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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Theoretical Accuracy for ESTL Bit Error Rate Tests

"Bit error rate" [BER] for the purposes of this paper is the fraction of binary bits which are inverted by passage through a communication system. BER can be measured for a block of sample bits by comparing a received block with the transmitted block and counting the erroneous bits. Bit Error Rate [BER] tests are the most common type of test used by the ESTL for evaluating system-level performance. The resolution of the test is obvious: the measurement cannot be resolved more finely than 1/N, the number of bits tested. The tolerance is not. This paper examines the measurement accuracy of the bit error rate test. It is intended that this information will be useful in analyzing data taken in the ESTL. This paper is divided into four sections and follows a logically ordered presentation, with results developed before they are evaluated. However, first-time readers will derive the greatest benefit from this paper by skipping the lengthy section devoted to analysis, and treating it as reference material. The analysis performed in this paper is based on a Probability Density Function [PDF] which is developed with greater detail in a past paper, Theoretical Accuracy for ESTL Probability of Acquisition Tests, EV4-98-609.

Lansdowne, Chatwin↗
NASA NTRS1978

Bit error rate measurement above and below bit rate tracking threshold

Bit error rate is measured by sending a pseudo-random noise (PRN) code test signal simulating digital data through digital equipment to be tested. An incoming signal representing the response of the equipment being tested, together with any added noise, is received and tracked by being compared with a locally generated PRN code. Once the locally generated PRN code matches the incoming signal a tracking lock is obtained. The incoming signal is then integrated and compared bit-by-bit against the locally generated PRN code and differences between bits being compared are counted as bit errors.

Kobayaski, H. S.↗
NASA NTRS1987

Effect of atmospheric turbulence on the bit error probability of a space to ground near infrared laser communications link using binary pulse position modulation and an avalanche photodiode detector

The effect of atmospheric turbulence on the bit error rate of a space-to-ground near infrared laser communications link is investigated, for a link using binary pulse position modulation and an avalanche photodiode detector. Formulas are presented for the mean and variance of the bit error rate as a function of signal strength. Because these formulas require numerical integration, they are of limited practical use. Approximate formulas are derived which are easy to compute and sufficiently accurate for system feasibility studies, as shown by numerical comparison with the exact formulas. A very simple formula is derived for the bit error rate as a function of signal strength, which requires only the evaluation of an error function. It is shown by numerical calculations that, for realistic values of the system parameters, the increase in the bit error rate due to turbulence does not exceed about thirty percent for signal strengths of four hundred photons per bit or less. The increase in signal strength required to maintain an error rate of one in 10 million is about one or two tenths of a db.

Safren, H. G.↗
NASA NTRS1989

Using Bit Errors To Diagnose Fiber-Optic Links

Technique for diagnosis of fiber-optic digital communication link in local-area network of computers based on measurement of bit-error rates. Variable optical attenuator inserted in optical fiber to vary power of received signal. Bit-error rate depends on ratio of peak signal power to root-mean-square noise in receiver. For optimum measurements, one selects bit-error rate between 10 to negative 8th power and 10 to negative 4th power. Greater rates result in low accuracy in determination of signal-to-noise ratios, while lesser rates require impractically long measurement times.

Bergman, L. A.↗
DOE OSTI2020

Layer-Dependent Bit Error Variation in 3-D NAND Flash Under Ionizing Radiation

In this paper, we studied the total ionization dose (TID) effects on the multilevel-cell (MLC) 3-D NAND flash memory using Co-60 gamma radiation. We found a significant page-to-page bit error variation within a physical memory block of the irradiated memory chip. Our analysis showed that the origin of the bit error variation is the unique vertical layer-dependent TID response of the 3-D NAND. We found that the memory pages located at the upper and lower layers of the 3-D stack show higher fails compared to the middle-layer pages of a given memory block. We confirmed our findings by comparing radiation response of four different chips of the same specification. In addition, we compared the TID response of the MLC 3-D NAND with that of the 2-D NAND chip, which showed less page-to-page variation in bit error within a given memory block. We discuss the possible application of our findings for the radiation-tolerant smart memory controller design.

3-D NAND flash↗
DOE OSTI2021

Bit error protection in cache memories

A computing device having a cache memory that is configured in a write-back mode is described. A cache controller in the cache memory acquires, from a record of bit errors that are present in each of a plurality of portions of the cache memory, a number of bit errors in a portion of the cache memory. The cache controller detects a coherency state of data stored in the portion of the cache memory. Based on the coherency state and the number of bit errors, the cache controller selects an error protection from among a plurality of error protections. The cache controller uses the selected error protection to protect the data stored in the portion of the cache memory from errors.

Kalamatianos, John↗
NASA NTRS1996

Bit Error Probability for Maximum Likelihood Decoding of Linear Block Codes

In this paper, the bit error probability P(sub b) for maximum likelihood decoding of binary linear codes is investigated. The contribution of each information bit to P(sub b) is considered. For randomly generated codes, it is shown that the conventional approximation at high SNR P(sub b) is approximately equal to (d(sub H)/N)P(sub s), where P(sub s) represents the block error probability, holds for systematic encoding only. Also systematic encoding provides the minimum P(sub b) when the inverse mapping corresponding to the generator matrix of the code is used to retrieve the information sequence. The bit error performances corresponding to other generator matrix forms are also evaluated. Although derived for codes with a generator matrix randomly generated, these results are shown to provide good approximations for codes used in practice. Finally, for decoding methods which require a generator matrix with a particular structure such as trellis decoding or algebraic-based soft decision decoding, equivalent schemes that reduce the bit error probability are discussed.

Lin, Shu↗
NASA NTRS1991

Multiple-Bit Errors Caused By Single Ions

Report describes experimental and computer-simulation study of multiple-bit errors caused by impingement of single energetic ions on 256-Kb dynamic random-access memory (DRAM) integrated circuit. Studies illustrate effects of different mechanisms for transport of charge from ion tracks to various elements of integrated circuits. Shows multiple-bit errors occur in two different types of clusters about ion tracks causing them.

Zoutendyk, John A.↗
NASA NTRS1988

Bounds of the bit error probability of a linear cyclic code over GF(2 exp l) and its extended code

An upper bound on the bit-error probability (BEP) of a linear cyclic code over GF(2 exp l) with hard-decision (HD) maximum-likelihood (ML) decoding on memoryless symmetric channels is derived. Performance results are presented for Reed-Solomon codes on GF(32), GF(64), and GF(128). Also, a union upper bound on the BEP of a linear cyclic code with either HD or soft-decision (SD) ML decoding is developed, as well as the corresponding bounds for the extended code of a linear cyclic code. Using these bounds, which are tight at low bit error rate, the performance advantage of SD and HD ML over bounded-distance decoding is established.

Cheng, Unjeng↗
NASA NTRS1985

Bit Error Rate of Coherent M-ary PSK

The bit error rate (BER) for the coherent detection of M-ary PSK signals with Gray code bit mapping is considered. A closed-form expression for the exact BER of M-ary PSK is presented. Tight upper and lower bounds on BER are also obtained for M-ary PSK with larger M.

Lee, P. J.↗
NASA NTRS1984

A Very Efficient Transfer Function Bounding Technique on Bit Error Rate for Viterbi Decoded, Rate 1/N Convolutional Codes

For rate 1/N convolutional codes, a recursive algorithm for finding the transfer function bound on bit error rate (BER) at the output of a Viterbi decoder is described. This technique is very fast and requires very little storage since all the unnecessary operations are eliminated. Using this technique, we find and plot bounds on the BER performance of known codes of rate 1/2 with K 18, rate 1/3 with K 14. When more than one reported code with the same parameter is known, we select the code that minimizes the required signal to noise ratio for a desired bit error rate of 0.000001. This criterion of determining goodness of a code had previously been found to be more useful than the maximum free distance criterion and was used in the code search procedures of very short constraint length codes. This very efficient technique can also be used for searches of longer constraint length codes.

Lee, P. J.↗
DOE OSTI2021

Analytical Bit-Error Model of NAND Flash Memories for Dosimetry Application

In this work, we provide an analytical model for the total ionizing dose (TID) effects on the bit error statistics of commercial flash memory chips. We have validated the model with experimental data collected by irradiating several commercial NAND flash memory chips from different technology nodes. We find that our analytical model can project bit errors at higher TID values (~ 20 krad(Si)) from measured data at lower TID values (<1 krad(Si)). Based on our model and the measured data, we have formulated basic design rules for using a commercial flash memory chip as a dosimeter. We discuss the impact of NAND chip-to-chip variability, noise margin and the intrinsic errors on the dosimeter design using detailed experimentation.

3-D NAND↗
NASA NTRS2019

Bit Error Rate Performance of a Free Space Optical Link Using Double Clad Fibers

Mobile and embedded applications are emerging in the growing field of free space optical links (FSOL). Some mobile applications for FSOL include spacecraft, aircraft, and automotive. These applications by nature require low size weight and power (SWaP) solutions. The main challenge with any FSOL system is the strict pointing requirements. Common solutions to pointing and alignment of FSOL include gimbals, fast steering mirrors, and adaptive optics. All of which provide viable solutions at the cost of increased SWaP. Previously, we presented the use of both large core fibers and double clad fibers (DCF) to interface FSOL transmit and receive optics with small form factor pluggable optical transceivers (SFP). Double clad fibers have been shown to enable a common optical path by transmitting through a single mode core and receiving through a large inner cladding. This enables a single set of symmetric transmit and receive optics, which decreases the SWaP. In addition, using DCF increases the received power stability of the link relative to a multi-mode fiber (MMF) transmitting. To determine the viability of the system, bit error rate performance needs to be investigated. The results of this paper show that at a bit rate of 10 Gbps, double clad fibers offer similar bit error rate performance to single mode fibers when transmitting and multi-mode fibers when receiving enabling a symmetric duplex FSOL reducing SWaP.

Double Clad Fiber↗
NASA NTRS2019

Bit Error Rate Performance of a Free Space Optical Link Using Double Clad Fibers

Mobile and embedded applications are emerging in the growing field of free space optical links (FSOL). Some mobile applications for FSOL include spacecraft, aircraft, and automotive. These applications by nature require low size weight and power (SWaP) solutions. The main challenge with any FSOL system is the strict pointing requirements. Common solutions to pointing and alignment of FSOL include gimbals, fast steering mirrors, and adaptive optics. All of which provide viable solutions at the cost of increased SWaP. Previously, we presented the use of both large core fibers and double clad fibers (DCF) to interface FSOL transmit and receive optics with small form factor pluggable optical transceivers (SFP). Double clad fibers have been shown to enable a common optical path by transmitting through a single mode core and receiving through a large inner cladding. This enables a single set of symmetric transmit and receive optics, which decreases the SWaP. In addition, using DCF increases the received power stability of the link relative to a multi-mode fiber (MMF) transmitting. To determine the viability of the system, bit error rate performance needs to be investigated. The results of this paper show that at a bit rate of 10 Gbps, double clad fibers offer similar bit error rate performance to single mode fibers when transmitting and multi-mode fibers when receiving enabling a symmetric duplex FSOL reducing SWaP.

Small Form-Factor Pluggable Optical Transceiver↗
NASA NTRS1986

Bit-error-rate testing of high-power 30-GHz traveling wave tubes for ground-terminal applications

Tests were conducted at NASA Lewis to measure the bit-error-rate performance of two 30 GHz, 200 W, coupled-cavity traveling wave tubes (TWTs). The transmission effects of each TWT were investigated on a band-limited, 220 Mb/sec SMSK signal. The tests relied on the use of a recently developed digital simulation and evaluation system constructed at Lewis as part of the 30/20 GHz technology development program. The approach taken to test the 30 GHz tubes is described and the resultant test data are discussed. A description of the bit-error-rate measurement system and the adaptations needed to facilitate TWT testing are also presented.

Shalkhauser, Kurt A.↗