TimeAcc
Precision Time Measurement Instrument

Introducing the latest addition to the Time & Frequency Solutions' range of precision timing instruments. TimeAcc precisely measures the time accuracy of a wide range of inputs against an internal precision GPS-controlled oscillator. Any difference is clearly displayed on the large, full colour Windows-based screen.

Features

Measures and displays the difference between input time signal and GPS
Capable of measuring a wide variety of time signal inputs
Full colour touch-screen with user-friendly Windows-based operating system
Timing resolution of better than 1 nanosecond
Absolute accuracy of up to 50 nanoseconds to UTC
Automatic identification and analysis of Modulated Carrier Timecodes
1 x USB port situated on the front of the instrument for easy access for downloading data to printer and/or removable memory for subsequent analysis
Robust, portable design for all industrial applications

Applications

TimeAcc is invaluable where time of day information is distributed from a central master clock to sub-master clocks or user systems over large distances via serial data links or packet networks. Substantial delays can occur due to high levels of network traffic or even due to the long distance between the master clock and the user.

Some commercially available software algorithms can reduce these errors but, unless the errors are accurately and independently measured at the point of use, the user cannot be certain of the accuracy of his time source in this type of application.

Additionally, the high accuracy of the TimeAcc means that it can also precisely measure the time error of free-running clocks and timing systems which are synchronised from untraceable sources, such as television and radio broadcasts, electrical power lines and via the internet.

Signal Inputs

Selectable via the front panel touch-screen:

1 Pulse per Second (1PPS) TTL
1 Pulse per Minute (1PPM) TTL
1 Pulse per Hour (1PPH) TTL
IRIG-B modulated onto a 1kHz carrier
IRIG-B DC level shift
ASCII Serial time message at RS232, RS422 or RS485 levels
Network Time Protocol (NTP) to RFC 1305
DCF-77 timecode

Ease of use
As the unit is portable and battery powered, it is simple to synchronise the unit to GPS outside by using the integral GPS antenna. Alternatively, synchronisation can take place inside if connected to an external GPS antenna, with the additional flexibility to use AC mains power.

Specifications

Outputs
USB Port for printer / data logger / removable memory
1pps       0V to 5V pulse from 50ohms (BNC connector)
10MHz      0V to 5V square wave from 50ohms (BNC connector)
User Interfaces
Network Connection 100Base-T Ethernet (RJ-45 connector)
User Serial Interface RS232 (9-way sub-D connector)
Measurement Reference Source
Internal C/A Code GPS Receiver with case-mounted antenna
Time Accuracy (2s) 30ns over 24hrs
Optional connection to external GPS Antenna
Internal Disciplined Rubidium standard (ovened Quartz or TXCO option)
Frequency Reference stability 3x10^-12 over 100s
Frequency aging without GPS     3x10^-11 per month
Loss of Time accuracy without GPS ±30ns per hour

Internal Time Interval Measurement

0.2 nanosecond resolution with built-in self-calibration

Measurement Accuracy Against GPS	Time	Resolution
1pps	±50 ns	0.2 ns
1ppm	±50 ns	0.2 ns
1pph	±50 ns	0.2 ns
IRIG-B AC & 1kHz	±1 µs	100 ns
IRIG-B DC	±50 ns	0.2 ns
RS232*	±1 µs	0.2 ns
RS422*	±100ns	0.2 ns
NTP**	±70ns	20 ns
DCF-77*	±50ns	0.2 ns

* rising edge of start-bit
** hardware timestamp of 100baseT
Ethernet packets