Telecommunications – Receiver or analog modulated signal frequency converter – Frequency or phase modulation
Patent
1985-12-13
1987-11-03
Ng, Jin F.
Telecommunications
Receiver or analog modulated signal frequency converter
Frequency or phase modulation
455223, 455225, 375104, H04B 110
Patent
active
047047364
ABSTRACT:
For elimination of pulse type interference in an FM receiver by intermittent blanking of the received signal while interfering pulses are present and substitution of a synthetic signal during the blanking intervals, the synthetic signal substituted during the blanking intervals is produced by interpolation using finite duration impulse response digital filters, instead of using the last undisturbed value of the received signal modified by integration of its last value of rate of change with respect to time. The determination of the blanking interval is optimized by reference to the maximum and minimum peak values of the output of an AM detector of the received signal and comparing an interference signal magnitude thus obtained with a threshold value of the interference signal, so as to define the blanking interval as the interval during which the interference signal exceeds the reference signal value. The interference signal compared with the reference value is produced by computing the sum and product of the maximum and minimum peak values, adding the product to the output of the squarer operating on the output of the AM demodulator, multiplying the sum of the maximum and minimum peak values by the AM demodulator output, dividing the product plus squarer sum by the multiplied output of the AM demodulator, forming the arc cosine of the output of the divider and then differentiating the arc cosine value.
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Blaupunkt-Werke GmbH
Ng Jin F.
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