LC-XO GPS Disciplined Oscillator Ultra Small GPSDO Module (OCXO and TCXO Versions)

Ultra small 0.97 x 0.97 inch GPS disciplined oscillator module in OCXO or TCXO versions for PCB soldering or DIP socket mounting.

1 PPS Accuracy: ±35 ns to UTC RMS (1-Sigma) GPS Locked
1 PPS Accuracy: ±50 ns to UTC RMS (1-Sigma) GPS Locked
Holdover Stability after 72 hours with GPS: <±20 us over 3 Hour Period
Holdover Stability after 72 hours with GPS: <±35 μs over 3 Hour Period

Datasheet

Overview

The VIAVI LC-XO is a GPS-disciplined oscillator (GPSDO) module measuring 0.97 x 0.97 inches. It is designed to be soldered onto a customer PCB or plugged into a standard 100-mil pin-spacing DIP socket for optional retrofitting, and is intended for high-volume, low-cost production applications.

The module provides the software features of the larger VIAVI GPSDO units, including full SCPI command support, NMEA output, a 10 MHz and 1 PPS input, a 1 PPS output and field-upgradable firmware. It is available in either OCXO or TCXO versions.

According to the manufacturer, the unit achieves a -155 dBc/Hz noise floor with better than 5 parts per trillion frequency stability over 5 hours of operation. Internal 3.3 V to 5 V DC-DC power supplies and filters are included, and the module can supply 5 V at up to 50 mA to external customer circuitry and to the external GPS antenna.

ALARM/EVENT/LOCK status signals are provided in TTL and serial format, and a dual LED on the board indicates status. The module is compatible with GPSCon, SNTP, GPSD and Z38xx software applications.

Key Features

Ultra small 0.97 x 0.97 inch GPSDO
Low cost OCXO or TCXO version
Less than 0.5 W (TCXO), +3.3 V power supply
+/-25 ppb stability over temperature
Can be soldered onto a PCB or socketed
Heater warmup of less than 1 minute
External 1 PPS input with auto-switchover function
Full SCPI command support and NMEA output
10 MHz and 1 PPS input, 1 PPS output
Field-upgradable firmware
Internal 3.3 V to 5 V DC-DC power supplies and filters
5 V at up to 50 mA available to external circuitry and GPS antenna
ALARM/EVENT/LOCK status signals in TTL and serial format
Dual on-board status LED

Specifications

Module Specifications

1 PPS Accuracy OCXO	±35 ns to UTC RMS (1-Sigma) GPS Locked
1 PPS Accuracy TCXO	±50 ns to UTC RMS (1-Sigma) GPS Locked
Holdover Stability after 72 hours with GPS OCXO	<±20 us over 3 Hour Period @+25°C (No Motion, no airflow)
Holdover Stability after 72 hours with GPS TCXO	<±35 μs over 3 Hour Period @+25°C (No Motion, No Airflow)
1 PPS Output	3.3 VDC CMOS
Serial Control	SCPI-99 TTL Level, GPS NMEA Output
TTL Alarm Output	GPS LOCK indicator
ADEV OCXO	10 Ks <5E-012 OCXO, GPS Locked, 25°C, no motion, no airflow
ADEV TCXO	10 Ks <2E-012 GPS Locked, 25°C, no motion, no airflow
Warm Up Time/Stabilization Time OCXO	<5 min to 1E-08 Accuracy at +25°C
Warm Up Time/Stabilization Time TCXO	<10 min to 1E-09 Accuracy at +25°C
Additional Features	Firmware field-upgradable, external 1 PPS input, status LEDs, compatible to GPSCon, SNTP, GPSD, and Z38xx software applications, full NMEA

GPS Receiver

GPS Frequency	L1, C/A 1574 MHz
GPS Antenna	Active or Passive
GPS Receiver OCXO	70 Channels, GPS, Glonass, Galileo, BeiDout, QZSS, SBAS capable Web page describes a WAAS/EGNOS/MSAS 50-channel GPS receiver; datasheet value used
GPS Receiver TCXO	72 Channels, GPS, Glonass, Galileo, BeiDou, QZSS, SBAS capable Web page describes a WAAS/EGNOS/MSAS 50-channel GPS receiver; datasheet value used
Sensitivity, Acquisition	–148 dBm
Sensitivity, Tracking	-167 dBm GPS and Glonass
GNSS TTFF, Cold Start	<30 sec
GNSS TTFF, Warm Start	2 sec
GNSS TTFF, Hot Start	2 sec

Oscillator Specification

Frequency Output	10 MHz CMOS 5 Vpp (3.3 Vpp optional)
10 MHz Retrace	±2 E-08 After 1 Hour @ +25°C
Frequency Stability Over Temperature (GPS Unlock Condition) OCXO	±2.5 E-08
Frequency Stability Over Temperature (GPS Unlock Condition) TCXO	±7.5 E-08 TCXO, 0C to +60°C
Output Amplitude	5 Vpp CMOS
OCXO Warm Up Time OCXO	< 1 min @ +25°C
TCXO Warm Up Time TCXO	Instant-on, no warmup period required

Phase Noise

1 Hz OCXO	-75 dBc/Hz With 33 uF or larger cap on 5V Output pin 6
10 Hz OCXO	-110 dBc/Hz With 33 uF or larger cap on 5V Output pin 6
100 Hz OCXO	-132 dBc/Hz With 33 uF or larger cap on 5V Output pin 6
1 kHz OCXO	-142 dBc/Hz With 33 uF or larger cap on 5V Output pin 6
10 kHz OCXO	-145 dBc/Hz With 33 uF or larger cap on 5V Output pin 6
100 kHz OCXO	<-150 dBc/Hz With 33 uF or larger cap on 5V Output pin 6
1 Hz TCXO	-65 dBc/Hz With 33uF or larger cap on 5V Output pin 6
10 Hz TCXO	-102 dBc/Hz With 33uF or larger cap on 5V Output pin 6
100 Hz TCXO	-132 dBc/Hz With 33uF or larger cap on 5V Output pin 6
1 kHz TCXO	-148 dBc/Hz With 33uF or larger cap on 5V Output pin 6
10 kHz TCXO	-152 dBc/Hz With 33uF or larger cap on 5V Output pin 6
100 kHz TCXO	<-155 dBc/Hz With 33uF or larger cap on 5V Output pin 6

Power

Supply Voltage (Vdd)	3.3 V Single-Supply only (5 V internally generated and filtered)
Power Consumption OCXO	0.7 W steady state
Power Consumption TCXO	0.4 W with TCXO Web page states less than 0.5 W (TCXO)

Environmental

Operating Temperature OCXO	0°C to +60°C
Operating Temperature TCXO	-10°C to +75°C, -40°C to +85°C optional
Storage Temperature	-45°C to +85°C

Connectors

Connections	1 PPS Output, 10 MHz Output, power, serial communication, system status, NMEA, 1 PPS in, ISP mode enable, antenna input
Connector Type	100 mil spacing on pins, can be soldered, or plugged into a socket, gold-plated pins

Physical