function readmud_gak, FilePath, FromSecond, ToSecond, sample_rate


;FilePath='c:\LYR_2007_01.MUD'
;FromSecond = long(long(3600) * 24)
;ToSecond = long(long(3600) * 24 * 2)

; open the MUD file:
dat_fh = 1
openr, dat_fh, filepath, /get_lun

; read header
FileFlag = bytarr(4)
NumChannels = 0
SampleRate = 0
SampleSize = 0
StartYear = 0
StartMonth = 0
StartDay = 0
StationName = bytarr(4)
NumSeconds = long(0)
Reserved1 = long(0)
Reserved2 = long(0)

readu, dat_fh, FileFlag
readu, dat_fh, NumChannels
readu, dat_fh, SampleRate
readu, dat_fh, SampleSize
readu, dat_fh, StartYear
readu, dat_fh, StartMonth
readu, dat_fh, StartDay
readu, dat_fh, StationName
readu, dat_fh, NumSeconds
readu, dat_fh, Reserved1
readu, dat_fh, Reserved2

; set sample buffer size
SampleBufferSize = SampleRate * SampleSize / 8

; allocate data array
Data_Array  = fltarr(2, (long(ToSecond)-long(FromSecond)) * sample_rate)

; allocate temp buffer
Buffer_Array = intarr(20, 2)

; move to the 1st data position
Offset = long(32)
Offset = Offset + FromSecond * (4 + SampleBufferSize * NumChannels)
POINT_LUN, dat_fh, Offset

; read samples
Second = 0L
FOR n = 0L, (long(ToSecond)-long(FromSecond)) - 1L DO BEGIN
    readu, dat_fh, Second

    ; read 20-sample chunk of 2 channels
    readu, dat_fh, Buffer_Array

    ; assign the samples to the data array
    FOR m = 0, 19 DO BEGIN
        Data_Array(0, n * 20 + m) = (Buffer_Array(m, 0) + 2048.0) / 4096.0 * 20.0 - 10.0;
        Data_Array(1, n * 20 + m) = (Buffer_Array(m, 1) + 2048.0) / 4096.0 * 20.0 - 10.0;
    ENDFOR
ENDFOR

; close the file
free_lun, dat_fh

return, Data_Array
end