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Spectrum Analyzer
This section covers the functions of Spectrum Analysis and Spectrum Analyzer measurements.
Power Input
This function is used to determine the total power input into a spectrum analyzer, radio or noise figure meter.
It is used to make sure that the receiver is not overloaded with noise power and operating outside its
dynamic range. Input the Temperature in Kelvin, Bandwidth in Hertz, ENR Excess Noise Ratio of Hot/Cold
noise source, PreAmp Gain, DUT Device Under Test Noise Figure in dBF and Gain in dB. Press Calculate
to compute and display. Clearto reset and reenter value to retry and Closeto Quit.
Figure 90 Spectrum Analyzer Input Power
Threshold/MDS
This function is used to determine the Threshold or Minimum Detectable Signal MDS. It is used to make surethat the signal is detectable. Input the Temperature in Kelvin, Bandwidth in Hertz, Noise Figure of Receiver in
dBF, Singal Level in dBm and Noise Level in dBm. The output is the Minimum Detectable Signal in dBm.
Press Calculateto compute and display. Clearto reset and reenter value to retry and Closeto Quit.
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Figure 91 Spectrum Analyzer Threshold/ Minimum Detectable Signal
EbNo-S/N
This function is used to determine the Eb/No to Signal to Noise Levels. Input the Eb/No ratio or the Signal to
Noise S/N ratio, the Data Rate in Bits/Sec and the Channel Bandwidth. The Eb/No or the S/n ratio that is not
input will be calculated. Press Calculateto compute and display. Clearto reset and reenter value to retry
and Closeto Quit.
Figure 92 Spectrum Analyzer Eb/No to S/N
Swp Time
This function is used to get a rough estimate of the Spectrum Analyzer sweep time for a trace to complete.
Enter the RBW- Resolution Bandwidth, the VBW Video Bandwidth, the Span all in Hertz and the constant
of choice. The output is an approximate sweep time for the spectrum analyzer. The constant can be
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determined for a spectrum analyzer by estimating backward to refine the value. I defaulted to the one most
used for Agilent Analyzers. Press Calculateto compute and display. Clearto reset and reenter value to
retry and Closeto Quit.
You can also calculate the Spectrum Analyzer Sweep Coverage. That is it determines if the sweep
parameters of the Spectrum Analyzer must be sufficient for RWB of each receive frequency point must totalequal to or greater than the total span bandwidth. This insures that each frequency bucket covers every
window needed to cover the entire band without any missed coverage for the point to point bandwidth. Enter
the Resolution Bandwidth and the Span of the sweep as well as the number of points in the sweep. Press the
associated Calculate button and the coverage Pass/Fail and percentage of coverage. Less than 100% means
that there are gaps in the point to point bandwidth coverage thru the span.
Figure 93 Spectrum Analyzer Sweep Time
Pwr Avg SN/N
This function set is to calculate the Power Average of Signal and Noise to Signal/Noise. There are two
functions, one absolute and the other relative. For the left one add the Signal + noise level and the Noise
Level all in dBm/Hz. In the other function, enter the signal Delta (i.e. Signal and Noise to Noise Level delta).
In either case it will figure the signal error due to the added noise contribution. Press Calculateto compute
and display. Clearto reset and reenter value to retry and Closeto Quit.
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Figure 94 - Spectrum Analyzer Power Average SN/N Error
Log Avg SN/N
This function set is to calculate the Logarithmic Average of Signal and Noise to Signal/Noise. The function
requires the Signal and Noise Level in dBm, the Delta Signal + Noise to Noise Level. It will figure the CW
Corrected signal level and CW signal error due to the added noise contribution. Press Calculateto compute
and display. Clearto reset and reenter value to retry and Closeto Quit.
Figure 95 - Spectrum Analyzer Log Average SN/N Error
Intermod
Intermod Order
This section is used to calculate the appropriate Inter-Modulation Level. Select the desired Inter-modulation
order that you wish to calculate and enter the Fundamental and IM Product levels in dBm. The Intermod level
of that order is calculated for the device. Press Calculateto compute and display. Clearto reset and reenter
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value to retry and Closeto Quit.
Normalize Unequal Power
This section calculates the Normalized power of two unequal level signals used in the adjoining Intermod
Level calculations. Enter signal levels 1 and 2 and Press Calculateto compute and display. Clearto resetand reenter value to retry and Closeto Quit.
Figure 96 Spectrum Analysis Intermod Order and Normalize Unequal Power
DANL/NF + BW
This function set calculates the Noise Figure in dBF, the DANL/ANL Displayed Average Noise level or
Average Noise Level and the Tangential Sensitivity. Enter the Temperature in Kelvin, the bandwidth in Hertz
and one of the three values of DANL, Noise Figure or Tangential Sensitivity. It will compute the missing
factor.
Displayed Average Noise Level
If the DANL/ANL check box is checked it computes to/from DANL and unchecked it computes to/from
ANL. In the case below I entered the temperature, bandwidth and checked the DANL box and entered the
DANL of 88dBm/Hz. It calculated the Noise figure and Tangential Sensitivity of the receiver. Press
Calculateto compute and display. Clearto reset and reenter value to retry and Closeto Quit.
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Figure 97 - Spectrum Analyzer DANL/NF and TSS
Average Noise Level Calculation
Here I entered an ANL of 120dBm/Hz, 290K, 1KHz Bandwidth and unchecked the box. It calculated the
Noise Figure and TSS. Also could have entered in either the TSS or the Noise Figure instead of the ANL
and it would have figured the other two.
Figure 98 Spectrum Analyzer ANL/NF and TSS
Crest Factor
Crest factor is a measure of the signal cresting due to random modulation variations and the probabilities of
them adding Fourier series manner to product above average peaks of instantaneous peaks in the signal
range. Enter any two of the three values and press Calculate to compute the remaining value. Press
Calculateto compute and display. Clearto reset and reenter value to retry and Closeto Quit.
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Figure 99 Spectrum Analyzer Crest Factor
Line Spectrum
Pulse De-sensitation Factor or PDF is the determining of or using the pulsed duty cycle power average offset
that can be applied to help determine signal measured levels from pulsed signals. For the line spectrum enter
any two of the three values Time On, Time Period and/or PDF to calculate the missing component. The PDF
is the decibel offset that can be added to a CW signal level to correct to what it would measure in a power-
integrating sensor as the pulsed average power.
Envelope Spectrum
This one uses any three of the four inputs to calculate the missing value. It will take the Time On, K constant
factor, the Bandwidth and/or finally the PDF. Enter any two of the three values on the right function and/or
any three of the four inputs on the right side function and Press Calculateto compute and display. Clearto
reset and reenter value to retry and Closeto Quit.
Figure 100 Spectrum Analyzer PDF
Two Tone
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This screen helps the operator to compute all the second and third order Intermodulation components of
mixed signals and the mixing products. Enter Fund1 and Fund2 values in Hz, KHz, MHz, GHz etc. The units
on the calculator being Hz, will scale units to whatever you wish. Press Calculateto compute and display.
Clearto reset and reenter value to retry and Closeto Quit.
Figure 101 Spectrum Analyzer Two Tone
Bandwidth Correction
Channel Power RBW
This calculator screen has several functions. The first is to calculate Span, Points and/or RBW Resolution
Bandwidth. Using the Spectrum Analyzer constant of computation (bandwidth integration factor) it will take
two of the three variables Span, Points and/or RBW Resolution Bandwidth and compute the missing variable.Press the Calculatebutton on the left to compute this function. Clearto reset and reenter value to retry and
Closeto Quit.
Bandwidth Correction
This function can be used to compute either the bandwidth offset or the converted signal integrated power
based on the signal and the bandwidth of integration of that signal. Note assumes flat bandwidth frequency
response of the range of integration. Press the Calculate button on the right to compute this function. Press
Calculateto compute and display. Clearto reset and reenter value to retry and Closeto Quit.
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Figure 102 Spectrum Analyzer Bandwidth Correction
