Ire Transactions on Space Electronics and Telemetry 

About: Ire Transactions on Space Electronics and Telemetry is an academic journal. The journal publishes majorly in the area(s): Frequency modulation & Antenna (radio). Over the lifetime, 96 publications have been published receiving 791 citations.

A Telemetering System by Code Modulation - Δ- ΣModulation

Abstract: A communication system by code modulation is described which incorporates an integration process in the original delta modulation system and is named delta-sigma modulation after its modulation mechanism. It has an advantage over delta modulation in dc level transmission and stability of performance, although both require essentially an equal bandwidth and complexity of circuitry. An experimental telemetering system employing delta-sigma modulation is also described.

On Coded Phase-Coherent Communications

Abstract: The merits of phase-coherent communications are widely recognized for both discrete and continuous modulation systems [1]-[3]. The relative performances of phase-coherent and noncoherent transmission of binary data in the presence of additive white Gaussian noise have been analyzed and compared [1] and [2]. This paper considers the result of encoding independent equiprobable binary words or sequences of independent binary digits into sets of binary code words. These are transmitted over a channel perturbed by additive white Gaussian noise and detected by correlating them with their stored or locally generated replicas at the receiver. The word error probabilities and bit error probabilities for low cross-correlation codes are determined as a function of the ratio (received signal energy)/bit/(noise power)/(unit bandwidth) The received information rate and the potential channel capacity are also computed. It is shown that in the limit as the code word length and the bandwidth approach infinity, the received information rate approaches the channel capacity for only one value of the above ratio.

Phase-Lock Loop Frequency Acquisition Study

Abstract: The ability of a phase-lock loop using a proportional plus integral control filter to acquire a noisy signal when the local oscillator is being swept was determined empirically by means of a low-frequency, GEESE1 model of such a system. The effects of the damping factor and natural frequency on the frequency acquisition properties of linear loops (as distinguished from a loop in which the IF signal is limited) are considered in this study. In addition, consideration is given to a loop in which the IF signal is ``hard'' limited and the loop designed to maximize the sweep rate under the constraint that the probability of acquisition is equal to or greater than 90 per cent for a given SNR. The rms phase jitter in the output signal was measured as a method of verifying the standard analytic approach to predicting phase jitter. The results of the study are as follows: 1) The range of damping factors from 0.5 to 0.85 yields near optimum acquisition performance. 2) Although a drop in loop gain produces lower phase jitter for a given (S/N) IF , it degrades the over-all ability of the loop to acquire and track a signal. 3) A ``hard'' limiter in the IF can be effectively used as a gain control to enhance loop performance. 4) Using an empirical formula derived from experimental results, the VCO sweep rate for 90 per cent probability of acquisition can be predicted accurately, given the (SNR) IF and loop parameters.

Frequency Domain Applications to Data Processing

Abstract: Filtering a set of (2N + 1) sampled data consists in taking a weighted average of these data. The operation can be compared to that of a linear transducer, characterized by its frequency response. The only filters discussed in this paper are those for which the weights are either symmetric or skew symmetric about the center weight. With these types of filters, it is possible to design low low-pass filters to determine means and trends, low-pass filters to smooth data, sampling filters for frequency analysis, differentiators, integrators, etc. It is shown that least square polynomial fitting and Fourier analysis of sampled data are particular cases of filtering. Power of filtering techniques and precautions to take in their use for data processing are discussed

Pulse-Frequency Modulation

Abstract: Pulse-frequency modulation (PFM) has been successfully employed as the encoding technique in a number of small U. S. Earth satellites where reduction of power and weight are prime considerations. This paper is concerned with the introduction of some of the more basic principles of PFM. Rather than presenting a rigorous proof on the orthogonality of this type of modulation, a comparison is made to the better-known characteristics of coded binary sequences. It is shown that PFM with quantized frequencies has the same communication efficiency in the presence of additive white Gaussian noise as a corresponding set of coded binary sequences with an equal number of quantized levels