Source: record ltafdb/74  Start: [20:33:33.000 18/07/2003]
val has 2 rows (signals) and 38400 columns (samples/signal)
Duration:  5:00
Sampling frequency: 128 Hz  Sampling interval: 0.0078125 sec
Row	Signal	Gain	Base	Units
1	ECG	0	0	mV
2	ECG	0	0	mV

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