We are now grappling with the design of the wireless data transfer protocol and associated hardware responsible for transferring data between the ground-nodes and the positioning server.
There are two options currently under consideration: 1) a broadband modem and 2) the sub-1-GHz CC1310 transceiver.
Extracted from Russell Silva's Summer 2018 project proposal draft:
Attaching a wireless mobile broadband modem to the Raspberry Pi similar to the procedure used in [1]. This procedure is relatively easy to implement and is cost effective; however, it comes with the cost of several drawbacks. The system clocks of several Raspberry Pi devices can differ up to 0.5 seconds which is detrimental to detection matching. This issue can be solved by using a dedicated beacon transmitter to pair detections with unique events, which can rectify timestamp offsets of up to 30 s [1]. The use of a usb broadband modem will also require mounting an external board to the Raspberry Pi with extra usb connections (the four on the Pi will be consumed with RTL SDR connections) and an internet connection, which may be unavailable in several wildlife tracking areas.
Considering the need for our system to be able to work in remote environments, we cannot depend on cellular or internet carrier access for data transfer. This suggests that a broadband modem is not a feasible choice.
Connect long range RF modules (i.e. CC1310) to each Raspberry Pi ground node and a central basestation through an I2C or SPI connection. These modules would transmit the data with frequencies that do not interfere with the radio frequencies used in localizing the radio tags. The major drawback of this method is that transmissions to the central basestation would have to be coordinated so that multiple receivers do not transmit data to the central basestation at the same time. Also, data might be lost if environmental conditions prevent these transmissions from reaching the central basestation.
Although unsynchronized base-stations may run the risk of simultaneous data transmission, the CC1310 is capable of "listen-before-talk" functionality, in which data is streamed only if no other unit is currently uploading data. Concerning the issue of poor environmental conditions, there are options to boost the signal strength for up to 20km LOS using the CC310 range extender.
Conclusion:
Although more complicated than a broadband modem, I believe wireless data transfer using the CC1310 transceiver is a superior option for the above reasons.
We are now grappling with the design of the wireless data transfer protocol and associated hardware responsible for transferring data between the ground-nodes and the positioning server.
There are two options currently under consideration: 1) a broadband modem and 2) the sub-1-GHz CC1310 transceiver.
Extracted from Russell Silva's Summer 2018 project proposal draft:
Considering the need for our system to be able to work in remote environments, we cannot depend on cellular or internet carrier access for data transfer. This suggests that a broadband modem is not a feasible choice.
Although unsynchronized base-stations may run the risk of simultaneous data transmission, the CC1310 is capable of "listen-before-talk" functionality, in which data is streamed only if no other unit is currently uploading data. Concerning the issue of poor environmental conditions, there are options to boost the signal strength for up to 20km LOS using the CC310 range extender.
Conclusion:
Although more complicated than a broadband modem, I believe wireless data transfer using the CC1310 transceiver is a superior option for the above reasons.
Additional thoughts welcome!