GSync II® Model 402

The GSync II is a compact 2U high, single-string, modular time and frequency system. There are 8 option module slots available, 1 of which can be used for I/O modules as well as output modules.



The GSync II is the 2U compact version of the popular and versatile GSync, and provides eight output module slots. The heart of the GSync II is the GTF (GPS Time and Frequency) module within the unit. It is self-contained with a Quartz or Rubidium oscillator, and a commercial C/A GPS receiver or a military SAASM/M-Code GPS receiver (Rockwell-Collins MPE-S GB-GRAM or Trimble Force 22E MRU).

If a system needs a Primary Reference Source (PRS), the GSync II provides either Standard Positioning Service (SPS) GPS (the civil C/A signal) or the very latest in GPS military technology—SAASM/M-Code Precision Positioning Service (PPS) GPS receivers
(for approved users only). With GPS as the reference source, the GSync II provides a frequency accuracy of 1E-12 and a time accuracy to < 50 ns Peak to UTC, for calibrated units. The GSync II is also designed to take external inputs to provide internal frequency
synchronization to the accuracy of the external source.

There are two choices of disciplined oscillator selection. An Ovenized Quartz Crystal Oscillator (OCXO) or a Rubidium Atomic Oscillator can be specified. The GSync II can be populated with up to (8) option modules.

There are a wide variety of output option modules available: Low-Phase Noise sine wave, T1/E1, Time Codes, and Network Time Protocol (NTP). The full line of common GSync II and CommSync II option modules are shown in the option module listing on our web site.

For Monitor and Control functions there is an RS-232 communication port on the rear panel of the chassis and a standard Ethernet port providing Telnet, SNMP, and Network Time Protocol (NTP), as well as IEEE PTPv2 IEEE 1588-2008.

FEI-Zyfer products come with a standard 2 year factory warranty (parts & labor).


  • 8 I/O Module Slots
    Extended Option
    Module Capability
    100+ Option Modules
  • Time Accuracy:
    < 50ns Peak (UTC)
  • GPS Receiver:
    Standard Civil C/A-Code
    and/or SAASM/M-Code MPE-S
    GB-GRAM or SAASM/M-Code
    Force 22E MRU Military
  • User Interface:
    Standard RS-232
    Ethernet I/O
    (Telnet, SNMP)
    Keypad, VFD display
  • Remote Access Utility:
    Zyfer™ Monitor
  • Standard Outputs:
    1 PPS, 10 MHz
  • Calibration:
    All units are calibrated
    with an in-house
    standard traceable
    to UTC


 24 Hour Average  Rubidium Oscillator  Quartz Oscillator
 Locked to GPS  < 1E-12  < 1E-12
 Holdover (b) first 24 hours  < 5E-12  < 1E-10


TIME ACCURACY: – to UTC, for calibrated units (c)

   Rubidium Oscillator  Quartz Oscillator
 Locked to GPS  < 50 ns Peak  < 50 ns Peak
 Holdover (b) first 24 hours  < 3 μs  < 7 μs



 Allan Deviation  Rubidium Oscillator  Quartz Oscillator
 1 sec  < 3E-11  < 1E-11
 10 sec  < 1E-11  < 1E-11
 100 sec  < 3E-12  < 1E-10



   Standard Output  Low Noise 5MHz
 1 Hz  < -90 dBc/Hz  < -105 dBc/Hz
 10 Hz  < -105 dBc/Hz  < -130 dBc/Hz
 100 Hz  < -125 dBc/Hz  < -150 dBc/Hz
 1 kHz  < -135 dBc/Hz  < -158 dBc/Hz
 Standard GPS Receiver – Civil C/A-Code:
 Type:  8 to 12 channel, independent tracking
 Frequency: 1575.42 MHz (L1)
 Code:  C/A
 Acquisition Time:  Warm Start: < 2 minutes, Cold Start: < 20 minutes.
 SAASM/M-Code GPS Receiver – Military P(Y)-Code:
 Type:  12 channel, independent tracking
 Frequency:  1575.42 MHz and 1227.60 MHz (L1 & L2)
 Code:  C/A and P(Y)
 Acquisition Time: (c)  Warm Start: < 2 minutes
Hot/Cold Start: Dependent on Initialization Device
 Keyload Interface:  DS-102
 FORCE 22E MRU SAASM/M-Code GPS Receiver – Military C/A and P(Y)-Code: (e)
 Type:  24 channel, simultaneous tracking of L1, L2 and C/A codes
 Frequency:  1575.42 MHz and 1227.60 MHz (L1 & L2)
 Code:  C/A and P(Y)
 Acquisition Time: (c)  Warm Start: < 2 minutes
Hot/Cold Start: Dependent on Initialization Device
 Keyload Interface:  DS-102

Reference Option Info

 Standard GPS Receiver  SAASM/M-Code GPS Receiver (e)
 1 PPS, 50 Ω, TTL level, SMA, Ext. Sync Input  1 PPS, 50 Ω, TTL level, SMA, External Sync Input
 RS-232 I/O connector  RS-232 I/O connector
 10 MHz, 50 Ω, TTL level, SMA connector  10 MHz, 50 Ω, TTL level, SMA connector
 1 PPS, 50 Ω,
TTL level, SMA connector
 1 PPS, 50 Ω,
TTL level, SMA connector
 Keyload Interface – DS-102
 Hot Start connector (optional)

Several Power Input options are available, including single or dual modules (for redundancy), 115/230 VAC 50/60 Hz, 12 VDC or 48 VDC, or a combination of AC and DC Power Input modules.


 Height: 87 mm (3.50″) (2U)
 Width:  438 mm (17.25″) (19″ EIA Rack)
 Depth:  419 mm (16.5″) including connectors
 Weight:  27 lbs. (max.)
 Operating Temperature: 0° C to 50° C
 Rate of Change:  10° C/Hour
 Storage Temperature:  -40° C to +85° C
 Relative Humidity:  5 % to 95 %, non-condensing
 Altitude, Operating:  60 m to 4000 m
 Altitude, Storage:  60 m to 9000 m

(a) After 24 hours of GPS locked operation, fixed antenna location, antenna delays entered.
(b) After 48 hours of continuous operation.
(c) 2σ (95.5 % probability).
(d) Detailed specifications for various output modules: See “Option Module User’s Manual 385-8003”.
(e) U.S. Government policy restricts the sale of Precise Positioning Service (PPS) equipment to those
authorized by the U.S. Department of Defense. Non-U.S. authorized users must purchase PPS equipment
through the Foreign Military Sales (FMS) process.
(f) Dependent on the accuracy of initialization parameters from PLGR or DAGR handheld SAASM/M-Code GB-GRAM receivers, or other initialization devices.

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