shown in figure a.

2. Adjust the Function Generator FREQUENCY to 30 kHz and the output level at V1 to 4.0 V p-p. Measure V2 (p-p).

1 3. Keeping V1 at 4.0 V p-p, measure V2 at 100 kHz.

4. Repeat this measurement (maintaining V1) at frequencies of 300, 500, 700 and 900 kHz. Continue for 1 and 3 MHz.

5. Switch the function generator to supply a triangle wave of frequency 100 kHz with V1 set to 4.0 V p-p. Sketch V1 and V2. Try to give an explanation for the shape of V2.

B. CROSSTALK IN CABLE ASSEMBLY 2 (Non-twisted, shared ground).

Connect the test leads to cable assembly 2 as shown in figure b. Switch the function generation back to a sinuosidal wave. Repeat steps 2,3 and 4 of part A.

C. CROSSTALK IN CABLE ASSEMBLY 3 (Twisted, separate ground).

Repeat part (B) for the twisted pair using the assembly shown in figure a.

D. CROSSTALK IN CABLE ASSEMBLY 4 (RG-58 coaxial cable).

Repeat again for the coaxial cable arrangement using the assembly shown in figure c.

III. ASSIGNMENT A. Your group should state the objective of this lab and write up your results

B. Provide a table which shows V2/V1 and 20*log(V2/V1) versus frequency for the results obtained in parts II.

C. Plot V2/V1 versus frequency using a semilog scale for frequency for all cases (i.e., put all cases on the same plot). Repeat this, but now plot 20*log(V2/V1) versus frequency using a semilog scale for frequency.

D. Comment on the differences observed in the various cases, giving possible explanations for the differences.