HIGH DATA RATE RECEIVER
HDR-4G+ USER’S MANUAL
Ref. DTU 100782
Is.Rev 3.5
Date: June 1, 2021
© Safran Data Systems – IMP000074 e14r1
This document is the property of Safran Data Systems.
It cannot be duplicated or distributed without expressed written consent.
Doppler and Integrated Phase Measurement 3.3.10
Introduction 3.3.10.1
The HDR provides Doppler measurements (measurements of the offset between the set up IF value
and the actual one) and integrated phase measurements. These measurements are available for the
user through a specific TC/IP port (refer to the STI 100013 HDR document).
The elementary Doppler measurements (IF offset measurements) are generated every 13.1072 ms.
They are sampled at the rate specified by the parameter « Doppler measurement sampling rate »
(every 100 ms to every 10 seconds). As the sampling rate and the generation rate are asynchronous, a
linear interpolation is applied for improved measurement accuracy. Samples are stored, for further
transmission, in a measurement block which size is programmable between 1 and 1000 elementary
measurement(s).
The Elementary integrated phase measurements are generated every 13.1072 ms. They are sampled
at the rate specified by the parameter « Doppler measurement sampling rate » (every 100 ms to every
10 seconds). As the sampling rate and the generation rate are asynchronous, a linear interpolation is
applied for improved measurement accuracy. Samples are stored, for further transmission, in a
measurement block which size is programmable between 1 and 1000 elementary measurement(s). The
integrated phase resolution is 2π/2
32-N
radian, with N tunable (see user’s manual for more information).
The 64-bit phase counter capacity is 2
32+N
/IF seconds. As an example, N = 15 gives a counter capacity
of 1 day 8 hours and 46 minutes at 1.2GHz.
The following demodulator menus support advanced Doppler measurements, integrating the
phase of the carrier oscillator: Menus # 5, 7, 8, 9, 10, 11, 12, 13, 15, 16, 23, 24, 39, 46, 57.
A single Doppler port is used for transmitting IF offset measurements or integrated phase
measurements.(refer to the STI 100013 HDR document).
Required setup for optimal performance 3.3.10.2
Accurate phase and Doppler measurements need a very precise and stable sampling period.
Moreover, the internal oscillators must also run at a very stable frequency. Even though it is possible to
get rough Doppler and phase measurements without any external reference, it is strongly
recommended to connect the demodulator to a 10MHz reference to obtain accurate results.
Doppler and phase measurements are time-tagged. For precise datation of Doppler and phase
measurements, it is strongly recommended to connect the demodulator to an IRIG-B generator. In such
case, the precision of the time tag is 1µs.
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