Central Recording System
Basic Sketch of the Overall System
BOX Central Recording System can be configured for use with varied energy sources including dynamite, vibrator and air gun. The system setup depends on the end user's specific application. A simplified functional block diagram of the Central Recording System is shown:
Radio data signals emanating from Remote Units are received by a high gain antenna and amplified by a masthead unit. The signals are routed via coaxial cable through a Command Unit to Data Receiver Units for demodulation and decoding. Digital data are forwarded to the Recording Module for distribution to storage and display devices. The accompanying diagram illustrates the received signal flow within the Central Recording System.
Dynamic User Interface at Core of Central Recording System
FairfieldNodal’s BOX system hardware and proprietary software are managed by and through the User Interface, which controls the Recording Module, Data Receiver Units and the Command Unit. The Command Unit is the link used to send command and control messages from the User Interface to Remote Units. Central Recording System equipment can be mounted easily into standard shock-mounted equipment racks.
BOX system User Interface actually is a workstation, which provides survey planning, line control and quality control. It allows the operator to interact with the system, and it can graphically display the status of the entire survey area.
Recording Module
The Recording Module performs and controls functions associated with the acquisition of seismic data, including:
- Data formatting
- Limited processing
- Data storage
- Data display
- Real-time system control
Each recording module includes the following hardware:
- Main microprocessor
- Radio interface
- Real-time peripheral controller
- SCSI interface
- Plotter interface
- Power supply
The SCSI is the interface between the Recording Module and an external data storage device, which usually is a cartridge tape drive. The Recording Module manipulates data to provide conformity to industry format standards. Data are output onto a separate common output bus for transmission to any compatible cartridge tape drive. Multiple cartridge tape drives may be connected to the SCSI Bus. The Recording Module reformats data into a suitable raster form for analog display on a plotter, and it can optionally filter or perform other manipulative functions prior to data display on a plotter.
Tape Drives
Multiple SCSI-compatible Tape Drives can be used (see Specifications).
Antenna
The antenna provides gain to radio signals received from BOX Remote Units. These signals are fed directly to a tower-mounted Masthead Unit. In command mode, the antenna transmits high-power command and control radio signals to Remote Units. Depending on the specific application of the system, the antenna can be either a high-gain directional Yagi or an Omni-directional dipole.
Masthead Unit
This unit is an integral part of the BOX radio system, and it generally is mounted on the tower and close to the antenna. In Receive Mode, the unit provides amplification of incoming radio signals to overcome any losses that may occur in the coaxial cable feeding to the Data Receiver Units. It also provides Transmit/Receive switching to disable and bypass the receive amplifier when command signals are transmitted to Remote Units.
Command Unit
The Command Unit provides the link for sending command and control messages to Remote Units via the high-power command transmitter, which has synthesized frequency control. The Command Unit equally distributes the incoming radio signals from the Remote Units to each Data Receiver Unit.
Data Receiver Unit
Data Receiver Units contain multiple radio receivers, which individually demodulate, decode and reformat incoming radio data prior to providing the output to the recording module. Each radio receiver has independent synthesized frequency control. Multiple Data Receiver Units are interconnected to provide greater system capacity. Each Data Receiver Unit contains 12 Radio Receiver cards, and each Radio Receiver card can receive data from eight Remote Units.