IF Signal Research Articles

A IF Signal Precessing System Design Based on Software Radio Platform

Software radio is a definition of a design thought about how to implement flexible functions by using fixed hardware platform. Any platform based on this is characterized to be universal, standardized, modular, open and highly flexible. Due to some realistic reasons, a software radio platform is hard to be realized. So, most signal processing is operated after mixing. According to software radio requirements, a “FPGA+ADC+DAC” structure is designed. Compared with former processors, this module has broad application prospects with the small size, low power, configurable and programmable feathers. It has multifunction, such as generating IF signals, performing digital down conversion and realizing the synchronous demodulation and the other functions. This module also provides the extended host interface to communicate with upper computers. According to the practical test, take MSK signal for example, if the bit rate is 1Mb/s, bit error rate is lower than 10-6.

Simultaneously frequency down-conversion, independent multichannel phase shifting and zero-IF receiving using a phase modulator in a sagnac loop and balanced detection

Photonic microwave frequency down-conversion with independent multichannel phase shifting and zero-intermediate frequency (IF) receiving is proposed and demonstrated by simulation. By combined use of a phase modulator (PM) in a sagnac loop and an optical bandpass filter (OBPF), orthogonal polarized carrier suppression single sideband (CS-SSB) signals are obtained. By adjusting the polarization controllers (PCs) to introduce the phase difference in the optical domain and using balanced detection to eliminate the direct current components, the phase of the generated IF signal can be arbitrarily tuned. Besides, the radio frequency (RF) vector signal can be also frequency down-converted to baseband directly by choosing two quadrature channels. In the simulation, high gain and continuously tunable phase shifts over the 360 degree range are verified. Furthermore, 2.5 Gbit/s RF vector signals centered at 10 GHz with different modulation formats are successfully demodulated.

90 GHz CMOS Phased-Array Transmitter Integrated on LTCC

This paper presents the design of a 90 GHz phased-array transmitter front end on low-temperature co-fired ceramic (LTCC) technology. The monolithic microwave integrated circuit components have been fabricated by the CMOS technology and flip chipped on the LTCC to realize the transmitter front end. The dc and differential hybrid IF signals are provided to the flip-chipped components through the bias and IF lines designed on the LTCC. An $1 \times 4$ patch antenna array has been designed for the transmitter and fabricated on the LTCC. The dc and IF signal pads on the LTCC were soldered to the designed printed circuit board pads for measurements. The measurement results show that by using a receiver horn antenna, the maximum received power at 92 GHz is −37.3 dBm at a communication distance of 1 m. The transmitter is capable of providing ±25° beam steering with respect to boresight and 20° half-power beamwidth at 90 GHz. The total power consumption of the transmitter front end is 656 mW.

A new method to measure the U-235 content in fresh LWR fuel assemblies via fast-neutron passive self-interrogation

The purpose of this paper is to provide a solution to a decades old safeguards problem in the verification of the fissile concentration in fresh light water reactor (LWR) fuel assemblies. The problem is that the burnable poison (e.g. Gd2O3) addition to the fuel rods decreases the active neutron assay for the fuel assemblies. This paper presents a new innovative method for the verification of the235U linear mass density in fresh LEU fuel assemblies that is insensitive to the burnable poison content. The technique makes use of the238U atoms in the fuel rods to self-interrogate the235U mass. The innovation for the new approach is that the238U spontaneous fission (SF) neutrons from the rods induces fission reactions (IF) in the235U that are time correlated with the SF source neutrons. Thus, the coincidence gate counting rate benefits from both the nu-bar of the238U SF (2.07) and the235U IF (2.44) for a fraction of the IF reactions. Whereas, the238U SF background has no time-correlation boost. The higher the detection efficiency, the higher the correlated boost because background neutron counts from the SF are being converted to signal doubles. This time-correlation in the IF signal increases signal/background ratio that provides a good precision for the net signal from the235U mass. The hard neutron energy spectrum makes the technique insensitive to the burnable poison loading where a Cd or Gd liner on the detector walls is used to prevent thermal-neutron reflection back into the fuel assembly from the detector. We have named the system the fast-neutron passive collar (FNPC).

A Wideband and High-Linearity <italic>E</italic>-B and Transmitter Integrated in a 55-nm SiGe Technology for Backhaul Point-to-Point 10-Gb/s Links

This paper presents the design of a wideband and high-linearity $E$ -band transmitter integrated in a 55-nm SiGe BiCMOS technology. It consists of a double-balanced bipolar ring mixer which upconverts a 16–21-GHz IF signal to the 71–76- and 81–86-GHz bands by the use of a 55/65-GHz local oscillator signal, followed by a broadband power amplifier which employs 2-way output power combining using an integrated low-loss balun transformer. The transmitter exhibits an average conversion gain of 24 dB and 22 dB at the 71–76- and 81–86-GHz bands, respectively, with an output 1-dB compression point greater than 14 and 11.5 dBm at each band. A maximum output power of 16.8 dBm is measured at 71 GHz. The dc power consumption is 575 mW. The presented transmitter is used to demonstrate the transmission of a 10.12-Gb/s 64 quadrature amplitude modulated signal with a spectral efficiency of 5.06 bit/s/Hz, which makes it suitable for use in future high-capacity backhaul and fronthaul point-to-point links.

An XPolM-Based All-Optical SSB Frequency Up-Conversion Technique in an SOA

A radio-over-fiber (RoF) downlink using a cross-polarization modulation (XPolM)-based all-optical single sideband (SSB) frequency up-conversion method in a semiconductor optical amplifier is experimentally demonstrated. A 10-Gb/s 16QAM orthogonal frequency division multiplexing signal at a carrier frequency of 60 GHz is transmitted. This RoF downlink shows a negligible power penalty associated with the chromatic dispersion of a single-mode fiber for a fiber length up to 20 km. The RoF downlink shows almost flat bit-error-rate performance for an optical IF signal wavelength range from 1550 to 1570 nm.

Broadband Microwave Photonic Sub Harmonic Downconverter with Phase Shifting Ability

A microwave photonic signal processor that is capable of simultaneously realizing sub-harmonic frequency down conversion and IF signal phase shifting operation is presented. The IF signal generated by the frequency down conversion process is obtained by the beating of the second-order local oscillator (LO) sideband with the fundamental RF signal sideband at the photodetector. The phase of the IF signal can be tuned continuously from 0° to 360° by controlling the optical phase of the RF signal sideband. The optical carrier is eliminated at the signal processor output to achieve high conversion efficiency mixing operation. The signal processor can be designed to have a very wide bandwidth as it only involves optical components. Experimental results are presented that demonstrate frequency down conversion with > 8.8 dB conversion efficiency over 6 to 40 GHz RF signal bandwidth and 0.05 to 10 GHz IF signal bandwidth, and a continuous 0° to 360° phase shift on the output IF signal.

Photonic Frequency Down-Converter based on a Frequency-Doubling OEO using Two Cascaded EAMs

A photonic frequency down-converter based on a frequency-doubling optoelectronic oscillator (OEO) using two cascaded electro-absorption modulators (EAMs) is proposed and experimentally demonstrated. The use of the two cascaded EAMs allows the OEO feedback loop used to generate the local oscillator (LO) signal and the down-conversion section to be structurally isolated, so that the proposed photonic frequency down-converter has high RF to LO isolation. The phase noise of the frequency-doubled 20-GHz LO signal and that of the down-converted 3-GHz IF signal were measured to be −97.80 and −95.32 dBc/Hz at an offset frequency of 10 kHz, respectively. The spurious free dynamic range measured using a two-tone test was 87.02 dB $\cdot $ Hz2/3. The bit error rate performance was also investigated with a 20-GHz RF signal modulated by 1.25 Gb/s data.

A new FFT acquisition scheme based on partial matched filter in GNSS receivers for harsh environments

FFT acquisition scheme based on partial matched filter is an important search method in GNSS receivers, which can scan the code phase and Doppler frequency by parallel search scheme. However, the detection probability reduces due to the coherent combing loss and scalloping loss. To solve this problem, we propose a new FFT acquisition method based on Partial Matched Filter (PMF-FFT) in GNSS receiver, in which, the IF signal is divided and central frequency is shifted before the matched filters, and the FFT results are combined to search the Doppler frequency. The performance of the scheme is analyzed by amplitude response of the system. Both analysis and simulation results show that the new scheme has a larger acquisition range without adding the FFT points, which is quite appropriate for dynamic and weak signal environments. We also do a comparison based on the collected data test, showing that the PMF-FFT scheme outperforms the other three methods generally used in the GNSS receivers. Moreover, we apply an FPGA&DSP hardware receiver to verify the practicability and superiority of our method, which turns out our method can extremely reduce the acquisition time in a cold start condition, compared to the serial scheme.

Multiple receivers in a high-resolution near-infrared heterodyne spectrometer.

The paper describes a modification of a high-resolution heterodyne NIR spectrometer described by Rodin, et al. in Opt. Express22, 13825 (2014), wherein the noise amplitude of the heterodyne signal squared was proportional to the power of the incoherent radiation source (the sun). The addition of a second receiver collecting radiation from the sun into a second single-mode fiber created up to a factor of two increase in detected source power spectrum. The ability to add uncorrelated heterodyne IF signals as Gaussian noise (variance) provides the means by which multiple heterodyne receivers of signal from an incoherent source can increase the detected source power by the same multiple, thus avoiding the limit imposed by the antenna theorem for a single receiver (A. E. Siegman, Appl. Opt.5, 1588 (1966)).

Multi-channel poloidal correlation reflectometry on experimental advanced superconducting tokamak.

A new multi-channel poloidal correlation reflectometry is developed at Experimental Advanced Superconducting Tokamak. Eight dielectric resonator oscillators with frequencies of 12.5 GHz, 13.5 GHz, 14.5 GHz, 15 GHz, 15.5 GHz, 16 GHz, 17 GHz, and 18 GHz are used as sources. Signals from the sources are up-converted to V band using active quadruplers and then coupled together. The output waves are launched by one single antenna after passing through a 20 dB directional coupler which can provide the reference signal. Two poloidally separated antennae are installed to receive the reflected waves from plasma. The reference and reflected signals are down-converted by mixing with a quadrupled signal from a phase-locked source with a frequency of 14.2 GHz and the IF signals pass through the filter bank. The resulting signals from the mixers are detected by I/Q demodulators. The setup enables the measurement of density fluctuation at 8 (radial) × 2 (poloidal) spatial points. A coherent mode with an increasing velocity from 50 kHz to 100 kHz is observed by using the system. The mode is located in the steep gradient region of the pedestal.

Design of a Broadband HEMT Mixer for UWB Applications

Background/Objectives: Microwave mixer is a crucial element in virtually all transmits and receives systems. Methods/Statistical analysis: In this paper, a novel distributed HEMT mixer with three layers is designed for Ultrawide-Band (UWB) receivers. We employ external capacitors in the proposed circuit to adjust the output phase shift between stages to equal the input phase shift. Findings: The simulation results show that the proposed structure, achieves vary broadband performances in Converstion Gain, Power Consumption and LO-RF Isolation, comparable to the recent reported cascode or dual-gate distributed mixers. With a local oscillator power of 12 dBm and RF power of -20 dBm, our mixer has a Conversion Gain of 0 ~ 4 dB (without IF signal amplification), LO-to-RF isolation better than 32 dB and 130 mW DC power consumption over bandwith 5-25 GHz. Applications/Improvements: In our scheme, an intermediate layer is considered to increase LO-RF Isolation and improve the Converstion Gain criterion. Moreover, Microstrip lines are used to form the artificial gate and drain transmission lines as well as phase equalization of the signal on drain transmission line.

A 260 MHz IF Sampling Bit-Stream Processing Digital Beamformer With an Integrated Array of Continuous-Time Band-Pass Modulators

We propose an ADC-digital codesign approach to IF sampling digital beamforming (DBF) that combines continuous-time bandpass ${\Delta \Sigma }$ modulators (CTBPDSMs) and bit-stream processing (BSP). This approach enables power- and area-efficient DBF by removing the need for digital multipliers and multiple decimators. The prototype beamformer digitizes eight 260 MHz IF signals at 1040 MS/s with eight CTBPDSMs, and performs digital down conversion and phase shifting with only multiplexers directly on the undecimated CTBPDSM outputs. With two sets of phase shifters, the prototype simultaneously forms two independent beams. Each phase shifter is controlled by a 12 bit programmable complex weight to provide a total of 240 phase-shift steps. By constructively combining inputs from eight elements, an 8.9 dB SNDR improvement is achieved, resulting in an array SNDR of 63.3 dB over a 10 MHz bandwidth. Fabricated in 65 nm CMOS, the eight-element two-beam prototype beamformer is the first IC implementation of IF sampling DBF. It occupies $\text{0.28}\;\text{mm}^{ 2}$ , and consumes 123.7 mW.

A 60 GHz CMOS up‐conversion double‐balanced mixer with wide if bandwidth

ABSTRACTA 60 GHz fully integrated double‐balanced up‐conversion mixer with wide IF bandwidth performance has been designed and fabricated using 90‐nm CMOS technology. In order to feed the single‐ended IF signal and to reduce the total power consumption, the active balun with an RC‐feedback architecture was designed in the Gilbert‐cell mixer. From dc to 10 GHz, a phase difference of 5° and a magnitude difference of 1 dB were obtained simultaneously in the proposed RC‐feedback active balun. Series inductive‐peaking techniques were also adopted to improve the IF bandwidth from DC to 3.8 GHz. The chip area of the mixer is 0.75 mm2. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:546–549, 2016

Microwave Photonic Mixer Based on Polarization Rotation and Polarization-Dependent Modulation

A microwave photonic mixer capable of both amplitude and phase modulation is proposed and experimentally demonstrated. This scheme utilizes single-sideband modulation in dual-drive Mach–Zehnder modulator and polarization rotation in semiconductor optical amplifier to generate a pair of phase coherent optical carriers with different polarizations, while a polarization sensitive Mach–Zehnder intensity modulator (MZM) is used for modulating the IF signal onto one of the generated carrier. Both the optical and the electrical spectra are measured and show successful frequency mixing. By setting the bias point of the MZM at slightly different voltages, our scheme supports binary-phase-shift keying, on–off keying, and amplitude-shift keying modulations. Widely opened eye diagrams and clear waveforms are experimentally obtained for all modulations. Moreover, the proposed scheme does not have a hard limit on the supported lowest local oscillator frequency and no reconfiguration is needed when a frequency change in the local oscillator is required.

Bioimaging: An Useful Tool to Monitor Differentiation of Human Embryonic Stem Cells into Chondrocytes.

To improve the recovery of damaged cartilage tissue, pluripotent stem cell-based therapies are being intensively explored. A number of techniques exist that enable monitoring of stem cell differentiation, including immunofluorescence staining. This simple and fast method enables changes to be observed during the differentiation process. Here, two protocols for the differentiation of human embryonic stem cells into chondrocytes were used (monolayer cell culture and embryoid body formation). Cells were labeled for markers expressed during the differentiation process at different time points (pluripotent: NANOG, SOX2, OCT3/4, E-cadherin; prochondrogenic: SOX6, SOX9, Collagen type II; extracellular matrix components: chondroitin sulfate, heparan sulfate; beta-catenin, CXCR4, and Brachyury). Comparison of the signal intensity of differentiated cells to control cell populations (articular cartilage chondrocytes and human embryonic stem cells) showed decreased signal intensities of pluripotent markers, E-cadherin and beta-catenin. Increased signal intensities of prochondrogenic markers and extracellular matrix components were observed. The changes during chondrogenic differentiation monitored by evaluation of pluripotent and chondrogenic markers signal intensity were described. The changes were similar to several studies over chondrogenesis. These results were confirmed by semi-quantitative analysis of IF signals. In this research we indicate a bioimaging as a useful tool to monitor and semi-quantify the IF pictures during the differentiation of hES into chondrocyte-like.Electronic supplementary materialThe online version of this article (doi:10.1007/s10439-015-1443-z) contains supplementary material, which is available to authorized users.

IQ quadrature demodulation algorithm used in heterodyne detection

In order to obtain better detection results of heterodyne, we used phase IQ quadrature demodulation algorithm to process the data which detected by laser heterodyne. Based on laser heterodyne interferometer, processing the data in the interferometer phase IQ quadrature demodulation algorithm from the signal to noise ratio, sampling rate, sampling rate, filter order and cutoff frequency, verify the effects of these system parameters to the phase precision, and choose the best parameters to obtain a better phase precision through experiment as: the signal to noise ratio is 25dB, the IF signal frequency is 98.3MHz, 98.5MHz, 99.1MHz, 99.5MHz and 100MHz, the sampling rate is 512–2048, the cutoff frequency and order of the filter are 0.11 and 40, respectively.

A 24 GHz Highly Linear Up-Conversion Mixer in CMOS 0.13 <formula formulatype="inline"><tex Notation="TeX">$\mu{\rm m}$</tex></formula> Technology

This letter reports a 24 GHz linear up-conversion mixer for high-power IF signal. In the proposed mixer, the double-balanced Gilbert-cell topology is employed with a low-distortion transconductance stage which combines voltage feedback and adaptive biasing schemes. The proposed adaptive biasing circuit improves the linearity of the transconductance stage by providing an additional bias current when IF input signals exceed the current-limited linear input range. Implemented in a 0.13 $\mu{\rm m}$ CMOS technology, the mixer showed a conversion gain of $-$ 1.9 dB and output 1 dB compression point of 0.3 dBm for the IF, LO, and RF frequency ranges of 10.0–314.7 MHz, 18.9–29.0 GHz, and 23.4–29.2 GHz, respectively, while dissipating 22.8 and 16.5 mW for the mixer and the LO buffer, respectively, from a 1.5 V supply.

펄스 모드 발진기와 지연선로를 이용한 버블형 동작감지기

본 논문에서는 펄스 모드 발진기와 지연선로를 이용하여 새로운 감지 형태를 갖는 버블형 동작감지기를 제안하고, 설계 및 제작하였다. 제안된 동작감지기는 송신 신호의 펄스폭으로 버블 형태의 감지 영역을 형성하며, 지연선로에 의해 시간 지연되는 거리에 해당하는 물체에서 반사된 신호만을 감지하여 IF 신호를 만들어낸다. 제작된 동작감지기는 중심주파수 8 GHz, 펄스 폭 2 nsec, 펄스 주기 30 nsec를 갖는 펄스 모드 발진기를 신호원으로 사용하였으며, 7 nsec와 12 nsec의 지연 시간을 갖는 선로 2개를 사용하여 1 m, 3 m, 5 m의 위치에 버블막 형태의 감지 영역을 성공적으로 형성하여 물체를 감지하였다. This paper presents a new motion detector that has a bubble-layer detection zone using a pulsed-mode oscillator and delay line. The proposed motion detector controls the bubble-layer detection zone with pulse width of transmitted signals and creates IF signals only by reflected signals from the target within the detection zone whose position is determined by time delay of the delay line. The fabricated motion detector uses the pulsed-mode voltage controlled oscillator as a signal source which has a center frequency of 8 GHz, pulse width of 2 nsec and pulse period of 30 nsec. It successfully makes the bubble-layer detection zones at 1 m, 3 m and 5 m distant from itself using two delay lines with 7 nsec and 12 nsec delay, and is also demonstrated to detect the target within the detection zones.

Modis data acquisition and utilization for forest fire management in india

Abstract. The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard Terra & Aqua Spacecrafts Scans the earth in 36 spectral bands & covers the entire earth in two days. MODIS data has proved to be very useful for ocean & land studies with resolution ranging from 250 m to 1000 meters. The Data Reception system at Shadnagar (Refer to the Block diagram Fig.1), receives the data transmitted in X-band on 8160 MHz carrier SQPSK modulated with a data rate of 15 MBPS from the Aqua satellite. The down converted IF signal is fed to the demodulator & bit-synchronizer unit. The data and clock output signals of bitsynchronizer unit are given to a PC based DAQLB system where real-time telemetry processing is carried out and data is recorded onto hard disk in real time. The effectiveness of the system in supporting the forest fire management during the 2011, 12, 13 & 14 is also presented in the paper. Near real-time active fire monitoring, interactive fire visualization, fire database and statistical analysis functions also presented. Preliminary results of the upgrading satellite receiving system and in expanding the utilization of satellite data for multi-disciplinary resources management will also be presented and discussed.