Agilent E7405A - Manual

8 Chapter 1 Making Basic Measurements What is in This Chapter What is in This Chapter This chapter demonstrates basic analyzer measurements with examples of typical measurements; each measurement focuses on different functions. The measurement procedures covered in this chapter are listed below. • “...

Chapter 1 9 Making Basic Measurements What is in This Chapter Test Equipment Test Equipment Specifications Recommended Model Signal Sources Signal Generator (2) 0.25 MHz to 4.0 GHzExt Ref Input E4433B or E443XB series Adapters Type-N (m) to BNC (f) (3) 1250-0780 Termination, 50 Ω Type-N (m) 908A Cab...

10 Chapter 1 Making Basic Measurements Comparing Signals Comparing Signals Using the analyzer, you can easily compare frequency and amplitude differences between signals, such as radio or television signal spectra. The analyzer delta marker function lets you compare two signals when both appear on t...

Chapter 1 11 Making Basic Measurements Comparing Signals Figure 1-1 Placing a Marker on the 10 MHz Signal 9. Press Marker , Delta , to activate a second marker at the position of the first marker. 10. Move the second marker to another signal peak using the front-panel knob, or by pressing Peak Searc...

12 Chapter 1 Making Basic Measurements Comparing Signals Figure 1-2 Using the Marker Delta Function Signal Comparison Example 2: Measure the frequency and amplitude difference between two signals that do not appear on the screen at one time. (This technique is useful for harmonic distortion tests wh...

Chapter 1 13 Making Basic Measurements Comparing Signals 10. Press Marker , Delta to anchor the position of the first marker and activate a second marker. 11. Press FREQUENCY , Center Freq , and the ( ↑ ) key to increase the center frequency by 10 MHz. The first marker moves to the left edge of the ...

14 Chapter 1 Making Basic Measurements Resolving Signals of Equal Amplitude Resolving Signals of Equal Amplitude Two equal-amplitude input signals that are close in frequency can appear as a single signal trace on the analyzer display. Responding to a single-frequency signal, a swept-tuned analyzer ...

Chapter 1 15 Making Basic Measurements Resolving Signals of Equal Amplitude Resolving Signals Example: Resolve two signals of equal amplitude with a frequency separation of 100 kHz. 1. Connect two sources to the analyzer input as shown in Figure 1-4 . Figure 1-4 Setup for Obtaining Two Signals 2. Se...

16 Chapter 1 Making Basic Measurements Resolving Signals of Equal Amplitude Figure 1-5 Unresolved Signals of Equal Amplitude 4. Since the resolution bandwidth must be less than or equal to the frequency separation of the two signals, a resolution bandwidth of 100 kHz must be used. Change the resolut...

Chapter 1 17 Making Basic Measurements Resolving Signals of Equal Amplitude 5. Decrease the video bandwidth to 10 kHz, by pressing Video BW , 10, kHz . Two signals are now visible as shown in Figure 1-7 . Use the front-panel knob or step keys to further reduce the resolution bandwidth and better res...

18 Chapter 1 Making Basic Measurements Resolving Small Signals Hidden by Large Signals Resolving Small Signals Hidden by Large Signals When dealing with the resolution of signals that are close together and not equal in amplitude, you must consider the shape of the IF filter of the analyzer, as well...

20 Chapter 1 Making Basic Measurements Resolving Small Signals Hidden by Large Signals 5. Set the 300 MHz signal to the reference level by pressing Mkr → and then Mkr → Ref Lvl . If a 10 kHz filter with a typical shape factor of 15:1 is used, the filter will have a bandwidth of 150 kHz at the 60 dB ...

Chapter 1 21 Making Basic Measurements Resolving Small Signals Hidden by Large Signals 7. Set the resolution bandwidth to 30 kHz by pressing BW/Avg , Res BW , 30, kHz . When a 30 kHz filter is used, the 60 dB bandwidth could be as wide as 450 kHz. Since the half-bandwidth (225 kHz) is wider than the...

22 Chapter 1 Making Basic Measurements Making Better Frequency Measurements Making Better Frequency Measurements A built-in frequency counter increases the resolution and accuracy of the frequency readout. When using this function, if the ratio of the resolution bandwidth to the span is too small (l...

Chapter 1 23 Making Basic Measurements Making Better Frequency Measurements NOTE Marker count properly functions only on CW signals or discrete spectral components. The marker must be > 26 dB above the noise. 9. Increase the counter resolution by pressing Resolution and then entering the desired ...

24 Chapter 1 Making Basic Measurements Decreasing the Frequency Span Around the Signal Decreasing the Frequency Span Around the Signal Using the analyzer signal track function, you can quickly decrease the span while keeping the signal at center frequency. This is a fast way to take a closer look at...

Chapter 1 25 Making Basic Measurements Decreasing the Frequency Span Around the Signal Figure 1-14 Detected Signal 8. Turn on the frequency tracking function by press FREQUENCY and Signal Track and the signal will move to the center of the screen, if it is not already positioned there. See figure Fi...

26 Chapter 1 Making Basic Measurements Decreasing the Frequency Span Around the Signal 9. Reduce span and resolution bandwidth to zoom in on the marked signal by pressing SPAN , Span , 200, kHz . If the span change is large enough, span will decrease in steps as automatic zoom is completed. See Figu...

Chapter 1 27 Making Basic Measurements Tracking Drifting Signals Tracking Drifting Signals The signal track function is useful for tracking drifting signals that drift relatively slowly. To place a marker on the signal you wish to track, use Peak Search . Pressing FREQUENCY , Signal Track (On) will ...

28 Chapter 1 Making Basic Measurements Tracking Drifting Signals Figure 1-17 Signal With Default Span 4. Press Peak Search . 5. Set the span to 10 MHz by pressing SPAN , Span , 10, MHz . See Figure 1-18 . Figure 1-18 Signal With 10 MHz Span 6. Press SPAN , Span Zoom , 500, kHz . Notice that the sign...

Chapter 1 29 Making Basic Measurements Tracking Drifting Signals Figure 1-19 Signal With 500 kHz Span 7. Tune the frequency of the signal generator in 10 kHz increments. Notice that the center frequency of the analyzer also changes in 10 kHz increments, centering the signal with each increment. See ...

30 Chapter 1 Making Basic Measurements Tracking Drifting Signals 8. The signal frequency drift can be read from the screen if both the signal track and marker delta functions are active. Set the analyzer and signal generator as follows: a. Press Marker, Delta . b. Tune the frequency of the signal ge...

Chapter 1 31 Making Basic Measurements Tracking Drifting Signals d. Set the center frequency to 300 MHz by pressing FREQUENCY, Center Freq , 300, MHz . See Figure 1-22 . Figure 1-22 Signal With Default Span 4. Press Peak Search . 5. Set the span to 10 MHz by pressing SPAN , Span , 10, MHz . See Figu...

32 Chapter 1 Making Basic Measurements Tracking Drifting Signals 6. Press SPAN , Span Zoom , 500, kHz . Notice that the signal has been held in the center of the display. See Figure 1-24 . Figure 1-24 Signal With 500 KHz Span 7. Turn off the signal track function by pressing FREQUENCY , Signal Track...

Chapter 1 33 Making Basic Measurements Tracking Drifting Signals Figure 1-25 Viewing a Drifting Signal With Max Hold and Clear Write

34 Chapter 1 Making Basic Measurements Measuring Low Level Signals Measuring Low Level Signals The ability of the analyzer to measure low level signals is limited by the noise generated inside the analyzer. A signal may be masked by the noise floor so that it is not visible. This sensitivity to low ...

Chapter 1 35 Making Basic Measurements Measuring Low Level Signals 10. Reduce the span to 1 MHz. Press SPAN , Span , and then use the step-down key ( ↓ ) until the span is set to 1 MHz. See Figure 1-26 . Figure 1-26 Low-Level Signal 11. Press AMPLITUDE , Attenuation . Press the step-up key ( ↑ ) to ...

36 Chapter 1 Making Basic Measurements Measuring Low Level Signals 12. To see the signal more clearly, enter 0 dB. Zero decibels of attenuation makes the signal more visible. See Figure 1-28 . Figure 1-28 Using 0 dB Attenuation CAUTION Before connecting other signals to the analyzer input, increase ...

Chapter 1 37 Making Basic Measurements Measuring Low Level Signals 9. Place the signal at center frequency by pressing Peak Search , Marker → , Mkr → CF . 10. Press BW/Avg , Res BW , and then ↓ . The low level signal appears more clearly because the noise level is reduced. As shown in Figure 1-29 . ...

38 Chapter 1 Making Basic Measurements Measuring Low Level Signals 3. On the analyzer, perform a factory preset by pressing Preset , Factory Preset (if present). 4. Set the center frequency of the analyzer to 300 MHz by pressing FREQUENCY , Center Freq , 300, MHz . 5. Set the span to 5 MHz by pressi...

Chapter 1 39 Making Basic Measurements Measuring Low Level Signals NOTE The video bandwidth must be set wider than the resolution bandwidth when measuring impulse noise levels. Figure 1-31 Decreasing Video Bandwidth Measuring Low Level Signals Example 4: If a signal level is very close to the noise ...

40 Chapter 1 Making Basic Measurements Measuring Low Level Signals 1. Connect a signal generator to the analyzer input. 2. Set the signal generator frequency to 300 MHz with an amplitude of − 80 dBm. 3. On the analyzer, perform a factory preset by pressing Preset , Factory Preset (if present). 4. Se...

Chapter 1 41 Making Basic Measurements Measuring Low Level Signals 11. To set the number of samples, use the numeric keypad. For example, press Average (On) , 25, Enter . As shown in Figure 1-33 . During averaging, the current sample number appears at the left side of the graticule. The number of sa...

42 Chapter 1 Making Basic Measurements Identifying Distortion Products Identifying Distortion Products Distortion from the Analyzer High level input signals may cause analyzer distortion products that could mask the real distortion measured on the input signal. Using trace 2 and the RF attenuator, y...

Chapter 1 43 Making Basic Measurements Identifying Distortion Products Figure 1-34 Harmonic Distortion 8. Change the center frequency to the value of one of the observed harmonics by pressing Peak Search , Next Peak , Marker → , Mkr → CF . 9. Change the span to 50 MHz: press SPAN , Span , 50, MHz . ...

44 Chapter 1 Making Basic Measurements Identifying Distortion Products 12. To determine whether the harmonic distortion products are generated by the analyzer, first save the screen data in trace 2 as follows: a. Press Trace/View , Trace (2) , then Clear Write . b. Allow the trace to update (two swe...

Chapter 1 45 Making Basic Measurements Identifying Distortion Products Figure 1-37 No Harmonic Distortion Third-Order Intermodulation Distortion Two-tone, third-order intermodulation distortion is a common test in communication systems. When two signals are present in a non-linear system, they can i...

46 Chapter 1 Making Basic Measurements Identifying Distortion Products Figure 1-38 Third-Order Intermodulation Equipment Setup NOTE The combiner should have a high degree of isolation between the two input ports so the sources do not intermodulate. 2. Set one source (signal generator) to 300 MHz and...

Chapter 1 47 Making Basic Measurements Identifying Distortion Products The analyzer automatically sets the attenuation so that a signal at the reference level will be a maximum of − 30 dBm at the input mixer. 10. Press BW/Avg , Res BW , and then use the step-down key ( ↓ ) to reduce the resolution b...

50 Chapter 1 Making Basic Measurements Measuring Signal-to-Noise 11. Press More , Function , Marker Noise to view the results of the signal to noise measurement. See Figure 1-41 . Figure 1-41 Measuring the Signal-to-Noise Read the signal-to-noise in dB/Hz, that is with the noise value determined for...

Chapter 1 51 Making Basic Measurements Making Noise Measurements Making Noise Measurements There are a variety of ways to measure noise power. The first decision you must make is whether you want to measure noise power at a specific frequency or the total power over a specified frequency range, for ...

52 Chapter 1 Making Basic Measurements Making Noise Measurements Figure 1-42 Setting the Attenuation 8. Activate the noise marker by pressing Marker , More , Function , Marker Noise . Note that the display detection automatically changed to “Avg” which can be manually set by pressing Det/Demod, Aver...

Chapter 1 53 Making Basic Measurements Making Noise Measurements Figure 1-43 Activating the Noise Marker 9. The noise marker value is based on the mean of 5% of the total number of sweep points centered at the marker. The points averaged span one-half of a division. To see the effect, move the marke...

54 Chapter 1 Making Basic Measurements Making Noise Measurements NOTE Notice the video bandwidth changed to 100 kHz. The ratio between the video bandwidth (VBW) and the resolution bandwidth (RBW) must be ≥ 10/1 to maintain the accuracy of the measurement. Figure 1-45 Increased Resolution Bandwidth 1...

Chapter 1 55 Making Basic Measurements Making Noise Measurements Figure 1-46 Noise Marker in Signal Skirt 13. Set the analyzer to zero span at the marker frequency by pressing Mkr → , Mkr → CF , SPAN , Zero Span , Marker . Note that the marker amplitude value is now correct since all points averaged...

56 Chapter 1 Making Basic Measurements Making Noise Measurements Noise Measurement Example 2: The Normal marker can also be used to make a single frequency measurement as described in the previous example, again using video filtering or averaging to obtain a reasonably stable measurement. While vide...

Chapter 1 57 Making Basic Measurements Making Noise Measurements 10. Measure the power between markers by pressing Marker , More, Function , Band Power . The analyzer displays the total power between the markers. See Figure 1-48 . 11. Add a discrete tone to see the effects of the reading. Turn on th...

58 Chapter 1 Making Basic Measurements Making Noise Measurements Figure 1-49 Measuring the Power in the Span

Chapter 1 59 Making Basic Measurements Demodulating AM Signals (Using the Analyzer As a Fixed Tuned Receiver) Demodulating AM Signals (Using the Analyzer As a Fixed Tuned Receiver) The zero span mode can be used to recover amplitude modulation on a carrier signal. The analyzer operates as a fixed-tu...

60 Chapter 1 Making Basic Measurements Demodulating AM Signals (Using the Analyzer As a Fixed Tuned Receiver) b. RF Output Power –10 dBm c. AM On d. AM Rate 1 kHz e. AM Depth 80% 2. Set the analyzer as follows: a. Press Preset , Factory Preset (if present). b. Set the center frequency to 300 MHz by ...

Chapter 1 61 Making Basic Measurements Demodulating AM Signals (Using the Analyzer As a Fixed Tuned Receiver) 6. Select zero span by either pressing SPAN , 0, Hz; or pressing SPAN , Zero Span . See Figure 1-51 . 7. Change the sweep time to 5 ms by pressing Sweep , Sweep Time (Man), 5, ms . 8. Since ...

Chapter 1 63 Making Basic Measurements Demodulating AM Signals (Using the Analyzer As a Fixed Tuned Receiver) Figure 1-54 Measuring Time Parameters 10. You can turn your analyzer into a % AM indicator as follows: a. Set trigger to free run by pressing Trig , Free Run . b. Set the sweep time to 5 sec...

64 Chapter 1 Making Basic Measurements Demodulating AM Signals (Using the Analyzer As a Fixed Tuned Receiver) Figure 1-55 Continuous Demodulation of an AM Signal

Chapter 1 65 Making Basic Measurements Demodulating FM Signals Demodulating FM Signals As with amplitude modulation (see page 59 ) you can utilize zero span to demodulate an FM signal. However, unlike the AM case, you cannot simply tune to the carrier frequency and widen the resolution bandwidth. Th...

66 Chapter 1 Making Basic Measurements Demodulating FM Signals 4. Set the span to 1 MHz by pressing SPAN , Span , 1, MHz . 5. Set the Y-Axis Units to dBm by pressing AMPLITUDE , More, Y-Axis Units, dBm . 6. Set the reference level to –20 dBm by pressing AMPLITUDE , Ref Level , –20, dB m . 7. Set the...

Chapter 1 67 Making Basic Measurements Demodulating FM Signals Figure 1-57 Determining the Offset Demodulate the FM Signal 1. Connect an antenna to the analyzer INPUT. 2. Perform a factory preset by pressing Preset , Factory Preset (if present). 3. Tune the analyzer to a peak the peak of one of your...

68 Chapter 1 Making Basic Measurements Demodulating FM Signals 12. Activate single sweep by pressing Single . See Figure 1-58 . Figure 1-58 Demodulating a Broadcast Signal

70 Chapter 2 Making Complex Measurements What’s in This Chapter What’s in This Chapter This chapter provides information for making complex measurements. The procedures covered in this chapter are listed below. • “Making Stimulus Response Measurements” on page 71 . • “Making a Reflection Calibration...

Chapter 2 71 Making Complex Measurements Making Stimulus Response Measurements Making Stimulus Response Measurements What Are Stimulus Response Measurements? Stimulus response measurements require a source to stimulate a device under test (DUT), a receiver to analyze the frequency response character...

72 Chapter 2 Making Complex Measurements Making Stimulus Response Measurements Figure 2-1 Transmission Measurement Test Setup 2. Perform a factory preset by pressing Preset , Factory Preset (if present). 3. Set the Y-Axis Units to dBm by pressing AMPLITUDE , More, Y-Axis Units, dBm . 4. Since we are...

Chapter 2 73 Making Complex Measurements Making Stimulus Response Measurements Figure 2-2 Tracking Generator Output Power Activated 7. Put the sweep time of the analyzer into stimulus response auto coupled mode by pressing Sweep , Swp Coupling (SR). Auto coupled sweep times are usually much faster f...

74 Chapter 2 Making Complex Measurements Making Stimulus Response Measurements Figure 2-3 Decrease the Resolution Bandwidth to Improve Sensitivity 10.You might notice a decrease in the displayed amplitude as the resolution bandwidth is decreased, (if the analyzer is an E7402A, E7403A, E7404A, or E74...

Chapter 2 75 Making Complex Measurements Making Stimulus Response Measurements 12.Reconnect the DUT to the analyzer. Note that the units of the reference level have changed to dB, indicating that this is now a relative measurement. Press Trace/View, More, Normalize, Norm Ref Posn to change the norma...

76 Chapter 2 Making Complex Measurements Making Stimulus Response Measurements Tracking Generator Unleveled Condition When using the tracking generator, the message TG unleveled may appear. The TG unleveled message indicates that the tracking generator source power ( Source , Amplitude ) could not b...

78 Chapter 2 Making Complex Measurements Making Stimulus Response Measurements NOTE To reduce ripples caused by source return loss, use 10 dB (E7401A) or 8 dB (all other models) or greater tracking generator output attenuation. Tracking generator output attenuation is normally a function of the sour...

Chapter 2 79 Making Complex Measurements Making Stimulus Response Measurements 11.The knob or the data entry keys can be used to change the N dB value from − 3 dB to − 60 dB to measure the 60 dB bandwidth of the filter. See Figure 2-7 . Figure 2-7 N dB Bandwidth Measurement at –60 dB 12.Press N dB P...

Chapter 2 81 Making Complex Measurements Making Stimulus Response Measurements Figure 2-9 Tracking Generator Output Power Activated in Log Sweep 10.Put the sweep time of the analyzer into stimulus response auto coupled mode by pressing Sweep , then Swp Coupling (SR). See Figure 2-9 . Auto coupled sw...

82 Chapter 2 Making Complex Measurements Making Stimulus Response Measurements Figure 2-10 Normalized Trace After Reconnecting DUT 14.Press Marker , Delta Pair (Ref), 10, MHz to place the reference marker at the specified cutoff frequency. 15.Press Delta Pair (∆) , 20, MHz to place the second marker...

Chapter 2 83 Making Complex Measurements Making Stimulus Response Measurements Figure 2-12 Minimum Stop Band Attenuation

84 Chapter 2 Making Complex Measurements Making a Reflection Calibration Measurement Making a Reflection Calibration Measurement The calibration standard for reflection measurements is usually a short circuit connected at the reference plane (the point at which the device under test (DUT) will be co...

Chapter 2 85 Making Complex Measurements Making a Reflection Calibration Measurement Reflection Calibration 1. Connect the DUT to the directional bridge or coupler as shown in Figure 2-13 . Terminate the unconnected port of the DUT. NOTE If possible, use a coupler or bridge with the correct test por...

86 Chapter 2 Making Complex Measurements Making a Reflection Calibration Measurement Figure 2-14 Short Circuit Normalized Measuring the Return Loss 1. After calibrating the system with the above procedure, reconnect the filter in place of the short circuit without changing any analyzer settings. 2. ...

Chapter 2 87 Making Complex Measurements Making a Reflection Calibration Measurement Converting Return Loss to VSWR Return loss can be expressed as a voltage standing wave ratio (VSWR) value using the following table or formula: Where: RL is the measured return loss value. VSWR is sometimes stated a...

88 Chapter 2 Making Complex Measurements Demodulating and Listening to an AM Signal Demodulating and Listening to an AM Signal The functions listed in the menu under Det/Demod allow you to demodulate and hear signal information displayed on the analyzer. Simply place a marker on a signal of interest...