To correctly read a spectrum analyzer, it's vital to understand all of the separate elements of the display entirely. Each element provides essential information to troubleshoot and solve signal issues.

The main display elements of a spectrum analyzer include the horizontal axis, vertical axis, scale, center frequency, and span. Here is a summary of those display elements. 

Understanding each display element will allow you to quickly identify and solve signal issues. Let's take a closer look at each element and how they work together.

The horizontal axis of the spectrum analyzer display represents the measured range of frequencies, with the frequency unit (such as MHz or GHz) and the range of frequencies displayed (such as 100 MHz to 1 GHz and higher). The frequency axis determines the location of the signal on display and identifies any frequency-related issues.

Frequency measures how often a wave oscillates, measured in hertz (Hz). For example, a signal wave with a frequency of 1 Hz oscillates once per second. A wave with a frequency of 2 Hz oscillates twice per second, and so on. 

The frequency measures how "fast" the wave oscillates and how "tight" the wave's oscillations are. A wave with a higher frequency oscillates more rapidly and the oscillations are closer together than a wave with a lower frequency.

The frequency of a signal can tell you a lot about the source of the signal and identifies different types of signals. For example, a low-frequency signal (such as a power line) will have a lower frequency than a high-frequency signal (such as a radio transmission).

The frequency axis also allows the user to zoom in and out of the display to focus on a specific range of frequencies. This feature can be helpful when identifying a particular signal or isolating a specific frequency range.

By understanding the frequency axis of the spectrum analyzer display, you will be able to quickly identify the location of the signal and any frequency spectrum issues that may be causing signal interference or distortion.

The spectrum analyzer's vertical axis represents the signal level, also known as the amplitude. You label it with the amplitude unit (such as dBm, dBV, or dBmV) and the range of amplitudes displayed (such as -80 dBm to 0 dBm). The amplitude determines the strength of the signal on display and identifies any amplitude-related issues.

The amplitude of a signal helps to identify different types of signals. For example, a low-amplitude signal will have a lower power level than a high-amplitude signal. The amplitude axis allows the user to adjust the display's gain to see weaker signals better.

By understanding the amplitude axis of the spectrum analyzer display, you will be able to quickly identify the strength of the signal and any amplitude-related issues. Understanding amplitude and its representation on the vertical axis is crucial to setting reference levels and precise measurements, especially when measuring very weak or very strong signals.

The scale of the spectrum analyzer display represents the amplitude and frequency of the analyzed signal. The scale is typically divided into equal intervals and labeled with the corresponding amplitude or frequency values.

You can adjust the scale to display the signal in different ways, such as linear or logarithmic.

• In a linear scale, the values on the vertical axis are equally spaced, meaning that the difference between the two scale divisions on the axis is the same at all points. The linear scale is less commonly used in spectrum analyzers because the dynamic range of signals can be very large, and the weaker signals can be challenging to see or hidden in the noise floor. But it can be helpful for certain types of measurements or situations where the range of amplitudes is not very wide, and the goal is to read and understand the measurements with high precision and accuracy.
• A logarithmic scale, also known as a log scale, displays signals in a logarithmic way, meaning that the amplitude or frequency is represented in a logarithmic relationship to the signal strength. Logarithms are mathematical functions that allow you to compress a wide range of values into a smaller range, allowing a more practical representation over a large range of signal values.

The logarithmic scale is most commonly used in spectrum analyzers and allows the user to view a wide range of amplitudes, making it easier to identify weaker signals.

The scale is usually calibrated to a specific band of frequencies and amplitudes, depending on the device and the application. For example, a spectrum analyzer designed to test RF devices is calibrated to a range of frequencies from a few MHz to several GHz and amplitudes from -80 dBm to 0 dBm.

It's important to understand the scale and how it's calibrated, as it directly affects the accuracy and resolution of the measurements and the ability to identify signals. Understanding the scale will also allow you to interpret the results of your measurements correctly.

The center frequency of the spectrum analyzer display is the reference point for the frequency axis. The location of the centre frequency is in the middle of the displayed frequency range. It is usually labeled with the corresponding frequency value represented as a vertical line on the display.

The center frequency is a user-defined value that you adjust depending on the measurement task. It is a reference point to help the user orient themselves on the frequency axis and identify the signal's location on display. The user can adjust the center frequency to change the displayed frequencies and zoom in or out of specific frequency ranges.

When you adjust the center frequency, the other frequencies on display will shift accordingly, with the new center frequency becoming the new reference point.

Understanding the center frequency is essential, as it directly affects the displayed frequency range and the ability to identify and isolate specific signals. It also allows you to correctly orient yourself on the frequency axis and make precise measurements.

The span of the spectrum analyzer display is the range of frequencies displayed on the frequency axis. It is labeled with the corresponding frequency range, such as 100 MHz to 1 GHz, and represents the distance between the start and end frequencies on the frequency axis.

You can adjust the span to change the range of displayed frequencies. When you increase the span, a wider range of frequencies is displayed on the frequency axis, allowing the user to see a larger portion of the spectrum. When the span decreases, a smaller range of frequencies is displayed on the frequency axis, allowing the user to zoom in and see a more detailed view of a specific frequency range.

When you adjust the span, you will also need to change the center frequency to ensure that the signal of interest stays centered on the display. This feature is useful when isolating a specific frequency range or identifying a particular signal.

A spectrum analyzer is a measurement tool used to visualize and analyze the spectral content of signals. It accomplishes this by measuring the magnitude of the input signal versus its frequency over the entire frequency span. 

Think of this as a means to see a signal's "frequency fingerprint." This fingerprint will help you determine the signal power of electronic devices and how that signal makes up different frequency components.

Its main test functions identify

1. Frequency
2. Power
3. Bandwidth
4. Amplitude
5. Phase and other parameters of a signal

A spectrum analyzer also has many applications. You can use a spectrum analyzer for radio, wireless communication, and audio signal engineering. They will also help troubleshoot and optimize electronic wireless networking equipment.

Reading the results of a spectrum analyzer can seem daunting at first. Although, it becomes relatively straightforward with a clear understanding of the display elements and the instrument's functions. Here is a step-by-step guide on how to correctly read a spectrum analyzer.

Before making any measurements, it's important to familiarize yourself with the different elements of the display. These include the frequency axis, amplitude axis, center frequency, span, and any markers or traces that may be present. Make sure you understand what each element represents.

Connect the signal you want to measure to the spectrum analyzer's input. Ensure that the signal is within the instrument's frequency range and the signal level is within the instrument's dynamic range.

Once you connect the signal, adjust the settings, such as the gain, attenuation, and scan rate, to optimize the display for your measurement. Set the gain correctly to get a clear and accurate signal reading.

Observe the display and note the signal's frequency and amplitude. Look for any peaks or dips and any unwanted frequency components. Use the markers or trace function to measure the specific frequency and amplitude of the signal.

Unlock the Secrets of Your Signal With a Keysight Spectrum Analyzer

Understanding how to read a modern spectrum analyzer is the first step in unlocking the secrets of your signal. With Keysight's wide range of spectrum analyzers, you can confidently make precise and accurate signal measurements.

If you are looking for a quality spectrum analyzer, look no further than Keysight. Our premium refurbished analyzers are the best on the market, available at a fraction of the price. We guarantee you will not have to compromise on performance and accuracy when buying from us.

Browse our premium used spectrum analyzer offers

1. Call tech support US: 1 800 829-4444
   Press #, then 2. Hours: 7 am – 5 pm MT, Mon– Fri
2. Talk to our sales support team by clicking the icon (bottom right corner) on every offer page
3. Talk to your account manager about your specific needs