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Register a new userتصميم و توصيف مركب ترددي ضمن المجال S لاستخدامه في قناة قياس الضجيج الطوري
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تقدمت تقانات التًرددات العالية خلال السنوات الماضية بشكل متسارع، لذلك ظهرت الحاجة الماسة لمكاملة هذه التقانات. و يعدّ المهتز المحلي العنصر الأهم في نظم الإرسال و الاستقبال اللاسلكية حيث يلعب النقاء الطيفي للمهتزات دوراً رئيساً في تحديد أداء هذه النظم و فعاليتها الطيفية، و يؤثر الضجيج الطوري المتولد عن هذه المهتزات بشكل سلبي على ذلك، حيث يظهر هذا الأثر جلياً على معدل خطأ الإرسال و على التداخل بين الأقنية المتجاورة.
Over the last few years, the radio frequency (RF) technology has experienced an exponential growth. With the requirement for more integration, new RF wireless architectures are needed. One of the most critical blocks in a wireless transceiver is the oscillator. Phase noise from radio frequency (RF) oscillators is one of the major limiting factors affecting wireless transceiver performance. Phase noise directly affects short-term frequency stability, Bit-Error-Rate (BER), and phase-locked loop adjacent-channel interference.
References used
T. Hajder, “Higher Order Loops Improve Phase Noise of Feedback Oscillators”, Applied Microwave & Wireless, pp. 24-31, Oct 2002
A.A. Abidi, “Analog Circuit Design, How Phase Noise Appears in Oscillators”, Kluwer Academic Publishers, 1997
D. Banerjee, “PLL Performance, Simulation, and Design”, National Semiconductor, 1998
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The aim of this research is to study a simplified approach for the design of low-noise bipolar
transimpedance preamplifiers for optical receivers. Analytical solutions for optimum biasing and
minimum equivalent input-noise current were derived. The
study was achieved by doing comparison
between the designed circuits. The equivalent input noise current was calculated by entering the
parameters in Matlab program and using Multisim as a simulation tool to detect a pulse signal of 30ns
width.
In this experimental work, the instruments used (detector, calibrating sources) has been calibrating, the calibration line of the detector deduced and it has been finding that the equation of calibration line takes the form:
The resolution power R
has been studying as function of the distance between the activity source and detector; the results obtained show that R decrease by increase the energy of the lines spectrum, this mean that the detector resolution power become bigger.
It has been measured the LC، LD and MDA using two different methods of background radiation value, trapezium method and classical method, for two different distances between radioactivity source and detector: (9,3cm) and (10cm). The results show:
1- There is similar comportment of the LC، LD and MDA in function energy and the distance between radioactivity source and detector.
2- The trapezium method gives better results from the classical method to the radiation background, and this leads to lesser MDA value, this means that the sensibility is bigger to measure this quantity.
3- The relative error using MDA is (5%) for large values, and (10%) for small values
Gamma rays
sodium iodide activated by Thallium
calibration line
resolution detector
source activity
detector efficiency
minimum detectable activity
background radiation level
أشعة غاما
كاشف يوديد الصوديوم المشوب بالتاليوم
مستقيم المعايرة
قدرة الفصل الطيفية
منبع مُشع
كفاءة كاشف
الحد الأدنى لمكشف
ضجيج خلفي
المزيد..
In this research, we simulate the wave propagation in surface duct by using the split step Fourier method to solve the parabolic wave equation. The relation between the path loss and the channel parameters as frequency, duct strength and duct height is studied
The wireless communication devices became very important. They have been fastly
developed fastly in the last few years, so, it was necessary to propose new types Antenna .
A new printed patched Antenna design as, printed, a lenses and wire Antenna,
are
objected to improve the performance, gain and beam width of Antenna.
This work propos a design and simuling of patch fractal Antenna, using Zeland. This
type which depends on fractal geometry (sierpinski carpet) has a very good radiation
pattern and has wide applications.
The proposed Antenna parameters were studied by the help of Zeland simulator, The
variation of the antenna parameters happens when the fractal parameters (as stage of
growth) changes, were analysed.
Finally, the proposed Antenna was praticly applied and measured at the frequency
10Ghz allowed by the microwave and Antenna laboratory.
Usually, a reflector dish with a loudspeaker or a microphone placed at
its focal point is used in directed acoustic systems to determine the
direction in which the acoustic wave is transmitted or received, in
addition to improve the gain in the ac
oustic transmission or reception.
As the parabolic reflector dish with an oval aperture has significant
advantages, and there is no relationship between parameters of this dish
and some variables that have direct influence on acoustical emission or
reception of this dish, this work is intended to find this relationship, and
this is achieved by carrying out a theoretical and experimental study to
find the optimum utilization of this dish in directed acoustic systems.
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