Introduction¶
The Distributed Oscilloscope (DO) is an application allowing to synchronously monitor analog signals in a distributed system, independently of the distance.
The idea of the DO is presented in Fig. 1.
Fig. 1 Synchronous acquisition of distributed data
Analog signals from various digitizers are time-stamped, aligned to the same moment in time and sent to the Graphical User Interface (GUI), to be displayed. The synchronization is obtained using the White Rabbit Trigger Distribution (WRTD) project.
Architecture¶
The DO consists of three layers:
The structure of the DO is presented in Fig. 2.
Fig. 2 Structure of the DO
The DO Server is a proxy between Devices and Users Applications. In single network, there could be one server, multiple users and multiple devices. The applications typically are run on different machines, but it is not a restriction.
User Applications¶
There are currently two User Applications available:
- GUI — it is designed to resemble standard oscilloscope.
- testbench — it is used to test the DO Server and the Device Applications as well as to perform statistical measurements of data acquisition speed and of the precision of the synchronization.
User Applications serve the following purposes:
- Sending the configuration settings
- Collecting and processing the acquisition data
Device Applications never communicate with the devices directly, always through the DO Server. This allows to hide all the implementation details and to provide a common interface for various types of applications. The details on how to write User Applications are described in section Developer Guide
DO Server¶
The DO Server is a central unit responsible for managing all the connections, preprocessing the data and providing a common interface for connected applications.
Device Application¶
Device applications provide direct access to hardware resources. At the moment the only available devices are ADCs supported by the adc-lib.
Hardware setup¶
The minimum hardware requirements necessary to demonstrate features of the DO are the following:
- computer with minimum 2 PCIe slots and CentOS 7.6.1810
Note
The DO is designed to run each application on a different machine. However, it is possible to run them on the same machine. To make the DO really distributed, the ADC cards should be installed in different locations in different machines. The described hardware setup should serve only as a demonstrator.
Note
CentOS 7.6.1810 guaranties that all the drivers will function properly. However, it is possible to use the DO with different OS. In case of machines where the Server and the GUI are run, the Linux version does not matter.
2 SPEC 150T boards
Important
The DO will work only with SPEC 150T version. Be careful not to purchase standard SPEC 45T version.
2 FMC ADC 100M 14b 4cha boards
2 fibers
4 SFP cages
signal generator
The minimum hardware setup of the DO is presented in Fig. 3.
Fig. 3 Minimum hardware setup for the DO
The SPEC boards together with ADC cards should be installed in PCIe slots of the computer and connected to any of the White Rabbit switch channels using the SFP cages and fibers. To be able to demonstrate the synchronization accuracy, the same signal from the generator should be provided to both ADCs, with cables of the same length or precisely known lengths.