Datasheet

A GUIDE TO RF SIGNALS
4 | TEK.COM/RSA
Additional Information:
• Wikipedia
A spectrum analyzer is the tool of choice for people who need to “see” a radio signal. In
general most spectrum analyzers provide the same display; they show lower frequency
signals on the left hand side of the display and higher frequency signals on the right
hand side of the display. The three basic controls for most spectrum analyzers are;
Frequency, Span & Amplitude (Reference Level). With these three controls we can
control the view of the spectrum. The next question is “what am I looking at?”
We can tell a lot about an RF signal from the basic spectrum display. It certainly helps
to know what you are looking for. Around the world there is a lot of dedicated spectrum
assignment, meaning certain frequency ranges are used for certain types of radio
signals.
The first step in identifying a radio signal is to determine the operating frequency of
the transmitter. Other than Industrial/Scientific/Medical bands, the radio spectrum is
a tightly managed resource. When we are trying to determine what type of signal we
are seeing, we need to first identify the operating frequency. A simple technique is to
look at the total width of the signal and find the mid-point in the signal. In general this
will indicate the operating frequency. With this first piece of information we can now
research frequency assignment tables to determine what type of radio service may be
assigned to specific frequency.
The second piece of information that is important is how “wide” the signal is that is
shown on the spectrum display. The “width” or occupied bandwidth of the signal
provides us additional information regarding the class of service of the transmitter.
We know for example that in the 2.4 GHz ISM frequency band, a Bluetooth signal is
approximately 1 MHz wide but a Wi-Fi signal could be up to 40 MHz wide.
In summary, the basic spectrum display allows us to determine the frequency, occupied
bandwidth and relative strength of a radio transmitter.
WHAT’S A SPECTRUM DISPLAY?
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Get a quick and inexpensive look at wireless signals with the USB Spectrum Analyzers.