我们根据SWRU295E 《CC112X/CC1175 Low-Power High Performance Sub-1 GHz RF Transceivers/Transmitter User’s Guide》文档中的第37页中关于RSSI Offset的说明,使用信号源对CC1120的RSSI Offset进行了实验测试。
得到以下数据
| 终端编号 | 信号源发射功率 (dBm) |
RSSI Offset |
| A | 0 | -93 |
| -5 | -98 | |
| -10 | -99 | |
| -15 | -99 | |
| -20 | -99 | |
| -25 | -98 | |
| -30 | -98 | |
| -35 | -99 | |
| -40 | -98 | |
| -45 | -99 | |
| -50 | -98 | |
| -55 | -98 | |
| -60 | -100 | |
| -65 | -100 | |
| -70 | -100 | |
| -75 | -102 | |
| -80 | -101 | |
| -85 | -101 | |
| -90 | -102 | |
| -95 | -102 | |
| -100 | -104 | |
| -105 | -108 |
| 终端编号 | 信号源发射功率 (dBm) |
RSSI Offset |
| B | 0 | -91 |
| -5 | -95 | |
| -10 | -95 | |
| -15 | -95 | |
| -20 | -95 | |
| -25 | -95 | |
| -30 | -95 | |
| -35 | -95 | |
| -40 | -95 | |
| -45 | -95 | |
| -50 | -95 | |
| -55 | -95 | |
| -60 | -95 | |
| -65 | -97 | |
| -70 | -97 | |
| -75 | -98 | |
| -80 | -98 | |
| -85 | -98 | |
| -90 | -98 | |
| -95 | -99 | |
| -100 | -101 | |
| -105 | -105 |
| 终端编号 | 信号源发射功率 (dBm) |
RSSI Offset |
| C | 0 | -93 |
| -5 | -97 | |
| -10 | -97 | |
| -15 | -97 | |
| -20 | -97 | |
| -25 | -97 | |
| -30 | -97 | |
| -35 | -97 | |
| -40 | -97 | |
| -45 | -97 | |
| -50 | -97 | |
| -55 | -97 | |
| -60 | -97 | |
| -65 | -98 | |
| -70 | -99 | |
| -75 | -99 | |
| -80 | -99 | |
| -85 | -100 | |
| -90 | -100 | |
| -95 | -101 | |
| -100 | -103 | |
| -105 | -108 |
| 终端编号 | 信号源发射功率 (dBm) |
RSSI Offset |
| D | 0 | -93 |
| -5 | -97 | |
| -10 | -97 | |
| -15 | -97 | |
| -20 | -97 | |
| -25 | -97 | |
| -30 | -97 | |
| -35 | -97 | |
| -40 | -97 | |
| -45 | -97 | |
| -50 | -97 | |
| -55 | -99 | |
| -60 | -99 | |
| -65 | -99 | |
| -70 | -99 | |
| -75 | -100 | |
| -80 | -100 | |
| -85 | -100 | |
| -90 | -100 | |
| -95 | -100 | |
| -100 | -101 | |
| -105 | -104 |
| 终端编号 | 信号源发射功率 (dBm) |
RSSI Offset |
| E | 0 | -93 |
| -5 | -97 | |
| -10 | -97 | |
| -15 | -97 | |
| -20 | -97 | |
| -25 | -97 | |
| -30 | -97 | |
| -35 | -97 | |
| -40 | -97 | |
| -45 | -97 | |
| -50 | -97 | |
| -55 | -97 | |
| -60 | -99 | |
| -65 | -98 | |
| -70 | -99 | |
| -75 | -100 | |
| -80 | -100 | |
| -85 | -100 | |
| -90 | -100 | |
| -95 | -101 | |
| -100 | -103 | |
| -105 | -108 |
根据测试结果来看,RSSI Offset并非一个固定的值,是会根据输入信号的强度来变化的。
现在有如下问题:
1. 这样设计的实验合理吗?CC1120的特性是否真如实验数据所显示的一致?
2. 对RSSI Offset的值造成影响的因素有哪些?关于这个值是否有更多说明,或者有官方的实验数据曲线可参阅?
3. 我们在程序设计时应该往AGC_GAIN_ADJUSTMENT寄存器中写入怎样的值?是否需要根据接收信号的强度来动态调整?