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Q15 is a format for representation of fractional numbers in fixed format.
As you in byte format, real value can be calculated as below:
If number = D7D6...D0 ==> value = 2 ^ 0 * D0 + 2 ^ 1 * D1 + ... + 2 ^ 7 * D7.
In fractional numbers for example Q15 the value calculated as below:
if number = Q15Q14Q13...Q0 ==> value = 2 ^ (-15) * Q0 + 2 ^ (-14) * Q1 + ... + 2 ^ (-1) * Q14 + -2 * Q15.
so if your number is between 1 and -1 you can represent it in Qformat.
to conver a number betwwen -1 and 1 to Q15, you should multiply it by (2 ^ 15 -1).
Now its clear. I think that ADSP have this representation of filter coeficiients.
I have wondered how to transform my real number coefficient into DSP readable form.
Do you know how shold it be done with motorola, and texas DSP?
As i said first you should find the required precision, then convert filter coeffs to selected value.
For example, if you found that 16-bit precision is enough normalize filter coeffes to lie between 1 and -1, then multiply them by 2 ^ 15 - 1.
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