Demodulation circuit, digital microwave system and demodulation method

Abstract

A demodulation circuit, a digital microwave system including the demodulation circuit, and a signal demodulation method are provided. The demodulation circuit includes a first circuit, a second circuit, a third circuit, and a fourth circuit connected in turn. The fourth circuit includes a pulse counting unit and a data decision unit connected in turn. The signal demodulation method includes: performing bandpass filtering on input signals; increasing gains of the bandpass filtered signals; extracting pulse signals are extracted from the gain-increased signals; counting the extracted pulse signals; filtering the pulse signals having counting values falling outside of a predetermined range, and outputting the filtered pulse signals.

1 . A demodulation circuit, comprising:
 a first circuit, configured to perform bandpass filtering on input signals;   a second circuit, configured to increase gains of signals generated by the first circuit after the bandpass filtering;   a third circuit, configured to extract pulse signals from signals output from the second circuit; and   a fourth circuit, configured to count the pulse signals extracted by the third circuit, perform a data decision based on the counting, and output digital demodulation data.   
   
   
       2 . The demodulation circuit according to  claim 1 , wherein the fourth circuit comprises:
 a first unit, configured to count the extracted pulse signals; and   a second unit, connected with the first unit, and configured to filter data having a counting value falling outside of a predetermined value range and output demodulated data.   
   
   
       3 . The demodulation circuit according to  claim 1 , wherein the third circuit comprises a comparator having an input end connected to an output of the second circuit and another input end connected to a threshold level. 
   
   
       4 . The demodulation circuit according to  claim 1 , further comprising a third unit connected in series between the third circuit and the fourth circuit, and configured to detect the pulse signals extracted by the third circuit and filter burr pulses having pulse widths smaller than a desired pulse width of the pulse signals. 
   
   
       5 . The demodulation circuit according to  claim 4 , further comprising a fifth circuit configured to provide a reference clock for the first unit and the third unit. 
   
   
       6 . The demodulation circuit according to  claim 1 , wherein the second unit is further connected to a component configured to record and store label information for determining a demodulation scheme. 
   
   
       7 . The demodulation circuit according to  claim 1 , wherein a gain of the second circuit is in the range of 10-35 dB. 
   
   
       8 . A digital microwave system, comprising an indoor unit, an outdoor unit, and an intermediate frequency cable connecting the indoor unit and the outdoor unit, wherein the outdoor unit and the indoor unit comprise a demodulation circuit, and the demodulation circuit comprises:
 a first circuit, configured to perform bandpass filtering on input signals;   a second circuit, configured to increase gains of signals generated by the first circuit after the bandpass filtering;   a third circuit, configured to extract pulse signals from signals output from the second circuit; and   a fourth circuit, configured to count the pulse signals extracted by the third circuit, perform a data decision based on the counting, and output digital demodulation data.   
   
   
       9 . The digital microwave system according to  claim 8 , wherein the fourth circuit comprises:
 a first unit, configured to count the extracted pulse signals; and   a second unit, connected with the first unit, and configured to filter data having a counting value falling outside of a predetermined value range and output demodulated data.   
   
   
       10 . The digital microwave system according to  claim 8 , wherein the third circuit is constituted by a comparator having an input end connected to an output of the second circuit and another input end connected to a threshold level. 
   
   
       11 . The digital microwave system according to  claim 8 , further comprising a third unit connected in series between the third circuit and the fourth circuit, and is configured to detect the pulse signals extracted by the third circuit and filter burr pulses having pulse widths smaller than a desired width. 
   
   
       12 . A demodulation method, comprising:
 performing bandpass filtering on input signals;   increasing gains of the filtered input signals after bandpass filtering;   extracting pulse signals from the gain-increased filtered input signals after increasing gains;   counting the extracted pulse signals; and   outputting filtered pulse signals after filtering pulse signals having counting values falling outside of a predetermined value range.   
   
   
       13 . The demodulation method according to  claim 12 , wherein extracting the pulse signals from the input signals after increasing gains comprises:
 comparing the gained-increased filtered input signals after increasing gains with a predefined threshold level, and filtering the pulse signals below the predefined threshold level.   
   
   
       14 . The demodulation method according to  claim 12 , wherein filtering the pulse signals having counting values falling outside of a predetermined value range comprises:
 filtering the pulse signals having counting values falling outside of the predetermined value range according to a demodulation scheme of amplitude shift keying (ASK) signals if the input signals include the ASK signals; and   filtering the pulse signals having counting values falling outside of the predetermined value range according to another demodulation scheme of frequency shift keying (FSK) signals if the input signals include the FSK signals.   
   
   
       15 . The demodulation method according to  claim 12 , before counting the extracted pulse signals, the method further comprising detecting the extracted pulse signals, and filtering burr pulses having pulse widths smaller than a desired width of the extracted pulse signals.