Claims
- 1. A method for demodulating a CPFSK-modulated signal, which comprises:
obtaining an estimate of an n−1-th substitute symbol, which occurs in a linear approximation of the CPFSK modulated signal, as a function of a previously determined n−1-th input data symbol; and determining an n-th input data symbol on which the CPFSK modulated signal is based by using the estimate of the n−1-th substitute symbol occurring in the linear approximation of the CPFSK modulated signal.
- 2. The method according to claim 1, wherein the step of obtaining the estimate of the n−1-th substitute symbol includes using an equation ân−1=ân−2exp{jπη{circumflex over (d)}n−1}, where ân−1 is the estimate for the n−1-th substitute symbol, ân−2 is an estimate for an n−2-th substitute symbol, {circumflex over (d)}n−1 is the n−1-th input data symbol that has been determined, and η denotes a modulation index.
- 3. The method according to claim 1, wherein the step of determining the n-th input data symbol includes determining the n-th input data symbol dn based on a phase angle of a currently obtained n-th complex-value sample symbol yn relative to a phase angle of the estimate of n−1-th substitute symbol ân−1 that has been estimated for an n−1-th time step.
- 4. The method according to claim 3, wherein the step of determining the n-th input data symbol dn includes obtaining a determined value of the n-th input data symbol dn using an equation:
- 5. The method according to claim 1, which comprises using a Viterbi equalizer for performing the step of determining the n-th input data symbol dn.
- 6. The method according to claim 1, which comprises obtaining an equalization by using an equalizer for performing the step of determining the n-th input data symbol dn.
- 7. The method as claimed in claim 6, wherein:
the step of obtaining the equalization includes basing the equalization on a trellis state diagram, in which an i-th channel state relating to a time step n is described by an L-tuple Zni=(znL−1,(i), . . . , zn1,(i), zn0,(i)); znL−1,(i), . . . , zn1,(i), zn0,(i) can each assume possible values of input data symbols dn; and L denotes a channel memory.
- 8. A device for demodulating a CPFSK-modulated signal, comprising:
an input data symbol decision device for determining an n-th input data symbol on which the CPFSK-modulated signal is based; and a substitute symbol estimation device for estimating an n−1-th substitute symbol occurring in a linear approximation of the CPFSK-modulated signal as a function of a previously determined n−1-th input data symbol; said input data symbol decision device configured for using the n−1-th substitute symbol that has been estimated for determining the n-th input data symbol.
- 9. The device according to claim 8, wherein:
said substitute symbol estimation device is constructed for estimating the n−1-th substitute symbol using an equation ân−1=ân−2exp{jπη{circumflex over (d)}n−1}; ân−1 is an estimate of the n−1-th substitute symbol, ân−2 is an estimate of an n−2-th substitute symbol; {circumflex over (d)}n−1 is the n−1-th input data symbol that has been determined; and η denotes a modulation index.
- 10. The device according to claim 8, wherein said input data symbol decision device is constructed for determining the n-th input data symbol dn based on a phase angle of a currently obtained n-th complex-value sample symbol yn relative to a phase angle of the n−1-th substitute symbol ân−1 that has been estimated for an n−1-th time step.
- 11. The device according to claim 8, wherein said input data symbol estimation device is an equalizer.
- 12. The device according to claim 8, wherein said input data symbol estimation device is a Viterbi equalizer.
Priority Claims (1)
Number |
Date |
Country |
Kind |
100 30 390.0 |
Jun 2000 |
DE |
|
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of copending International Application No. PCT/DE01/02200, filed Jun. 11, 2001, which designated the United States and was not published in English.
Continuations (1)
|
Number |
Date |
Country |
Parent |
PCT/DE01/02200 |
Jun 2001 |
US |
Child |
10328917 |
Dec 2002 |
US |