Hinet Speed

[Aron Eugine]

TheManhattan Hi-Speed USB Pocket Hub easily adds four ports to any USB compatible desktop or notebook computer expanding connectivity for keyboards, mice, Web cameras and other peripherals. Its high-speed ports are USB 1.1 compatible to support older devices and provide data transfer speeds up to 480 Mbps for external storage, printing, and other activities.

A durable case, compact size and bus-power make it easily transportable to add USB connectivity almost anywhere. Installation is simple with Plug and Play and hot-swappable capabilities and a built-in, self-storing USB cable that quickly connects the Manhattan Hi-Speed USB Pocket Hub to any USB port.

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Refinery gas streams vary considerably in composition. Determining individual components of each gas stream is a challenge. An exact measure of stream components is essential in achieving optimum control and assuring product quality. PAC's AC Analytical Controls offers the Hi-Speed Refinery Gas Analyzer, a high speed solution that determines and reports the composition of refinery gas streams in only five minutes.

The model 1740 high-speed microohmmeter has similar capabilities to the 1750 high-speed microohmmeter but limits the maximum output current to 100 mA, which serves to protect sensitive test samples. Fuse manufacturers can use it for nondestructive tests where the unmatched precision increases the process yield to the point where the 1740 pays for itself in weeks. Resistors from 1 m Ohm to 20 M Ohm can be tested and sorted to accuracy better than 0.1% by the 1740. Automotive suppliers can use it to consistently meet the stringent quality requirements of welds, bonds and electrical connections in sub-assemblies. Battery manufacturers employ the 1740 to measure the integrity of interconnects between individual cells in large battery arrays. The capability of the 1740 enables the accurate real-time measurement of electro-plating thickness and conductive coatings on housings and shields.

TEGAM's 1740 microohmmeter employs multiple techniques to achieve its impressive accuracy. A four-wire kelvin technique eliminates the effects of lead resistance, and offset compensation removes the errors caused by thermal contact voltages. The 1740 even monitors its performance over time and adjusts its calibration against a set of internal low temperature coefficient resistors to ensure consistent measurement performance without constant recalibration.

TEGAM specializes in low resistance measurement. Our technical sales people and applications engineers understand both the measurement challenges you face and your manufacturing environment. They can help you solve your product yield or quality problems with low resistance measurements.

Rossignol's quest for a medium width all-mountain performance machine that will compete head to head with the likes of Lange RX, Tecnica Mach1 and Nordica Speedmachine appear to have been realized with the arrival of the Hi-Speed Pro 120 MV. Testers ranked all four of these models at the very top of a large heap within two-tenths of a point of each other at this year's test and said that this was the brand's best boot ever released in that highly competitive category.

Gone were the caveats about Rossignol's roomier-than-average fit tension--this was a tight, performance narrow that grasped the foot and leg everywhere in a comfortably snug embrace yet without hot spots in typical bony or wide zones. Testers were impressed that the Hi-Speed Pro combined surprisingly smooth and easy entry and exit with a stronger-than-120 flex feel that never collapsed on hard hits or during aggressive skiing. They said the cuff fit in ideal fashion against the shin, around to the calf and they liked the angles both front-to-back and side-to-side. They appreciated that the cuff is doubly adjustable in forward lean angle as well as adjustable in both lateral geometry and flex, but they didn't feel that any adjustment was needed beyond the out-of-box set up which they called dead on the money dialed.

Rossignol's use of Dual Core plastic injection, first started in sister brand Lange's models, continued to impress our test team with the boot's snappy, resilient quickness and accuracy that doesn't sacrifice traditional polyurethane and polyether stability and dampness. This new Hi-Speed line also utilizes and interesting sandwich of different density plastic material in the cuff construction as a way to increase flex rebound energy and simultaneously improve smoothness of the flex feel. While we don't fully understand the engineering of this manufacturing magic, we can attest to the resulting feel and performance on snow which would support those rebound and smoothness claims.

The cuff's attachment to the lower shell remains adjustable in lateral angle, which we applaud, but it was also moved up and forward from its previous Allspeed location to better match the anatomical hinge point of the ankle, which our test team liked. The so-called Generative Design of the shell employs a lattice-work of thickened ribs in structurally critical zones to create a transmissive and stable feel at high speeds, on hard snows and through funky terrain while keeping other shape- or entry-prioritized areas rib-free to maximize wrapping and flexibility. Testers said all this marketing fluff bore fruit for them in terms of it being easy on and off and easy to ski well in those aforementioned situations.

I have a USB isolator which provides galvanic isolation of a USB device from my PC, but only works for low speed and full speed USB. I can't find any alternative electric isolators which do provide Hi-speed connection; USB fiber extenders, however, are offered with hi-speed throughput and should provide both galvanic isolation and high bandwidth, though perhaps at higher cost?

The question thus is this:What makes a hi-speed USB isolator so much more expensive than a full-speed USB isolator? Is there a physical limitation to the approach used for the full-speed devices which makes it inapplicable and/or cost prohibitive for hi-speed devices?

A fiber-optic USB extender basically works a bit like an opto-coupler except that the light source and the light receiver are on separate chips. Combining the functions of a fiber extender into a single package should be cheaper, not more expensive. Using magnetic or capacitive coupling instead of optical coupling should be cheaper again.

There are a few applications, e.g. medical or low electrical noise, which require or benefit from galvanic isolation. All of those applications are specialized and the existing fiber extender solutions fully cover the galvanic isolation requirement.Additionally, wireless solutions like Bluetooth, Zigbee, etc also satisfy the isolation requirement (at slow speeds). In conclusion, there is probably not much of a market niche for USB isolators.

Edit:As for the part of the question "Are actual laws of physics involved, ..."No, there are many faster, galvanically isolated communications links such as Gigabit Ethernet, 10G Ethernet and even wireless solutions.

"... or is this merely an engineering challenge or cost issue?"Yes, as of 2018, the engineering challenge is less than it would have been a few years ago, but would still be a significant effort. But who would fund development of such solutions if the demand appears very limited?

There are ready-made isolated repeater chips for the 12Mbps USB transfer rate:ADuM4160 by Analog Devices or LTM2884 by Linear Technology. Surprisingly to me, both contain inductive coupling = miniature on-chip signal transformers as the coupling elements, interfaced to the outside world by silicon (CMOS?) buffered transceivers. Makes me wonder why the isolation is not optical these days...

Note that 100Base-TX Ethernet, SATA, PCI-e or RS422, all use a balanced pair in either direction, together comprising a 4-wire full-duplex link. Gigabit and 10Gb Ethernet works that way only on fiber optics I guess.

In contrast, USB low/full/high-speed uses a single balanced pair, in half-duplex mode, where the host and device take turns in talking on the bus, and have to tri-state the line driver when they're finished talking, to give a chance to the other party (somewhat similar to RS485, though many electrical and framing details are different).

Any galvanic isolator, including the chips mentioned above, has to respect that half-duplex direction-switching style of communication. A single signal trafo should theoretically work at 12 Mbps, except for the DC biasing resistors, and the framing possibly isn't "free of DC offset on average" either, making it difficult to just use a passive trafo. Attenuation aside.

Perhaps it's precisely this need for the active isolator to "turn the table" fast enough, to detect the end of transmission in the first place, that makes implementation of a "stupid USB repeater" at 480 Mbps impractical, even in today's silicon. There are supposedly some other changes in the electrical interface for high-speed USB 2.0 (constant current signaling) which may be another factor why high-speed USB doesn't lend itself easily to this kind of 485-style RX/TX switching in a dumb repeater.

Note that there's an alternative approach to the "direction switching" problem: rather than detect a high-Z on the line in an analog fashion, which brings along some inherent latency (lag), the isolator would have to understand the USB protocol, just like a USB hub does - so that it would know when to expect an end of the frame being currently received. And possibly, it would buffer whole frames, before relaying them onto the other side - just like a USB hub does. (Or does it?) Effectively the isolator would have to become a USB hub, with an isolation gap somewhere in there.

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