Signal Hound SM200A, Руководство по эксплуатации продукта

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Understanding the SM-series Hardware |
Front End Architecture
18
IF output is centered at 1.5 GHz, has >800 MHz 3-dB bandwidth, and may be used from 24 to
43.5 GHz. The IF output option limits the maximum RF frequency it can digitize and send to the
PC to about 41 GHz.
3.2.3 Preselector
The preselector is a collection of sub-octave filters spanning 20 MHz to 20 GHz / 43.5 GHz. It
removes out-of-band energy from the RF input before any amplification or mixing occurs. The low
frequency preselector filters may be bypassed to increase sweep speed and increase available
bandwidth at low frequencies, at the expense of IP2.
In sweep mode, the insertion loss of the optional preselector filters is compensated for by the API,
but when I/Q streaming below 645 MHz with the preselector on, only an average amplitude
correction is applied. This will increase the typical amplitude error observed at the filter edges by
a small amount (typically 0.5 dB). In spectrum analysis modes, this error is removed and full
amplitude accuracy is maintained. A minimum overlap of 6 MHz ensures commonly used VHF
signals can be streamed even with preselector on.
When the optional preselector filters are bypassed, the full 40 MHz of I/Q streaming is available
at all frequencies. However, below 645 MHz, the 160 MHz hardware real-time is not available.
Below 650 MHz, all the preselectors have a shape similar to the one shown (filter 7):
-50.00
-45.00
-40.00
-35.00
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
50.00 150.00 250.00 350.00 450.00 550.00
Typical Preselector Insertion Loss (dB) vs. Frequency (MHz)