Digital realization method of cpm modulation based on look-up table method and digital cpm modulation module
An implementation method and a table look-up technology, which are applied in digital transmission systems, modulated carrier systems, phase modulated carrier systems, etc., and can solve the problems of high complexity and inability to accommodate the phase information of the lower modulated signal.
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Problems solved by technology
Method used
Image
Examples
Embodiment 1
[0140] For the PCM / FM modulation system, M=2, L=1, R=1, single modulation index, h=0.7, the baseband signal phase expression is as follows:
[0141]
[0142] where a i ∈{±1}, the expressions of phase impulse function q(t) and frequency impulse function g(t) are as follows:
[0143]
[0144] The specific implementation steps are as follows:
[0145] (1) Calculate the relative phase of the PCM / FM modulated signal in advance, and the discretization expression of the relative phase is as follows:
[0146] φ n (j)=2πha n q(j),j=0,1,...,2 N -1
[0147] Quantize it, the quantization bit width is W, and the quantized phase value is according to [a n ,j] The addressing mode is stored in the phase table. Since PCM / FM uses a single modulation index, that is, h (n) =h=0.7, so h in addressing address (n) Items can be omitted. In the present embodiment, W=16, N=7, [a n , j] have a total of M L ·2 N = 2·2 7 =256 combinations, the depth D=256 of the phase table, and the wi...
Embodiment 2
[0160] For the ARTM CPM modulation system, M=4, L=3, R=2, h∈{4 / 16,5 / 16}, the baseband signal phase expression is as follows:
[0161]
[0162] where a i ∈ {±1,±3}, h (i) Alternately equals 4 / 16 or 5 / 16, where the subscript (i) means i modulo 2. The expressions of phase pulse function q(t) and frequency pulse function g(t) are as follows:
[0163]
[0164]
[0165] The specific implementation steps are as follows:
[0166] (1) Pre-calculate the relative phase of the ARTM CPM modulation signal, and its discretization expression is as follows:
[0167] φ n (j)=2π(h (n-2) a n-2 q 2 (j)+h (n-1) a n-1 q 1 (j)+h (n) a n q 0 (j)),j=0,1,...,2 N -1
[0168] Quantize it, the quantization bit width is W, and the quantized phase value follows [h (n) ,a n ,a n-1 ,a n-2 ,j] The addressing mode is stored in the phase table. In the present embodiment, W=16, N=7, [h (n) ,a n ,a n-1 ,a n-2 ,j] There are 2·M L ·2 N = 2·4 3 ·2 7=16384 combinations, the depth D=...
Embodiment 3
[0182] For the SOQPSK-TG modulation system, M=3, L=8, R=1, single modulation index, h=0.5, the baseband signal phase expression is as follows:
[0183]
[0184] where a i ∈{±1,0}, it is through the binary bit data b i obtained by precoding. b i ∈{0,1}, the corresponding relationship between the two is shown in Table 4 below.
[0185] Table 4{b n} with {a n} mapping relationship
[0186]
[0187] The expressions of phase pulse function q(t) and frequency pulse function g(t) are as follows:
[0188]
[0189] g(t)=n(t)·w(t)
[0190]
[0191]
[0192] n(t) is a modified raised cosine function. In the expression, A is the normalization coefficient, ρ is the roll-off coefficient, and B is the time scaling factor. w(t) is a time-domain window function used to limit the duration of g(t). T is the symbol period, T 1 , T 2 are two time-related parameters of the time-domain window function. Four parameters (ρ, B, T 1 ,T 2 ) specific value is ρ=0.70, B=1.25, T...
PUM
Login to View More Abstract
Description
Claims
Application Information
Login to View More