Hi, I am working on SimpleBLEPeripheralObserver project on a sensortag. I am doing an experiment to see how many advertising packets sent from an iPhone can be scanned by the sensortag. However, I can only get at most approximately 82% instead of 100% of the packets at merely a distance of 3 cm between the two devices. The parameters I have set are…
1. sensortag with scanning duration of 80 ms
2. sensortag with scanning interval of 80 ms
3. iPhone with advertising interval of 240 ms
The code that has been fired periodically on the sensortag for scanning is…
GAPObserverRole_StartDiscovery( DEFAULT_DISCOVERY_MODE,
DEFAULT_DISCOVERY_ACTIVE_SCAN,
DEFAULT_DISCOVERY_WHITE_LIST );
In other words, the sensortag parameters above result in full scanning duty cycle. Furthermore, by changing the parameters to something else other than 80ms, I get significantly lower advertising packets receiving rates, such as 70%, 60%, or even lower.
Question 1: Does anyone have any idea to fix this problem? Or anything I should check?
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I have also done another experiment using the same project on a sensortag. I have collected the current over time. This time, I change the parameters as listed below…
1. sensortag with scanning duration of 50 ms
2. sensortag with scanning interval of 100 ms
The sensortag for this part of the experiment has 50% scanning duty cycle. However, I get an interesting result shown in the figure. There seems to have some “downward spikes” as circled in the figure below during the scanning duration. The current drops significantly from 22mA down to 7mA every 10ms during the scanning duration. I have no idea how this occurs or whether it is functioning properly. I also suspect that the sensortag cannot scan for any advertising packets during the drop, so that’s why I am unable to let the sensortag receive all the advertising packets sent from iPhone.
Moreover, I did another experiment with 100% scanning duty cycle. The same “downward spikes” occurred as well. I computed the average current, and I got 17 mA, which is the same as that on the sensortag specs. So, I infer that the “downward spikes” may be for power saving.
Question 2: According to the figure, are the “downward spikes” supposed to occur during scanning duration?
Question 3: Is is because of the “downward spikes” that lowered the receiving advertising packets on the sensortag?
Question 4: Whether or not the sensortag is working properly, how do I make the “downward spikes” go away or reduce the numbers of the spikes?
Question 5: How do I increase my advertising-packets-receiving rate if I cannot make the “downward spikes” go away?
Sorry for asking so many questions. I have been looking for answers for weeks. Please help me! Thanks. If there is any additional information I have to provide, please let me know.
