struct spectrogram {
int nsub,nchan;
double *mjd;
double freq,samp_rate;
float *length;
float *z;
char nfd0[32];
};
struct spectrogram read_spectrogram(char *prefix,int isub,int nsub,double f0,double df0,int nbin,double foff);
void write_spectrogram(struct spectrogram s,char *prefix);
