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When designing a microwave circuit involving substrate integrated coaxial lines (SICLs), it is important to know what real crosstalk between SICLs is. A measured crosstalk will be a good reference value in a practical design. In addition, it is also needed to compare and check the crosstalk from the simulation and calculation formula with measured results. However, it is very difficult to measure the crosstalk between SICLs because it is theoretically very low. In this study, for the first time, the crosstalk characteristics of a SICL are evaluated through experimental design and measurements. By adjusting the layout of the structures and implementing controlled experiments, interference caused by the presence of leaks and radiation at the interface and structural transitions is effectively suppressed. The experimental results show that for two parallel SICLs with a length of 30 mm and an interval of 5 mm, the isolation is greater than 80 dB for the measured frequency range of 1&ndash, 8 GHz, significantly better than the results of the grounded coplanar waveguide (GCPW).

An improved integrating power method is proposed to enhance the accuracy of distributed polarization crosstalk measurements of the polarization maintaining fiber (PMF). This method obtains crosstalk via calculating the power of the interference peaks. However, when the coupling coefficients of the crosstalk points are weak enough, the amplitudes of the interferogram are vulnerable to the noise. It will diminish the accuracy of the crosstalk measurement. When the coupling is excessive, the crosstalk calculated by the method is inconsistent with the true value because the coupling mode cannot be ignored compared to the exciting mode. The theoretical analysis and experimental results demonstrated that the error sources can be predicted and then be eliminated by using the methods proposed in this paper.

Recently, interchip/intrachip optical interconnection networks have been proposed for ultrahigh-bandwidth and low-latency communications. These networks employ the microresonators (MRs) to modulate, direct, or detect the optical signal. However, utilized MRs suffer from intrinsic crosstalk noise and signal power loss, degrading the network efficiency via the signal-to-noise ratio (SNR). The amount of crosstalk noise and signal power loss may differ from network to network. Hence, there exists a need to systematically analyze the effect of the crosstalk noise and the power loss issues. In this paper, we have developed the analytical models considering both coherent and incoherent crosstalk for both the interchip and intrachip optical networks. The interchip/intrachip optical interconnection networks—the $\text{I}^{2}$ CON—are analyzed as a case study. The quantitative results on the individual networks have demonstrated that the architectural design determines the impact of crosstalk on the SNR. We have also demonstrated that the optical interconnection networks with interchip/intrachip interconnects result in better bit error rate (BER) compared with that of only intrachip interconnect. Our analyses of the worst case can be utilized as a platform to compare the realistic performance among different optical interconnection networks via the degradation of SNR/BER and data bandwidth.

Temporal resolution and crosstalk of an ultra-high-speed image sensor operating at 1 Gfps are analyzed by using Monte Carlo simulation. An impulse response method is proposed to analyze crosstalk and to cancel large crosstalk involved in output signals of the sensor. The sensor is backside-illuminated (BSI) with multi-collection-gate (MCG) at central area of a pixel on the front side. Signal electrons generated by incident light near the back side travel to the central area of the pixel and are collected by the collection gates. The travel time and the path of a signal electron randomly distribute due to randomness in arriving spot on the backside of the sensor and penetration depth of an incident photon which generates the electron, and in the motion of the generated electron. The travel time is analyzed to define the temporal resolution of the sensor. A collecting gate is defined as one of the collection gates which is supposed to collect all the signal electrons at a certain time interval. However, due to the randomness, some of signal electrons migrate to other collection gates than the collecting gate, resulting in mixture of signal electrons at neighboring collection gates and/or pixels, causing crosstalk in time and space. The proposed impulse method is used to analyze crosstalk when the sensor operating at 1 Gfps. From the analysis, a cancellation method of crosstalk involved in output signals is presented and successfully applied in cancellation of crosstalk in an example of 2 dimensional images.

A photo-detecting system based on photo-detector with calibrated optical response is developed to characterize the global crosstalk of three-dimensional (3D) displays over the entire display screen. Local screens areas are investigated, revealing that the crosstalk can be very inhomogeneous over the entire screens for typical stereoscopic display and autostereoscopic display. New quantification parameters for crosstalk, including average crosstalk and crosstalk uniformity, are introduced to give a panorama view of the display system. The crosstalk measurement and characterization method not only show good agreement with the practical visual experience, but also give a global quantitative description of crosstalk.

Traditional crosstalk measurements require more ports on the test equipment, especially for differential configuration and are therefore costly. Another challenge is the need of perfect termination on the non-measurement ports, which is not practical in the actual implementation. In this paper, we introduce a novel crosstalk measurement method using the EUL (Extended Unterminated Line) structure. The test method overcomes the aforementioned shortcomings of the traditional techniques with minimum amount of test ports, and are suitable for non-50-ohm interconnects such as 40-Ohm for DDR or 85-Ohm for PCI Express. We report both simulation and measurement results to validate the EUL algorithm.

We experimentally study the impact of crosstalk in multicore fibers, using polarization-multiplexed quadrature phase-shift keying signals. Using a 7-core fiber, we perform single-span transmission experiments, where the level of crosstalk to the core under test can be varied. We find the penalty in the required optical signal-to-noise ratio (OSNR), compared to a system with no crosstalk, for different signal-to-crosstalk ratios and at different pre-forward-error-correction target bit-error rates (BERs). We show that, for a 1-dB penalty, a 15.7-dB signal-to-crosstalk ratio can be tolerated at BER = 1 × 10-3. We also perform recirculating loop experiments with varying amount of crosstalk per span to find the impact on the achievable transmission distance.

In today's high-speed interconnect design, crosstalk is a critical parameter and the accurate measurement is very important. However, in the calibration procedure, the fixture crosstalk is usually ignored to avoid over-complicated de-embedding algorithms. This leads to certain levels of error in the de-embedded results of crosstalk value. Engineers have been struggling in assessing the quality of crosstalk measurement data as there is no clear indicator as to how much of the measured crosstalk is attributed to the fixture design. In this paper, we propose a dogleg/ spiderleg structure as a method to quantify the fixture crosstalk which remains after a calibration/de-embedding. The validity as a test fixture crosstalk assessment structure is examined extensively and the usage is verified.

In multiview three-dimensional (3D) displays, crosstalk is one of the most annoying artefacts degrading the quality of the 3D image. In this paper, we present a system-introduced crosstalk measurement method and derive an improved crosstalk reduction method. The proposed measurement method is applied to measure the exact crosstalk among subpixels corresponding to different view images and the obtained results are very effective for crosstalk reduction method. Furthermore, an improved crosstalk reduction method is proposed to alleviate crosstalk by searching for the optimal integral intensity values of subpixels on the synthetic image. The derived algorithm based on modified Schnorr-Euchner strategy is implemented to seek the optimal solution to this box-constrained integer least squares (BILS) problem, such that the Euclidean distance between solution and its target decreases substantially. The method we develop is applicable to both multiview 3D parallax barrier displays and multiview 3D lenticular displays. Both simulation and experimental results indicate that the derived method is capable of improving 3D image quality more effectively than the existing method on multiview 3D displays.

3D crosstalk is one of the disturbing things to recognize 3D images. This is caused by the phenomenon that input image for left eye is transferred at the right eye and right eye is transferred at the left eye because of the imperfect isolation by the device characteristics. In this paper, we review the 3D PDP (Plasma Display Panel) operation using active shutter glasses and crosstalk measurement method and investigate the major cause of 3D crosstalk and extend conventional 3D crosstalk using full white and full black image input to Gray-to-Gray (GtoG) 3D crosstalk. We suggest a specific method to reduce Gray-to-Gray 3D crosstalk by using Look up Table (LUT) and sub-field mapping in PDP. And then, we verify the method by measuring GtoG 3D crosstalk rate through specific test images and numerical results.

Crosstalk between two wire pairs in three different configurations is compared to investigate the influence of replacing aluminium by carbon-fibre-reinforced plastic composite material in ground returns. Measurements and simulations show the same interesting effect involving a transition frequency at which the influence of the composite ground plane changes. For low frequencies it acts as a transparent layer on crosstalk behaviour, whereas for higher frequencies it can significantly decrease crosstalk levels. This phenomenon can be explained physically by investigating the skin effect of the composite ground plane. Reverse engineering can even lead to an estimation of the conductivity of the composite material when a crosstalk measurement is at hand.

An efficient signaling scheme for serial-data transceivers (TRXs) has been proposed, which can properly reduce inter-symbol interference (ISI) and crosstalk (Xtalk) in memory interfaces. The proposed architecture relies on fully-digital implementation rather than analog/multi-tone approach, which can offer a very power-efficient and versatile silicon implementation. Moreover, the Xtalk induced noise can be fairly reduced by applying the proposed signaling, and the whole TRX can customize to the communication link trough digital calibration, while the aggregate data rate is kept fixed.

A method for crosstalk detection and removal in multichannel time-of-arrival measurement systems is proposed. The method, based on low-complexity processing of cross-correlation results, is evaluated by numerical simulations and experimental characterization. Results show the capability to detect and remove crosstalk by processing the signals acquired by two mutually-interfering electrical channels. The validation, carried out on a time-of-arrival positioning system, yielded centimeter-level accuracy in the presence of relevant inter-channel interference. The proposed method is of a general nature and is not limited only to positioning scenarios.

We propose a new crosstalk measurement method for multi-core fiber fan-in/fan-out devices utilizing the Fresnel reflection. Compared with the traditional method using core-to-core coupling between a multi-core fiber and a single-mode fiber, the proposed method has the advantages of high reliability and much shorter measurement time. Statistical properties of the measured crosstalk by the new method are found to be very similar to the ones by the traditional coupling method.

For the multi-channel data acquisition system, crosstalk significantly affects the sample accuracy. Through analyzing the mode of multiplexer and the sampling timing sequence, we demonstrated that crosstalk effect mainly results from the switch of multiplexer for the low- frequency multi-channel data acquisition system. A new crosstalk testing method based on phase-shift rectangular waveform for the multi-channel data acquisition system was proposed. The phase-shift rectangular waveform was designed. Experiments were conducted to test crosstalk effect of the multi-channel data acquisition system. The experimental results were demonstrated that the proposed approach based on the phase-shift rectangular waveform exhibits a distinct feature in effective channel crosstalk testing, compared with waveforms of other types. Thus, the proposed method is effective to detect crosstalk of the multi-channel data acquisition system.

A DSP-aided transmitter-side crosstalk (XT) suppression technique for mode-unbundled transmission is proposed and demonstrated. The cooperatively-modulated OFDM subcarriers suppress the modal XT and enable the treatment of modes as individual channels without MIMO-DSP in a 30-km two-mode fiber link.

The impact of inter-band crosstalk due to nonlinear fibre transmission on the performance of direct-detection single-sideband multi-band orthogonal frequency division multiplexing metro networks is evaluated through numerical simulation for one optical channel. Distortion powers with single-band and with five bands are compared. The number of independent signal runs required to achieve accurate performance estimates is assessed. An average over 16 independent signal runs is shown enough to guarantee an error vector magnitude (EVM) discrepancy not exceeding 0.5 dB from the average EVM obtained with 32 independent signal runs. Inter-band crosstalk due to nonlinear transmission of 5 bands over 240 km of standard single-mode fibre limits the average power at the fibre input to levels not exceeding −2.5 dBm.

Optical coherent technology leads to the coexistence of signals with different modulation formats and different bit rates in optical networks. Due to this coexistence, several in-band crosstalk scenarios are possible. In this work, the impact of in-band crosstalk due to M-QAM interferers on the performance of PDM-QPSK and PDM-16-QAM coherent receivers at a bit rate of 100 Gbps is studied. The influence of the duty-cycle, time misalignment and phase difference between interferers and selected signal on the receiver performance is also assessed. We show that the QPSK signal with a duty-cycle of 33% is, generally, the most tolerant selected signal to in-band crosstalk and the less detrimental interferer to the coherent receiver performance. Additionally, we show that the time misalignment has a strong influence on the in-band crosstalk impact, when the duty-cycles of the interferers or selected signal are low.

In this paper a procedure for crosstalk (CT) measurements on spatial-multiplexed multi-user autostereoscopic 3D displays with so-called viewing distance control (VDC) is presented. VDC makes use of a rendering method which allows shifting of the viewing distance for multiview displays by using a novel distribution of the content at sub-pixel level. Methods for CT measurements to date cannot be used as the measurements have to be executed at distances that are not defined in the standard procedures for stereoscopic displays. The measuring procedures used so far are not applicable, as neither a measurement process nor any test images are defined for the use at different viewing distances. As separate CT-measurement specifications for two-view and multiview autostereoscopic displays already exist, the authors propose a unified measurement process. This process is supposed to utilize both, the equipment, as well as the physical arrangement of measuring subject and instrument that are used so far. It has to be considered that, due to the basic functional principles, several quality measurement and evaluation criteria for 3D displays have emerged. Different autostereoscopic display technologies lead to different measurement procedures. A unified method for analyzing image quality features in 3D displays, requiring no enhanced effort but offering comparable results, is desirable.

Acoustic crosstalk cancelation is a signal processing technique that uses two or more loudspeakers reconstruct the acoustic pressures at the listener's ears. The crosstalk arises because each speaker sends sound to the ipsilateral ear, as well as undesired sound to the contra lateral ear. Taking crosstalk cancelation technique can deliver desired signals exactly at the listener's ears that would result from the natural listening situation to be simulated and using crosstalk cancelation technique people can enjoy spatial audio without wearing a headphone. Classical crosstalk cancelation systems (CCS) employ only two loudspeakers, and their performance is usually unsatisfactory in practice. While the idea of using more loudspeakers has been investigated, we design a new 3-channel system to improve the performance on sound separation and robustness to head. The simulation results indicate that multichannel loudspeaker can improve the performance and the robustness of three-dimensional (3D) audio system.

In this paper, the influence of the In-band crosstalk-crosstalk beat noise on the Bit Error Rate (BER) of a preamplified WDM receiver is investigated assuming Gaussian approximation. From the analysis and comparison it is evident that in case of many interferers the crosstalk-crosstalk beat noise can significantly affect the value of BER and modify the optimum detection threshold for obtaining minimum BER. Bit Error Rate including the presence of crosstalk-crosstalk beat noise are calculated and the effect of the variation of number of interfering channels have been investigated which is essential for improvement of the practical receiver design.

This paper investigates the impact of optical crosstalk in fiber-radio systems incorporating wavelength division multiplexing, (WDM). We present a simple analytical model that allows the impact of optical crosstalk in such networks to be assessed and validate the results via experiment for both in-band and out-of-band optical crosstalk. We show that crosstalk-induced power penalties in fiber-radio WDM networks are reduced compared to baseband modulation for the case of in-band crosstalk. In addition, in contrast to baseband modulated optical links, the crosstalk channel in fiber-radio systems can be filtered electrically if the crosstalk signal carries a different wireless frequency. However, a power penalty is still observed for the case of in-band crosstalk, even for perfect electrical filtering of the crosstalk channel.

We propose the concept of gentle acoustic crosstalk cancelation, which aims at reducing the crosstalk between a loudspeaker and the listener's contralateral ear instead of eliminating it completely as aggressive methods intend to do. The expected benefit is higher robustness and a tendency to collapse less unpleasantly. The proposed method employs a linear loudspeaker array and exhibits two stages: 1) Use the Spectral Division Method to illuminate the ipsilateral ear using constructive interference of the loudspeaker signals. This approach provides only little channel separation between the listener's ears at frequencies below approximately 2000 Hz. 2) There we additionally use destructive interference by Recursive Ambiophonics Crosstalk Elimination (RACE). RACE was chosen because of its tendency to collapse gently. In a sample scenario with realistic parameters, the proposed method achieves around 20 dB of channel separation between 700 Hz and 9000 Hz, which appears to be sufficient to achieve full perceived lateralization when only one ear is illuminated.

This paper presents an analysis as well as experimental results on developing receiver arrays for parallel digital datalinks for 10-100 m in the Gb/s range. Interchannel crosstalk can be a dominant limiting factor on the bit-error-rate in such parallel arrays. We present a novel analysis of the physical origins of crosstalk arising from the power-supply distribution, as well as an efficient circuit simulation technique for the effect of crosstalk on digital signal transmission in multichannel systems. It is shown that while differential receivers exhibit a far lower crosstalk than single-ended ones, it is possible to obtain low crosstalk values in the latter case by means of suitable power supply decoupling. Experimental results in the form of two low crosstalk multichannel receiver arrays are presented to corroborate the theory. >

Crosstalk is one of the problems that affect the performance operation of global system mobile (GSM) network. Among the effect of crosstalk are call mute, call drop, wire propagation delay, dynamic power dissipation etc. Crosstalk is an undesirable signal arising due to the coupling capacitances between adjacent interconnecting wires and measured in decibel. In this paper some literature were reviewed and different ways of measuring crosstalk such as Near end croosstalk (NEXT), far end crosstalk (FEXT), Power sum crosstalk (PSNEXT) and alien crosstalk (AXT) were analyzed.

This work investigates how the noise coupling is affected for a guard trace with different trace spacings in stripline structure. For a guard trace maintaining the same trace separation, although reducing crosstalk noise can achieve good efficiency, a guard trace with different trace spacings induces residual crosstalk voltage on the guard trace. Residual crosstalk voltage can be regarded as a main signal and capable of inducing a significant amount of extra crosstalk noise at both the near end and far end on the victim line. To address this issue, 3D full-wave simulation is performed. Compared to the same trace spacing, due to the different trace spacings, the increasing amount of magnitude of time-domain crosstalk noises exceeds 70 % on the victim line. Additionally, in the frequency domain, the increasing amount of magnitude of the first and largest resonant crosstalk peak at about 1GHz is more 25dB.

A digital inter-channel-crosstalk pre-compensator for WDM “superchannel” systems is proposed and demonstrated to outperform a conventional ISI pre-compensator with 2dB crosstalk suppression at the optimum optical filter bandwidth and increase tolerance to net filter bandwidth.

An inter-core crosstalk measurement method in a multi-core erbium-doped fibre amplifier that uses a single-wavelength signal with multiple intensity tones is investigated. Its feasibility is confirmed and the output signal power dependence of the crosstalk values for the same signal gains between cores is successfully characterised.

In this paper the authors present techniques for crosstalk measurements in via arrays using broadband microprobes and a multiport vector network analyzer. The desegmentation method is used for probe deembedding in the bandwidth from 10 MHz up to 50 GHz. In contrast to the common approach which relies on T-matrices the desegmentation procedure ensures flexible fixture extraction using directly the S-parameter or Z-parameter matrices of the multiport network that has to be deembedded. The main advantage of the deembedding by desegmentation technique is that it does not require any S- to T-parameters conversion and if desired allows stepwise extraction of the embedded error networks. A typical application of the desegmentation method is presented by the authors where in the case of microprobe based measurement the error boxes of the microprobes are obtained at first by the use of a two-tier calibration technique and in the next step the desegmentation is applied to remove their detrimental effect on the measurement data.

International audience; In this paper we address the problem of crosstalk reduction for autostereoscopic displays. Crosstalk refers to the perception of one or more unwanted views in addition to the desired one. Specifically, the proposed approach consists of three different stages: a crosstalk measurement stage, where the crosstalk is modeled, a filter design stage, based on the results obtained out of the measurements, to mitigate the crosstalk effect, and a validation test carried out by means of subjective measurements performed in a controlled environment as recommended in ITU BT 500-11. Our analysis, synthesis, and subjective experiments are performed on the Alioscopy® display, which is a lenticular multiview display.

In this paper, we present a new method to estimate the crosstalk channels in VDSL systems, allowing to implement well-known pre-compensation schemes. As opposed to previously presented methods, this estimation only requires minimal changes to the current standard and equipments. It is based on the concept of adding small, controlled, perturbations to the transmitted signal and observing the related changes to the SNR at the receiver. It is shown in this paper that, based on a limited amount of SNR measurements from the receivers, it is possible to accurately estimate the crosstalk channels, both in amplitude and phase.

The operation of a two 10 Mbit/s channels mode group diversity multiplexing system with crosstalk pre-correction was demonstrated over a 300 m of a SI fiber. Employed was an entirely optical pre-correction that requires additional lasers as well as optical attenuators and couplers. As the pre-correction is performed at the transmitter it is necessary to feed the crosstalk data from the receiver back to the transmitter. Contrary to the ZF algorithm, the pre-correction does not increase the noise level at the receiver.

An efficient crosstalk delay degradation measurement method with a 65 nm process is proposed. The voltage drop impact on the crosstalk delay is measured. The test module incorporates filters which omit glitches high speed complicated circuits unintentionally create. The module consists of standard cells only, that makes designing very easy. An intensive comparison of measured results with simulations for 64 times 216 patterns of six aggressor activations (timing and combinations) shows precise matching with less than 10% errors.

International audience; We report on the performance of an optical switch based on the use of narrow deep-etched InP waveguides. A DOS-like structure has been designed and fabricated. First characterization results are reported. They show an optical crosstalk value close to -20dB.

The goal of this paper is to describe some of the design choices made in a BladeCenter system design. This paper will focus on the connector modeling that was used to make design trade-offs, unique to a 10 Gbps serial system. Connectors are a significant source of crosstalk noise in a system, which could increase jitter in the resulting eye pattern. Since crosstalk jitter is uncorrelated from the link data pattern, it is hard to remove through equalization techniques. This paper provides a process to extract accurate coupled models from connectors. It also describes how modeling was used to predict crosstalk noise and shows how a small percentage of connector crosstalk can have a significant impact on the over all signal distortion, if the connector pin assignment is done randomly.

Autostereoscopic displays utilizing slanted lenticular sheets produce specific artifacts. These artifacts affect the perception of a 3D scene, and are caused by a process which can be modeled as inter-channel crosstalk. We propose methodology for measuring such a crosstalk for arbitrary multiview 3D display. The measured data might be used for optimizing multiview image sets for a given display.

When analog terrestrial broadcasting and Gigabit Ethernet signals co-exist in the same network, the Raman crosstalk effect might damage the analog video signal. In this paper, we have investigated the effectiveness of adding some dispersion at the input-end of the fiber to manage the Raman crosstalk and successfully demonstrated adequate suppression of the interference on the analog video signal.

A statistical model for crosstalk in twisted pair cables is presented, where all individual pair combinations in the cable are modeled separately. The model is realistic because all parameters are based on measurements, and an extensive set of crosstalk measurements will be necessary in order to describe all relevant pair combinations. The model is well suited for simulations of crosstalk, and Monte Carlo simulations in particular. In this paper, the model has been used to calculate the performance for partial crosstalk cancellation in one particular 10-pair cable. The results show that 10 dB crosstalk reduction may be obtained by canceling the approximately 50% of the disturbers both for far end and near end crosstalk.

Crosstalk originating from multiple high-speed data services in the same telephone bundle is a limiting factor for the maximum bit rate, the loop length and the number of data services that a bundle can support. Due to the nature of twisted-pairs, external interferences (including crosstalk) mostly couple to the twisted-pair line in common mode, and then leaks to differential mode due to line imperfect balance. The result is a degradation of the received differential signal quality. This paper uses the common mode signal as a reference to an adaptive wideband crosstalk canceller, as an attempt to remove the effect of crosstalk on the differential signal. Simulation results show the potential benefits of using this technique to reduce the crosstalk levels.

Calculations based on the exact probability density function of the received power show that for a fixed total crosstalk power, the incoherent crosstalk penalty increases with the number of crosstalk signals. Performed experiments verify this.

A facility for making near-end crosstalk measurements on multipair cable is described. This facility yields pair-to-pair frequency- and time-domain responses, useful for characterizing crosstalk in digital loop transmission. Through measurements with multiple synchronous ISDN (integrated services digital network) loop transmitters, it also allows measurement and characterization of cyclostationary crosstalk variation. Preliminary results clearly show this cyclostationary characteristic. >

We report the electronic cancellation of WDM demux crosstalk at 10 Gb/s. We demonstrate a power penalty reduction of up to 2 dB for an optically amplified system, and 1 dB for a thermal noise limited system. We also analyse and quantify the limits of such a technique in a real system.

A 2 Gb/s/pin single-ended 4-PAM parallel bus interface uses transmit crosstalk cancellation and equalization techniques as well as integrating data receivers to improve system margin in low-cost packaging despite inherent coupling noise and data distortion.

This paper proposes an all digital on-chip bus delay and crosstalk measurement methodology. A diagnosis procedure is derived to distinguish the delay faults in drivers, receivers, and wires. The crosstalk profile is plotted by monitoring the changes in delay with the presence of the crosstalk. The distinguished features include all digital design and low hardware overhead. The SPICE simulation results prove the feasibility of the methodology.

Interferometric crosstalk, also called incoherent crosstalk, occurs when reception of a desired signal is disturbed by undesired crosstalk contributions having the same wavelength as the desired signal but independent amplitudes and phases. This crosstalk type is known to be among the most destructive phenomena in optical networks owing to its accumulative nature and strong impact on the transmission quality. New formulas state the crosstalk penalty as a function of the total crosstalk power, the number of contributions carrying this power and the signal extinction ratio. We consider both PIN and optically preamplified receivers. The authors know of no other published formulas which include the number of crosstalk contributions. The crosstalk penalty formulas are empirical, and they are based on a numerical model. This model is described briefly along with its experimental verification before the formulas themselves are presented.