HD CSAC Chip Scale Atomic Clock GPS Disciplined Oscillator (GPSDO) Time and Frequency Standard

Low-SWaP chip scale atomic clock GPS disciplined oscillator board with 10 MHz and 1 PPS outputs for man-pack, airborne and vehicle use.

Long-Term Oscillator Aging: Less than 0.3 ppb per month in holdover without GPS
Frequency Stability Over Temperature: Better than ±0.5E-09
1 PPS Accuracy: ±15 ns to UTC RMS (1-Sigma)
Frequency Accuracy: Better than ±2E-010

Datasheet

Overview

The HD CSAC (Chip Scale Atomic Clock) GPSDO is a time and frequency standard board that reduces size, weight and power (SWaP) by removing some of the generic features of the CSAC GPSDO. It operates from a +12 V power supply and is intended for mobile applications such as man-pack, airborne and vehicle installations.

The board provides an RS-232 serial port for command and control, CMOS and LVDS 10 MHz outputs, and an LVDS 1 PPS output. It is function-compatible with the FireFly-II board and shares the same IO connector, while reducing power consumption and improving performance during GPS holdover.

The integrated mobile-mode GPS receiver has 50 channels with SBAS (WAAS/EGNOS/MSAS) support and better than -160 dBm tracking capability. The HD CSAC supports industry-standard NMEA output sentences, SCPI control and command interfaces. The board is offered in standard temperature and extended temperature versions, the latter covering -10 °C to +70 °C.

Key Features

Designed for mobile applications such as man-pack, airborne and vehicle applications
Cesium vapor Chip Scale Atomic Clock (CSAC) for holdover
Less than 2 minute warmup
RS-232 serial port for command and control
CMOS and LVDS 10 MHz outputs
1 PPS LVDS output
Small form factor of 2” x 2.5” x 0.7”
1.2 W power consumption
Operates from a +12 V power supply
Functionally compatible with the FireFly-II board and shares the same IO connector
50-channel mobile-mode GPS receiver with SBAS (WAAS/EGNOS/MSAS) support
Better than -160 dBm GPS tracking capability
Industry-standard NMEA output sentences and SCPI control

Specifications

Frequency and Timing

Long-Term Oscillator Aging	Less than 0.3 ppb per month in holdover without GPS Zero aging with GPS
Frequency Stability Over Temperature	Better than ±0.5E-09 CSAC only, no GPS Disciplining, 0°C to +70°C
1 PPS Accuracy	±15 ns to UTC RMS (1-Sigma) GPS Locked in Position Hold mode
Frequency Accuracy	Better than ±2E-010 After 3 minutes operation with GPS lock
Holdover Drift	<±2.5 µs drift per hour over worst case temperature range After 5-minute warmup with GPS lock
Typical Holdover Drift	<±1 µs drift per hour at 25°C ±5°C After 5-minute warmup with GPS lock
Warm Up Time/Stabilization Time Without GPS	<180 s at +25°C to <5E-010 accuracy typical
g-sensitivity	<0.2 ppb per-g per-axis
Magnetic Sensitivity	Less than 0.4 ppb per Gauss

ADEV (with GPS lock)

1 s	<1E-10
10 s	<2.5E-11
100 s	<2E-11
1K s	<1E-11
10K s	<2E-12

Phase Noise

10 Hz	-75 dBc/Hz
100 Hz	-115 dBc/Hz
1 kHz	-128 dBc/Hz
10 kHz	-134 dBc/Hz
100 kHz	-140 dBc/Hz

Outputs and Interfaces

1 PPS Output (CSAC Flywheel Generated)	LVDS output, can be shifted in 1 ns steps relative to UTC
10 MHz Outputs	10 MHz LVDS, 10 MHz CMOS 5 V
RS-232 Control (Including USB Port)	Full SCPI-99 Control Commands at 9.6 K, 19.2 K, 38.4 K, 57.6 K, 115.2 K
RS-232 NMEA Output Sentences	NMEA 0183 rev. 2.3, Sentences: GGA, RMC, ZDA, PASHR, and others
External GPS option	1 PPS input for optional external SAASM GPS receiver
TTL Alarm Output	Hardware Event Indicator
Connectors	Compatible to FireFly-IIA connector

GPS Receiver

GPS Frequency, Antenna	L1 C/A 1574 MHz, Passive or Active Antenna 3.3 V, MMCX Connector
GPS Receiver	50 Channels, Mobile, SBAS: WAAS, EGNOS, MSAS supported
Sensitivity, Acquisition	-147 dBm
Sensitivity, Tracking	-160 dBm
Time To First Fix, Cold Start	<30 sec
Time To First Fix, Warm Start	1 sec
Time To First Fix, Hot Start	1 sec
Motion Adaptive Filter Settings	Optimized depending on vehicle velocity (Auto-sensing, Auto-switching) Dynamic mode enabled

Power

Supply Voltage (Vdd)	+12 V ±5%
Power Consumption	<1.25 W at +25°C Web page highlights state 1.2 W Power Consumption

Environmental

Operating Temperature	-10°C to +70°C Page lists -10 °C to +70°C for extended temperature versions
Storage Temperature	-45°C to +85°C
MTBF	>100,000 Hours