matlab_对接收信号进行转化和功率谱分析。得到信号的统计特性，主要是噪声方面

function [Header, Volts, FSample, Schedule] = NL_load_logger_data(FileName,timeS, TimeL) %Load_LogDataTime.m Loads a logger raw data file %[Header, Volts, FSample, Schedule] = Load_LoggerDataNEW(FileName,timeS); %Volts is a vector of volts at AD convertor %timeS is required length in s use [] as default to get full record %FSample is the sampling frequency in Hz % TimeL is the time delay from zero %test %FileName='d:\robm\otway\loggertest\WNSun_1.dat'; %FileName='c:\robm\ldata\wn130wed21nov.dat'; %timeS=1000; NHeader = 5; %Number of header lines NMarker = 5; %Number of marker lines HeaderLength = 207; %Number of characters in header MarkerLength = 121; %Number of characters in footer HeaderLine = 1; %stores user input information ScheduleLine = HeaderLine+1; %line number of header line containing schedule information RateLine = ScheduleLine+1; %Line number of header line containing sample rate and duration Filter0Line = RateLine+1; %Line number of header line containg filter 0 parameters Filter1Line = Filter0Line+1; %Line number of header line containg filter 1 parameters SchStart = 24; % character number of start of schedule information RateStart = 13; %Character number of start of sample rate info NextRateStr = 'Duration'; %String that follows sample rate PChStart = 13; %Character number of start of Primary channel enabled info SChStart = 18; %Character number of start of Secondary channel enabled info LFStart = 23; %Character number of start of low frequency cut off info HFStart = 30; %Character number of start of high frequency cut off info PGStart = 39; %Character number of start of pre filter gain info GStart = 45; %Character number of start of post filter gain info EndStr = 'Record Marker'; %String that denotes last record in file Fid = fopen(FileName, 'r', 'b'); Header=[]; for ISub = 1:NHeader tmp=fgetl(Fid); Header = strvcat(Header,tmp); end ScheduleStr = Header(ScheduleLine,:); RateStr = Header(RateLine,:); Filter0Str = Header(Filter0Line,:); Filter1Str = Header(Filter1Line,:); %extract which schedule this is Schedule = str2num(ScheduleStr(SchStart:SchStart)); %Extract the sample frequency EndInd = findstr(NextRateStr, RateStr); FSample = str2num(RateStr(RateStart:EndInd-1)); %Extract the sample length zLength = findstr(RateStr,'Duration'); SLength=min([timeS str2num(RateStr(zLength+9:zLength+19))]); NumSamples=ceil(SLength*FSample); %Extract Filter 0 information Ch1Enable = str2num(Filter0Str(PChStart:PChStart)); Ch2Enable = str2num(Filter0Str(SChStart:SChStart)); Ch1Ch2lowFreq = str2num(Filter0Str(LFStart:LFStart+2)); Ch1Ch2highFreq = str2num(Filter0Str(HFStart:HFStart+4)); Ch1Ch2PreGain = str2num(Filter0Str(PGStart:PGStart+2)); Ch2PostGain = str2num(Filter0Str(GStart:GStart+2)); %Extract Filter 1 information Ch3Enable = str2num(Filter1Str(PChStart:PChStart)); Ch4Enable = str2num(Filter1Str(SChStart:SChStart)); Ch3Ch4lowFreq = str2num(Filter1Str(LFStart:LFStart+2)); Ch3Ch4highFreq = str2num(Filter1Str(HFStart:HFStart+4)); Ch3Ch4PreGain = str2num(Filter1Str(PGStart:PGStart+2)); Ch4PostGain = str2num(Filter1Str(GStart:GStart+2)); NumActiveCh = Ch1Enable + Ch2Enable + Ch3Enable + Ch4Enable; FSample = FSample/NumActiveCh; %Extract the sample length zLength = findstr(RateStr,'Duration'); SLength=min([timeS str2num(RateStr(zLength+9:zLength+19))]); NumSamples=ceil(SLength*FSample); %read data PointsToRead=NumActiveCh*NumSamples; %%%Start read data at the TimeL fseek(Fid,ceil(TimeL*FSample)*NumActiveCh*2,'cof'); NumActiveCh Volts = fread(Fid, [NumActiveCh,PointsToRead], 'uint16'); %not actually volts at this stage Volts = Volts'; %limit to sample length (as reads text at file end and all samples are diff length) %Volts=Volts(1:NumSamples,:); %Convert to Volts %Modified Franks method Fullscale = 5; %0 to 5 V %Multiply by this factor to convert A/D counts to volts 0-5 CountsToVolts = Fullscale/65536; szVolts=size(Volts); for i=1:szVolts(2); %need to correct each column Volts(:,i) = (CountsToVolts.*Volts(:,i))-mean(Volts(:,i).*CountsToVolts); end %read last few lines into Header fseek(Fid,-MarkerLength,'eof'); for ISub = 1:NMarker tmp=fgetl(Fid); Header=strvcat(Header,tmp); end fclose(Fid);