I am working on a similar project and having the same issues. As a matter of fact, recognition results are very poor. The biggest problems I am having with letters E, D, P, A. Below is the dictionary file that I compiled. In many cases it recognizes E as P, D, C. Letter A recognizes as 8 or H.
What techniques would you recommend for improving accuracy? Doesn’t more combinations for the same letter help?
0 Z IY R OW
1 W AH N
2 T UW
3 TH R IY
4 F OW R
5 F AY V
6 S IH K S
7 S EH V AH N
8 EY T
9 N AY N
A AH
A(2) EY
B B IY
C S IY
D D IY
E IY
E(2) EH
E(3) IH
F EH F
G JH IY
H EY CH
H(2) EY JH
I AY
J JH EY
K K EY
L EH L
M EH M
M(2) AE M
N EH N
N(2) AE N
O OW
P P IY
Q K Y UW
R AA R
S EH S
S(2) AE S
T T IY
U Y UW
V V IY
W D AH B AH L Y UW
X EH K S
X(2) AE K S
Y W AY
Z Z IY