Model 1201B/C GNSS Synchronized Clock (100ns)

Model 1201B/C GNSS Synchronized Clock (100ns)

Next generation multi-satellite timing source for precision applications. Featuring enhanced performance and security (EPS).


Model 1201B/C User Manual
Download PDF(5 MB) »

Model 1201B/C Quick Setup Guide
Download PDF(570 kB) »

Model 1201B/C Data Sheet
Download PDF(621 kB) »

GNSS Antenna Data Sheet
Download PDF(4 MB) »

Model 1201B/C delivers better than 100 ns accuracy and includes the most highly sought after features in a precision time clock as standard plus many enhancements.

Three terminal strip outputs are jumper selectable to unmodulated IRIG-B, modulated IRIG-B, 1 PPS, programmable pulse, or event input. The 1201 is capable of driving multiple loads in parallel.

Like other Arbiter clock models, various options are available to add features such as NTP/PTP (Network Time Protocol/Precision Time Protocol [IEEE 1588]) support, four additional configurable outputs, high drive IRIG-B outputs, power system time, frequency, and Phase Monitor functions, one Form C (SPDT) fail-safe, LOCKED relay that is compatible with 129 Vdc digital fault recorder inputs; plus many more.

Model 1201B/C is available with two front panel configurations (see photos and Key Features tab). Each product includes the GNSS antenna and cable, a terminal power strip, and a rack mount kit, all backed by a Five Year Limited Warranty to the original owner/purchaser.

Accéder au résumé en français  

  • Accuracy of ± 100 ns
  • Standard: Unmodulated IRIG-B, modulated IRIG-B, 1 PPS, and One Form C (SPDT) fail-safe locked relay
  • Options include an internal NTP/PTP server, High Drive IRIG-B outputs, and Power System Time, Frequency and Phase Monitor
  • 1201C includes both the operating status LEDs, the LCD display and keypad, and includes a large LED time display.
  • IEEE C37.118 compliant for Synchrophasor use.


  • Enhanced Performance and Security (EPS)
    • EPS benefits include multi-system timing sources (GPS/ GLONASS/Galileo/BeiDou), standard holdover oscillator, multiple levels of security, secure communications, and anti-spoofing technology
  • Redundant power supply available
  • Second serial port standard
  • IRIG-B compliant with IEEE Std. C37.118.1-2011

Build-a-Part Ordering Structure:
* denotes standard selection

1201 -   -   -   -   -   -  
Series    Model    Power Supply A    Power Supply B    Holdover Oscillator    Fiber Optic Output    I/O Options
     B = LCD Display    A01* = 85 Vac to 264 Vac, 100 Vdc to 350 Vdc    B00* = Not Installed    C01* = 1 ms/day    D00* = Not Installed    E00* = Not Installed
     C = LCD Display & Large Segment LED Time Display    A02 = 22 Vdc to 67 Vdc    B01 = 85 Vac to 264 Vac, 100 Vdc to 350 Vdc    C02 = 10 µs/day    D01 = IRIG/PP Output, 820 nm Type ST multimode    E01 = Four Configurable Outputs
             B02 = 22 Vdc to 67 Vdc            E02 = Four configurable Fiber-Optic Outputs
                         E03 = 8-Channel High Drive IRIG-B Outputs
                         E04 = Power System Time, Frequency, and Phase Monitor
                         E05 = Four Additional Outputs with Dry Contact and + 25/50 Vdc
                         E06 = Network Time Protocol (NTP) / Precision Time Protocol (PTP) Server Copper/Copper
                         E07 = Network Time Protocol (NTP) / Precision Time Protocol (PTP) Server Copper/Fiber
                         E08 = Network Time Protocol (NTP) / Precision Time Protocol (PTP) Server Fiber/Fiber
                         E09 = Four BNC Connectors, (Parallel to Pluggable Terminal Strip)

Receiver Characteristics

Timing Accuracy

Accuracy Note

Specifications apply at the 1 PPS/IRIG_B unmodulated/PP outputs when receiving four or more satellites, as of date of publication.

Accuracy UTC/USNO

± 100 ns peak

Position Accuracy

2 meters, rms

Satellite Tracking

Seventy-two (72) channel receiver: L1 GPS/SBAS C/A, L1 GLONASS CT, Galileo, and BeiDou.


  • 40 seconds typical, cold start
  • 25 seconds, typical, warm start
  • 3 seconds, typical, hot start



Standard: OCXO, 1 ms/day
Optional: OCXO, 10 µs/day

I/O Configuration

Output Connectors

Three standard pluggable terminal strip connectors with jumper-selectable signals:
Port 1: IRIG-B unmodulated, 1 PPS, Programmable Pulse or Event Input
Port 2: IRIG-B modulated, 1 PPS, IRIG-B unmodulated, Programmable Pulse or Event Input
Port 3: IRIG-B unmodulated, 1 PPS, Programmable Pulse or Event Input

Output characteristics:

  • 5 V CMOS bus drivers with 10 ohms source impedance and ± 75 mA drive capability.
  • 4 Vpp, 20 ohms source impedance (IRIG- B modulated only)
  • 400 V, 220 mA, 1 W power dissipation open-drain FET drivers

Output Signals

One IRIG-B channel that controls both the unmodulated and modulated outputs. Configurable to Local or UTC time with C37.118.1 on or off, settings independent from Programmable Pulse IRIG-B output.

Event Inputs

One event timer channel with 100 ns resolution is standard. This function may be driven by the start bit of a received character on the serial port, or an external 5 V CMOS/TTL signal at one of the terminal strip connectors (jumper-selectable).

Programmable Pulse Output

One programmable pulse output (by a jumper connection) that may be output on a terminal strip connector or the AUX OUT pin on either COM port.
Six modes:

  • IRIG-B unmodulated (UTC/Local, C37.118.1 On/Off. Settings are independent from main IRIG-B signal.)
  • Every 1 second to 60,000 seconds, starts top of the second
  • Hourly at a specified offset
  • Daily at a specified time of day
  • One shot at a specified time of year
  • Slow Code (UTC/LCL)

Pulse duration is programmable from 0.01 seconds to 600 seconds, except in one-shot mode, where the output is Low prior to the specified time and High thereafter.

Relay Contacts

One Form C (SPDT) fail-safe, 0.3 A at 130 Vdc; configurable to Out-of-Lock, Fault, Alarm, Stabilized, or Programmable Pulse



  • 2 character x 20 character supertwist LCD with white LED backlight
  • Status LEDs
  • 20 mm (0.8 in) LED; 6 digits (Model 1201C)
  • Time and date
  • Antenna status and position
  • Timing status
  • System status
Status LEDs
  • Normal (green)
  • Learn (orange)
  • Unlocked (red)
  • Alarm (red)
  • Operate (green)
  • Power A (green)
  • Power B (green)
  • Fault (red)

Eight keys; select display functions or setup menus

  • COM 1 (RS-232 port 1)
  • COM 2 (RS-232 port 2)
  • Local Time Offset
  • Out-of-Lock Time
  • Relay Configuration
  • Backlight control
  • Event/Deviation
  • Programmable Pulse
  • System Delays
  • IRIG Time Data
  • Option Configuration



1200 baud to 230,400 baud; 7 or 8 data bits; 1 or 2 stop bits; even/odd/no parity

RS-422/485 (TXD+, TXD-)


AUX OUT can provide programmable pulse function at RS-232 levels

Broadcast modes
  • Standard ASCII (IRIG-J)
  • Extended ASCII
  • ASCII with Time Quality
  • ASCII with Time Quality and Year
  • Vorne large-display
  • Status/Alarm
  • Event data
  • User configurable serial time code

Male 9-pin D-subminiature

Power Requirements

Accommodates any combination of the two available power supplies in a single or redundant configuration. Choices include an universal supply or a low dc supply, both with surge withstand capability.



85 Vac to 264 Vac, 47 Hz to 440 Hz, 20 VA maximum or 100 Vdc to 350 Vdc, 30 W maximum.

Low DC
22 Vdc to 67 Vdc; 30 W maximum.


Secure Pluggable Terminal Strip




425 mm x 280 mm x 44 mm (16.75 in x 11 in x 1.75 in)
19 in, 1 Rack Unit; 280 mm deep FMS.
Rack mounts and feet for tabletop included
635 mm x 381 mm x 229 mm (25 in x 15 in x 9 in), shipping


2 kg (4.5 lbs), net
5.5 kg (12 lbs), shipping


Cable Connection: F-type
Size: 80 mm dia. x 84 mm (3.2 in x 3.3 in)
Weight: 170 g (6 oz)
Temperature: - 55 °C to + 65 °C
Ground Block: Antenna protective ground. Copper, with M5 (10-32) stud and nut. Connects internally to gas discharge tube (GDT) lightning surge suppressor.

Antenna Cable

Type: RG-6, 15 m (50 ft) provided
Weight: 0.69 kg (1.52 lbs) per 15 m

Antenna Mounting

0.75 in pipe (1 in - 14 marine) thread



Operating: - 40 °C to + 65 °C
Nonoperating: - 40 °C to + 75 °C




Conducted emissions: power supply complies with FCC 20780, Class A and VDE 0871/6.78 Class A

Surge withstand capability (SWC), power inlet: designed to meet ANSI/IEEE C37.90-1 and IEC 61000-4

Certificates and Approvals

CE mark/label and certificate

One option can be selected from each of the categories listed below; except Power Supply which accommodates two.

A power supply and holdover oscillator must be specified.

1201optD01 1 Single Configurable Fiber-Optic Output
1201optE01 Four Configurable Outputs
1201optE02 Four Configurable Fiber-Optic Outputs
1201optE03 8-Channel High Drive IRIG-B Output
1201optE04 Power System Time, Frequency, and Phase Monitor
1201optE05 Four Additional Outputs with Dry Contact and + 25/50 Vdc
1201optE06 Network Time Protocol (NTP) / Precision Time Protocol (PTP) Server Copper/Copper
1201optE07 Network Time Protocol (NTP) / Precision Time Protocol (PTP) Server Copper/Fiber
1201optE08 Network Time Protocol (NTP) / Precision Time Protocol (PTP) Server Fiber/Fiber
1201optE09 Four BNC Connectors, (Parallel to Pluggable Terminal Strip)
1201optA01 85 Vac to 264 Vac, 100 Vdc to 350 Vdc Secure Pluggable Terminal Strip and Surge Withstand
1201optA02 22 Vdc to 67 Vdc Secure Pluggable Terminal Strip and Surge Withstand
1201optB01 85 Vac to 264 Vac, 100 Vdc to 350 Vdc Secure Pluggable Terminal Strip and Surge Withstand
1201optB02 22 Vdc to 67 Vdc Secure Pluggable Terminal Strip and Surge Withstand
1201optC01 Holdover OCXO 1 ms/day
1201optC02 Holdover OCXO 10 µs/day

1 Located on mainboard. May be combined with options Exx.

AS0094800 Rack Mount Kit (1200 series)
AS0099200 Arbiter GNSS Active Timing Antenna
AS0105000 Cover Screw Kit 1201/1205/1206
CA0021315 1 15 m (50 ft) RG-6 Antenna Cable
PD0051900 Quick Setup Guide (1201)
AP0003400 2 BNC (Male) Breakout to 100 mm Wires
AP0008900 2 BNC (Female) Breakout to 100 mm Wires
AP0013400 GPS Antenna Cable Splitter, F-Type, 950-2150 MHz, One Port Pass DC
AP0014900 3 BNC (Male) Breakout to Screw Terminal
AP0015000 3 BNC (Female) Breakout to Screw Terminal
AS0044600 Antenna Mounting Kit
AS0044700 4 21 dB In-Line Pre-amplifier
AS0048900 Antenna Grounding Block Kit
AS0094500 GNSS Surge Protector
AS0096700 Operation Manual (1201)
CA0019806 RS-232 Null Modem Cable, DB9F-DB9F, 2 m (6 ft) length
CA0021302 1 2 m (6 ft) RG-6 Antenna Cable
CA0021306 1 6 m (20 ft) RG-6 Antenna Cable
CA0021330 1 30 m (100 ft) RG-6 Antenna Cable
CA0021345 1 45 m (150 ft) RG-6 Antenna Cable
CA0021360 1 60 m (200 ft) RG-6 Antenna Cable
CA0021375 1 75 m (250 ft) RG-6 Antenna Cable
CA0022500 Option 28 System Frequency Reference Cable, 6 m (20 ft)
CN0019202 Mating Connectors, 2-pole, 5 mm (5 ea.)
CN0019203 Mating Connectors, 3-pole, 5 mm (4 ea.)
CN0027700 Type F, Male, RG-6 Antenna Cable Crimp-on Connector
CN0027800 Type F, Male, RG-11 Antenna Cable Crimp-on Connector
CN0031400 Type F, Male, RG-6 Plenum Rated Antenna Cable Crimp-on Connector
TF0006000 Type F, RG-11 Antenna Cable Crimp Tool
TF0006400 Type F, RG-6 Antenna Cable Crimp Tool
TF0013200 Antenna Cable Stripping Tool, RG-6
TF0013300 Antenna Cable Stripping Tool, RG-11
WC0004900 1 300 m (1000 ft) Roll RG-11 Cable
WC0005000 1 300 m (1000 ft) Roll RG-6 Cable
WC0005200 1 300 m (1000 ft) Roll RG-6 Plenum Rated Cable
WC0006600 IRIG-B Distribution Cable (custom length)

1 Stocked length. Custom lengths available from 0.3 m (1 ft) to 300 m (1000 ft). Contact factory.
2 Converts pair of wires to BNC.
3 Note: The gender designation is not the same as our other BNC Breakout offering. The manufacturer of this breakout does not follow traditional naming conventions.
4 Used for cable lengths greater than: RG-6 100 m (328 ft) ; RG-11 195 m (640 ft)

Click to Download Latest Version of Software
1201_Utility_26Feb2016_0103 View and modify configuration settings.
Arbiter Time Service_01Jan2010_1500 PC Clock Synchronization Service for WIN NT/2000/XP/Vista/7. Not compatible with WIN 8.
Tera Term_01Jan2010_23 This is a very good HyperTerminal replacement. Able to capture data from Models 930A and 931A. Also able to program the GPS Satellite Controlled Clocks via serial commands.
TimeRC_3.0 NTP Server Test Utility. Screen Capture Utility.


Software Version and Related Information


The software interface specifically written for the Model 1201B/C.

  • Allows configuration of Model 1201B/C
  • Supports viewing and modification of existing configuration on Model 1201B/C from your PC.
  • Saves the existing configuration file from the 1201B/C to your PC.
  • Compatible with Windows XP, Vista, 7, 8, 10
VersionRev LevelVersion Notes
26Feb2016 01.03
  1. The Model 1201B/C firmware must be version 1.03 to read and write configurations. Use this utility to update the firmware.
  2. Improved compatibility with multiple receivers.
  3. Update copyright to 2016.
26Oct2015 01.02
  1. Improved compatibility with the latest firmware release.
18May2015 01.00
  1. Initial release.

Arbiter Time Service Tool (Arbiter Time Service)

PC Clock Synchronization Service for WIN NT/2000/XP/Vista/7. Not compatible with WIN 8. The Arbiter Time Service installs on Microsoft® Windows NT/2000/XP and runs as a service to keep the PC clock synchronized to an Arbiter GPS clock. The Arbiter Time Service connects with an RS-232 cable and interrogates the clock for the time signal

VersionRev LevelVersion Notes

Terminal Emulation Program (Tera Term)

Free software terminal emulator (communications program) for Microsoft Windows.

  • Tera Term (Pro) is a free software terminal emulator (communication program) for MS-Windows.
  • Supports VT100 emulation, telnet connection, serial port connection, etc.
  • Compatible with Windows 98, Windows NT, Windows 2000, Windows XP, Vista, Windows 7


Used as a test tool for NTP servers, synchronizes computer time over a network. Also used to save screen captures from the Model 930A, Model 931A, and Model 933A.

VersionRev LevelVersion Notes
Firmware Information (EPROM based firmware is not available for download)
1201_Firmware_01.09 Downloadable. Requires 1201_Utility (See Software tab).
NTP/PTP Firmware_2.08_update-00.08 Downloadable. UNZIP, read instructions, and use the web/SSH interface to import apf file(s) into unit.
Power System Time, Frequency, and Phase Monitor Firmware_05Apr2012 Requires an EPROM update from Arbiter.


Firmware Version and Related Information

Downloadable Firmware (1201_Firmware)

VersionRev LevelVersion Notes

Updates are not security related.

  1. Fixed NMEA GLL broadcast to work properly when Longitude is greater than 127 degrees.

Updates are not security related.

  1. Fixed NMEA GLL broadcast longitude (BZ 739).
  2. Fixed power LED's to properly indicate which power supply is in use.
  3. Increased maximum saved events to 50.
  4. Fixed leap seconds in event data. The offset was applied twice to the recorded event time.
  5. EA command now sends "NO DATA" when event buffer is empty to match other clock's response.

Updates are not security related.

  1. Fix leap second operation.
  2. Update IRIG output to only set direction bit when LS is pending.
  3. Improved the antispoofing platform.
  4. Improved GNSS operation.
  5. Fix event data formatting.
  6. Fix event seconds value issue that would sometimes occurs around the top of second (seconds value would be from next second).

Updates are not security related.

  1. Fixed PPS reference error that was introduced in version 01.04.
  2. Performance enhancements to speed satellite synchronization.
  3. Hold-over oscillator health test improvements.
  4. Reworked trajectory code to improve recovery after an out-of-lock condition.
  1. Fixed DCF77 output. Removed the 59th pulse at the top of the hour.
  2. Fixed IRIG-B output. Leap second pending bit was always on. Year changeover temporarily changed the IRIG-B time zone
  3. Internal message handler improvements.
  4. Power-up broadcast selection improvements.
  5. Code changes for improved compiler compatibility.
  6. Anti-spoofing foundation added.
  1. First release for u-blox receiver. No longer supporting the NV08 receiver.
  2. Corrected leap second implementation.
  3. Leap second default changed to 17 seconds.
  4. Added ability to clear faults from the front panel.
  1. Corrected leap second implementaion.
  2. Update NTP/PTP IP display to remove leading "0"s.
  1. Fixed intermittent dashes on display for holdover uncertainty.
  2. Continuous Time Quality (C37.118) corrected for response to out-of-lock and fault conditions.
  3. 1201C LED date display changed to dot separator in place of slashes.
  4. Humidity sensor compensation activated to improve holdover performance.
  5. Position alarm algorithm is now qualified with locked and tracking satellites.
  1. Initial release.

Downloadable Firmware (NTP/PTP Firmware)

The zip file contains all files and PDF instructions necessary to update the Network Time Protocol (NTP) / Precision Time Protocol (PTP) firmware. Reminder: Unzip the downloaded file to access the PDF instructions and individual update files.

VersionRev LevelVersion Notes

Updates are not security related.

1. Updates sys_monitor-01.05. The new sys_monitor corrects a bug in the frequency tuning algorithm that results in high system time offsets on some units. Whether or not a system is susceptible to this bug depends on the initial frequency of the on-board oscillator prior to tuning. It is likely that a system showing low offset now will continue to work. However, to be safe, the update is recommended.

Support  > Version
Core: 2.4
Auth01: 2.2
TPS UI Content: 2.2
Startup App: 1.3
System Monitor: 1.5
CLOI: 1.10

Reminder: Unzip the downloaded file to access the PDF instructions and individual apf update files.



  1. Update NTP to latest release (4.2.8p8) to protect against a known vulnerability.
  2. Modified the NTP server configuration to allow correct responses to queries at a rate higher than once every 4 seconds.
  3. Fixed a bug that prevents the proper network filter configuration for vlan interfaces resulting in vlans not functioning.
  4. Fixed a bug preventing getting the OS version from the serial port
  5. Improved robustness of the update process.

EPROM Update (Power System Time, Frequency, and Phase Monitor Firmware)

VersionRev LevelVersion Notes
  1. The frequency was unstable off nominal frequency with an error proportional to frequency deviation. Fixed a conversion factor in the calculation. (BZ 692)
  1. Improved compatibility during transfer of correction values to option 28.

GPS Substation Clock Requirements
Download gps_substation_clock_requirements.pdf (25 kB) »

IRIG-B Time Code Accuracy, IED and System Design Issues
Download irig_accuracy_and_connection_requirements.pdf (31 kB) »

NERC PRC-08 Compliance Statement
Download pd0042900a_NERC_PRC-018_compliance_statement.pdf (75 kB) »

Time in the Power Industry: How and Why We Use It
Download TimeInThePowerIndustry.pdf (407 kB) »

Why GPS Clocks Are Not Free
Download why_gps_clocks_arent_free.pdf (12 kB) »

App Note 101: Distributing Timing Signals in a High-EMI Environment
Download application_note_101.pdf (90 kB) »

App Note 103: Large Format Displays with Arbiter products
Download application_note_103.pdf (16 kB) »

COMTRADE Sample Rate Generator
Download ds_comt.pdf (27 kB) »

Continual Self Calibration with Power System Time, Frequency and Phase Monitor Option 28
Download power_system_time_freq_phase_monitor_continually_cal.pdf (12 kB) »

GPS Antenna Mounting Bracket
Download antenna_mnt_bracket_brief.pdf (462 kB) »

GPS Antenna Mounting Bracket Instructions
Download pd0024700_gps_antenna_mounting_bracket.pdf (580 kB) »

GNSS Antenna Preamplifier Installation Instructions
Download pd0025300_gnss_antenna_preamplifier.pdf (3 MB) »

IRIG Standard 200-16
Download irig-b_200-16.pdf (857 kB) »

IRIG-B Specifications
Download irig_b_spec_brief.pdf (488 kB) »

Option 34: Network Time Protocol (NTP)/Precision Time Protocol (PTP) Server Data Sheet
Download Option34_NTP_PTP.pdf (22 kB) »

Power System Time, Frequency and Phase Monitor
Download power_system_time_freq_phase_monitor.pdf (152 kB) »

Windows® Time Service Configuration
Download w32time.pdf (14 kB) »

Arbiter Time Service Installation Instructions
Download pd0041300_ArbiterTimeServiceInstall.pdf (382 kB) »

Chassis Dimensions
Download chassis.pdf (27 kB) »

Clock Option Selection Guide
Download clock_option_selection_guide.pdf (22 kB) »

Clock Selection Guide
Download clock_selection_guide.pdf (22 kB) »

Timing Products Options and Accessories
Download timing_and_frequency_options.pdf (36 kB) »

Option 28 Firmware Upgrade Instructions
Download Option28_DST_ROM_instructions.pdf (154 B) »

GPS Surge Protector Installation Instructions
Download pd0045800_surge_protector_installation_instructions.pdf (80 kB) »

Reducing Overshoot and Ripple in Arbiter Products with High Drive Outputs
Download pd0046200_reducing_high_drive_overshoot.pdf (277 kB) »

Timing Signals, IRIG-B and Pulses
Download pd0043200_timing_signals_overview.pdf (197 kB) »

Catalogo de Productos de Sincronizacion y Frecuencia
Download catalogo_de_productos_de_sincronizacion_y_frecuencia.pdf (216 kB) »

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