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

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.


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


Stability 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)
Keyboard 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


RS-232 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
Connector 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.


Voltage Universal
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.

Inlet Secure Pluggable Terminal Strip



Size 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
508 mm x 381 mm x 203 mm (20 in x 15 in x 8 in), shipping
Weight 2 kg (4.5 lbs), net
5.5 kg (12 lbs), shipping
Antenna 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


Temperature Operating: – 40 °C to + 65 °C
Nonoperating: – 40 °C to + 75 °C
Humidity Noncondensing
EMC 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