Continuous satellite two-way time transfer using commercial modems

Celano, Tom; Francis, S.; Gifford, G.A.

doi:10.1109/freq.2000.887423

Cited by 2 publications

(6 citation statements)

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“…At the same time, to reduce the impact of the bit error on the final time comparison, the frame synchronization bits (FSB) will be inserted at the rising edge of the 1 PPS signal. The bit error means that in signal transmission, decay causes the signal to be damaged, so the originally transmitted signal is '1', but the received signal is '0' (it should also be '1'), and the FSB is a specific set of bits at the beginning of each frame of signal [38]. The spreading spectrum consists of 1 PPS and PN, which is completed when the 1 PPS signal combines with the synchronized PN code by way of modulo-2 sum in the code generator (CG).…”

Section: Transmission Of 1 Pps Signalmentioning

confidence: 99%

Measuring Height Difference Using Two-Way Satellite Time and Frequency Transfer

et al. 2022

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According to general relativity theory (GRT), the clock at a position with lower geopotential ticks slower than an identical one at a position with higher geopotential. Here, we provide a geopotential comparison using a non-transportable hydrogen clock and a transportable hydrogen clock for altitude transmission based on the two-way satellite time and frequency transfer (TWSTFT) technique. First, we set one hydrogen clock on the fifth floor and another hydrogen clock on the ground floor, with their height difference of 22.8 m measured by tape, and compared the time difference between these two clocks by TWSTFT for 13 days. Then, we set both clocks on the ground floor and compared the time difference between the two clocks for seven days for zero-baseline calibration (synchronization). Based on the measured time difference between the two clocks at different floors, we obtained the height difference 28.05.4 m, which coincides well with the tape-measured result. This experiment provides a method of height propagation using precise clocks based on the TWSTFT technique.

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Section: Transmission Of 1 Pps Signalmentioning

confidence: 99%

Measuring Height Difference Using Two-Way Satellite Time and Frequency Transfer

et al. 2022

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“…Time-based communications (TBC) is a generic technology in which two-way time transfer is accomplished using a communications channel that meets a few basic requirements [1]. Implementation of these concepts has been accomplished over fiber [2] and satellite channels [1,3] with excellent results.…”

Section: Time Based Communicationsmentioning

confidence: 99%

“…Implementation of these concepts has been accomplished over fiber [2] and satellite channels [1,3] with excellent results. TBC has a long history of successes including 20 ps time synchronization over fiber and subnanosecond time synchronization over satellite communications channels.…”

Section: Time Based Communicationsmentioning

confidence: 99%

“…The dynamic two way time transfer equation can be represented as, T 2 -T 1 = .5*[( Meas 2 -Meas 1 ) + ∆prop_delay + ∆Sagnac] (1) where ∆prop_delay= change in the propagation delay over the measurement interval and ∆Sagnac = Sagnac time-of-flight correction between node 1 and node 2 [5,6].…”

Section: Time Based Communicationsmentioning

confidence: 99%

“…Each hardware suite included RF equipment (antenna, upconverter and downconverter) as well as two-way time transfer equipment (modem, measurement chassis and cesium). The modems were commercial satellite communications units that were modified to provide two-way measurements in the background of standard data transmission [1]. The measurement chassis consisted of precision timing equipment including twochannel timers, amplifiers and a controlling computer.…”

Section: Time Based Communicationsmentioning

confidence: 99%

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Dynamic two-way time transfer to moving platforms

Celano¹,

Warriner²,

Francis³

et al.

IEEE International Frequency Control Sympposium and PDA Exhibition Jointly With the 17th European Frequency and Time Forum, 200

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Time based communications (TBC) involves the use of an active data channel for time transfer [1]. In 2002, testing was conducted with the Air Force Research Lab (AFRL) at Wright Patterson Air Force Base to demonstrate a TBC implementation from the ground to an airborne platform using standard communications channels and equipment. Algorithms to perform Dynamic Two-Way Time Transfer (DTWTT) were developed and demonstrated to correct raw time transfer data for platform motion and measurement effects. Flight tests were conducted in November 2002 to demonstrate the algorithms and determine the level of performance that can be expected from dynamic two-way time transfer. Tests were conducted using Satellite Relay links and line-of-sight (LOS) links between the ground and the aircraft. The results from the Satellite Relay case were presented in a PTTI 2002 paper entitled "Two-Way Time Transfer to Airborne Platforms Using Commercial Satellite Modems". The LOS results are presented here. This paper begins with a review of Dynamic Two-Way Time Transfer for the line-of-sight communications link case. The flight experiment is presented with a description of the data collection hardware as well as a detailed presentation of the flight data. Conclusions on the use of DTWTT are drawn based on the results of the flight tests.

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Continuous satellite two-way time transfer using commercial modems

Cited by 2 publications

References 0 publications

Measuring Height Difference Using Two-Way Satellite Time and Frequency Transfer

Measuring Height Difference Using Two-Way Satellite Time and Frequency Transfer

Dynamic two-way time transfer to moving platforms

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