摘要 :
Synthetic Impulse and Aperture Radar (SIAR) is a kind of Multiple Input Multiple Output (MIMO) radar. It is a four‐dimensional radar that has advantages against stealth targets, multi targets, anti‐radiated missile, reconnaissan...
展开
Synthetic Impulse and Aperture Radar (SIAR) is a kind of Multiple Input Multiple Output (MIMO) radar. It is a four‐dimensional radar that has advantages against stealth targets, multi targets, anti‐radiated missile, reconnaissance and interference, as well as valuable features in high range resolution and high detection probability. SIAR uses special frequency coding separately in each antenna. This code has an essential function in SIAR, such as separating frequency bandwidth, satisfying orthogonality in transmitted signals, suppressing range‐angle and range‐Doppler frequency coupling. Pulse‐to‐pulse frequency code agility is a kind of radar signal coding that is used to suppress the sidelobes in range‐Doppler frequency. In this study, a design method is suggested to transmit waveform based on non‐sequential positive, negative and random carrier frequency coding with the dot product approach in pulse‐to‐pulse frequency code agility, to reduce sidelobes in range‐Doppler frequency coupling. The simulation results showed that this method could effectively remove the strong coupling between range‐Doppler frequency. Removing coupling in the range‐Doppler frequency decreases the sidelobes.
收起
摘要 :
The parameter estimation of the frequency agility (FA) signal using the coding Nyquist folding receiver (CNYFR) is presented. The estimation algorithm adopting linear frequency modulation (LFM) as the local analogue modulation is ...
展开
The parameter estimation of the frequency agility (FA) signal using the coding Nyquist folding receiver (CNYFR) is presented. The estimation algorithm adopting linear frequency modulation (LFM) as the local analogue modulation is derived. The Nyquist zone is estimated by the pseudo Wigner-Ville distribution (PWVD) and the hopping frequencies are calculated by the maximum likelihood (ML) method. Simulations show that CNYFR with analogue modulation of LFM has better performance than the sinusoidal frequency modulation (SFM) one, and the parameter estimation accuracy is acceptable when the SNR is above OdB.
收起
摘要 :
An f.s.k. signal keyed at 75 bauds with 850 Hz frequency shift, can have one of several frequency allocations within any given h.f. voice channel. In the presence of interference from other users, the f.s.k. system performance may...
展开
An f.s.k. signal keyed at 75 bauds with 850 Hz frequency shift, can have one of several frequency allocations within any given h.f. voice channel. In the presence of interference from other users, the f.s.k. system performance may be improved by choosing the f.s.k. tone frequencies before message transmission, to correspond to frequencies within the voice channel where the interference is least. This paper reports on an 800 km point-to-point h.f. link experiment which investigated this principle, combined with forward error-correcting codes, with the aim of improving aeromobile data transmission.
收起
摘要 :
The theoretical limit of the forward link (base to mobile) user capacity of fast frequency hopping code division multiple access (FFH/CDMA) mobile communication systems with error correction coding is investigated. The channel cut...
展开
The theoretical limit of the forward link (base to mobile) user capacity of fast frequency hopping code division multiple access (FFH/CDMA) mobile communication systems with error correction coding is investigated. The channel cutoff rate of coded FFH/CDMA channels is calculated and the optimal code rate that maximises the user capacity is determined. It is shown that with deletion-free transmission, the frequency efficiency of an FFH/CDMA channel coded at the optimal code rate is 47% higher than without coding.
收起
摘要 :
Synthetic impulse and aperture radar (SIAR) is an orthogonal multiple input multiple output radar. It has several advantages, including the ability to detect multiple targets, Antiradiated Missiles (ARM), and stealth targets. Desp...
展开
Synthetic impulse and aperture radar (SIAR) is an orthogonal multiple input multiple output radar. It has several advantages, including the ability to detect multiple targets, Antiradiated Missiles (ARM), and stealth targets. Despite its four-dimensional (4-D) nature, it exhibits a strong coupling between range and angle, which dictates how well SIAR performs in the range-angle domain. Not only does the SIAR use frequency codes to separate the antennas, but also to ensure orthogonality. They can, however, mitigate the strong coupling between range and angle. Pulse-to-pulse frequency code agility is a technique for suppressing the SIAR radar's sidelobes. In this letter, we propose a method for reducing the coupling between range and angle by combining sequential positive, negative and random code with the dot product. The idea of coupling reduction presented in this letter is based on the ratio of each antenna position and frequency codes, which is referred to $\alpha $k, and multiple $\alpha $k in an array provides new advantages for target detection. This technique has the potential to significantly reduce the sidelobe levels.
收起
摘要 :
We propose the use of prime sequences in pulse repetition agile radar to increase the immunity of the radar to reconnaissance and deceptive jamming. The prime sequences are mapped into state agile mapped (SAM) sequences and are us...
展开
We propose the use of prime sequences in pulse repetition agile radar to increase the immunity of the radar to reconnaissance and deceptive jamming. The prime sequences are mapped into state agile mapped (SAM) sequences and are used to determine the pulse repetition interval (PRI) of the radar. We show that this produces a system with low mutual interference between radars and with a low probability of ambiguous range measurement resulting in good resistance to active deceptive jamming
收起
摘要 :
The forward link (base to mobile) user capacity of Reed Solomon (RS) coded FFH/CDMA channels is investigated. A new error-and-erasure correction scheme for the RS coded FFH/CDMA channels is proposed. It is shown that the proposed ...
展开
The forward link (base to mobile) user capacity of Reed Solomon (RS) coded FFH/CDMA channels is investigated. A new error-and-erasure correction scheme for the RS coded FFH/CDMA channels is proposed. It is shown that the proposed error-and-erasure correction scheme for the RS(255, 223) code with the optimal code rate 0.87 can increase the normalised user capacity by 17% over that without coding when the deletion probability is 0.01.
收起
摘要 :
A new construction of Costas sequences, based on the logarithm of the linear congruence function over GF(p), when p is prime, is presented. It is shown that for every prime p, the set of p-1 Costas sequences of length p-1 can be generated.
摘要 :
We have concluded that the spectrum efficiency can be achieved in
wireless PCS systems by applying the intelligent cell concept. The
intelligent cell can either reduce interference by intelligently
delivering the signal to the mob...
展开
We have concluded that the spectrum efficiency can be achieved in
wireless PCS systems by applying the intelligent cell concept. The
intelligent cell can either reduce interference by intelligently
delivering the signal to the mobile unit, or can tolerate a great deal
of interference while receiving with it. The former isolates the signal
with multiple zones. In the latter, the signal resides with the
interference but retains its processing gain. This paper presents the
philosophy of achieving spectrum efficiency by applying the intelligent
cell concept in wireless PCS systems
收起
摘要 :
A power and spectrally efficient slow frequency hopping FQPSK
(SFH-FQPSK) is proposed for future personal communications systems
(PCS). The authors apply the constant envelope FQPSK modem/radio
architecture (filtered QPSK (Feher, ...
展开
A power and spectrally efficient slow frequency hopping FQPSK
(SFH-FQPSK) is proposed for future personal communications systems
(PCS). The authors apply the constant envelope FQPSK modem/radio
architecture (filtered QPSK (Feher, 1982)) to a slow frequency hopping
system to achieve higher spectrum efficiency as well as higher power
efficiency. Being a constant envelope system, SFH-FQPSK can operate with
class C power amplifier without output backoff (OBO). Therefore, it is
4-7 dB more power efficient than T/4-QPSK which is currently adopted as
the US digital cellular and Japanese handyphone PCS standards. As
compared to the European DECT and GSM standard GMSK, the proposed
SFH-FQPSK is about 50% more spectrally efficient. The BER performance of
this system, employing convolutional coding and Viterbi decoding for
FEC, is evaluated in a Rayleigh fading/AWGN environment. Results show
that the BER performance of the authors hard-limited SFH/FQPSK is as
good as that of linear SFH coherent QPSK (SFH-CQPSK), and is 3 and 5 dB
better than ideal coherent QPSK and differentially encoded coherent QPSK
(DEQPSK) systems, respectively. With the higher spectral and power
efficiency and superior BER performance, the authors conclude that the
proposed SFH-FQPSK is an excellent candidate for the future
high-capacity PCS networks
收起
原文获取