[aprssig] APRS tone encode question

[Andrew Rich]

I threw the tinytrak audio onto a CRO and compared it to a sine wave from a
sig gen.

How come a DAC ladder network of 4 resistors only produces 8 steps ?

Should it not end up being 16 steps ?

0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111

image

http://www.tech-software.net/139_3935.JPG