get_lfm.m

国外大学的同志作出来的好程序

function lfm_seq=get_lfm(sim);
%
%
%
fmin=sim.carrier_freq-sim.bandwidth/2;
fmax=sim.carrier_freq+sim.bandwidth/2;


if findstr(lower(sim.lfm_type), 'lfm_doppler'),
    ilen=length(sim.lfm_type);
    lfm_time=str2num(sim.lfm_type(12:ilen))*1e-3;
    lfm_type='lfm_doppler';
elseif findstr(lower(sim.lfm_type), 'lfm'),
    ilen=length(sim.lfm_type);
    lfm_time=str2num(sim.lfm_type(4:ilen))*1e-3;
    lfm_type='lfm';
end

[s] = lfm(fmin, fmax, lfm_time, sim.sampling_rate, lfm_type);
lfm_seq=s;


if sim.tx_num>1;
    %expand to multiple transmitter
    hydro=floor(sim.tx_num/2)+1;
    st_s=zeros(size(s, 1),sim.tx_num);
    st_s(:, hydro)=s;

    lfm_seq=st_s;
end

qlen=round((sim.lfm_time-lfm_time)*sim.sampling_rate);
lfm_seq=[lfm_seq; zeros(qlen, size(lfm_seq, 2))];