IMES has provided seamless positional information both indoor and outdoors as an indoor GPS.
Along with technological innovations such as the advent of IoT and 5G communication, the need for not only positional information but also highly precise temporal information and time synchronization is rapidly rising.
After many years of research geared towards meeting this demand, we have successfully developed iPNT (patent pending) in 2018, where a high-precision time synchronization function has been added to IMES.
IEEE1588 PTP (Precision Time Protocol) is a parallel technology that provides high-precision time synchronization capabilities for indoor settings.
PTP uses the Ethernet cable which is widely used in LAN connections as its transmission channel. A synchronization precision of less than 1 microsecond can be achieved through the use of time packets.
However, as a result of jitters, packet delays, and packet loss due to congestion in the LAN network, it is challenging to establish a stable synchronization accuracy using this method.
At the same time, as the delays are compensated for via packet switching, there is a limit to the number of PTP devices that can be connected to the master device known as the GMC. This setup has multiple issues including its inability to be deployed in a WAN environment where delays may fluctuate dramatically.
iPNT can reduce the deterioration in precision due to external factors and is capable of stable transmission of temporal and synchronization signals.
While IMES delivers positional information and message information (short ID, medium ID) as GNSS signals, iPNT expands the scope of information that can be provided in addition to positional information, such as temporal information, disaster prevention information, extended messages, etc.
In particular, as the temporal information frames are repeatedly transmitted at regular intervals, the GNSS receiver can synchronize the time with high precision by reading the first bit, which is one of its major features.
We have succeeded in developing a technology that synchronizes this iPNT temporal information with the GNSS temporal signals from space in real time, and we are currently working on the commercialization of a GNSS signal transmitter with a time synchronization precision of less than 1 microseconds even in indoor settings.
While the IMES transmission signal specifications are subject to the IS-IMES protocol issued by JAXA, the iPNT transmission signal specifications have been formulated by the Association of Indoor Messaging Service under the IS-iPNT protocol.