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LMX2571的4FSK调制问题



目前寄存器配置如下:
data[1] = 0x3CA000;
data[2] = 0x3A8C00;
data[3] = 0x357806;
data[4] = 0x2F6000;
data[5] = 0x2A0210;
data[6] = 0x290808;
data[7] = 0x28081C;
data[8] = 0x2711FB;
data[9] = 0x230C87;
data[10] = 0x221001;
data[11] = 0x210000;
data[12] = 0x200000;
data[13] = 0x1F0000;
data[14] = 0x1E0000;
data[15] = 0x1D0000;
data[16] = 0x1C0000;
data[17] = 0x1B0000;
data[18] = 0x1A0000;
data[19] = 0x190000;
data[20] = 0x18000E;
data[21] = 0x170E44;
data[22] = 0x168080 | MULT | (chdiv1_F2 << 8) | (chdiv2_F2 <<10);
data[23] = 0x150101;
data[24] = 0x143000 | N_interger_F2;
data[25] = 0x130000;
data[26] = 0x120000 | (NUM_F2 & 0x00FFFF);
data[27] = 0x110000 | (NUM_F2 >> 16);
data[28] = 0x100000;
data[29] = 0x0F0000;
data[30] = 0x0E0000;
data[31] = 0x0D0000;
data[32] = 0x0C0000;
data[33] = 0x0B0000;
data[34] = 0x0A0000;
data[35] = 0x090000;
data[36] = 0x08040E;
data[37] = 0x070E84;
data[38] = 0x068080 | MULT | (chdiv1_F1 << 8) | (chdiv2_F1 <<10);
data[39] = 0x050101;
data[40] = 0x043000 | N_interger_F1;
data[41] = 0x030000;
data[42] = 0x020000 | (NUM_F1 & 0xFFFF);
data[43] = 0x010000 | (NUM_F1 >> 16);
data[44] = 0x000083;
根据我输入的频率,计算出相应参数,并且频率正确,其中,晶振20M,fpd80M,MULT=4,RFout230M

但是我在F1上加入4FSK调制信号,采用I2S模式,主要参数如下:
4FSK modulation baud rate = 4.8 kSps
Raised Cosine pulse-shaping filter, BT = 0.2
FSK frequency deviation = 648 Hz and 1944 Hz
Over-sampling factor = 10x
Over-sampling rate = 48 kHz
Fractional denominator, DEN = 2^24

用技术手册上的公式4和6计算steps,在648Hz下应该为1359,1944Hz下为4077,然后用DSP的mcbsp口送数
据,出现几个问题:
1、发现调制信号不正确,与计算出来的频偏不一致。
2、我直接一直发送4077,频偏不是1944Hz,发700的时候频偏正好为1944Hz,不知道什么原因?
3、还发现一个奇怪的现象,我先给出一组测量值:
steps       频偏
233          469Hz
255          479Hz
256          719Hz
700         1938Hz
1400       3816Hz

可以看出700的时候,频偏为1938Hz,那么233时,应该为700的三分之一,但是明显不对,在233-255区
间,频偏几乎没有变化,到256时一下跳变很多,并不是线性关系。并且每到二进制进位的节点上都会有
跳变。

问题描述大概就是这样,看帖子说跟环路带宽有关系,想问一下这个环路带宽和信号速率有什么关系?
希望大神帮忙分析一下。