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A Type Of Electro-Magnetic Frequency Bandwidth Compatible-Detecting
Algorithm for Space Devices’ Radiofrequency Equipment
一种航天器射频设备电磁频谱兼容性检测方法
Assistant Research Scientist Professor in Mechatronics Department
Harbin Institute of Technology Harbin Institute of Technology
Feng A. An (fengan@iupui.edu) Hou Zhen Xiu (houzx5629@hit.edu.cn)
Abstract:
Nowadays, modern astronautics require highly advanced equipment
and detecting devices. The Detecting Devices ordinarily do not require
EMIC (ElectroMagnetic Interference Control) check before the whole body
of the testing board can be fully developed.
However, we invent one kind of EMIC algorithm and implement this
algorithm into a small rocket and then using a small 3-axis accelerator, we
find out the EMIC parameters to be exactly what we are trying to acquire.
1. Introduction
In Modern Astronautics Devices and Space Shuttles, many
source-powered and non-source-powered navigation devices are installed.
In the Overall Run, the whole system require overall smoothly in
Electro-Interference part. However, since different devices all working at
GHz-level and the transmitting radio-frequency are nearly the same. Many
by-passes and collisions have occurred.
2. EMIC System Design Algorithm
The forecasting analysis Algorithm is highly advanced in the
following three areas: No.1 Anti harmonic wave Interference; No.2 Anti
combination wave Interference; No.3 Anti intermediation wave Interference.
To forecast the astronautics devices in Electro-Magnetic compatible
features parts, main emphasis is focused on finding out how the device in
itself can produce potentially additional and unexpected signals and then
self-managed to transmit outside without any forms of antennas and RF PCB
parts.
Another fear is the parasite capacitors around those main bus lines,
those capacitors are supposed to be able to produce very high speed
oscillating RF signals and moment-powered unilateral streams of
electroshock across the board wires.
We managed to collect those samples from the rocket's PCB board:
base frequency bandwidth of the transmitter and the overall main base
bandwidth frequency; oscillator start frequency of the transmitter; base RF
signal's frequency bandwidth; operating frequency base bandwidth of the
receiver and the upper/lower thresholding frequencies of the receiver.
In order to get the quality of the receiver’s selected-band pass feature,
the first VXO frequency of the receiver and overall main bandwidth
frequency needs acquiring. And the same theory can also helps to maintain
the receiver’s first midband bandwidth frequency and the overall bandwidth
value itself. For the transmitter side, we manage to use the idea to acquire
the second VXO bandwidth frequency and overall main bandwidth
frequency values. And the second midband frequency and its relevant
bandwidth can be measured too.
Since the frequency convertors are not ideal multipliers, but a kind of
non-linear devices. Using those devices, we only can manage to accomplish
many sorts of multiplying. The cross modulation features of those devices
are easily troubled by unexpected parasite channels.
For the first type: harmonic wave Interference. Based on the analysis about
the base waves, we manage to analysis unforecasted harmonic wave features.
Basically, those troubles in the components of the transmitter’s harmonic
waves.
For the second type: combination wave Interference. Since this type is
mainly because two or more signals are mixed in non-linear components.
New types of signals are produced, several or more frequency components
are proved to be harmful to the overall astronautics system.
For the third type: intermediation wave Interference. The point is
many outside signals are linearly combined with the transmitter’s VXO
signals in the mixer. Those new signal components combine in midband
frequency and the overall signal is useless.
3. Implementing Details
The basic laws in implementing are in three stages: considering
several major fractional degrees in the signals, aiming at anti
intermodulation, anti signal mirroring, anti harmonic waves, and anti
VXO/combined signals’ troubling individually, first is to acquire parameters;
build software models using Matlab; those models include interference
source model and sensitive device models. Second, decide problem values
precision level, decide number of troubled degrees in the software and types
of troubled models.
For astronautics applications, commonly accepted law is to set the
considered troubled degree numbers to 10.
The simulation model deletes useless interference pairs. For instance,
interference sources and those sensitive devices all have interferences at the
same frequencies. This can be achieved by comparing the time spots during
the operating time.
One exception in the implementing process: the non-pole
intermodulation. The non-pole intermodulation is one kind of signal
distortion. While two or more frequency signals are in the same non-pole RF
part, since the non-linear V-A relevance, multi-band frequency signals’
mixing combination will produce cross modulation products: its frequencies
are sum or difference of many kinds of harmonic waves.
Some Telecommunication Systems share one antenna for transmit and
receive purpose. Since the non-pole RF parts’ non linear features, useful
band frequencies may also contain cross modulation products and those
useless ones also enter the receive systems. This sign cause interference
noises and lower the receiver sensitivity.
In common experiments, the considered interference noises’ fraction
precision degrees are 20.
4. Detailed Explanations about the Testing Results
One instance is the analysis of two RF systems’ inter-interference. We
managed to divide the systems into interference sources and sensitive parts
(the receivers). To set up empirical model, choose one interference source
and one receiver, based on the input and output distortion features, since
ordinarily natural noises can be decided by several specific designed
Gaussian Random Variables and their simple sums and subtractions, we can
set up a formulation for the forecasting. For each type of interference, an
individual equation can be drawn. We specify the fraction precision degrees
of those equations to be linearly approaching the DEGREE 2. Using several
pairs of interference samples, we can decide the empirical factor values in
those equations.
We then can decide the status of each type of interference sources by
inventing a quality identifier M. This parameter shows the ponderance of the
interference type in the overall system. The M value can be placed at the left
side of those equations mentioned. In the final results, the higher the M
value, the worse effects the interferences are causing.
5. Conclusion
For ordinary telecommunication systems, different antennas usually
have different characteristics, in extreme cases, the telecommunication
system’s input and output parts share the same antenna and the working
modes are divided by time and by tasks specifically. In our experiments, we
use Matlab to draw the diagram and charts and try to class the input and
output antenna behaviors into two realms and show them on graph.
Graph 1. Consider Only Type 1 Interference
Graph 2. Consider Only Type 2 Interference
Graph 3. Consider Only Type 3 Interference
In total, if consider the three in total, the overall white noise
environment in the astronautics devices themselves is extremely weak when
the electric wires inside have high voltage transmitted. And the temperature
and humidity measures should use uniform way to curve them down.
6. Biograph
Feng Anderson An (1987-), Assistant Research Scientist in Hongdu
Aviation Group, Nanchang, China.
Hou Zhen Xiu, Professor in Department of Mechatronics, Harbin Institute of
Technology. Harbin, China.