How is Performance Measured?

Accordingly, the measurement method for blocking efficiency as stipulated in Circular 29 is implemented as follows:

- The output signals of the two signal generators will be combined with equal weighting. The combined signals must be appropriately and rationally matched with the LNB inputs.- A spectrum analyzer must be connected to the LNB output, allowing for the provision of LNB power.- fc is the center frequency of the received frequency band.- The first signal from the signal generator frequency will be set to fc.- The first level signal from the signal generator must be set to a level within the LNB's operational input range.- The spectrum analyzer is set to measure the first converted signal level at the LNB output.- The second signal from the signal generator frequency must be set to fc - 20 MHz.- The second level signal from the signal generator must be adjusted so that the measured level is 1 dB lower when there is no second signal.- The second level signal from the signal generator must be recorded as the reference level.- The second signal from the signal generator frequency must be set to the frequency of interest.- The second level signal from the signal generator must be adjusted so that the measured level is 1 dB lower when there is no second signal.- The rejection of the frequency of interest is equal to the second level signal from the signal generator minus the reference level determined in the second level signal step.- Steps from the second signal generator frequency to the rejection of the frequency of interest must be repeated with frequencies within the range.

See details at Circular 29/2017/TT-BTTTT which takes effect from July 01, 2018.

-Thao Uyen-

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