GLENAIR
Some readers may wonder why there is an Ethernet protocol for backplanes. This has emerged from embedded systems (or computers), where the computation capacity can be increased modularly by populating more slots in a backplane. The communication protocol of choice is still Ethernet, but the physical link is so different that it warrants its own family of specifications. USB After Ethernet, this is the most widely deployed mode of data transmission. But unlike Ethernet, it is not a network protocol and is meant to be used as a point- to-point connection between a host and a device (or several devices). As mentioned earlier, the product lifespan is shorter for devices using this protocol, and the protocol revisions are frequent. It also tends to be closer to a user and have more frequent mating cycles compared to Ethernet connections. Ruggedizing USB links is more challenging than traditional Ethernet because the signal spectrum reaches to much higher frequencies, and because the link configuration budgets do not explicitly allow for disconnect points. Evolutions of the USB standard have revolved around higher data rates and more power delivery options (battery charging and device power). The most significant recent hardware development is the USB-C connector because it merges the serial port standard with display capability; HDMI and DisplayPort can both be carried through a USB-C cable. USB 2.0 This protocol just turned 20 years old a few months ago, roughly the same age as our Mighty Mouse connector family. It’s interesting to note that to this day, a double digit percentage of our Mighty Mouse connectors we ship end up carrying USB 2.0 because that’s what most soldier systems use to connect the various devices. The maximum data transmission capability is 480Mb/s and the power delivery can go up to 100W when supporting battery charges (in more recent editions). The signal and power are delivered over 4 wires.
Glenair offers USB 3.0 connectors in ruggedized mil/aero connectors with outstanding metal-to-metal grounding and enhanced environmental sealing (IP68 in mated condition)
USB 3.0 Just 10 years after its predecessor, this protocol was a major revision in terms of speed and largely backward compatible. But with the addition of 2 SuperSpeed pairs, the link can support close to 10 times the data rate of USB 2.0. The hardware implementation looks exactly like USB 2.0 (except for USB-C cables which we will discuss in more detail below), but the electrical requirements are different. SuperSpeed USB connectors are distinguished by the blue color of their inserts. Rugged implementations of this protocol require much closer attention to signal integrity compared to USB 2.0, impedance matching through the interconnect is very important. Ensuring backwards compatibility has led to a strange nomenclature, where newer revisions of the specifications re-named the older protocols. The table below identifies the relationships between the specification, protocol, brand and data transmission rate
USB 3
Previous Name
USB-IF Branding
Transfer Speed
Specification Name
USB 3.2 Gen 1 USB 3.2 Gen 2
USB 3.1 Gen 1 USB 3.2 Gen 2
SuperSpeed USB 5Gbps SuperSpeed USB 10Gbps SuperSpeed USB 20Gbps
USB 3.0
5 Gbit/s
USB 3.1
10 Gbit/s
USB 3.2 Gen 2 x 2
USB 3.2
N/A
20 Gbit/s
Cables for USB 3.X protocols require two high-speed pairs, a power pair and the legacy data pair to support
USB 2.0. HDMI
A USB 2.0 cable. USB has become ubiquitous in our world, from computer peripherals to smartphone charging
HDMI (High-Definition Multimedia Interface) is a compact audio/video interface for transmitting uncompressed video data. It is a digital alternative to consumer analog standards, such as radio
QwikConnect • July 2020
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