FAQ of Bluetooth gateway

Q: the gateway is based on classrooms, one for each classroom. What should we do when there is a signal string from upstairs to downstairs?

Bluetooth is frequency hopping, and the RSSI value will jump. It is recommended to process the RSSI value on average for 5-10 seconds. In addition, the signal below - 90dB should be filtered out. This is what we usually need to process. Our Bluetooth gateway has pa in it. If you don't need to scan too wide, you can remove PA, but in this way, the scanning range of the gateway will be reduced, the radius will be 10-15m, and the coverage will be particularly limited, The gateway installation density will be very high.

Processing method: the installation and coverage of each gateway are different. When installing, confirm the range of RSSI value at the edge, record it, add a special column in the system to filter the threshold value, and fill it in the system directly.

Q: how to determine the average RSSI value of Bluetooth gateway?

First of all, the average RSSI value is to prevent RSSI jumping, improve the effective signal value, filter the equipment in the far area, and prevent crosstalk. For example: device a is between gateway 1 and gateway 2. Gateway 1 collects RSSI values five times, and gateway 2 also receives RSSI values five times. After average, the signal of gateway 1 is better than that of gateway 2. That is to say, device a is in the range of gateway 1

Q: how does Bluetooth gateway do signal filtering?

For example: device a is in the range of gateway 1, and the RSSI value is low. It can be calculated according to the field situation. Suppose that the room is 10 * 10 square, the gateway is installed in the center, and the device is placed at the farthest point from the gateway. Test the average RSSI value, and assume that the value is - 65dB. At this time, this value can be taken as the lowest filtering value, and all devices below this value can be filtered, In order to prevent the loss of valid data, it can be adjusted to - 70dB. The equipment outside the wall should be scanned in time, and the attenuation should be at least 10dB

Q: does the Bluetooth gateway process the received data and save the data in the gateway?

Background database, MySQL ，Oracle is OK. This data structure is relatively simple and can be designed by ourselves.

The data collected by the gateway needs to be processed before it can be put into storage, mainly for de reprocessing. The analysis of some JSON fields shows that the amount of Bracelet data is very small, which is less than 1K. However, the gateway will upload multiple Bracelet devices at the same time, and the overall number is less than 5m, which is the same as the way of processing a single bracelet, just the superposition of the number. The gateway parses and encapsulates the received data. The general data is parsed into standard JSON fields. The gateway will not save the data. By default, the data is uploaded by 1 second, and the upload frequency can be adjusted. The data frequency of the bracelet is 1 second, and the gateway scans and uploads the data once a second. If the server can bear it, it can save the data in seconds. If it can't handle it, it can do the average processing or the number of intervals.