Source: record ptbdb/patient117/s0291lre
val has 15 rows (signals) and 115200 columns (samples/signal)
Duration:     1:55
Sampling frequency: 1000 Hz  Sampling interval: 0.001 sec
Row	Signal	Gain	Base	Units
1	i	2000	0	mV
2	ii	2000	0	mV
3	iii	2000	0	mV
4	avr	2000	0	mV
5	avl	2000	0	mV
6	avf	2000	0	mV
7	v1	2000	0	mV
8	v2	2000	0	mV
9	v3	2000	0	mV
10	v4	2000	0	mV
11	v5	2000	0	mV
12	v6	2000	0	mV
13	vx	2000	0	mV
14	vy	2000	0	mV
15	vz	2000	0	mV

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