Perseus metadata is contained in a special chunk just before the
'data' chunk. It is named 'rcvr' and has the following data structure
(longs are 32 bit, time_t is 32 bits)

typedef struct {
char chunkID[4]; // ="rcvr"
long chunkSize; // chunk len - 8
long nCenterFrequencyHz; // center freq in Hz
long nSamplingRateIdx; // 0=125k, 1=250k, 2=500k, 1 M
time_t timeStart; // UTC rec time init
unsigned short wAttenId; // 0=0dB, 1=10dB, 2=20dB, 3=30dB
char bAdcPresel; // 0=Presel Off, 1=Presel On
char bAdcPreamp; // 0=ADC Preamp Off, 1=ADC Preamp ON
char bAdcDither; // 0=ADC Dither Off, 1=ADC Dither ON
char bSpare; // for future use (default = 0)
char rsrvd[16]; // for future use (default = 000..0)
} RcvrChunk;


// Formato chunk "rcrv" di Perseus

  struct rcvrhdr
  {
	char  		chunkID[4];	          // ="rcvr" (chunk perseus beta0.2)
	long  		chunkSize;	          // lunghezza del chunk
	long		nCenterFrequencyHz;   // Frequenza centrale di acquisizione
	long 		SamplingRateIdx;      // 0=125K, 1=250K, 2=500K
	time_t 		timeStart;	          // Ora inizio registrazione (ottenuta con time(&timeStart))
	unsigned short 	wAttenId;	      // 0=0dB, 1=10dB, 2=20dB, 3=30dB
	char		bAdcPresel;	          // 0=Presel Off, 1=Presel On
	char		bAdcPreamp;	          // 0=ADC Preamp Off, 1=ADC Preamp ON
	char		bAdcDither;	          // 0=ADC Dither Off, 1=ADC Dither ON
	char		bSpare;		          // for future use (default = 0)
	char        rsrvd[16];	          // for future use (default = 000..0)
  };

  struct auxihdr     // used by SpectraVue in WAV files
  {
	char  	   chunkID[4];	          // ="auxi" (chunk rfspace)
	long  	   chunkSize;	          // lunghezza del chunk
	SYSTEMTIME StartTime;
	SYSTEMTIME StopTime;
	DWORD CenterFreq; //receiver center frequency
	DWORD ADFrequency; //A/D sample frequency before downsampling
	DWORD IFFrequency; //IF freq if an external down converter is used
	DWORD Bandwidth; //displayable BW if you want to limit the display to less than Nyquist band
	DWORD IQOffset; //DC offset of the I and Q channels in 1/1000's of a count
	DWORD Unused2;
	DWORD Unused3;
	DWORD Unused4;
	DWORD Unused5;
	char  nextfilename[96];
  };
