What is a spectrum analyzer? You will never come across this product in everyday life, it is a rather specific device, and quite expensive. In this article, we will look at the general purpose and application of such devices. In a nutshell, a spectrum analyzer is a device that can be described as a frequency-selective voltmeter that responds to amplitude, it is configured in such a way as to display the RMS value of a sinusoidal wave. And that's just in a nutshell, in fact, everything is much more complicated and interesting.
It is important to understand that this instrument is not a power meter, even though the spectrum analyzer can directly display the value of this parameter. If we know the average or peak value of the sine wave and the resistance value, then we can set the device to display the power value. Thanks to the development of digital technologies, today's spectrum analyzers are truly powerful.
To understand the purpose of this device, it is necessary to consider what is measured by the analyzerspectrum. From the name of the device, one can understand that it serves to measure the spectrum. And what is this characteristic? The spectrum is a set of sinusoidal waves, which, under certain combinations, are capable of producing the considered signal in the context of the time domain. Ideally, the signal has the form of a single classical sinusoid. In practice, in the frequency domain, using a spectrum analyzer, you can see that the signal spectrum consists of two or more waves, it may contain a second harmonic, etc. In the time domain, you can easily measure the duration of the pulse front and its decay, as well as signal spikes and beats. Signal measurements with a spectrum analyzer in the frequency domain are a must when designing wireless communication circuits. Only with the help of this device can out-of-band and spurious radiation be detected and subsequently eliminated. As mentioned above, the device allows you to identify additional harmonics of the signal, and this parameter in radio transmitting equipment is of great importance, because additional harmonics can fall on occupied frequencies and thereby create interference.
Also, this device acts as an audio spectrum analyzer. What does it mean? Sometimes it is necessary to measure the noise as if it were a normal signal. Any device or active circuit generates noise. Measurements of this noise figure and signal-to-noise ratio are important characteristics of the device and the overall performance of the system.
Summarizing, let's say that radio designers for checking and debugging the projectedequipment simply needs a spectrum analyzer. The price of such a device is quite significant and fluctuates in a wide range. For example, one of the simplest devices (Rigol DSA815) will cost about 50-60 thousand rubles, but for a professional spectrum analyzer (Agilent Technologies) you will have to pay 750-800 thousand rubles. A radio amateur for his home workshop is unlikely to buy such a device, but firms or laboratories of enterprises involved in the development of electronic equipment simply need it.
