Permanent wireless links

Permanent wireless connection for real time data transmission over 14km using Mykerinos-R devices

In february 2007 Agecodagis went to Aigion with Anne Deschamps (Geosciences Azur) and Alexandre Nercessian (IPGP) in order to install three Mykerinos-T devices as compagnons for the Titan3NT digitizers. The site equiped with Titan3NT were operating as part of the Corinth Rift Laboratory Network since 2000.
The operation aimed to convert the static local recording based on Titan3NT stations into up-to-date Osiris-like systems (remote management, real time data transfer). Three sites were chosen to receive the Mykerinos-T devices: Agios Giorgios (AGE), Psaromita (PSA) and Aliki (ALI).


The Mykerinos-T device is a compagnon for any Titan-family digitizer that provides all the Osiris features. Mykerinos-T is plugged on the DIALOGUE port of the Titan digitizer (or the TitanGPS if any). The data are stored on a solid state device and the regular Osiris interface (including OSH, the SeedLink server, the user friendly web interface, and the dynamic routing system) is available over a 10/100Mbit/s ethernet or PPP (dialin/dialout) connection.


In the case of AGE, an ADSL modem has been connected to  the Mykerinos-T device and the data could be sent directly to a computer in France in real time. Mykerinos-T is running at station AGE since February.

In stations ALI and PSA, where the ADSL connection could not be installed, we used Mykerinos-R devices (eth/wireless relays) to reach two other Mykerinos-R on the top of the Aigion TEI on the seaside of Aigion.
At home, we have verified the ability to establish a wireless connection over distances longer than 16km in very various and difficult conditions (e.g. fog, wind, and rain) so we were confident in the feasability of the connection.

During our first visit in February, we faced some unattended problems. For both PSA-TEI and PSA-ALI links, each Mykerinos-R device could 'see' the other party over the wireless link but the actual IP connection could not be established due to the apparent poor quality of the link.

Several tests performed during the three days spent on the sites evidenced some very strong Wi-Fi sources located in the vicinity of Aigion.
These omni-directionnal sources were (and are still) sufficiently powerfull to be 'heard' from the top of TEI in Aigion, and at site PSA. Also, on the seaside road to ALI (more than 45 degrees away from the ferry route, 12km eastward), the signal from the same group of wireless network was still very strong.

We went back home with the idea that the our receivers must be more selective in order to ignore the unwanted wireless networks. After some tests performed in situations similar to the one of Aigion, we came back in Greece in the beginning of June 2007 with 4 Mykerinos-R.

In a few hours, the four Mykerinos-R were operating and provided the connection between TEI and PSA and ALI.

After a few days of tests and adjustements, the two stations PSA and ALI continuously transmitted their data over the air to the PC at Aigion and then to computer at the Ecole Normale Supérieure. The Titan2 files are stored for furtherprocessing and the SeedLink streams are injected to Earthworm (see ephesite.ens.fr/~eworm/ew/).

The only network configuration required for the system to work is performed on the PC at Aigion: it consists of defining the default gateway and the IP address of the interface connected to the Mykerinos-R devices. All the network configuration for the other devices (the four wireless relays and the two Mykerinos-T) is fully automatic thanks to the Osiris dynamic routing system.

At PSA, using a regular laptop running the dynamic routing daemon, we were able to connect the Internet over the Mykerinos-R without any IP configuration, the only required information is the wireless encryption key, the Osiris dunamic rtouting system does the job.

Thanks to our growing experience with wireless links, permanent or temporary, we are able to study and propose a solution for almost any type of wireless connection requirement, also in a noisy environment. We can provide any type of antenna, depending on the coinfiguration, link length etc.