Source: record sleep-edfx/sleep-cassette/SC4281G0-PSG.edf  Start: [13:46:00.000 28/08/1991]
val has 7 rows (signals) and 1000000 columns (samples/signal)
Duration:     0:03
Sampling frequency: 100 Hz  Sampling interval: 0.01 sec
Row	Signal	Gain	Base	Units
1	EEG Fpz-Cz	11.2809917355	5	uV
2	EEG Pz-Oz	10.6363636364	5	uV
3	EOG horizontal	2.17703349282	3	uV
4	Resp oro-nasal	1	0	nd
5	EMG submental	500	0	uV
6	Temp rectal	1000	-15000	nd
7	Event marker	1	-1	nd

To convert from raw units to the physical units shown
above, call the 'rdmat.m' function from the wfdb-matlab
toolbox: https://physionet.org/physiotools/matlab/wfdb-app-matlab/