If anyone still wonders about the DCR arena..this taken from the new ADS page on industry news..
<< Hard and Fast Data Handling
New recorders measure up to the needs of intelligence hunter-gatherers.
John M. Howard
Today's surveillance platforms, such as the RC-135 Rivet Joint, require ever-greater recording bandwidth and ease of data distribution. New technology recorders are rising to the challenge. (Boeing photo)
The signs are that solid-state and disk-based data recorders now represent a serious alternative to conventional tape recorders for a broad range of high-end data capture applications. As the number of RFQs specifying these so-called "new technology" solutions increases, virtually every major manufacturer has responded with the announcement of new off-the-shelf products. A NATO technical support team has even been tasked with drafting standards for certain aspects of solid-state and disk recorders.
But what has caused this sudden explosion of interest? Strange to say, in almost every case, it has been the perceived shortcomings of the new technologies that have forced the issue. For all their other apparent advantages, disk and solid-state recorders are essentially only temporary storage devices. To overcome this problem manufacturers have found it necessary to address the total data capture/storage/distribution/archiving scenario--with some interesting results. For the first time in many cases, manufacturers have taken the opportunity to look beyond the narrow confined of the data recorder itself and to offer complete capture/analysis/archival systems. In the past, it was often a case of "We'll record the data, but what you do with it is up to you." Now, manufacturers are offering systems that merge seamlessly with the user's environment. It is in the data-handling area, therefore, that some of the most significant advances of the last twelve to eighteen months are to be found.
To see how the manufacturers of "new technology" recorders have overcome the apparent shortcomings of disk and solid-state storage to the practical benefit of the user, it is convenient to discuss several representative applications in turn. As will be seen, manufacturers have been quick to recognize that four important user requirements must be addressed if their products, for all their esoteric properties, are actually to be considered for active service:
1) Does the new recorder significantly increase the data collection capability of the platform (wider bandwidth, greater resolution and accuracy, longer mission duration, higher probability of successful data capture, etc.)?
2) Can the new recorder significantly enhance the overall capabilities of the data collection/analysis activity in terms of delivering data to where it is needed faster, more conveniently and more reliably?
3) Can the advantages of "new technology" solutions be secured without ultimately compromising the ever-present need for secure, permanent storage?
4) How easy is it to integrate the new product into an existing data collection system without major disruption? (Unless undertaken as part of a major refit, users would ideally prefer a cut-and-paste solution when the existing legacy recorder can be simply substituted.)
Cost in all its guises (purchase price, installation costs, training, media cost, spares, maintenance, equipment availability, etc.) compared to the existing recorder fit (and possible alternative solutions) are also important considerations. But perhaps the most important considerations are applications related. How, where and why is the data capture/storage being done? Broadly, there are two categories of application types, and the criteria listed above must be examined in the context of each.
The DDRS 200 and DDRS 400 recorders offer 50 GB and 100 GB of disk storage in compact, hermetically sealed cartridges that are resistant to moisture and dust. The packaging is suited high-altitude applications, and UAVs in particular. (Ampex photo)
High-Altitude Platforms
High-altitude platforms have a demanding set of requirements. Such platforms typically include high-performance aircraft, strategic/surveillance aircraft, UAVs and most helicopters. Applications include the recording of imagery, COMINT, ELINT, ASW, mission video, avionics and flight test/evaluation data. By definition, the environment is anything but benign, the available space is invariably limited and the crew (if there is one) will generally have little time to worry either about the recorder or any data it may be recording. Perhaps the opportunity exists to dispatch certain key images to base, but more often the recorder has to look after itself. In essence it is vital that all mission data be brought back alive for others to deal with later.
From the survival standpoint, a solid-state recorder starts firm favorite, particularly if it is designed to emulate the legacy recorder that it is intended to replace. In recent years, two classes of tape recorder have dominated the high-altitude area the 1-in. transverse-scan DCRsi family from Ampex Data Systems (Redwood City, CA) and the 19mm helical scan ANSI ID-1 products from Enertec (Clamart, France) and Metrum-Datatape (Monrovia, CA). Not surprisingly, therefore, both Calculex (Las Cruces, NM) and the Ampex/L-3 Communications (Camden, NJ) team offer full DCRsi and ID-1 emulation/compatibility with their solid-state recorders. Calculex also offers compatibility with the Metrum-Datatape S-VHS VLDS recorder.
These solid-state recorders all have removable memory canisters or cartridges that can be inserted into a compatible ground-replay unit for data analysis at the end of the mission. This procedure is generally quite acceptable in a fight-test scenario, for example, where the aircraft may not be flown again for some time but may cause difficulties under battlefield conditions where the aircraft must be readied for use again in minutes. Several cartridges can be rotated, of course, so that a fresh one is available for each new mission. But the high cost of multiple memory modules often renders this approach impractical. A further complication arises when an aircraft lands at an unfamiliar base where no compatible replay facilities exist. To overcome these problems, NATO is working with industry and others to develop a new standard NATO agreement (STANAG 4575). The intent of this effort is to define a download port for airborne storage media (particularly disk and solid state) so that any ground station with a compatible port can access the stored data in situ. The intention is that STANAG 4575 will define the physical connector, the power requirements, the data and control interface (copper FibreChannel) and the protocol (a sub-set of SCSI-3). In the past, this functionality could only be achieved by deploying compatible ground replay equipment wherever tapes from airborne data recorders might have to be replayed. This new approach is an important example of how manufacturers and users are taking advantage of the opportunities offered by "new technology" products to ease the flow of data through the overall data path.
The AE7000 Disk Recorder is intended to emulate a tape recorder as closely as possible. Analog input/output modules cover bandwidths up to 50 MHz. Telecommunications I/O modules interface with all protocols between E1 to OC-12. (Avalon Electronics photo)
Enertec offers a family of disk-based recorders for high environmental electro-optical/IR/SAR reconnaissance imagery, ASW and flight test applications. Although the company still sees a long-term future for its conventional ID-1 helical scan tape products it has nevertheless developed the necessary airborne and ground-support elements to permit the smooth flow of imagery, acoustic, digital and video data from sensor to analysis equipment. The larger DS4100 recorder can capture 72 GB of data at up to 240 Mbps in a 33 lb package measuring only 7.7 (h) x 11.8 (w) x 10 (d) in. Ampex's DDRS 200 and DDRS 400 recorders offer 50 GB and 100 GB of disk storage in extremely compact, hermetically sealed cartridges that are capable of operation at high altitude without regard to the effects of moisture and dust. A standard DCRsi data interface is provided for compatibility with existing installations and a dubbing facility allows data to be transferred straight to the company's wide range of mass storage DIS/DST mass-storage devices, tape libraries and computer interfaces.
It is evident, therefore, that the strategy in the high-altitude-platform area is for manufacturers to offer "new technology" products as direct replacements for existing legacy recorders, facilitating this transition with a range of compatible data and control interfaces. This way, a user's investment in existing technical and operational infrastructure can still be utilized, while at the same time establishing a clear migration path in order to take advantage of the improved capabilities and/or cost advantages of the new disk or solid-state products.
Large Platforms and Bases
Away from the rarefied high environmental environment, the story takes a different turn. Although there are some obvious differences between large aircraft, ships, submarines and static environments from the data collection point of view, these can nevertheless be considered as a group for this particular discussion. Firstly, the more benign "shirtsleeve" environment of these locations does not generally justify the cost premium associated with a solid-state recorder. Consequently, the interest here is currently on the capabilities of disk recorders. But one further consideration also comes into play. As with high- altitude applications, there are many cases where all recorded data must be transferred from temporary to permanent storage as soon as possible. It is generally essential for example that all COMINT and reconnaissance imagery data be archived so that this material can be accessed quickly at some unspecified point in the future.
FASTdisk RAID-3 recorders can serve as a direct replacement for the DCRsi digital cartridge tape recorder. Data rates for the laboratory and ruggedized versions are 960 Mbps and 672 Mbps, respectively. Both comfortably out-perform the 240-Mbps capabilities of the fastest DCRsi, but at a fraction of the cost. (Ampex photo)
In other cases, the "good" data recorded during a mission may represent only a small fraction of the total dataset. For example, the calibration data and test-measurement telemetry from a missile firing may occupy only a few minutes of a morning's work. In this situation, the ability to edit and transcribe these short passages to a low- cost medium immediately after each test often simplifies the subsequent analysis process considerably. Similarly, in some ELINT applications, the number and duration of "interesting" contacts during a mission may be limited. Here too some immediate editing and sifting will often be an advantage. A subtle but important subset of this concept is the ability of operators to replay recently recorded data without interrupting the recording process. Disk recorders with a read-while-write capability allow operators to recall possible contacts for more detailed examination.
Not surprisingly, the exact approach taken by the manufacturers of disk recorders tends to be based on their own background and experience. For example, Ampex offers its FASTdisk RAID-3 recorders as a direct replacement for its DCRsi digital cartridge tape recorder. With data rates of 960 Mbps for the laboratory version and 672 Mbps for the ruggedized variant, both comfortably outperform the 240-Mbps capabilities of the fastest DCRsi, but at a fraction of the cost. So too does the company's 400-Mbps DDRS system. For easy integration into an existing Ampex UNIX or NT platform or analysis facility, these new units can all transcribe data directly to Ampex's DCRsi and/or DIS mass storages tape recorders.
Avalon has taken a slightly different approach with its AE7000 Disk Recorder. Designed specifically to emulate a tape recorder as closely as possible, this unit is offered with a range of interchangeable analog, digital and telecommunications interfaces. Since Avalon's background is mainly in SIGINT and ASW, it has elected to concentrate on the high-bandwidth and storage- capacity features of disk recording. Analog input/output modules cover bandwidths up to 50 MHz. Telecommunications I/O modules interface directly with all protocols between E1 to OC-12. Its generic 1- Gbps digital I/O module can be used with any conventional serial or parallel digital data source. When the AE7000 disk recorder is integrated with an NT4 Workstation as the AE7800 SIGINT Data Capture System, the user is able to transcribe selected passages of data directly to disk as a computer file that is then immediately available to any other authorized user on a linked NT or UNIX network. This process can be automated and permits almost immediate access by other users to recorded data provided that the volume of 'interesting' data is compatible with the available disk space on the host computer network.
The S/TAR series offers data rates to 400 Mbps and capacities to 16 GB (RM-3000) and 100 GB (RM-8000) in a removable cartridge. The recorders use non-volatile FLASH memory in favor of more bulky DRAM devices. (L-3 Communications photo)
Metrum-Datatape's Model 80 Disk Recorder is another example of where a company's heritage is used to good effect. Its ARMOR data multiplexers are used in multi-channel telemetry applications as the front-end for its Model 64 and buffered VLDS S-VHS cassette recorders. Offered as a direct replacement for these helical-scan tape recorders, the PC-based Model 80 acquires data as a file on its internal disk storage. Data can then be transferred to an archive device, forwarded by FTP over a 10/100 Ethernet network or replayed using the ARMOR system. The highest data rate is 80 Mbps and the maximum storage capacity is 72 GB.
Past and Future Perfect
Paradoxically, amid all the excitement, magnetic tape still has an important part to play. Although the industry focus has been on digital recording for many years, throughout the intelligence- gathering world much source data is analog in nature. Consequently, many platforms still prefer the convenience and low cost of analog tape recorders. Notable recent entrants in this area include Avalon's 18 MHz AE3200FL S-VHS recorder and Metrum-Datatape's 25 MHz DTR-25 D-3 format product.
When it comes to archiving data, users have two basic choices. Either they want to archive everything in case they need to look again later (typically COMMs and imaging applications), or they edit "the good bits" and junk the rest (typically ELINT applications). If you want to keep everything, you can go with something like the Ampex DIS/DST very-high-capacity helical-scan tape systems. Ampex has everything you need to keep these tapes in near-line automated libraries. But the transfer rates are slow in this context (16 MB/s). Avalon offers realtime archiving with its Redundant Array of Tape Streamers (RATS) concept. If you only want to keep edited highlights, then a small format medium may suit. Typically ExaByte or AIT. Certainly DC or DVD could be used, but bear in mind that the fastest disk recorders can record at 1 Gbit/sec. This means that a 1-GB CD would only store about eight seconds worth of data. Generally, people feel that this is a bit on the low side, even for telemetry or ELINT.
Industry sources forecast a period of some stability for the next five years or so as disk and solid-state recorders consolidate their positions in the marketplace, fuelled by low media costs and greater speed and capacity. Other promising storage technologies including ATS (Advanced Tape System), DVD, Optical tape, holography, photon technology and proton memories seem unlikely to reach maturity as deliverable products during this period.
Meanwhile, the movement to replace legacy recorders with "new technology" devices is already well underway. In some cases, particularly where the installed base of 14- and 28-track IRIG recorders is concerned, the need is becoming urgent as critical spares become more difficult to source. Owners of later- generation DCRsi and ID-1 systems can perhaps afford to take a longer- term view, and it is anticipated that sales of these units will continue for the foreseeable future. Nevertheless, many programs would welcome the enhanced capabilities that "new technology" recorders can offer, not just in terms of raw bandwidth and capacity but also the ease with which data can now be handled and processed. This carrot has been made even more enticing by the way that manufacturers have eased the transition from the old to the new with a low risk cut-and-paste approach to recorder substitution. For the first time ever, perhaps, the next generation of recorders may not be accompanied by a heavy cost penalty or a requirement for substantial levels of NRE. They can be tried and tested within existing environments and implemented without significant disruption to existing systems. Perhaps they aren't pretending anymore! *
Hard-Disk Recorders
The evolution of recorders based on hard-disk technology has been astounding. Just 15 months ago, this approach was little more than a promising concept (see "Disk Arrays: Pretenders to the SIGINT Storage Throne," JED, Nov. 1999). But now at least four major manufacturers have introduced one or more disk-based products. Disk recorders come in two flavors: RAID (Redundant Array of Independent Disks) and JBOD (Just a Bunch of Disks). While both use similar high-end computer peripheral hard-drives, it is important to understand the differences between the two approaches.
RAID-based recorders generally convert the data input (typically digital, analog, pcm, telecommunications or video data) to a conventional computer file that is written to an array of disks according to industry-standard RAID conventions. Although these files may later be converted back to their native format for analysis it is also common for them to be analyzed directly in a Windows or UNIX environment. This means that the traditional problems of getting instrumentation data into a computer format for analysis are largely overcome. Typical of this approach are the Ampex FASTdisk and the Metrum-Datatape Model 80, both of which use RAID-3 level parity (see Table below). In contrast, JBOD recorders simply commutate a digital bit stream across all the available disks in a continuous, relatively unstructured fashion in order to gain the maximum possible speed advantage.
The JBOD technique also is a more efficient use of the available disk space since no redundancy is involved. Although implementations differ, JBOD recorders tend to emulate traditional tape recorders so that conversion to a computer file or other data format will generally involve a separate process. Examples of JBOD recorders include the Ampex DDRS family, the Avalon (Shepton Mallet, UK) AE7000 and Enertec's DS2000 and DS4000 range.
Disk-based recorders (RAID or JBOD) are an attractive proposition on several counts. Digital data rates as high as 1 Gbps (1 Gigabit/sec - equivalent to 125 GigaBytes/sec) can be supported by as few as eight inexpensive 36-GB hard-disks operating in parallel. That's around 50 MHz of signal bandwidth in analog terms, or more than double the capability of the fastest tape recorders currently available. For SIGINT, reconnaissance imaging and similar applications where bandwidth really matters, this is an important gain. An 8x36-GB disk configuration has a storage capacity of some 275 GB (2.2 Terabits) nearly three times that of the largest ANSI ID-1 tape cartridge, for example. The random access element of disk recording has been used to good effect in several recorders where a true read-after-write mode has been implemented. This has the advantage not just of allowing the user to confirm that error-free data is being collected but, much more importantly, offers the possibility of being able to hand off recently acquired signals for analysis by others without interrupting the recording process in any way.
Now capable of operating reliably in all but the most severe platform environments, disk recorders share many of the advantages of a solid-state recorder high recording rates, high storage capacity, random access and a read-after-write capability but at a significantly lower unit cost. Hard-drives also have a good roadmap. When ultra-fast, high-capacity SIGINT disk recorders where first introduced a little over a year ago they typically incorporated 9- or 18-GB drives. Already 36-GB drives are the norm, with the promise of 72 GB just around the corner. But the two technologies also share the same fundamental drawback from the standpoint of their use for capturing critical mission data. Neither offers a direct means of long-term, "permanent" storage. Consequently, transcription to another form of archival medium is invariably required. It is the inventiveness of manufacturers in this particular area where the most important advances have been made.
Solid-State Recorders
High-capacity solid-state recorders have been around for several years. Their fundamental raison d'être is obvious. With no critical moving parts, a carefully designed solid-state recorder can be expected to outperform an electro-mechanical (e.g., tape or disk) device under extreme conditions of shock, vibration, temperature and acceleration. Maximum data rates and capacities are not really an issue since the architecture of the device can be scaled as required. Calculex, a major player since 1997, has delivered more than forty of its MONSSTR recorders for reconnaissance, missile and flight-testing applications, primarily aboard fighter aircraft and helicopter platforms.
Present implementations of MONSSTR offer data rates to 1 Gbps and scaleable storage to 415 GB in one or more hot-swappable canisters. A more recent entrant is L-3 Communications with its S/TAR range, offering data rates to 400 Mbps and capacities to 16 GB (RM-3000) and 100 GB (RM-8000) in a removable cartridge. Both manufacturers favor the non-volatile FLASH memory technology to the more bulky DRAM devices found in some early examples of solid-state recorder. L-3 Communications already has contracts with several major US aerospace companies to supply S/TAR units. It has also formed a marketing partnership with Ampex, manufacturers of the widely used DCRsi airborne tape recorder, in order to be able to offer total collection-to-archive system solutions. Under this arrangement, Ampex markets the S/TAR as its SSRS product.
The relatively high cost of memory compared to tape and disk media is an important factor when considering very high capacity (say, 100+ GB) applications particularly when a number of cartridges might be involved. Although disk and solid-state technologies are at about the same level of maturity, FLASH memory is currently about fifty times more expensive than disk storage. Although the cost per MB of FLASH memory can be expected to improve as 256-Mbit chips displace the existing 64-Mbit devices, most observers expect this differential to remain a significant factor in the short to medium term.
Industry Resources
For more information on the products and technologies discussed in this article contact the manufacturers listed below:
Ampex Data Systems Corp.
500 Broadway, M.S.1101
Redwood City, CA 94063 USA
Tel: +650-367-2011
Internet: www.ampexdata.com
Avalon Electronics Ltd.
High Street,
Shepton Mallet, BA45AQ England
Tel: +44 (0)1749-345-266
Fax: +44 (0)1749-345-267
Internet: www.avalon-electronics.com
Calculex, Inc.
132 W. Las Cruces Av.
Las Cruces, NM 88001 USA
Phone: +505-525-0131
Fax: +505-524-4744
Internet: www.calculex.com
Enertec S.A.
185 avenue du Général de Gaulle
BP 316
92143 Clamart Cedex France
Tel: +33 (0) 1 41 28 87 87
Fax : +33 (0) 1 41 28 87 00
Internet: www.enertec.avicore.com
L-3 Communications Systems-East
1 Federal Street
Camden, NJ 08103 USA
Tel: +856-338-3000
Fax: +856-338-6014
Internet: www.L-3Com.com/CS-Eas
Metrum-Datatape, Inc.
605 E. Huntington Dr.
Monrovia, CA 91016 USA
Tel: +626-358-9500
Fax: +626-930-9479
Internet: www.metrum-datatape.com |
