Abstract: A system for recovering accurate time data from a received satellite signal, including an antenna connected to a remote digital receiver by synchronous communication channel. The antenna converts the satellite signal to IF and digitizes it. A packetizer packetizes digital samples with a time stamp form a local clock domain, which is continuously corrected to match, but for transmission delay, a remote master clock. The digital receiver includes a master clock driven by an oscillator and corrected to the satellite time. It includes a depacketizer to depacketize the digital samples and obtain the time stamp. A satellite signal process obtains the satellite time data and the master clock is corrected based upon the satellite time data and the time stamp. The corrected master time is transmitted to the antenna for updating of the local clock domain at the antenna.

Abstract: Described are methods, devices and systems for communicating data measurements from a sampling device to a remote master device in a distributed power measurement system using high-speed isochronous data links. The sampling device receives a time-stamp packet from the master device over the isochronous data link, the time-stamp packet containing a sequence number of the time-stamp packet, and the sampling device starts a counter clocked by a local clock signal to determine an offset time since receipt of the time-stamp packet. The sampling device obtains power system data and generates and transmits framed output data to the remote master device over the isochronous data link. The framed output data includes the sequence number, the offset time, and a data payload that includes the power system data.

Abstract: A method for correcting long-term phase drift of a crystal oscillator in a numerically-controlled oscillator is described. The method includes determining the phase error in an oscillator signal in comparison with an external time base; delta-sigma modulating the phase error to generate a delta-sigma error bitstream; conditionally adding or subtracting an error correction step size from a phase increment value in each clock cycle based on the delta-sigma error bitstream, to create a modulated phase increment value; and adding the modulated phase increment value to a phase accumulator to generate an error-corrected output digital signal. The delta-sigma-based error correction method avoids the use of multipliers. The same delta-sigma error signal can be used in multiple numerically-controlled oscillators configured to different output frequency if driven by the same reference oscillator.

Abstract: Described is a method and devices to determine root-mean-square of a delta-sigma modulated signal. The method includes filtering the delta-sigma modulated signal to produce a multi-bit filtered signal, delaying a copy of the delta-sigma modulated signal by a fixed number of samples to align with the filtered input, setting a sign of each multi-bit value of the multi-bit filtered signal based upon a corresponding sample value of the delayed copy of the delta-sigma modulated signal, to generate a hybrid signal, summing the hybrid signal to produce a summed signal, and determining the average of the summed signal and the square root of the average to produce a root-mean-square value.

Abstract: Described are methods, devices and systems for communicating data measurements from a sampling device to a remote master device in a distributed power measurement system using high-speed isochronous data links. The sampling device receives a time-stamp packet from the master device over the isochronous data link, the time-stamp packet containing a sequence number of the time-stamp packet, and the sampling device starts a counter clocked by a local clock signal to determine an offset time since receipt of the time-stamp packet. The sampling device obtains power system data and generates and transmits framed output data to the remote master device over the isochronous data link. The framed output data includes the sequence number, the offset time, and a data payload that includes the power system data.

Abstract: Described are methods, devices and systems for communicating data measurements from a sampling device to a remote master device in a distributed power measurement system using high-speed isochronous data links. The sampling device receives a time-stamp packet from the master device over the isochronous data link, the time-stamp packet containing a sequence number of the time-stamp packet, and the sampling device starts a counter clocked by a local clock signal to determine an offset time since receipt of the time-stamp packet. The sampling device obtains power system data and generates and transmits framed output data to the remote master device over the isochronous data link. The framed output data includes the sequence number, the offset time, and a data payload that includes the power system data.

Abstract: A method for correcting long-term phase drift of a crystal oscillator in a numerically-controlled oscillator is described. The method includes determining the phase error in an oscillator signal in comparison with an external time base; delta-sigma modulating the phase error to generate a delta-sigma error bitstream; conditionally adding or subtracting an error correction step size from a phase increment value in each clock cycle based on the delta-sigma error bitstream, to create a modulated phase increment value; and adding the modulated phase increment value to a phase accumulator to generate an error-corrected output digital signal. The delta-sigma-based error correction method avoids the use of multipliers. The same delta-sigma error signal can be used in multiple numerically-controlled oscillators configured to different output frequency if driven by the same reference oscillator.

Abstract: A power measurement device for sampling current or voltage signals of a power system to produce a 1-bit delta-sigma bitstream. The power measurement device includes a frequency locked loop for determining the power system frequency directly from the 1-bit delta-sigma bitstream. The frequency locked loop includes a 1-bit rotate CORDIC that is configured to produce difference signals having a multi-bit word for each bit of the 1-bit delta-sigma bitstream, and a phase error calculator that determines the difference between the phase of the power system frequency and a phase ramp generated from a frequency measurement value in a frequency register. The phase error calculator feeds back a phase correction signal to the frequency register to lock the frequency measurement value to the power system frequency.

Abstract: Described are methods, devices and systems for communicating data measurements from a sampling device to a remote master device in a distributed power measurement system using high-speed isochronous data links. The sampling device receives a time-stamp packet from the master device over the isochronous data link, the time-stamp packet containing a sequence number of the time-stamp packet, and the sampling device starts a counter clocked by a local clock signal to determine an offset time since receipt of the time-stamp packet. The sampling device obtains power system data and generates and transmits framed output data to the remote master device over the isochronous data link. The framed output data includes the sequence number, the offset time, and a data payload that includes the power system data.

Abstract: Described is a method and devices to determine root-mean-square of a delta- sigma modulated signal. The method includes filtering the delta-sigma modulated signal to produce a multi-bit filtered signal, delaying a copy of the delta-sigma modulated signal by a fixed number of samples to align with the filtered input, setting a sign of each multi-bit value of the multi-bit filtered signal based upon a corresponding sample value of the delayed copy of the delta-sigma modulated signal, to generate a hybrid signal, summing the hybrid signal to produce a summed signal, and determining the average of the summed signal and the square root of the average to produce a root-mean-square value.

Abstract: A power measurement device for sampling current or voltage signals of a power system to produce a 1-bit delta-sigma bitstream. The power measurement device includes a frequency locked loop for determining the power system frequency directly from the 1-bit delta-sigma bitstream. The frequency locked loop includes a 1-bit rotate CORDIC that is configured to produce difference signals having a multi-bit word for each bit of the 1-bit delta-sigma bitstream, and a phase error calculator that determines the difference between the phase of the power system frequency and a phase ramp generated from a frequency measurement value in a frequency register. The phase error calculator feeds back a phase correction signal to the frequency register to lock the frequency measurement value to the power system frequency.

Abstract: A power measurement device for sampling current or voltage signals of a power system to produce a 1-bit delta-sigma bitstream. The power measurement device includes a frequency locked loop for determining the power system frequency directly from the 1-bit delta-sigma bitstream. The frequency locked loop includes a 1-bit rotate CORDIC that is configured to produce difference signals having a multi-bit word for each bit of the 1-bit delta-sigma bitstream, and a phase error calculator that determines the difference between the phase of the power system frequency and a phase ramp generated from a frequency measurement value in a frequency register. The phase error calculator feeds back a phase correction signal to the frequency register to lock the frequency measurement value to the power system frequency.

Abstract: A circular chambered rope grab is provided for removably attachable fastening of a workman or climber to a safety line allowing mobility in a relaxed state while providing positive braking action in the event of a fall. The device includes a frame of equally spaced parallel walls and a horseshoe-shaped cross-section (i.e. ?) merged to the back of these opposing walls. The frame allows passage for receiving a safety line in the ?-shaped interior and the ?-shaped interior is vertically grooved in a manner that provides low frictional resistance with the safety line during motion while achieving high frictional resistance on the safety line when brake is engaged. The device includes the frame with a levered braking arm having a braking surface, lanyard attachment point and centered additional aperture allowing a pivotal connection to the frame with the removable pivot pin.