Abstract: A method of determining a propagation time of signals from a USB Host Controller to an attached USB device is presented. In an embodiment, the method insludes: the USB device sending a message or data packet to the USB Host Controller; the USB device starting a local timer upon transmission of the message or data packet; the USB Host Controller responding to the message or data packet by issuing a handshake token; and the USB device stopping the local timer on receipt of the handshake token; wherein the local timer value represents twice the propagation time of signals from the USB Host Controller to the USB device.

Abstract: A method of reducing jitter in a local clock of a synchronised USB device attached to a USB Hub, the USB Hub having a local clock and repeater circuitry, comprising: observing a USB data stream with the USB Hub, the data stream having a data stream bit rate; the USB Hub decoding a periodic signal structure in the USB data stream; the USB Hub generating an event signal in response to decoding of the periodic signal structure; and the USB Hub locking a frequency of the local clock of the USB Hub to the periodic event signal. The local clock of the USB Hub is adapted to be a clocking source for the repeater circuitry of the USB Hub at substantially an integer multiple of a frequency of the data stream bit rate.

Abstract: A synchronization apparatus, comprising: a USB device having a USB microcontroller, circuitry for observing USB traffic, and circuitry for decoding from a USB data stream a periodic data structure (such as a clock carrier signal) containing information about a distributed clock frequency and phase and outputting a decoded carrier signal; and circuitry for receiving the decoded carrier signal, for generating a software interrupt upon receipt of a predefined data packet (such as a SOF packet) and for passing the software interrupt to the USB microcontroller; wherein the USB microcontroller is configured to respond to the software interrupt (such as with an interrupt service routine provided therein) by generating an output signal adapted to be used as a synchronization reference signal.

Abstract: A method and apparatus for controlling the phase and frequency of the local clock of a USB device, the apparatus comprising circuitry for observing USB traffic and decoding from the USB traffic a periodic data structure containing information about the frequency and phase of a distributed clock frequency, and phase and circuitry for receiving the periodic data structure and generating from at least the periodic data structure a local clock signal locked in both frequency and phase to the periodic data structure. The circuitry for receiving the periodic data structure and generating the local clock signal can generate the local clock signal with a frequency that is a non-integral multiple of a frequency of the periodic data structure.

Abstract: A method of synchronising a compound SuperSpeed USB device, comprising: providing data communication between a host computing device and the compound SuperSpeed USB device across the SuperSpeed USB communication channel; establishing a SuperSpeed USB communication channel to a SuperSpeed USB function of the compound USB device; establishing a non-SuperSpeed synchronisation channel to a non-SuperSpeed USB function of the compound USB device; and synchronising a local clock of the compound USB device to a periodic data structure within a data stream in the non-SuperSpeed synchronisation channel so that the local clock can enable synchronous operation of the compound USB device with one or more comparable USB devices.

Abstract: A method of determining the downstream propagation time of signals from a USB Host Controller across one or more USB cables and one or more USB Hubs to a SuperSpeed USB device, including locking a clock of the SuperSpeed USB device to information that includes a first timestamp, transmitting a plurality of signals to the USB Host Controller, each of the signals containing a second timestamp indicative of a local time of the SuperSpeed USB device when the respective signal was generated by the SuperSpeed device; the USB Host Controller creating a third timestamp indicative of a time of reception from the SuperSpeed USB device; determining a time period from one or more respective time differences between corresponding second and third timestamps, the time period being indicative of a sum of a downstream propagation time and an upstream propagation time; and determining the downstream propagation time from the time period.

Abstract: A method and apparatus for controlling the phase and frequency of the local clock of a USB device, the apparatus comprising circuitry for observing USB traffic and decoding from the USB traffic a periodic data structure containing information about the frequency and phase of a distributed clock frequency, and phase and circuitry for receiving the periodic data structure and generating from at least the periodic data structure a local clock signal locked in both frequency and phase to the periodic data structure. The circuitry for receiving the periodic data structure and generating the local clock signal can generate the local clock signal with a frequency that is a non-integral multiple of a frequency of the periodic data structure.

Abstract: A method of synchronizing a compound Super Speed USB device, comprising: providing data communication between a host computing device and the compound Super Speed USB device across the Super Speed USB communication channel; establishing a Super Speed USB communication channel to a Super Speed USB function of the compound USB device; establishing a non-Super Speed synchronization channel to a non-Super Speed USB function of the compound USB device; and synchronizing a local clock of the compound USB device to a periodic data structure within a data stream in the non-Super Speed synchronization channel so that the local clock can enable synchronous operation of the compound USB device with one or more comparable USB devices.

Abstract: A method of controlling one or more devices in data communication with a common controller to perform one or more functions, each of the devices having a synchronous clock, a synchronized real time clock register and a memory, the method comprising: arming the devices such that the devices commence performing the functions synchronously, receive and store to their respective memory data acquired as a result of performing the functions and store to their respective memory time stamp information indicative of the time of acquisition of the acquired data; a trigger device in data communication with the common controller responding to a command to perform the functions by sending a first message to the host controller that includes data indicative of a time of receipt of the command; the host controller responding to the first message by sending the devices a second message including data indicative of the time of receipt by the further device of the command; and the devices responding to the second message by re

Abstract: A method of providing a synchronization channel to a SuperSpeed USB device is provided. The method including a SuperSpeed communication channel connection to the SuperSpeed USB device with a USB cable that has USB 2.0 D+ and D? data signalling lines disabled or disconnected at an upstream connection point; multiplexing synchronization information onto the D+/D? data signalling lines at the upstream connection point; and demultiplexing the synchronization information from the D+/D? signalling lines at a downstream connection point of the cable; whereby the synchronization channel is maintained across the D+/D? data signalling lines.

Abstract: A method of providing high density expansion of a USB network, the method comprising: attaching a plurality of USB hubs to adjacent slots in a PXI instrumentation chassis; configuring one of the USB hubs as a primary USB Hub; connecting an upstream port of the primary USB Hub to a USB network; configuring a first downstream port of the primary USB Hub to communicate across a first PXI Local Bus to a first adjacent USB Hub of the USB Hubs other than the primary USB Hub, the first adjacent USB Hub being adjacent to the primary USB Hub; configuring a plurality of other downstream ports of the primary USB Hub to provide expansion of the primary USB Hub; connecting an upstream port of the first adjacent USB Hub to the first PXI Local Bus, wherein the first PXI Local Bus is in the direction of the primary USB Hub; configuring a first downstream port of the first adjacent USB Hub to communicate across a second PXI Local Bus to a second adjacent USB Hub of the USB Hubs other than the primary USB Hub, the second adjac

Abstract: The invention provides a method and apparatus for providing a synchronized multichannel universal serial bus, the method in one aspect comprising supplementing the signal channels in the USB specification to provide synchronization information from an external source, and in another aspect comprising observing USB traffic and locking a local clock signal of a USB device to a periodic signal contained in USB data traffic, wherein the locking is in respect of phase and/or frequency.

Abstract: A synchronization apparatus, comprising: a USB device having a USB microcontroller, circuitry for observing USB traffic, and circuitry for decoding from a USB data stream a periodic data structure (such as a clock carrier signal) containing information about a distributed clock frequency and phase and outputting a decoded carrier signal; and circuitry for receiving the decoded carrier signal, for generating a software interrupt upon receipt of a predefined data packet (such as a SOF packet) and for passing the software interrupt to the USB microcontroller; wherein the USB microcontroller is configured to respond to the software interrupt (such as with an interrupt service routine provided therein) by generating an output signal adapted to be used as a synchronization reference signal.

Abstract: A synchronization apparatus, comprising: a USB device having a USB microcontroller, circuitry for observing USB traffic, and circuitry for decoding from a USB data stream a periodic data structure (such as a clock carrier signal) containing information about a distributed clock frequency and phase and outputting a decoded carrier signal; and circuitry for receiving the decoded carrier signal, for generating a software interrupt upon receipt of a predefined data packet (such as a SOF packet) and for passing the software interrupt to the USB microcontroller; wherein the USB microcontroller is configured to respond to the software interrupt (such as with an interrupt service routine provided therein) by generating an output signal adapted to be used as a synchronization reference signal.

Abstract: A method of reducing jitter in a local clock of a synchronised USB device attached to a USB Hub, the USB Hub having a local clock and repeater circuitry, comprising: observing a USB data stream with the USB Hub, the data stream having a data stream bit rate; the USB Hub decoding a periodic signal structure in the USB data stream; the USB Hub generating an event signal in response to decoding of the periodic signal structure; and the USB Hub locking a frequency of the local clock of the USB Hub to the periodic event signal. The local clock of the USB Hub is adapted to be a clocking source for the repeater circuitry of the USB Hub at substantially an integer multiple of a frequency of the data stream bit rate.

Abstract: A method of synchronising the operation of a plurality of SuperSpeed USB devices and a plurality of non-SuperSpeed USB devices is provided. The method includes establishing a SuperSpeed synchronisation channel for each of the plurality of SuperSpeed USB devices; establishing a non-SuperSpeed synchronisation channel for each of the plurality of non-SuperSpeed USB devices; synchronising a respective local clock of each of the plurality of SuperSpeed USB devices; synchronising a respective local clock of each of the plurality of non-SuperSpeed USB devices; and synchronising the SuperSpeed and non-SuperSpeed synchronisation channels so that the SuperSpeed and non-SuperSpeed devices can operate in synchrony.

Abstract: A method of synchronising a compound Super Speed USB device, comprising: providing data communication between a host computing device and the compound Super Speed USB device across the Super Speed USB communication channel; establishing a Super Speed USB communication channel to a Super Speed USB function of the compound USB device; establishing a non-Super Speed synchronisation channel to a non-Super Speed USB function of the compound USB device; and synchronising a local clock of the compound USB device to a periodic data structure within a data stream in the non-Super Speed synchronisation channel so that the local clock can enable synchronous operation of the compound USB device with one or more comparable USB devices.

Abstract: A system for synchronising the operation of a measurement instrument having a microcontroller, a local oscillator and function circuitry to an external timebase is provided. The system includes a USB Host Controller; an interrupt generator adapted to respond to ITPs by generating respective interrupts and passing the interrupts to the microcontroller; and a timer for measuring an interval between receptions of the ITPs in a time domain of the local oscillator.

Abstract: A method of determining the downstream propagation time of signals from a USB Host Controller across one or more USB cables and one or more USB Hubs to a SuperSpeed USB device, including locking a clock of the SuperSpeed USB device to information that includes a first timestamp, transmitting a plurality of signals to the USB Host Controller, each of the signals containing a second timestamp indicative of a local time of the SuperSpeed USB device when the respective signal was generated by the SuperSpeed device; the USB Host Controller creating a third timestamp indicative of a time of reception from the SuperSpeed USB device; determining a time period from one or more respective time differences between corresponding second and third timestamps, the time period being indicative of a sum of a downstream propagation time and an upstream propagation time; and determining the downstream propagation time from the time period.

Abstract: A method of providing a synchronisation channel to a SuperSpeed USB device is provided. The method including a SuperSpeed communication channel connection to the SuperSpeed USB device with a USB cable that has USB 2.0 D+ and D? data signalling lines disabled or disconnected at an upstream connection point; multiplexing synchronization information onto the D+/D? data signalling lines at the upstream connection point; and demultiplexing the synchronization information from the D+/D? signalling lines at a downstream connection point of the cable; whereby the synchronisation channel is maintained across the D+/D? data signalling lines.