Performance of Multichannel Commonview

1
Performance of Multi-channel Common-view
Victor Zhang National Institute of Standards and
Technology Time and Frequency Division
2
Overview

• Common-view operations at NIST
• GLONASS common-view
• GPS multi-channel common-view
• Summary

3
Common-view operations at NIST

• Secondary method for contributing the NIST time
  scale to the computation of TAI and UTC
• Global Time Service (calibrate remote clocks with
  respect to UTC(NIST))
• Synchronize the clocks at radio stations
  WWV/WWVB, WWVH to UTC(NIST)
• Calibration of the two-way links between NIST and
  other laboratories

4
GLONASS common-view

• GLONASS common-view with multi-channel C/A code
  and single channel P-code contains more transfer
  noise in short term due to the small number of
  satellites in orbit
• GLONASS common-view is degraded due to the
  difficulties in making ionospheric delay
  correction

5
GPS multi-channel common-view

• Evaluation of three different types multi-channel
  receivers (NISTM1, NISTM2, and NISTM3)
• ?x ? 200ps _at_ 1day with single channel common-view
• NISTM3 receiver behaves similar to the NBS-type
  single channel receiver
• Performance of multi-channel common-view is
  degraded by diurnal

6
GPS multi-channel common-view

• Distance ? 2,400 km
• ?x? 600 ps _at_ 1 day for single channel common-view
  (36-point everyday)
• ?x? 500 ps _at_ 1 day for the best multi-channel
  common-view (400-point everyday)
• Multi-channel common-view lowers the transfer
  noise for averaging time from 16 minutes to a few
  days

7
GPS multi-channel common-view

• Distance ? 7,150 km
• ?x? 800 ps _at_ 1 day for single channel common-view
  (17-point everyday)
• ?x? 600 ps _at_ 1 day for the best multi-channel
  common-view (235-point everyday)
• Multi-channel common-view lowers the transfer
  noise for averaging time from 16 minutes to a few
  days

8
GPS multi-channel common-view

• Distance ? 7,530 km
• ?x? 900 ps _at_ 1 day for single channel common-view
  (16-point everyday)
• ?x? 700 ps _at_ 1 day for the best multi-channel
  common-view (160-point everyday)
• Multi-channel common-view lowers the transfer
  noise for averaging time from 16 minutes to about
  two days

9
Summary

• Performance of GLONASS common-view is degraded
  due to the small number of satellites in orbit
  and the difficulties in making the ionospheric
  delay correction.
• Multi-channel GPS common-view considerably
  reduces the transfer noise out to a few days.
  With IGS ionospheric delay and precise ephemeris
  corrections, the noise is 700 ps or less when
  averaged over 1 day.