[LONG] The newest Ampex patent was issued on 3/25/97....
patent.womplex.ibm.com
Method and apparatus for buffering a user application from the timing requirements of a DRAM
This is an interesting development in many respects but most of all I think this is yet another indication of some of the steps Ampex is taking to improve the performance and marketability of their tape drives in the years ahead.
Buffers are typically used to synchronize the flow of data between subsystems with different speeds. For example, a fast processor uses a buffer to send and receive data from a slower disk drive or RAID array. A fast RAID array uses a buffer to send and receive data from a slower tape drive or library.
Now, there are solid-state memory buffers (see chrislin.com or myriadlogic.com that are being sold right now that can be used as interfaces for most of the popular military data recorders in use today. Because these interfaces are typically built using SRAMs they are very expensive and can run anywhere from $100,000 to $200,000 or even more. Data recorders typcially start at around $200-250,000 so you can see how expensive these combinations can be. This Ampex patent describes a memory controller system for an interface using DRAMs. DRAMs are semiconductor memory chips that are similar to SRAMs except that SRAMs have at least 4 transistors per cell while DRAMs only have one per cell. So DRAMs are cheaper than SRAMs.
A sensor (camera, probe, temperature, etc) is typically connected by wires to the recorder. The sensor acquires measures a particular aspect of analog nature (e.g., images) and converts it to voltage streams that are then streamed into the data recorder. The data recorder has an ADC or an analog to Digital Converter that collects the voltage streams (analog = continuous and varying) in some kind of buffer, or temporary holding memory, and converts it into the discrete 1s and 0s that the data recorder can layout in orderly fashion with tags and addresses and even GPS (Global Positioning Satellite code). Ideally, the interface allows more sensors to acquire data at increasingly faster speeds without fear of overflowing the data recorder since all that data is pipelined through a large buffer that holds and feeds the data recorder at a constant rate
It works the other way too because the buffer holds the data being read by the tape drive and streams it to a processor at a constant rate..
At this point it may be useful to look at the technology roadmap that Ampex presented last October at THIC (http://www.thic.org/thic/). If you recall, Ampex laid out their plans to increase the speed of their top of the line DCRsi data recorders from the current 240 megabits per second (at 8 bits = 1 byte, 30 Megabytes per second) to 480 megabits per second (or 60 Megabytes per second) within the next 12 months. They also indicated that they were going to release a clip-on interface to their data recorders with the following features:
1) 2-10 Gigabytes of solid state FIFO memory.
2) Burst data rate of up to 100 MB/sec
3) Integral cache memory of up to 500 MB for instant access to selected frames
4) Automatic backup to DCRsi tape.
Ampex further stated this is aimed initially at tactical reconnaissance, or RECCE, imagery applications.
That was in October 1996. During this year's Paris Air Show to be held from June 15-22, 1997 this is how Ampex is going to pitch the same interface which I assume is close to shipping, if not shipping already.
parisairshow-usa.com
DCRsi Clip-On: adds 5 GigaBytes of data buffer to a standard DCRsi recorder for a unique 1 Gigabit/sec SNAP-SHOT imaging capability, with instant access to cached data.
This link - lmtas.com - takes you directly to a fairly detailed account of how Lockheed Martin is using advanced CCD camera systems in conjunction with Ampex DCRsi data recorders to improve the flow of information in the cockpit and in the command and control sites out in the battlefield. Towards the end of the article there is this excerpt that details the kind of enhancements they want to implement. Ampex's clip-on interface was designed to accomodate those future enhancements.
For reasons of economy and schedule, the recce pod was kept relatively simple. Additional sensors and new technologies, however, may eventually be accommodated. Multispectral sensors and a datalink are prime candidates. Dual-spectrum systems with infrared as well as daylight sensors would allow the pod to be used at night. A datalink would allow images to be transmitted directly from the aircraft to a ground station. Hardware for allowing pilots to sort through images in flight before transmitting is also on the horizon. This spring, Recon/Optical expects to fly an expanded (twenty-five megapixel) electro-optical back that increases the field of view by a factor of 2.4 for a given lens. The new back is a drop-in replacement and uses data compression to maintain an output data rate equivalent to the four-megapixel configuration. The company is also working on infrared capability, which would add another camera to the pod.
The only way those features could have been added to the recce pod was for Lockheed to use solid-state data recorders which are 100s of times faster than tape drives or even disk drives. Ampex. however, is providing a solution that allows the 2-10 GB solid-state front end to approximate the functions of a
solid-state data recorder at a fraction of the cost (still very high which is why the margins on these products are very high) AND at the same time retain the extremely low cost advantages of a 50 GB data recorder.
More --> |
