Source: record slpdb/slp45  Start: [00:15:00.000 31/08/1989]
val has 7 rows (signals) and 900000 columns (samples/signal)
Duration:  1:00:00
Sampling frequency: 250 Hz  Sampling interval: 0.004 sec
Row	Signal	Gain	Base	Units
1	ECG	-500	0	mV
2	BP	11.0938	-811	mmHg
3	EEG (C3-O1)	-9653.33	0	mV
4	Resp (nasal)	-1402	0	l
5	Resp (abdominal)	-1632	0	l
6	EOG (right)	-2382.86	0	mV
7	EMG	-34054.3	0	mV

To convert from raw units to the physical units shown
above, subtract 'base' and divide by 'gain'.