Practical consideration for bandpass sampling

The uniform bandpass sampling theorem has been modified to cope with sampling frequency instability and carrier frequency variations. Minimum sampling rates for given sampling and carrier frequency variations are derived. A robust bandpass sampling method is proposed which requires the sampling frequency to be such that the carrier frequency is on the 1/4 or -1/4 sampling frequency grid     

Signal combination using bandpass sampling

A signal combination technique, based on the spectral replication property of sampling, is presented. The technique uses second-order bandpass sampling to provide some phase control over the component signals. Although the phase control is not independent between the signals and is constrained by inherent amplitude scaling, quasi-independent control can be achieved. The performance of the combination technique is established for three applications. These applications are diversity antenna combination, interception of slow frequency hopping spread spectrum, and a switchable beam, linear antenna array     

A generalization of nonuniform bandpass sampling

Nth-order nonuniform sampling is described for generalized bandpass signal frequency position, bandwidth, sampling rate, frequency-shift and phase-shift. A bandpass extension to the Nyquist criterion is derived, showing that restrictions on bandpass frequency position for odd orders of nonuniform sampling tend to zero as N tends to infinity. Bandpass interpolants based on the sinc function are derived for the generalized Nth-order sampled bandpass signals. It is shown that, for minimum (Nyquist) rate sampling, these interpolants are comprised of N bandpass filters, each with independent phase. The number of bandpass filters comprising the interpolant is found to decrease as the sample rate increases. The advantage of describing Nth-order sampling as the Nth replication and uniform sampling of a signal is demonstrated. Finally, digital implementation of the Nth-order bandpass sampling interpolants is discussed. It is established that it is not practicable to attempt to perform nonuniform bandpass sampling at the theoretical minimum rate, where the interpolation is to be performed digitally     

基于带通采样软件无线电接收子系统的实现

软件无线电在通信中有着重要的作用,采用中频带通采样数字化结构,通过实例给出了软件无线电接收系统的具体软、硬件设计和实现方式。     

Direct bandpass sampling of multiple distinct RF signals

A goal in the software radio design philosophy is to place the analog-to-digital converter as near the antenna as possible. This objective has been demonstrated for the case of a single input signal. Bandpass sampling has been applied to downconvert, or intentionally alias, the information bandwidth of a radio frequency (RF) signal to a desired intermediate frequency. The design of the software radio becomes more interesting when two or more distinct signals are received. The traditional approach for multiple signals would be to bandpass sample a continuous span of spectrum containing all the desired signals. The disadvantage with this approach is that the sampling rate and associated discrete processing rate are based on the span of spectrum as opposed to the information bandwidths of the signals of interest. Proposed here is a technique to determine the absolute minimum sampling frequency for direct digitization of multiple, nonadjacent, frequency bands. The entire process is based on the calculation of a single parameter-the sampling frequency. The result is a simple, yet elegant, front-end design for the reception and bandpass sampling of multiple RF signals. Experimental results using RF transmissions from the US Global Positioning System-Standard Position Service (GPS-SPS) and the Russian Global Navigation Satellite System (GLONASS) are used to illustrate and verify the theory     

Direct downconversion of multiband RF signals using bandpass sampling

Abstract-Bandpass sampling can be used by radio receivers to directly digitize the radio frequency (RF) signals. Although the bandpass sampling theory for single-band RF signals is well established, its counterpart for multiband RF signals is relatively immature. In this paper, we propose a novel and efficient method to find the ranges of valid bandpass sampling frequency for direct downconverting multiband RF signals. Simple formulas for the ranges of valid bandpass sampling frequency in terms of the frequency locations of the multiple RF bands are derived. The result can be used to design a multiband receiver for software defined radios.     

A NEW QUADRATURE SAMPLING APPROACH FOR ARBITRARY BANDPASS SIGNAL WITHIN BASEBAND SAMPLING RATE

A new quadrature sampling technique for arbitrary bandpass signal within baseband sampling rate is presented. The input bandpass signal whose carrier frequency lies in the A/D baseband sampling rate is first decimated by factor 2 and modulated by (- 1)n, and then is interpolated by a linear phase FIR all-pass filter, finally the modulated complex envelope of bandpass signal can be produced.     

First-order sampling of bandpass signals--A new approach (Corresp.)

The first-order sampling of a bandpass signal when the upper cutoff frequency is a multiple of the bandwidth is reduced to an application of the low-pass sampling theorem. In the general case, a simple band-imbedding procedure restores the positioning constraint and yields the expansion.     

Complex bandpass sampling and direct downconversion of multiband analytic signals

The kernel concept of the software defined radio architecture is to eliminate the analogue mixers and to place analogue-to-digital converters as near the antenna as possible. Bandpass sampling can be used for direct downconversion without analogue mixers. In this paper, we report an efficient method to find the ranges of valid bandpass sampling frequency for direct downconverting multiple bandpass analytic signals (single-sideband RF signals). The algorithm results in the ranges of valid bandpass sampling frequency for the complex signals in terms of bandwidths and band positions of the single-sideband RF signals. Compared to real bandpass sampling, the valid sampling frequency ranges are easier to find and the ranges thus obtained having much wider interval than those of real sampling. As a consequence, the complex sampling scheme is more flexible in choosing sampling frequency and more robust to the sampling frequency variation. Furthermore, if spectral inversion is not permitted, then in some cases there will have no applicable sampling frequency under Nyquist rate for real sampling.     

Determination of the minimum sampling frequency in bandpass sampling by geometric approach and geometric programming

This paper presents a simple and fast approach to find a minimum sampling frequency for multi-band signals. Instead of neighbor and boundary conditions, constraints on the sampling frequency were derived by using the geometric approach to the bandpass sampling theorem. Reformulation of the constraints on the minimum sampling frequency enabled to represent the problem as an optimization problem which was structured by the geometric programming and mixed-integer nonlinear programming methods. The convex optimization problem was then solved by the proposed algorithm applying interior point approach in the line search framework. It was demonstrated that this unified structure directly linked the geometric approach of the bandpass sampling theorem to the optimization problem. The proposed method was verified through numerical simulations in terms of the minimum sampling frequency and the computational efficiency. Results illustrated the feasibility of the geometric approach and the proposed algorithm in the determination of the minimum sampling frequency by providing the savings in the number of iterations and the decrease in the valid minimum sampling frequency.     

基于带通采样的椭圆球面波函数数值解法

针对椭圆球面波函数原数值解法存在计算量大、计算时间长的问题,提出了基于带通采样的新数值解法.新数值解法根据带通采样定理确定采样频率,利用原数值解法求得椭圆球面波函数带通采样值,对带通采样值进行上抽样、数字滤波和格拉姆-施密特正交化,求得椭圆球面波函数的近似数值解.理论分析和仿真结果表明,新数值解法能有效降低计算量、计算...     

Nonuniform sampling theorems for bandpass signals at or below theNyquist density

In this paper, the problem of recovery of bandpass signals from a set of nonuniform samples is discussed. Interpolation formulas for particular sets of irregular samples are given. Issues such as the Nyquist rate are studied, and practical methods for sampling and recovery are suggested     

Application of mismatched filter theory to bandpass impulse response measurements

The Letter shows how a mismatched filter for the compression of a bandpass arbitrary length pseudorandom bit sequence (PRBS) may be generated. A comparison is made between the standard matched filter and the mismatched filter in terms of accuracy, dynamic range, noise gain, simplicity of implementation and flexibility to shape the probing pulse, when such filters are used for the determination of wideband bandpass impulse response measurements. This study was carried out in the context of mobile radio channel sounding.<>     

Error analysis in sampling theory

A basic problem in signal theory is the reconstruction of a band-limited function f(t) from its sampled value f(nT). Because of a number of errors, the computed or physically realized signal is only approximately equal to f(t). The most common sampling errors are: round-off of f(nT), truncation of the series generating f(t), aliasing of frequency components above half the sampling rate 1/T, jitter in the recording times nT, loss of a number of sampled values, and imperfect filtering in the recovery of f(t). In the following we study the effect of these errors on the reconstructed signal and its Fourier transform.     

电流模式带通滤波器设计

随着电子技术的发展,电流模式电路也越来越受到人们的关注,尤其是CCII(第二代电流传输器),本文针对以往电路过于复杂的特点,利用CCII(第二代电流传输器)设计基于单个CCII的带通滤波器电路,该电路仅使用一个CCII和几个R,C元件,与同类电路相比,该电路结构简单,且具有更低的无源灵敏度。     

小波空间中采样理论研究

本文研究了小波理论在非带限信号采样中的应用，分析了Walter子波空间采样定理及其突破Nyquist率限制的理论依据；介绍了在信号恢复的过程中可以避免无限冲激响应滤波器出现的周期性非均匀采样及导数采样理论，并以紧支信号为例分别进行了仿真验证。     

A novel algorithm for frequency de-hopping in radars using agile bandpass sampling for electonic support measurement

Telecommunication Systems - Modern radars use frequency hopping as an effective anti-jamming technique by changing their frequencies from pulse-to-pulse and thus making their blind estimation a...     

基于DSP_C54X窄带中频抽样的理论与实现

本文在讨论带通抽样理论的基础上,使用TI公司DSP_C54X和AD／DA转换芯片构成窄带中频抽样系统,对普通AM接收机的中频输出进行了欠抽样处理,完成了中频调制信号的解调、滤波和输出功能。     

A general sampling theory for nonideal acquisition devices

The authors first describe the general class of approximation spaces generated by translation of a function ψ(x), and provide a full characterization of their basis functions. They then present a general sampling theorem for computing the approximation of signals in these subspaces based on a simple consistency principle. The theory puts no restrictions on the system input which can be an arbitrary finite energy signal; bandlimitedness is not required. In contrast to previous approaches, this formulation allows for an independent specification of the sampling (analysis) and approximation (synthesis) spaces. In particular, when both spaces are identical, the theorem provides a simple procedure for obtaining the least squares approximation of a signal. They discuss the properties of this new sampling procedure and present some examples of applications involving bandlimited, and polynomial spline signal representations. They also define a spectral coherence function that measures the “similarity” between the sampling and approximation spaces, and derive a relative performance bound for the comparison with the least squares solution