User's Manual

Specification of modulation type and data protocol

In normal operation the SRT PT-01 is configured using advertisement over Bluetooth 5 Low Energy

The modulation is GFSK.

Running in advertising mode, advertising packets are sent periodically on each advertising channel.

The time interval between packet set has both a fixed interval and a random delay. The interval is

specified between the set of 3 packets over the 3 used channels (37, 38 and 39).

The Bluetooth Specification defines the top-level packet in Bluetooth LE with two data units. The

packet itself has several parts including a preamble and access address, as well as a CRC.

The Packet data unit for the advertising channel (called the Advertising Channel PDU) includes a 2-

byte header and a variable payload from 6 to 37 bytes. The actual length of the payload is defined by

the 6-bit Length field in the header of the Advertising Channel PDU.

Description of integrity and authenticity measures

The SRT PT-01 relies on the Bluetooth protocol for managing message integrity. The protocol

handles checksum validation for every received package (based on 3 bytes of CRC included in the

package itself). Regarding authentication, the SRT PT-01 will not accept any inbound connections

from other devices as the device is not connectable. Advertisements from SRT PT-01 includes a

unique identifier describing the SRT PT-01 as a type of device. This unique identifier is used by the

SRT MN-01 when filtering for SRT PT-01 devices. In addition, the system uses whitelisting of both SRT

PT-01 and SRT-MN-01 based on unique MAC addresses

. This ensures external or unknown devices

are not able to connect or join the network. Data from unrecognized mesh nodes or tags will be

discarded.

Mesh node and Personnel communication pattern

The SRT PT-01 (wearable tag) will typically be used in conjunction with SRT MN-01 (static located

mesh node). A mesh node will listen for advertisements from all nearby tags based on the unique

advertisement identifier. The mesh-node will forward the information from tag advertisements to an

upstream gateway where this information will be used to create value. If the gateway is not

reachable directly the mesh node will depend on other upstream mesh nodes to forward the

information. As already mentioned, whitelisting of both mesh nodes and tags is used ensuring

unwanted access.

https://en.wikipedia.org/wiki/MAC_address