Frequency & Time - Calibration Services
Ordering Calibrations
Services
The Frequency and Time Group is responsible for Canada's standards of
time and length. The SI second and metre are defined and maintained, and
calibrations are perfomed relative to these standards. NRC, through activities
of this Group, produces the official time for Canada and is one of the
many international organizations contributing to the formation of Coordinated
Universal Time (UTC), the international time scale produced by the Bureau
Internationale des Poids et Mesures (BIPM). Canada's SI time standards
are coordinated with the UTC. The metre is realized in accordance with
the guidelines published by the BIPM - "Mise en Pratique 1992"
- which specify the construction and operating conditions for sources
of radiation at a variety of recommended wavelengths. The uncertainty
for the published wavelengths depends on the source and ranges from 6x10-12
for the helium-neon lasers stabilized on a specific absorption line of
methane (an infrared wavelength), to 2x10-8 for discharge lamps filled
with cadmium-114. Calibrations services are available for frequency, time,
and laser frequency for defining length in terms of wavelength.
Uncertainties Facilities Laboratory
Services Remote
Services Fees
for Service
Contact: Dr. Jean-Simon
Boulanger Tel. (613) 993-5698
The uncertainties quoted here are expanded uncertainties representing
a confidence level of approximately 95%. They were obtained assuming a
normal distribution and multiplying the standard uncertainty (one standard
deviation) by a coverage factor of k = 2.
The Group operates an atomic clock ensemble consisting of three primary
cesium beam time standards and two commercial cesium clocks. These clocks
operate on a continuous basis and produce the NRC time scale. In addition
to these cesium clocks, the laboratory operates atomic hydrogen masers
whose stable output frequencies are used in the evaluation of various
standards.
The Group maintains three 633 nm (visible red wavelength helium-neon
lasers stabilized on the 11-5 R(127) component of iodine-127. The fractional
uncertainty of the frequency of these lasers relative to the primary cesium
standard is 5x10-11. These constitute the primary length standards for
Canada.
The Group performs in-house calibrations on a variety of instruments
such as commercial cesium atomic frequency standards, rubidium frequency
standards, quartz oscillators, signal generators, synthesizers, and electronic
counters and timers. The frequency drift and frequency stability of a
frequency standard can also be measured. The uncertainty of the calibration
is usually limited only by the quality of the instrument submitted. The
basic reference for the measurements is the primary cesium standard, which
has an uncertainty as good as 1 x 10-13 relative to the SI second. Its
frequency stability over one day is 10-14. Hydrogen masers provide a reference
that has a stability as low as 10-15 over 1000 seconds. The indicated
time of clocks brought to the Council can be related to time scales in
other countries, usually with an uncertainty of less than 100 ns.
Facilities for calibrating frequency-stable helium-neon lasers used in
length metrology and scientific research are maintained. The absolute
values of wavelengths of lasers are determined by comparing the laser
frequencies against the primary standard laser frequencies. An ongoing
research program in the development of new optical frequency standards
provides many accurately known infrared laser frequencies that can be
used as standards for laser frequency/wavelength calibrations. This service
is available only by special arrangement and on an experimental basis.
The Group assists clients in making traceable time and frequency comparisons
with NRC. The comparisons are made on equipment at the client's site and
can have uncertainties in frequency as low as 10-13. Clients can arrange
service by contacting the laboratory. Comparisons are made via television
signals within the Ottawa area, by LORAN-C signals within range of the
Great Lakes LORAN-C chain, or from GPS (Global Positioning Service) satellites
across Canada. NRC can also assist in comparing the frequency of a client's
standard with the frequency of the time scales of other laboratories such
as BIPM (Bureau International des Poids et Mesures), PTB (Physikalisch
Technische Bundesanstalt), and NIST (National Institute of Standards and
Technology).
Users can make frequency calibrations and obtain time of day information
from a variety of time signals disseminated across Canada by NRC. Short
wave radio station CHU broadcasts time signals at three frequencies: 3.33
MHz, 7.335 MHz, and 14.67 MHz, with a frequency uncertainty of 5 x 10-12
as transmitted. The time of day is available from a telephone signal provided
by NRC to the CBC AM radio network and retransmitted daily at 13:00 Eastern
Time in English and 12:00 Eastern Time in French. The time of day can
also be obtained by dialling (613) 745-1576 for English, (613) 745-9426
for French, or (613) 745-3900 for computer readable code. These numbers
are not toll free.
Ordering Calibrations
Services NEW procedures effective March 23, 2006.
A33-07-00-00 Custom Frequency or Time Standards Measurements
or Services Fee on request. |
Contact Dr. Jean-Simon
Boulanger for further information |
A33-07-00-01 Handling Fee $150 |
A charge is levied for any instrument
found to be unsuitable for calibration. This fee covers opening, inspection
and return and is based on the work done prior to discovery of the
fault. |
A33-07-00-02 50% of calibration fee |
Unsuitable
instrument handling fee |
A33-07-00-03 $150 |
Special set-up handling
fee |
Time
Measurements Time
Interval & Frequency Measurements Frequency
Stability Laser
Frequency/Wavelength Authenticated
NTP Service
TIME
MEASUREMENTS A33-07-01-01 to A33-07-01-02) |
A33-07-01-01 Time Measurement $320 |
This service measures
the time of a portable clock providing 1 pps (pulse per second) output
to within 100 ns with respect to any international time scale or to
within 2 ns of the NRC time scale. |
A33-07-01-02 Time Measurement and Setting $320 |
This service measures and sets the time of an easily
adjustable clock that provides a 1 pps output. |
(A33-07-02-01 to A33-07-02-06)
The uncertainty quoted in each of the following descriptions is for the
specified measurement period under normal laboratory conditions only.
Investigations of the effects of ambient temperature, other environmental
factors, or instrumental parameters are not included. The overall uncertainty
depends on the stability of the standard under test both during the test
and during transit to and from NRC.
Repeated measurements can be taken upon request. Additional fees are
charged only to cover the added time required for the test and are generally
significantly lower than for the original test. The calibration of equipment
which cannot be interfaced electronically with the measuring system, for
example, stop-watches or oscillators with non-standard output, will generally
cost more and produce much higher uncertainty than that shown below.
A33-07-02-01 Counter-timers and Synthesizers $320 |
Measurement
is taken of the crystal oscillator frequency of frequency counter-timers
and synthesizers to an uncertainty commensurate with the crystal quality,
but not less than 5 x 10-9. |
A33-07-02-02 Frequency Measurement and Setting (Crystal
Oscillator) $392.50 |
The measurement and setting of the
crystal oscillator frequency of frequency counter-timers and synthesizers
are determined to an uncertainty commensurate with the crystal quality
and the ease of adjustment, but not less than 5 x 10-9. |
A33-07-02-03 Frequency Measurement (Crystal Frequency
Standard) $565 |
The
mean output frequency of a quartz crystal frequency standard is measured
over a period of one hour to an uncertainty commensurate with the
crystal quality, but not less than 1 x 10-11. |
A33-07-02-04 Frequency Measurement and Setting (Crystal
Frequency Standard) $670 |
The measurement and setting of the
mean output frequency of a quartz crystal frequency standard are determined
over a period of one hour to an uncertainty commensurate with its
stability and re-setability, but not less than 1 x 10-11. |
A33-07-02-05 Frequency Measurement (Rubidium or Cesium
Frequency Standard) $755 |
The
mean output frequency of a rubidium or cesium frequency standard is
measured over a period of 24 hours to an uncertainty commensurate
with its stability, but not less than 2 x 10-13. |
A33-07-02-06 Frequency Measurement and Setting (Rubidium
or Cesium Frequency Standard) $930 |
The measurement and setting of the
mean output frequency of a rubidium or cesium frequency standard are
determined over a period of 24 hours to an uncertainty commensurate
with its stability and re-setability but not less than 2 x 10-13. |
(A33-07-03-01 to A33-07-03-02)
For each service described below, the frequency stability is measured
over the specified period and under normal laboratory conditions. It is
preferable that the unit be operating on battery power when it is delivered
to NRC. If this is not possible, a warm-up period should be specified
indicating the length of time to wait after the unit is switched on at
NRC before measurements can begin.
A33-07-03-01
Measurement of Crystal Oscillator Drift
Rate $917.50 |
The frequency
and frequency drift of a quartz crystal frequency standard are measured
over a period of one week to uncertainties commensurate with the crystal
quality, but not less than 1 x 10-12 in frequency nor 1
x 10-13/day in frequency drift. |
A33-07-03-03 Customized Measurement of Allan Variance
of Frequency Standard Fee on request |
Customized, shorter-term
stability measurements of the Allan variance can be made over periods
as short as one second for frequency standards with a 5 MHz output.
Uncertainties of 2 x 10-15 can be obtained for time intervals
of 1000 - 105 seconds. |
A33-07-03-04 Time and Frequency Traceability to NRC Fee on request |
Customized assistance is available for establishing
time and frequency traceability to NRC using signals from GPS satellites
using the common view technique to overcome the effects of SA (selective
availability). |
Publication |
A33-07-04-01 Canada's Time Service $160 |
This
brochure provides an overview of NRC's time measurement services.
It is available in lots of 50, in English or French. |
(A33-07-05-00 to A33-07-05-02)
Calibration of Helium-Neon Lasers at 633 nm
The Optical Frequency Standards (OFS) project can offer routine frequency and vacuum wavelength calibration of client helium-neon lasers at 633 nm with an uncertainty of less than 1x10-10, normally limited by the reproducibility and stability of the client laser. The calibration method involves comparing the frequency of the client's laser with that of the National Standard (a known frequency) and measuring the difference frequency. This is done by overlapping the output beams of the two lasers so that the combined beams illuminate a fast-response photodiode. A beat frequency equal to the relatively small difference (typically less than a few hundred megahertz) between the two laser frequencies is generated at the photodiode and this signal is measured with a calibrated frequency counter.
Frequency measurements are performed with the NRC laser stabilized on a series of four hyperfine lines in the R(127) line of the 11-5 band of the B-X 127I2 (iodine) transition to obtain an unambiguous determination of the client's laser frequency. During a typical calibration, the client's laser frequency is checked on over five different occasions over a period of at least three days in order to determine the overall stability and frequency reproducibility. Estimates of the client's laser warm-up period and sensitivity to optical feedback are also provided.
In most requested calibrations, the client's 633-nm helium-neon laser system employs a frequency stabilization method that is inferior to locking on an iodine resonance. For example, polarization stabilization, Lamb-dip stabilization, Zeeman stabilization, etc. are used. For these types of lasers, the frequency is calibrated to an uncertainty commensurate with its stability: generally, the uncertainty will not be worse than 5 parts in 10^9. This is more than sufficient for most industrial applications.
Client helium-neon lasers that are iodine-stabilized can be calibrated to uncertainties approaching the limits of the NRC laser which has been calibrated through comparison with a laser at the Bureau International des Poids et Mesures (BIPM) and directly through the NRC optical frequency comb. Under optimal operating conditions, the NRC laser has an uncertainty of less than 2 10-11. More precautions and additional measurements must be taken to realize this level of accuracy and the fee is accordingly higher.
Calibration of Lasers at 1511 to 1552 nm
These calibrations use one of two similar NRC built laser systems which are frequency stabilized on saturated absorption overtone lines in 12C2H2 and 13C2H2 (acetylene). Our acetylenestabilized lasers have been calibrated at over one hundred different lines with traceability to the SI second by means of the NRC optical frequency comb and through frequency difference measurements. These lasers are calibrated periodically with the NRC optical frequency comb. The large number of absorption lines between 1511 nm and 1552 nm permits client lasers to be calibrated over much of this region through heterodyne beat measurements. The calibration procedure is similar to that described previously for helium-neon lasers at 633 nm.
Custom Calibration of Lasers at 550 to 1150 nm and 1530 to 1560 nm
Custom calibrations of laser frequency/wavelength with traceability to the SI second through the NRC optical frequency comb are offered for lasers in the ranges 550 nm to 1150 nm and 1530 nm to 1560 nm.. Laser frequency is determined by measuring the heterodyne beat between the client laser and a single element of the optical comb. The frequencies of the comb elements are fixed by locking both the comb's repetition frequency and its offset to a signal from a calibrated hydrogen maser. In this way, an uncertainty of less than 10 Hz is achievable from 193 to 550 THz. In practice, the uncertainty is determined by the reproducibility and stability of the client laser.
Contact: Dr. John Bernard Phone: 1-613-993-2181 Email: john.bernard@nrc-cnrc.gc.ca
A33-07-05-00 Custom Calibration of laser frequency/wavelength for wavelengths in the ranges of 550nm to 1100 nm and 1510nm to 1555nm |
Fee on request |
A33-07-05-01 633-nm
Helium-Neon Laser |
$1925 |
A33-07-05-02 633-nm Iodine-Stabilized Helium-Neon Laser |
Fee on request |
(A33-07-06-01 to A33-07-06-03)
NRC offers NTP (Network Time Protocol) servers with optional authentication
procedures. Using authentication a client's server can have assurance
that the Internet data packets containing the NTP time stamp comes from
NRC. Authentication is obtained by encrypting the data in MD5 ( Message Digest 5) format. MD5
is restricted for use in Canada and U.S.A. only.
At present there is no fee for unauthenticated NTP time service. To receive
authenticated NTP service, for a one-time fee, a client will receive a
key code and a password on an NTP server at NRC. Authentication is available
on our stratum-1 and stratum-2 servers.
The client must specify how many servers they will synchronize to, and whether each is stratum-1 or stratum-2. The client will specify how the keyID and password will initialy be sent. They can be sent by telephone, fax, email or courier.
A33-07-06-01 Time service, secure NTP, set-up fee $110 |
A
one time set-up fee will be charged for a key ID and a password on
each server that will provide authenticated time service. This fee is valid for one client host installation. |
A33-07-06-02 Time service, secure NTP, annual maintenance
fee $110 |
A yearly fee, paid in advance,
will be charged to maintain one authentication key for a client on
one NRC NTP server. |
A33-07-06-03 Time service, secure NTP, annual maintenance
fee, extra server $50 |
A
yearly fee, paid in advance, will be charged to maintain each additional
authentication key for a client on another NRC NTP server. |
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