R&S FSV-K70, Руководство пользователя

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Brief Description of Vector Signal Analysis
R&S
®
FSV-K70
43 Operating Manual 1176.7578.02 ─ 09
The Figure 2-42 provides an overview of the demodulation stages of the vector signal
analysis option. The function blocks of the signal processing kernel can be found at the
left (in grey) and their appropriate settings at the right (in blue).
Burst Search
In this stage, the Capture Buffer is searched for bursts that comply with the signal
description. The search itself can be switched on or off via the "Burst Search" dialog
(see
"Burst Search" on page 158). A list of the detected bursts is passed on to the
next processing stage.
IQ Pattern Search
The "IQ Pattern Search" is performed on the Capture Buffer. This means the
R&S
FSV-K70 option modulates the selected pattern according to the transmit filter (Tx
filter) and the modulation scheme. Subsequently, it searches the Capture Buffer for this
IQ pattern, i.e. the IQ waveform of the pattern. It is assumed that patterns can only
appear within bursts, i.e. the IQ pattern search range is limited to the bursts detected
by the Burst Search stage. If the burst search is switched off, the whole Capture Buffer
is searched for the IQ pattern. A list of all detected IQ patterns is passed on to the next
processing stage. It is important to note that the R&S
FSV-K70 option can only search
for one pattern at a time.
The pattern search can be switched on or off via the "Pattern Search" dialog (see "Pat-
tern Search" on page 160).
Extraction of Result Range
The Result Range can be aligned to a burst, a pattern or simply the start of the Cap-
ture Buffer (see
"Result Range" on page 165). Within this stage, the Result Range is
cut from the Capture Buffer starting at a point that is specified by the user, e.g. the start
of a detected burst. The R&S
FSV-K70 option automatically takes into account filter
settling times by making the internal buffers sufficiently longer than the selected Result
Range.
Demodulation & Symbol Decisions
This stage operates on the extracted Result Range and aims at making the correct
symbol decisions. Within this stage, a coarse synchronization of the carrier frequency
offset, the carrier phase, the scaling and the timing takes place. Furthermore, an auto-
matically selected internal receive filter (Rx filter) is used in order to remove the inter-
symbol interference as effectively as possible. The outputs of this stage are the
(coarsely) synchronized measurement signal and the symbol decisions (bits). The
symbol decisions are later used for the "Pattern Symbol Check" stage and for the "Ref-
erence Signal Generation" stage.
Pattern Symbol Check
The "IQ Pattern Search" stage can only detect whether the similarity between the IQ
pattern and the Capture Buffer exceeds a certain threshold and, in this way, find the
most likely positions where a pattern can be found.
Demodulation Overview