Planar IT-088, Руководство по эксплуатации

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The view displayed on the screen in DVB-T/H reception quality parameters
measurement mode is the numeric values and graphic representation of the measured
digital parameters (MER, BER before and after the Viterbi decoder, error bit counter after
Reed-Solomon decoder, and immunity margin). The constellation diagram mode shows
the vector structure of the quadrature components of the demodulated digital signal on the
phase plane. The spectrum analyzer mode shows the signal magnitude (signal frequency
bar-graph). The mode of signal level measurement in a frequency point displays the
numeric value of the signal level, V/A and C/N ratios.
2.6.2. Block Diagram
The block diagram of IT-088 is shown in figure 2.3.
Figure 2.3
After the Low-Pass Filter (LPF), the input signal if necessary is strengthened by the
Wide-Band Amplifier (WBA) or reduced by the two Attenuators (A1) and (A2). Then it is
transformed into the second IF signal by the Tuner (T). The WBA can be activated only for
digital channel measurements. The Tuner is the superheterodyne detector with double
frequency conversion. The first IF is 1220 MHz. In the signal level measurement mode the
second IF is 39 MHz, for digital channels demodulation the second IF is 36.125 MHz.
The signal of the second IF, after the Bandpass Filter (BPF1) and conversion in the
Mixer (M1) has the third IF, and further filtered at 10.7 MHz frequency by BPF3, which
determines the receiver frequency band.
Logarithmic Gain Amplifier Limiter (LGAL) performs logarithmation and signal detection.