VBW is video bandwidth, a smoothing filter applied to the displayed data.
A narrow RBW will display that sine wave as a spike, or nearly so. So setting this to a big number means a perfect sine wave, which should show as a infinitely-narrow spike in a perfect world, will be broad and mushy. It’s the width of the filter after the SA’s mixer stage. The DSA815’s frequency display is spot on, measured with a high-end HP signal generator. If you’re doing any sort of wireless work an SA is an essential bit of test equipment. In contrast, the SA is just like a superhet radio – a local oscillator sweeps from a user-selected low frequency up to a desired high frequency, with phenomenal gain since a mixer stage isolates just the frequency being swept at any time. You’re lucky to be able to see tens of mV. So why spend precious bucks on another instrument?Ī scope is not particularly sensitive. When in the noise I found them just about impossible to recognize.Īll of the important settings are clearly shown on the screen.Įvery modern digital scope can show the FFT of an input signal, which is exactly the same display. WBJC, at 91.5 MHz in the photo, comes in at -75 dBm, or around 50 picowatts.Īnd, though the instrument can display four markers and do delta math between them, they sure are hard to see. In this case the SA’s input is one meter of wire acting as an antenna.Ī couple of things to note: first, while the DSA815 and all other SA’s will display amplitude in a variety of units, the most useful is dBm, or dB referenced to 1 milliwatt. The peaks are various radio stations’ carrier frequencies. It’s positioned at 91.5 MHz, the Baltimore classical station. The marker is barely visible as a “1” towards the left side of the screen. The center frequency is 100 MHz with a span of 20 MHz (that is, the SA is sweeping from 90 to 110 MHz), RBW and VBW (more on these later) of 3 KHz. The following picture shows the Rigol displaying the FM radio band. An SA shows amplitude on the vertical and frequency on the horizontal. Everyone knows that an oscilloscope displays voltage on the vertical axis, and time on the horizontal. One large wheel can adjust pretty much anything.
#Used rigol dsa815 tg spectrum analyzer plus#
Picture swiped from Rigol’s web site.Īs is apparent from the picture, the front panel is well-laid out with individual buttons for each function, plus soft-buttons used to select sub-modes.
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