Agilent Spectrum Analysis Basics - Agilent Technologies

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Chapter 8 Modern <strong>Spectrum</strong> Analyzers In previous chapters of this application note, we have looked at the fundamental architecture of spectrum analyzers and basic considerations for making frequency-domain measurements. On a practical level, modern spectrum analyzers must also handle many other tasks to help you accomplish your measurement requirements. These tasks include: • Providing application-specific measurements, such as adjacent channel power (ACP), noise figure, and phase noise • Providing digital modulation analysis measurements defined by industry or regulatory standards, such as GSM, cdma2000, 802.11, or Bluetooth • Performing vector signal analysis • Saving data • Printing data • Transferring data, via an I/O bus, to a computer • Offering remote control and operation over GPIB, LAN, or the Internet • Allowing you to update instrument firmware to add new features and capabilities, as well as to repair defects • Making provisions for self-calibration, troubleshooting, diagnostics, and repair • Recognizing and operating with optional hardware and/or firmware to add new capabilities Application-specific measurements In addition to measuring general signal characteristics like frequency and amplitude, you often need to make specific measurements of certain signal parameters. Examples include channel power measurements and adjacent channel power (ACP) measurements, which were previously described in Chapter 6. Many spectrum analyzers now have these built-in functions available. You simply specify the channel bandwidth and spacing, then press a button to activate the automatic measurement. The complementary cumulative distribution function (CCDF), showing power statistics, is another measurement capability increasingly found in modern spectrum analyzers. This is shown in Figure 8-1. CCDF measurements provide statistical information showing the percent of time the instantaneous power of the signal exceeds the average power by a certain number of dB. This information is important in power amplifier design, for example, where it is important to handle instantaneous signal peaks with minimum distortion while minimizing cost, weight, and power consumption of the device. 102
Other examples of built-in measurement functions include occupied bandwidth, TOI and harmonic distortion, and spurious emissions measurements. The instrument settings, such as center frequency, span, and resolution bandwidth, for these measurements depend on the specific radio standard to which the device is being tested. Most modern spectrum analyzers have these instrument settings stored in memory so that you can select the desired radio standard (GSM/EDGE, cdma2000, W-CDMA, 802.11a/b/g, and so on) to properly make the measurements. Figure 8-1. CCDF measurement 103
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Agilent Spectrum Analysis Basics Ap
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Table of Contents — continued Cha
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Some measurements require that we p
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Figure 1-3. Harmonic distortion tes
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While we have defined spectrum anal
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Since the output of a spectrum anal
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We need to pick an LO frequency and
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To separate closely spaced signals
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Agilent data sheets describe the ab
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This allows us to calculate the fil
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Some modern spectrum analyzers allo
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On the other hand, the rise time of
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The width of the resolution (IF) fi
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The “bucket” concept is importa
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Peak (positive) detection One way t
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The normal detection algorithm: If
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EMI detectors: average and quasi-pe
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The effect is most noticeable in me
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Thus, the display gradually converg
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In some cases, time-gating capabili
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Timeslots 0 1 2 3 4 5 6 7 Timeslots
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Gated sweep Gated sweep, sometimes
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In Chapter 2, we did a filter skirt
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Custom signal processing IC Turning
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Chapter 4 Amplitude and Frequency A
Page 51 and 52: Following the input filter are the
Page 53 and 54: Improving overall uncertainty When
Page 55 and 56: Examples Let’s look at some ampli
Page 57 and 58: In a factory setting, there is ofte
Page 59 and 60: Because the input attenuator has no
Page 61 and 62: Noise figure Many receiver manufact
Page 63 and 64: Using these expressions, we’ll se
Page 65 and 66: Let’s first test the two previous
Page 67 and 68: This is the 2.5 dB factor that we a
Page 69 and 70: When we add a preamplifier to our a
Page 71 and 72: 2D dB 3D dB 3D dB 3D dB With a cons
Page 73 and 74: We can construct a similar line for
Page 75 and 76: Figure 6-2 shows the dynamic range
Page 77 and 78: Dynamic range versus measurement un
Page 79 and 80: Let’s see what happened to our dy
Page 81 and 82: The range of the log amplifier can
Page 83 and 84: Chapter 7 Extending the Frequency R
Page 85 and 86: Next let’s see to what extent har
Page 87 and 88: In examining Figure 7-5, we find so
Page 89 and 90: Can we conclude from this discussio
Page 91 and 92: Amplitude calibration So far, we ha
Page 93 and 94: From the graph, we see that a -10 d
Page 95 and 96: Pluses and minuses of preselection
Page 97 and 98: Table 7-1 shows the harmonic mixing
Page 99 and 100: Figure 7-15. Which ones are the rea
Page 101: Figure 7-18. The image suppress fun
Page 105 and 106: Digital modulation analysis The com
Page 107 and 108: Data transfer and remote instrument
Page 109 and 110: Summary The objective of this appli
Page 111 and 112: Delta marker: A mode in which a fix
Page 113 and 114: Frequency stability: A general phra
Page 115 and 116: LO feedthrough: The response on the
Page 117 and 118: Residual responses: Discrete respon
Page 119 and 120: Video: In a spectrum analyzer, a te
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