Features of a spectrum analyzer
A spectrum analyzer is one instrument that is often used in the conversion of higher frequencies, often those that range up to 10s gigahertz. It is a sensitive receiver that works based on the super-heterodyne receiver principles.
Once received by the spectrum analyzer, the frequency signal is swept through a pre-selected set of frequencies. The selected frequency is then converted into a DC level, a logarithmic scale, that can be measured. It is also displayed on the CRT, where the y-axis contains the signal strength while the frequency is seen on the x-axis.
Spectrum analyzers, however, cannot detect signals that are too weak or weaker than the noise in the background. This is the reason why the spectrum analyzer is often used in tandem with an RBW. In fact, RBW is one of the vital considerations in choosing or buying a spectrum analyzer.
Here, the received signal strength is measured in dBm or what is called decibels, the zero of which corresponds to 1mWatt on the logarithm scale. The reason for the use of power or decibels instead of the usual voltage is the fact that what is being measured are the low signal strengths and the frequency range of measurement.
Spectrum analyzers can only measure the response of a device powered at 120 dBm. These are the power levels that are normally seen in microwave receivers.
In addition to the RBW, there are other key features of spectrum analyzers that people need to consider before buying one. One of these vital components is the resolution width, which affects the sensitivity of the spectrum analyzer. In fact, the sensitivity is directly dependent on this feature. For instance, if the measurements are the over a wide band, a 3 KHz RBW will normally be effective.
However, if you need to analyze a much narrower spectrum, such as with filters, then you may need a bandwidth resolution of 300Hz or a 10 Hz RBW. All depends on how the spectrum analyzer will be used.
Another feature is the frequency range, which refers to the frequencies that you will be needing in order to take measurements. Spectrum analyzers have ranges from 100 Hz to 50.
Another is the frequency stability, which allows the spectrum to maintain its frequency within a specific levels that is precise and accurate.
Often, the frequency stability is entirely dependent on the stability of the oscillator. A provision for Narrow band measurements for instance is an important parameter because spectrum analyzers do not usually have very high stability clocks.
About The Author
Low Jeremy maintains http://Spectrum.ArticlesForReprint.com. This content is provided by Low Jeremy. It may be used only in its entirety with all links included.
|
