Options - Option 23 COMTRADE Sample Rate Generator
Provides a GPS-synchronized sampling signal at rates of 200 PPS to 192 kPPS, as defined in IEEE Standard C37.111-1991. Available on the Models 1084, 1088.
COMTRADE Sample Rate Generator, as installed on rear of chassis.
The Arbiter Systems®, Inc. GPS Satellite-Controlled Clock, equipped with the COMTRADE Sample Rate Generator, generates any one of the 48 standard sampling rates for waveform digitization in 50 Hz or 60 Hz systems as defined in IEEE Standard C37.111-1991, Data Exchange (COMTRADE) for Power Systems. Standard COMTRADE Sampling Rates are listed in Tables 1 and 2.
The selected sample rate is available as a 5 V CMOS-level square wave in both normal (rising edge of clock synchronous with 1 PPS) and complemented (falling edge of clock synchronous with 1 PPS) polarities. The sampling pulse is synchronized to within ± 50 ns of 1 PPS, and has sample-to-sample jitter less than 1 ns.
Principles of Operation
The assembly generates sampling signals which are precisely locked to 1 PPS-GPS by phase locking a precision voltage-controlled crystal oscillator (VCXO) to the internal 1 kPPS signal present in the clock. This VCXO output signal is then divided down to obtain the desired sampling rate. Synchronization logic is also provided, to ensure that the output divider is synchronized to 1 PPS-GPS. By using a precision VCXO, pulse-to-pulse sampling jitter is held to an absolute minimum, and is specified not to exceed 1 ns rms. The output signals have a 50 % duty cycle (square wave).
This assembly includes four configurable BNC outputs, which are in addition to those available for the standard model clock. Either normal or complemented-polarity COMTRADE sampling frequency signals may be made available at each of these additional outputs. Furthermore, any output not configured for a COMTRADE sampling rate output can be used as a general-purpose configurable output, and can deliver any of the standard signals that are available in the clock.
Comtrade Sample Rate Generator Specifications
- Accuracy: ± 50 ns from 1 PPS, maximum, (- 10 ns, typical)
- Jitter: 1 ns rms, maximum pulse to pulse (guaranteed by design, not production tested)
- Connectors Four, BNC 50-ohm, configurable
- Normal Polarity COMTRADE Sample Rate, 50 % Duty Cycle
- Complemented COMTRADE Sample Rate, 50 % Duty Cycle
- All Other Signals Available in 1088B or 1084A/B/C Clocks
- Digital 5 V CMOS Buffer, 50 Ohms Impedance
- Analog Opamp Buffer, 600 Ohms Impedance