VIAVI LC 1x1 GPS Disciplined Oscillator (GPSDO) Module

Compact 1.6 x 1.9 x 0.8 inch GPS disciplined oscillator module with 10 MHz and 1 PPS outputs for LTE timing applications.

1 PPS Accuracy: LVDS level, ±35 ns to UTC RMS (1-Sigma) GPS Locked
Holdover Stability: <±15 µs over 24 hours
Serial Control: RS-232 level GPS NMEA output and SCPI control
TTL Alarm Output: GPS LOCK and Event indicator

Datasheet

Overview

The VIAVI LC 1x1 is a GPS Disciplined Oscillator (GPSDO) measuring 1.6 x 1.9 x 0.8 inches. It is designed for cost-sensitive LTE applications and to meet LTE holdover specifications that previously required Rubidium references. The LC 1x1 is backwards compatible with the FireFly-IIA GPSDO.

The module provides Stratum-1 long-term performance, typically better than 1 part per trillion (1E-012) averaged over 24 hours. It is offered as a low-profile single-oven oscillator version with a total height of 0.63 inches, allowing integration into legacy applications such as VME enclosures, and as a higher-performance double-oven oscillator version. Both versions operate from -40°C to +85°C. A ruggedized, extended temperature range version is also available.

A built-in 50-channel GPS receiver supports WAAS/EGNOS/MSAS, and the unit works with both passive and active GPS antennas. The LC 1x1 provides an OCXO-sourced, low-jitter 1 PPS output and a 10 MHz output, each available as LVDS or CMOS.

Control and software

The unit is monitored and controlled over an RS-232 port using standard SCPI commands and generates standard GPS NMEA-0183 output sentences for integration into existing infrastructure. It is supported by software and freeware applications such as GPSD, GPSCon and Z38xx, which provide NTP, SNTP, graphing, and command and control functionality.

Key Features

10 MHz LVDS and 1 PPS LVDS outputs, CMOS option
Warm-up/stabilization time of <9 min at +25°C to 5E-09 accuracy
Compact 1.6 x 1.9 x 0.8 inch module
Stratum-1 long-term performance, typically better than 1E-012 averaged over 24 hours
Low-profile (0.63 inches high) single-oven oscillator version
Higher performance double-oven oscillator version available
Built-in 50-channel GPS receiver with WAAS/EGNOS/MSAS support
Works with passive and active GPS antennas
RS-232 control via SCPI commands with NMEA-0183 output
Backwards compatible with the FireFly-IIA GPSDO
Ruggedized, extended temperature range version available

Specifications

Module Specifications

1 PPS Accuracy	LVDS level, ±35 ns to UTC RMS (1-Sigma) GPS Locked Web page states 1 PPS stability better than 30 ns rms (typ. <10 ns rms)
Holdover Stability	<±15 µs over 24 hours @+25.0°C (No Motion or Airflow, 5+ days with GPS); web page states <±10 us (3+ days with GPS)
Serial Control	RS-232 level GPS NMEA output and SCPI control
TTL Alarm Output	GPS LOCK and Event indicator
Warm Up Time/Stabilization Time	<9 min at +25°C to 5E-09 Accuracy no airflow
Output Signal Levels	10 MHz LVDS, 1 PPS LVDS, CMOS option

GPS Receiver

GPS Frequency	L1, C/A 1574 MHz
GPS Antenna	Active or Passive
GPS Receiver	50 Channels, Mobile, SBAS WAAS, EGNOS, MSAS capable
Sensitivity, Acquisition	-142 dBm
Sensitivity, Tracking	-158 dBm Web page states -160 dBm tracking capability
TTFF Cold Start	<45 sec
TTFF Warm Start	1 sec
TTFF Hot Start	1 sec

ADEV

1K s	<1E-010 GPS Locked, 25°C, no motion
10K s	<8E-012 GPS Locked, 25°C, no motion

Oscillator Specification

Frequency Output	10 MHz CMOS/LVDS
10 MHz Retrace	±2E-08 After 1 hour @ +25°C (no GPS)
Frequency Stability over Temperature, and over 24 hours	<±5E-09 (no GPS), <1E-012 over 24 hours (with GPS, no airflow)
Output Amplitude	LVDS, or CMOS option
OCXO Warm Up Time	<3 min @ +25°C

Phase Noise

1 Hz	-90 dBc/Hz
10 Hz	-120 dBc/Hz
100 Hz	-140 dBc/Hz
1 kHz	-150 dBc/Hz
10 kHz	-155 dBc/Hz
100 kHz	<-155 dBc/Hz

Power

Supply Voltage (Vdd)	12 V ±5%, <0.21 A steady state
Power Consumption	<2.4 W steady state, <8 W warmup Web page states less than 2.3 W at room temperature

Environmental