The TMG5020 can synchronize on a choice of time source and can manage several sources with a priority list for redundancy.

PPS accuracy is within +-100ns of PPS UTC when synchronized by GNSS.

It also features an NTP server.

Optionnally this equipement can provide countdown.

Download datasheet

Should you need any further information please mail to: pv@timelinkmicro.com

Modern multi constellation GNSS receiver as the one embedded within the Timelink products are capable of detecting unconsistent satellite data and exclude them from the time calculation which makes it more difficult to spoof.

Nevertheless critical infrastructure tend not to rely on the GPS signal while critical synchronisation is required. Instead they rely on the internal pilot of their synchronisation system which garantee a low enough hold over to maintain the required accuracy.

This is made possible on the latest Timelink product line by excluding the synchronisation source (GNSS in our case) and let the disciplined Time & Frequency generator run on its internal pilot. The synchronisation source can then be included again once the mission critical events have been passed.

It is also recommended to monitor the time and the internal to GNSS PPS deviation by the remote control. Any spoofing activity would lead to a jump in time and PPS deviation which should be considered a critical alert.

 TMO3000-T/R is a transmitter/receiver system made of 2 units allowing transmission of 3 analogs and 4 digitals signal over an optical fiber

Signals are digitalized at the input transmitted and regenerated at the output allowing the system to be signal agnostic

Its optical fiber SFP connector makes it flexible to a large choice of optical fiberstransceivers allowing transport over multi-mode or single mode fiber types

3 analog signals and 4 digital signals multiplexed over one Optical Fiber

All IRIG code, PPS transmission

Receiver Optical fiber signal indicator

Choice of Rack 1U or Compact Box

check the datasheet at : http://www.timelinkmicro.info/products/optical-fiber-generator-distributor/

Timelink is following closely the security aspects of its products and is committed to improving it.

1) INTRODUCTION

NTP Protocol is built on following architecture:

• At the highest level, one finds a NTP server called Stratum 1 server (or primary server), its role is to provide a UTC time. This server is synchronized on a reference clock: atomic clock, GPS,…
• UTC Time is then available for a client which can synchronize its internal clock. Once synchronized, this calculator is able to provide its time to another group of calculator. This calculator is named “server Stratum 2″.
• We will call server Stratum N, any calculator which is synchronized on a server stratum N-1. Consequently, the smaller the stratum number, the higher the accuracy.

2) OPERATING MODE

The following figure shows the client/server mechanism:

• T1 or “Originate TimeStamp” time at the time when the request is sent according to the client clock
• T2 or “Receive TimeStamp”, time at the time when the server received the request according to its clock
• T3 or “Transmitted TimeStamp” time to the moment when the answer is returned according to the server clock
• T4 or “TimeStamp Reference” time to the moment when the answer is received by the client according to his clock.

The delay or time to go and return is given by the formula:

delays = (T4-T1) – (T3-T2)

The offset is obtained by:

Offset = ½ * ((T2- (T1+Délais/2)) + ((T3+Délais/2) – T4))

Offset = ½ * ((T2-T1) + (T3-T4))

To make an right estimate of the time to go and return and the offset between the two clocks, the protocol NTP must record four information of time in its NTP frame.

3)FORMAT OF NTP MESSAGE

Protocol NTP is built on UDP/IP, which implies:

• No concept of opening and closing connection
• In the event of loss of packet, there is no re-emitting mechanism

After the  UDP header, the NTP message is found:

The significance of the various fields is as follows:

• LI or Leap Indicator: it is a field of two bits for the indication of the jumps of seconds in time NTP. The codes are:
  • No alarm
  • The duration of the last minute of the day will be 61 seconds
  • The duration of the last minute of the day will be 59 seconds
  • Indicator of alarm (not synchronized clock)
• VN or Number Version: this field of three bits, gives the version of NTP message.
• Mode: this field of three bits gives us the mode of the transmitter. The various codes are:
  • 0: reserved
  • 1: active symmetric
  • 2: passive symmetric
  • 3: customer
  • 4: server
  • 5: broadcast
  • 6: reserved for the monitoring of NTP message (additional information on mode 6 are given in the appendix B of the RFC 1305)
  • 7: reserved for personal use
• Stratum: this field of 8 bits indicates the level of the transmitting server.
  • 0: no indication
  • 1: Primary server (atomic clock, GPS…)
  • 2 – 255: secondary server (via NTP)

• Interval poll: this field of eight signed bits indicates the maximum number of second which can run out between two messages (expressed in power of two).
• Precision: this field of eight signed bits indicates the precision of the clock in second (expressed in power of 2, -10 means 2-10, that is to say 1/1024=0.97ms)
• Root Delay: this signed value of 32 bits, indicates in fixed point, total time to go and return, in second, between the customer and the primary server. The comma is between bit 15 and bit 16. The value of this field can be positive or negative according to the precision of the clock of the server.
• Root Dispersion: this signed of 32 bits, indicates in fixed point, the estimated dispersion of the primary server. The comma is between bit 15 and bit 16. Only the values higher than zero are authorized.
• Clock reference identifier: for the primary servers, this field of 32 bits indicates the type of reference clock. This indication is carried out with a character string, justified on the left with one zero terminal. This chain can take the following values:

Note: When the number of stratum is higher than 1, this field contains address IP of the reference server.

• Reference TimeStamp, Originate TimeStamp, Receive TimeStamp, Transmit TimeStamp: those fields of 64 bits contain the four informations of time in connection with the “delays” and “the offset”. The first 32 bits indicate the number of seconds passed since January 1, 1900 to 0h00 UTC. The last 32 bits indicate the 1/232 seconds number spent since the beginning of the current second. In Broadcast mode, the fields Originate TimeStamp and Receive TimeStamp are by convention set to zero.
• TimeStamp reference: time of the last update of the clock
• Originate TimeStamp: time of departure of the request.
• Receive TimeStamp: time of arrival of the request
• TimeStamp transmitted: time of departure of the response to the request.
• Authenticator (optional): this fields is kept for the mechanism of authentication of NTP messages.  This mechanism authorizes the encoding of NTP data with the DES (Data Encryption Standard). It is packed up in the appendix C of the RFC 1305.

Disciplined Mode 

When the pilot is disciplined, the quality of the algorithm used and the pilot stability characteristics will determine the overall clock stability performance.

The short term stability will be driven by the pilot characteristics while the long term stability will be maintained below a value defined within the algorithm whatever the duration.

Free Running Mode

When the pilot is not disciplined anymore, the pilot will drift by its own stability performance.

In that case : ∆Τ = ½ *a * t² (without taking into account noises)

where ∆Τ = Time Error,  a = aging,  t = Elapsed Time

To calculate the time error over a duration, the frequency aging or long term stability to be considered must be the one matching the requested duration.

Exemple

To calculate a time error over 20 days, one must consider the 1 month stability of the pilot.

So for a pilot featuring a 1 month stablity of 1E-11, its accuracy over 1 second is 1e-11/(30*24*3600)=3,85e-18.

Time Error =  ½ * 3,85e-18 * (20/30 * 24 * 3600)² = 5,76μs.

Depending on the requested Time error, Timelink can adjust any product to various pilots within TCXO, OCXO, Rubidium, Cesium : Contact.

Signal Input

1 KHz sinusoidal signal modulated in amplitude1 / 3, 1/1 Level 0.5 to 6 V peak-peaks, Isolated by transformer Impedance 600 Ohms
Signal DCLS level TTL or RS422 (coming).

Time Codes

Compatible with IRIG B12x (x = 0 to 3) according to standard IRIG STANDARD 200-98, AFNOR and IEEE1344
TD, H0 and TU / TD composite time code.

Access to information

The card incorporates registers that allow access to time information on the fly and to program modes of operation.Linux and Windows drivers available as well as examples of code to manage card resources

Download pdf datasheet               Télécharger la fiche produit

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Communication systems, data handling systems, tracking and telemetry systems require time-of-the day information for data correlation with time.
Parallel and serial formatted time codes are used to efficiently interface the timing system to the user system. Parallel time codes are defined in IRIG standard 205-87. Standardization of time code is necessary to ensure system compatibility among the various ranges, ground networks, industrial projects and international cooperation.The IRIG standard 200-98, define IRIG serial time code formats. The characteristics of six serial time codes presently used are defined :A, B, D, E, G, H.For a detailed presentation of these characteristics, download the pdf version of the IRIG standard :
IRIGB standard 200-04, pdf file (372 Ko)    For a first introduction to IRIGB characteristics, we provide the main information through the two following figures :

The figure below shows the IRIG format B: BCD time-of-the year in days, hours, minutes and seconds

 

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