APD Measurements of V-8 Ignition Emanations

Amplitude-probability-distribution (APD) data are presented for ignition emanations from V-8 engines of used motor vehicles. Outputs from both single and multiple engines running at 1500 rpm were measured with an omnidirectional antenna over the frequency range from approximately 20 MHz to 1 GHz. In each case, the antenna was oriented similarly with respect to the vehicle(s)-vertical, height 3 m, distance 10 m. Results are presented on Weibull-distribution sheets and compare favorably with those of Hsu et al. [1] using a different technique. On each sheet, APD distributions are given for various received bandwidths between 1 and 300 kHz. For the larger bandwidths, curves are straight lines with large negative slopes. At narrower bandwidths and for multiple vehicles, slopes are less steep. Major conclusions from the APD results include the following. 1) Although overlapping of successive pulses at a detector becomes more prominent at narrower bandwidths, measurements are still valid and representative for a given bandwidth. 2) Measurements indicate good repeatability. 3) Curve shapes are essentially independent of tuned frequency, but do depend upon bandwidth and number of vehicles. 4) Amplitudes are functions of tuned frequency and number of vehicles.     

VHF Radio Noise Measurements Near a Roadway Carrying 10 000 Vehicles per Hour

Measurements of noise power spectral density were recorded with a vertical monopole at 47 MHZ, about 0.5 km from Interstate Highway I-95 (Massachusetts Route 128), in Waltham, Massachusetts, which was carrying traffic approaching 10 000 vehicles per hour. Average noise power values were found to be in excellent agreement with predictions based on vehicle density reported by Spaulding in 1972.     

Automotive Noise from a Motorway: Part I, Measurement

This paper describes 100-MHz measurements of the amplitude-probability (APD) and crossing-rate distributions (CRD) for automotive-traffic radio noise at Toyokawa, Japan. Two different categories of the results of measurements for automotive-traffic radio noise are described: 1) one category is the aggregate of APD/CRD pairs measured for the noise samples of 15-min duration, each of which gives a statistically stationary datum, and 2) the other is the aggregate of APD/CRD pairs measured for the noise samples of 2-s duration, each of which gives a transient datum belonging to the components of a statistically stationary datum. A series of the noise grades for single-motor vehicles passing on a motorway is described in terms of APD/CRD pairs for the noise samples of 2-s duration.     

A multipath fading simulator for mobile radio

A simple device to simulate the Rayleigh distributed fast fading encountered in mobile radio is described and evaluated. The Rayleigh envelope statistics are obtained by adding two independent Gaussian noise sources in quadrature. The theoretical spectrum of the received signal is approximated by shaping the spectrum of the noise sources with filters. A design is given whose performance is shown to agree very closely with theory.     

A Multipath Fading Simulator for Mobile Radio

A simple device to simulate the Rayleigh distributed fast fading encountered in mobile radio is described and evaluated. The Rayleigh envelope statistics are obtained by adding two independent Gaussian noise source in quadrature. The theoretical spectrum of the received signal is approximated by shaping the spectrum of the noise sources with filters. A design is given whose performance is shown to agree very closely with theory.     

Ignition noise of foreign and domestic vehicles in use in the United States

Electromagnetic noise from the ignition systems of more than 11000 individual vehicles in service in the United States in mid- 1977 was measured at 50 and 153 MHz. Very little difference was found between the noise of U.S. domestic and foreign vehicles. Older vehicle groups are noisier than new vehicle groups, a fact which may be accounted for by either of two causes: a) some vehicles in a group become noiser with age, b) newer vehicles may have improved noise suppression systems. Measurements made in a single year will not show which effect predominates. We found the greatest noise differences between vehicle types (cars, trucks, and so on).     

Impact of large Doppler on error performance of FH/MFSK with RS orBCH coding in Rayleigh and Rician fading

The degradation of performance caused by Doppler shift to frequency hopped (FH)/M-ary frequency shift keying (MFSK) Reed-Solomon (RS) coded signal over a Rayleigh and Rician channel is analyzed. The receiver employs a digital processing scheme, consisting of an analog-to-digital (A/D) converter followed by quadrature decomposition and complex-valued envelope discrete Fourier transformation (DFT). Predecoder symbol error probability and post-decoder word error probability are presented as a function of Doppler shift, channel randomness parameter, and the symbol energy-to-noise ratio. The noise is assumed to be white and Gaussian distributed. Results show that for a typical symbol error rate of 10^-3, the margin for 8-ary uncoded transmission must be increased by 8 dB to account for Doppler in a Rician fading channel     

Distribution and Frequency Dependence of Unintentionally Generated Man-Made VHF/UHF Noise in Metropolitan Areas. Part II-Theory

The frequency and range dependence of unintentionally generated man-made VHF/UHF noise in metropolitan areas may be interpreted by assuming that it is composed of random impulses which have been attenuated by propagation over irregular terrain. Man-made noise power per cycle of bandwidth measured for the frequency interval 150 to 500 Mc/s is shown to possess decrements of -10.4 dB/decade change in frequency and -17.9 dB/decade change in range. Theoretical computations of the frequency and range decrements based on a random impulse, irregular terrain model yield frequency and range decrements of -11.1 to -11.3 dB/frequency decade and -17.3 to -18.3 dB/range decade which are in good agreement with the measured results. Comparison of the measured VHF/UHF decrements for unintentionally generated man-made noise in urban and suburban areas with those derived from data which were predominantly of automotive ignition origin supports the conclusion that automotive ignition interference is the major source of man-made noise at these frequencies.     

Automotive Noise from a Motorway: Part II, Analysis

Modeling for automotive traffic radio noise is presented. A model is basic for single running vehicles with ignition-system radio emissions on a roadway. An equivalent source for the impulsive noise, continuously distributed over the distance traversed by a vehicle, with the same source density, is assumed to be acting only for the differential time length which is required for a vehicle to run through the differential distance. Based upon this model, the impulse amplitude distributions at the input to a narrowband receiver are derived mathematically, when a vehicle runs through a definite distance at a constant speed. Applications of the derived formula for the distribution are discussed in detail for the cases: 1) when the traversed distance varies, 2) when the emitting characteristic of impulses of the ignition system varies, and 3) when many vehicles with various emitting characteristics of impulses run on the roadway for a time long enough to provide statistically stationary data for automotive traffic radio noise.     

Digital Optical Receiver Sensitivity Degradation Caused by Crosstalk in Bidirectional Fiber Optic Systems

Receiver sensitivity degradation caused by Rayleigh backscattering and coupler reflections is investigated for bidirectional digital transmission systems. Experimental values for APD receiver sensitivity degradation in a system operating at a bit rate of 10 Mbits/s and at a wavelength of 830 nm were found to be within 2 to 3 dB (optical) of the values predicted by a simple theoretical model.     

A 71-MHz CMOS IF-baseband strip for GSM

An intermediate-frequency (IF) baseband strip for a superheterodyne GSM receiver developed in a 0.25-μm CMOS technology is presented. It contains a 71-MHz IF amplifier, programmable between -20 and +60 dB in 2-dB steps; a quadrature demodulator; and two low-pass output filters for channel selection. Measurements show an overall maximum gain of 89 dB and a noise figure of 3.8 dB. Phase and amplitude mismatches of the demodulator are below 10 and 0.1 dB, respectively. The high linearity required by the blocking and intermodulating signals, which are not completely suppressed by the IF filter, has been achieved using 4.7 mA from the 2,5-V power supply     

A 0.7 to 3 GHz wireless receiver front end in 65-nm CMOS with an LNA linearized by positive feedback

This paper presents a wireless receiver front-end intended for cellular applications implemented in a 65 nm CMOS technology. The circuit features a low noise amplifier (LNA), quadrature passive mixers, and a frequency divider generating 25 % duty cycle quadrature local oscillator (LO) signals. A complementary common-gate LNA is used, and to meet the stringent linearity requirements it employs positive feedback with transistors biased in the sub-threshold region, resulting in cancellation of the third order non-linearity. The mixers are also linearized, using a baseband to LO bootstrap circuit. Measurements of the front-end show about 3.5 dB improvement in out-of-band IIP3 at optimum bias of the positive feedback devices in the LNA, resulting in an out-of-band IIP3 of 10 dBm. With a frequency range from 0.7 to 3 GHz the receiver front-end covers most important cellular bands, with an input return loss above 9 dB and a voltage gain exceeding 16 dB for all bias settings. The circuit consumes 4.38 mA from a 1.5 V supply.     

On the Graphical Method of Drawing APD's for Atmospheric Radio Noise

It has been found that an amplitude probability distribution (APD) of a defined form factor cannot be drawn on a Rayleigh graph by the well-known graphical method using the three statistical moments for a significant part of a large number of samples of atmospheric radio noise in VLF-LF bands. An attempt has been made to approximate an individually measured APD for a sample of atmospheric radio noise using the concept of the form factor. It has been found that the great majority of measured APD's for the noise at a few frequencies can be approximated with reasonable accuracy. Based upon a large number of pairs of APD's, measured and approximated, each pair being obtained for a single noise sample, various parameter relations are obtained for the purpose of comparison with the original parameter relations associated with the graphical method. The results of the comparison show that some agreements as well as some disagreements exist between the two groups of the parameter relations. It is worthy of note that the agreements and disagreements are due to two types of atmospheric radio noise with different characteristics.     

On Impulsive Noise from Shinkansen

Measurements of impulsive noise radiating from individual bullet trains on the New Tokaido Line (called Shinkansen in Japanese) have been performed with the APD-CRD measuring apparatus using dipole antennas of vertical and horizontal types. Both an APD and a CRD have been simultaneously measured in a narrowband and at two frequencies of 50 and 100 MHz for noise samples taken in time succession for individual bullet trains. Based on the analysis of these measured APD's and CRD's, the following remarkable results have been obtained: APD's and CRD's, together with the parameters derived from individual APD's, average, rms, antilog of noise amplitudes, and the statistical parameter V0.1, can be grouped into three different environments of train speed and acceleration or deceleration. on. A model for the impulsive noise is presented, saying that any elementary section of overhead electric wire radiates impulses with amplitudes varying randomly during the time interval when it makes contact with pantographs on the top of vehicles. Good fits are shown between time variations of values of the statistical parameter V0.1 obtained as individual trains pass in front of the measuring site, and those of a certain related electric field calculated based on this model.     

OTDR in a 147 km single-mode fibre in 1.55 ?m wavelength region using an LD and GaInAs/InP APD at room temperature

A Rayleigh backscattered signal over 147.7 km of single-mode optical fibre has been observed for the first time by long-range, optical time-domain reflectometry (OTDR) usinga 1.54 ?m high-power semiconductor laser (LD) and a GaInAs/InP APD with a small dark current at room temperature. A one-way backscattered dynamic range of 29.3 dB at room temperature has been achieved.     

Improved figure of merit for noise in avalanche photodiodes

The authors propose a new noise figure for avalanche photodiodes (APDs). This new noise figure overcomes the difficulty of estimating the internal multiplication and quantum efficiency in complex APD structures, such as III-V SAM APDs. Measurements of the new noise figure are presented for two commercial SAM APDs and the authors show theoretically that it represents a more complete figure of merit for comparing the performance of one APD with another, and with the ideal     

Performance of a TDM/TDMA portable radio link for interference,noise, and delay spread impairments

Presents the measured/simulated performance of a time division multiplexing/time division multiple access (TDM/TDMA) portable radio link for noise, interference and delay spread impairments. The radio link transmits short TDMA bursts of 82 symbols at 450 kbits/sec using 4QAM. This modulation is also referred to 4PSK, but phase shift modulation is constant envelope. Nyquist filtering of quadrature signal components yields quadrature amplitude modulation which, of course, also contains π/2 phase variations at the sampling instants. Demodulation is performed by a low-overhead digital coherent demodulator with 2-branch selection diversity. The port or base has two receivers for diversity but the portable or handset uses only a single receiver to perform selection diversity. Signal-to-noise ratio and signal-to-interference ratio performance of the link was measured for a stationary channel and for a channel with different fading rates. In a Rayleigh fading environment, increasing the fading rate causes only a small performance degradation. The results also show that selection diversity is effective against interference in a slow Rayleigh fading environment. A separate set of experiments were performed to measure the effects of delay-spread on the link. Selection diversity is effective in reducing the word-error ratio floor caused by frequency-selective fading. As a result, relatively high data rates can be supported by a multipath fading channel without using adaptive equalization. Thus, a portable radio communications system using low complexity hardware design incorporating selection diversity can achieve good performance     

Measurement and Analysis of Impulsive Noise from Bullet Trains

Measurements of impulsive noise radiating from bullet trains running either an upward or downward slope on the New Tokaido Line have been performed with the amplitude probability distribution-crossing rate distribution (APD-CRD) measuring apparatus using vertical dipole antennas. APD and CRD pairs have been simultaneously measured in a narrow bandwidth for some VHF. It is noted that APD's and CRD's change remarkably, depending on whether the bullet train runs an upward or downward slope. Generally, this effect is reduced to the following. These two distributions change remarkably, depending on whether the bullet train runs with or without current feeding the main motors of the vehicles. Models of the two categories of noise are presented; they lead to reasonable agreements between the measured and calculated CRD and/or ADP curves.