· Low Data Rate Optimization
Given the potentially long duration of the packet at high spreading factors the option is given to improve the robustness ofthe transmission to variations in frequency over the duration of the packet transmission and reception. The bit LowDataRateOptimize increases the robustness of the LoRa link at these low effective data rates. Its use is mandated when the symbol duration exceeds 16ms. Note that both the transmitter and the receiver must have the same setting for LowDataRateOptimize.
考慮到數(shù)據(jù)包在高傳播因子下的潛在長時(shí)間, 該選項(xiàng)用于提高傳輸?shù)綌?shù)據(jù)包傳輸和接收期間的頻率變化的魯棒性祷愉。LowDataRateOptimize位開啟后可以增強(qiáng)Lora 連接在低速率條件下的魯棒性黑滴。當(dāng)單個(gè)符號傳輸時(shí)間超過16毫秒時(shí)每瞒，必須使能LowDataRateOptimize位躲雅。請注意，發(fā)射機(jī)和接收機(jī)都必須具有相同的LowDataRateOptimize設(shè)置碘耳。
· Symbol Duration
Symbol Duration其實(shí)就是Rs的倒數(shù):
where BW is the programmed bandwidth and SF is the spreading factor. The transmitted signal is a constant envelopesignal. Equivalently, one chip is sent per second per Hz of bandwidth.
LowDataRateOptimize作為低速優(yōu)化薄扁，是針對Symbol Rate（簡稱Rs）需要大于16ms/per symbol情況下。當(dāng)SF設(shè)置較低捧挺，BW設(shè)置較大情況下，Ts會很大尿瞭，此時(shí)必須開啟這個(gè)優(yōu)化功能闽烙。
那TS小于16ms情況下，是否也可以打開筷厘？是可以的鸣峭，但是傳送時(shí)間會增加不少宏所，設(shè)計(jì)時(shí)請注意酥艳。
· 舉例分析：
- 以BW=500K，SF=10為例：
此時(shí)RS = 500kHz / 1024爬骤，TS = 1 / RS = 1024/500 (ms) = 2 ms
這種情況下充石，不一定需要開啟Low Data Rate Optimization，但是也可以開啟霞玄。 - 以BW=25K骤铃，SF=10為例：
此時(shí)RS = 25kHz / 1024，TS = 1 / RS = 1024/25 (ms) = 40.96 ms
這種情況下坷剧，必須開啟Low Data Rate Optimization惰爬。
