Q4120宽带记录器
Advanced Broad Band Acquisition System
　

General Description
The Q4120 is an advanced integrated data acquisition system that incorporates Quanterra’s proven broad-band technology. The system combines a 4 or 8-channelhigh-resolution digitizer having greater than 24-bit resolution and independent digital signal processors (DSP). It has a powerful CMOS computer system with RAM, DAT tape and disk memory. The unit supports both Quanterra’s world-standard dial-up interface, a real-time packetized

protocol, and TCP/IP communications.  Sampling rates available to the user are sub 1-Hz up to 1 kHz.

140+dB resolution A/D + DSP:

The Q4120 incorporates one or two independently optically-isolated4-channel high-resolution analog front ends, an 8-channel DSP module,a power conversion module, a CPU/RAM module containing 8 or16Mb. Optical isolation of the two channel groups, a unique Quanterra feature, allows attainment of full resolution using 2 sensors.

 The analog front-end incorporates Quanterra’s own patented delta-sigma modulator and operates at a fixed sample rate of 32kHz, with other rates derived by digital filtration and decimation in the DSP module. This is the same technique employed in Quanterra's Q52K-1and Q680 family of 24-bit digitizers that are in use worldwide in leading programs such as the IRIS GSN, TERRAScope, and US National Seismic Network. Our design is unique in that we are not limited by the use of under-performing “24-bit” chips.

The CPU/DSP module is an enhanced CMOS 68030 that uses up-to-date VLSI in-circuit programmable gate arrays.  The CPU/DSP supports Quanterra's SHEAR data acquisition and real-time dial-up data access software. Sampling configuration (rates, filter characteristics, detectors, etc.) are programmable on a per-channel basis. The users may install their own FIR or IIR digital filters to provide any sample rates independently on all channels that are integer divisible into 2kHz.

Minimum or Linear Phase Filters:

The FIR digital filters are specified in simple ASCII text files, and may be either linear-phase (constant delay) or minimum-phase, which are causal. Causal filters may be essential where unambiguous on set times are a principal requirement. The system may simultaneously support both minimum and linear-phase filters. The user may also specify recursive filters to perform simple functions such as high-pass and band-pass where full broad-band coverage is not desired.

Real-time Packetized Transmission:

All Quanterra processors support a protocol jointly developed by Quanterra and Martin-Marietta for use in the IRIS Global Seismic Network (GSN) stations. The protocol allows selective user-definable priority transmission of specific data types, such as broad-band event or long-period continuous, over a simple serial asynchronous link, or over a standard TCP/IP socket interface. Extensive CRC error correction and sliding-window retransmission virtually eliminate the possibility of incorrectly received data. The protocol also contains system advisory messages and event detections from the remote stations. It also allows central-site triggering and reconfiguration without stopping data acquisition.

The transmitting system, or DA (data acquisition) processor will retain all data that are not acknowledged for later transmission. As buffer memory fills in the DA, previously acquired data will be over-written in reverse-priority order to give the highest probability that the user’s preferred data is transferred through the link. The link temporarily may be cut completely, and the receiver powered down without loss of data.  Software to receive the packetized data are available for both MS Windows ™ and Sun SPARC™ systems. Quanterra is developing the Sun package jointly with UC Berkeley and IRIS. It will provide central-site collection of data from multiple SHEAR-equipped systems.

Extensive Logging:

Quanterra’s SHEAR package records on tape and disk not only the basic compressed data, but extensive timing information, detection logs, and complete logs of console text, all in FDSN-standard SEED format. Even a log of every keystroke is maintained for remote access users! These capabilities provide extensive performance analysis, and support remote maintenance, an essential feature in today’s advanced systems, and a principal reason for selection of Quanterra’s field-proven technology in demanding applications such as the Global Networks.

Data Compression:

Quanterra’s SHEAR package records on tape and disk not only the basic compressed data, but also extensive timing information, detection logs, and complete logs of console text. It is all recorded in FDSN-standard SEED format. Even a log of every keystroke is maintained for remote access users! These capabilities provide extensive performance analysis, and support remote maintenance, an essential feature in today’s advanced systems for global networks.

Data are stored using Federation of Digital Seismic Network standard Level 1 or Level 2 compression algorithms used on IRIS stations, and developed by Quanterra. The compression method achieves up to 600% improvement over 32-bit data, and features quick and efficient decompression and exact reconstruction. Field systems directly generate mini-SEED format data. This allows maximum data integrity through subsequent processing: Data are distributed and transferred exactly as recorded.

Dial-up Data Access:

Quanterra developed the world-wide defacto standard dial-up interface for broad-band seismic data. Quanterra's proven SHEAR software includes sophisticated file and resource management allowing data storage to be configured optimally for a user's requirements. As an example, our systems support transmission by Kermit of binary, compressed 'mini-SEED' data files containing an entire day of event segments, or any user-specified data request. The `bufserv' data manager indexes recorded data by time to allow user requests to retrieve only relevant data. Data files transmitted are uniquely named automatically according to time and data type. With Quanterra compression, binary data file transfer can be up to 5 times as efficient as the best compression provided by high-speed modems on ASCII text files.

TCP/IP Network Access:

Because Quanterra’s SHEAR application software package operates with a true real-time operating system, many features are built in, such as remote login, data transmission to multiple independent clients, and standard functions such as telnet, ftp, and a Berkeley “sockets” programming Interface. Quanterra’s latest-release SHEAR package supports a powerful data collection over a TCP/IP network using the commonly available “finger” program that is familiar to most e-mail users with a single command-line from your workstation, such as:

finger “retrieve:I bh? 94/7/22 94/7/23”@mystation.university.edu

 you can collect all channels of broad-band (bhz,bhn,bhe) compressed data covering the user-specified time interval of 94/07/22 through94/07/23. Time intervals may be specified to the nearest second.

SHEAR ®software:

Our sophisticated system and application software gives our field systems capabilities that are impossible in simple ‘field’ boxes and ‘recorders’. The system includes multiple, simultaneous data access modes, simple reconfiguration, remote status acquisition, diagnostics, and software updates (by dial-up or network), TCP/IP login, and more. SHEAR is real, mature software, for your critical data acquisition needs.

Desk-Top or Rack-Mount Package:
The Q4120 is also available in a small totally-shielded metal package that requires minimum space and is suitable for installation in a facility. Connection is made via standard “D” connectors:
Q4120 Data Sheet PDF Format
　

Installation and Repair Services

Quanterra installation and repair services fully support the Q4120 and all our family hardware. Quanterra maintains and supports our MSHEAR software suite across our line of Q4120, Q730, and Q680 products.

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