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An 80-year-old woman presented with subacute right lower limb pain and bilateral lower limb weakness. MRI of the spine showed marked cauda equina enlargement with contrast enhancement. Cerebrospinal fluid (CSF) examination showed elevated cell count, decreased glucose, and elevated protein. Cytology of the CSF showed class V, which together with B-cell clonality by flow cytometry, led to the diagnosis of primary central nervous system lymphoma (PCNSL). The patient was treated with steroid, radiation, and chemotherapy. Despite the reduction in lesion size, her neurological symptoms revealed no improvement. PCNSL with cauda equina lesions are rare and often require highly invasive cauda equina biopsy for diagnosis. In recent years, some studies reported useful CSF biomarkers, but they may have some problems. Therefore, as in this case, the combination of cytology, flow cytometry and, CSF biomarkers could be a substitute method for invasive biopsies, and contribute to the early treatment of PCNSL.

Background: Coronavirus disease 2019 (COVID-19) continues to spread worldwide. Because of the absence of reliable rapid diagnostic systems, patients with COVID-19 symptoms are suspected of disease. Computed tomography (CT) in patients with suspected COVID-19 may be reasonable for triaging, and CT-first triage strategies have been proposed. However, clinical evaluation of a CT-first triage protocol is lacking. The aim of this study is to investigate the real-world efficacy and limitations of a CT-first triage strategy in patients with suspected COVID-19.Methods: This was a single-center cohort study evaluating outpatients with suspected COVID-19 who underwent a medical examination at Yokohama City University Hospital and who were prospectively registered between 9 February and 5 May 2020. We treated patients according to the CT-first triage protocol. CT findings were classified into five categories according to the COVID-19 Reporting and Data System (CO-RADS). With the CT-first triage protocol, patients with a suspicious clinical history, symptoms, or suspicious findings on chest CT were allocated to the COVID-19 suspected group. The primary outcome was efficacy of the CT-first triage protocol for outpatients with suspected COVID-19. We conducted additional analyses of the isolation time of outpatients with suspected COVID-19 and reached final diagnoses.Results: In total, 108 outpatients with suspected COVID-19 were examined at our hospital. Forty-eight patients (44.9%) were categorized as CO-RADS 1, 26 patients (24.3%) as CO-RADS 2, 14 patients (13.1%) as CO-RADS 3, 6 patients (5.6%) as CO-RADS 4, and 13 patients (12.1%) as CO-RADS 5. One patient was excluded because of pregnancy. Using the CT-first triage protocol, 48 (44.9%) patients were suspected of having COVID-19. Nine patients (18.8%) in this group were positive for severe acute respiratory syndrome coronavirus 2 using polymerase chain reaction; no patients in the group not suspected of having COVID-19 were diagnosed with COVID-19 during follow up. The protocol significantly shortened the duration of isolation for the not-suspected versus the suspected group (70.5 vs. 1037.0 minutes, P < .001). Conclusions: Our CT-first triage protocol was acceptable for triaging outpatients with suspected COVID-19. This protocol will be helpful for appropriate triage, especially in areas where polymerase chain reaction is limited.

Background: The Coronavirus disease 2019 pandemic continues to spread worldwide. Because of the absence of reliable rapid diagnostic systems, patients with symptoms of Coronavirus disease 2019 are treated as suspected of the disease. Use of computed tomography findings in Coronavirus disease 2019 are expected to be a reasonable method for triaging patients, and computed tomography-first triage strategies have been proposed. However, clinical evaluation of a computed tomography-first triage protocol is lacking.The aim of this study is to investigate the real-world efficacy and limitations of a computed tomography-first triage strategy in patients with suspected Coronavirus disease 2019.Methods: This was a single-center cohort study evaluating outpatients with fever who received medical examination at Yokohama City University Hospital, prospectively registered between 9 February and 5 May 2020. We treated according to the computed tomography-first triage protocol. The primary outcome was efficacy of the computed tomography-first triage protocol for patients with fever in an outpatient clinic. Efficacy of the computed tomography-first triage protocol for outpatients with fever was evaluated using sensitivity, specificity, positive predictive value, and negative predictive value. We conducted additional analyses of the isolation time of feverish outpatients and final diagnoses.Results: In total, 108 consecutive outpatients with fever were examined at our hospital. Using the computed tomography-first triage protocol, 48 (44.9%) patients were classified as suspected Coronavirus disease 2019. Nine patients (18.8%) in this group were positive for severe acute respiratory syndrome coronavirus 2 using polymerase chain reaction; no patients in the group considered less likely to have Coronavirus disease 2019 tested positive for the virus. The sensitivity, specificity, positive predictive value, and negative predictive value of our computed tomography-first triage protocol for Coronavirus disease 2019 were 100%, 60.2%, 18.8%, and 100%, respectively. The protocol significantly shortened the duration of isolation for the not-suspected versus the suspected group (70.5 vs. 1037.0 minutes, P < .001). Conclusions: Our computed tomography-first triage protocol was acceptable for screening patients with suspected Coronavirus disease 2019. This protocol will be helpful for appropriate triage, especially in areas where polymerase chain reaction is inadequate.

The Optical Inter-orbit Communications Engineering Test Satellite (OICETS) was successfully launched on 23th August 2005 and thrown into a circular orbit at the altitude of 610 km. The main mission is to demonstrate the free-space inter satellite laser communications with the cooperation of the Advanced Relay and Technology Mission (ARTEMIS) geostationary satellite developed by the European Space Agency. This paper presents the overview of the OICETS and laser terminal, a history of international cooperation between Japan Aerospace Exploration Agency (JAXA) and ESA and typical results of the inter-orbit laser communication experiment carried out with ARTEMIS.

Ground-to-satellite laser communication experiments between the optical ground station located in Koganei, central Tokyo, and a low earth orbit (LEO) satellite were jointly performed by the Japan Aerospace Exploration Agency and the National Institute of Information and Communications Technology. In 18 trials during three non-consecutive months, the satellite was acquired and tracked 61 % of the time, when clear or partly-clear conditions were predominant. The optical link was maintained for about 6 minutes when the satellite was visible in spite of the high angular velocity of the satellite. In 3 of the 18 trials, the link was not interrupted due to clouds during the six-minute transit. The failures (39% of the time) occurred when cloudy or rainy conditions were predominant. Fluctuation in the uplink received signal power was minimized by using multiple laser beam transmissions. The measured uplink and downlink bit error ratios were 10-7-10-4. These results demonstrate the applicability of free-space laser communication for not only geostationary earth orbit-LEO optical links but also ground-to-LEO optical links.

Japan Aerospace Exploration Agency (JAXA) developed the optical inter-orbit communications engineering test satellite (OICETS), which has a laser communications terminal called the laser utilizing communications equipment (LUCE). On August 23, 2005, OICETS was successfully launched and injected into a sun synchronous orbit at the altitude of 610 km. OICETS planned to demonstrate the free-space inter-orbit laser communications with the cooperation of the advanced relay and technology mission satellite (ARTEMIS) developed by the European Space Agency (ESA). On December 9, 2005, JAXA and ESA succeeded in a bidirectional optical inter-orbit communications experiment using a laser beam between OICETS and ARTEMIS. This is the world first bidirectional optical inter-orbit communication successfully established. This paper will describe the outline of OICETS satellite system and LUCE, the result of initial functional verifications on-orbit, the results of inter-orbit communications experiment between OICETS and ARTEMIS, and between OICETS and the ground station.

The KODEN is a first in-orbit laser communication demonstration between a low earth orbit satellite called OICETS/Kirari and an optical ground station at the National Institute of Information and Communications Technology (NICT) in Koganei, Tokyo. Optical links could always be established even under atmospheric turbulence when partly clear skies were predominant in March, May, and September, 2006. The uplink and downlink bit error ratios were measured to be 10−7–10−3. This achievement is a milestone for future high-data-rate satellite communications.

近年、指向安定度劣化の主要因として検討が盛んな機械的振動擾乱について、OICETS (Optical Inter-orbit Communications Engineering Test Satellite:きらり)に搭載したMVE (Micro Vibration Equipment)の軌道上加速度データ出力をもとに、軌道上で実際に発生した振動擾乱についての評価を行う。軌道上データから構造伝達特性を評価し、この結果と地上試験データから得られる構造伝達特性との比較を行うことで、地上試験の結果が軌道上でどの程度再現しているかを確認し、地上試験の有効性について、考察を行う。, The microvibration generated by some instruments on orbit is considered as a key factor of pointing stability deterioration. Therefore it is important that the influence of the microvibration is estimated before the launch. In this paper the results of the ground tests by using of OICETS (Optical Inter-orbit Communications Engineering Test Satellite: KIRARI) MTM (Mechanical Test Model) and the on orbit measured result by the accelerometer (MVE: Micro Vibration Equipment) installed in OICETS are described. By using these results and an assumption, the transfer characteristics from main disturbance sources to MVE installed in OICETS are calculated. We compare these structural transfer characteristics and confirm the reproducibility of the ground test on orbit and the effectiveness of the ground test., 資料番号: AA0063481054

Optical devices in free-space laser communication systems are affected by their environment, particularly in relation to the effects of temperature while in orbit. The mutual alignment error between the transmitted and received optical axes is caused by deformation of the optics due to temperature variation in spite of the common optics used for transmission and reception of the optical beams. When a Gaussian beam wave for transmission is aligned at the center of a received plane wave, 3rd-order Coma aberrations have the most influence on the mutual alignment error, which is an inevitable open pointing error under only the Tip/Tilt tracking control. As an example, a mutual alignment error of less than 0.2 microrad is predicted for a laser communication terminal in orbit using the results from space chamber thermal vacuum tests. The relative power penalty due to aberration is estimated to be about 0.4 dB. The results will mitigate surface quality in an optical antenna and contribute to the design of free-space laser communication systems.

The experimental results of an inter-orbit laser communication performed under an atmospheric influence is presented. The demonstration was planned so that the optical link was supposed to graze the earth's rim because of the satellite revolution around the earth. The trial was successfully carried out on 5th April, 2006. The measured experimental data are introduced to show the temporal behavior of the OICETS's optical terminal. The atmospheric influence on the optical link is calculated with a theoretical model to obtain a probability density of normalized intensity as a predictive value. The probability density is also estimated from the experimentally measured data. The comparison shows that the theoretical prediction well describes the experimental results.

The first bi-directional laser communications demonstration between the optical ground station developed by the National Institute of Information and Communications Technology (NICT) located in Koganei, Tokyo and the Optical Inter-orbit Communication Engineering Test Satellite (OICETS) was successfully conducted in March, May, and September, 2006. The Kirari Optical communication Demonstration Experiments with the NICT optical ground station (KODEN) were jointly conducted by the Japan Aerospace Exploration Agency (JAXA) and NICT. Data from the uplink and downlink optical communication links were analyzed. For the downlink, the scintillation index agreed well with the theoretical results calculated based on the strong fluctuation theory. The aperture averaging effect was the dominant factor in reducing the variation of the downlink signals. The probability density functions as a function of elevation angles were measured and compared with the theoretical model, showing good agreement. For the uplink, the scintillation index disagreed with the calculated results based on the strong fluctuation theory. The multiple beam effect of the uplink transmission with large beams will have an additional reduction factor, which will help to establish ground-to-satellite laser communication links in the future. Four laser beams transmitted from the optical ground station to the OICETS satellite also helped to reduce the optical signal's intensity fluctuation due to atmospheric turbulence.

The first bi-directional laser communication demonstration between an optical ground station and the Optical Inter-orbit Communication Engineering Test Satellite (OICETS) was successfully conducted in March, May, and September, 2006, with an uplink of 2 Mbps and a downlink of 50 Mbps. The optical ground station, located in Koganei, Tokyo, Japan, is operated by the National Institute of Information and Communications Technology (NICT), Japan. Four laser beams were transmitted from the optical ground station to the OICETS satellite in order to reduce the optical signal's intensity fluctuation due to atmospheric turbulence. The optical scintillation as a function of the number of beams and the frequency response were measured, and the uplink and downlink laser transmission results were obtained.

The experiment results on the inter-orbit laser communications between OICETS and a geostationary satellite and the results of two kinds of orbit-to-ground laser communications between OICETS and ground stations are summarized. The geostationary satellite for the inter-orbit demonstrations is the European Space Agency's geostationary satellite, ARTEMIS, and the ground stations for the orbit-to-ground demonstrations are of the National Institute of Information, and Communications Technology (NICT) in Japan and the German Aerospace Center (DLR), respectively. The descriptions of those experiments contain some statistically analyzed results as well as data samples measured during the demonstrations. The authors present the overview of these demonstration progresses and discuss on the results.

The tracking and pointing performance of the Laser Utilizing Communications Equipment (LUCE) equipped on the Optical Inter-orbit Communications Engineering Test Satellite (OICETS) is presented. The operation characteristics of LUCE observed in the ground-satellite communication demonstrations are focused on. Since the angular movement of LUCE's optical antenna required in the ground-satellite trials exceeds the specification demanded in the inter-satellite communications, the marginal performance for proper tracking and pointing can be observed. During the ground-satellite communication trials, the ground stations found periodical discontinuances in the optical link. By looking at the LUCE's telemetries, the cause of the repeated breaks is revealed.

[Abstract] Bi-directional ground-to-satellite laser communication experiments between the optical ground station developed by the National Institute of Information and Communications Technology (NICT) located in Koganei of downtown Tokyo and a low earth orbit (LEO) satellite, the Optical Inter-orbit Communications Engineering Test Satellite (OICETS) called “Kirari”, were successfully performed in March, May and September, 2006. The Kirari Optical Communication Demonstration Experiments with the NICT optical ground station (KODEN) was conducted in cooperation between the Japan Aerospace Exploration Agency (JAXA) and NICT. The ground-to-OICETS laser communication experiment is the first in-orbit demonstration with respect to the LEO satellite. Phase-1 laser communication experiment was conducted in March, 2006 and the downlink bit error ratio (BER) of around 1e-5 was measured. Phase-2 laser communication experiment was done in May, 2006 but there was no significant improvement due to bad weather. The uplink and downlink BERs of 1e-4 ~ 1e-7 were simultaneously measured in Phase-3 in September, 2006 with an uplink of 2 Mbps and a downlink of 50 Mbps, respectively. Eighteen trials over the course of three months were conducted during the test campaign. There were eleven successful passes out of all the trials. Acquisition and tracking of the OICETS satellite were always successful when partly clear skies were predominant, showing the optical link was successfully established by 100 % without bad weather conditions. For the uplink, multi-beam laser transmission was used from the optical ground station to the OICETS satellite in order to reduce the intensity fluctuation of the optical signal due to atmospheric turbulence. The fluctuation of the received signal power was well minimized by using four-beam laser transmission. The applicability of the onboard optical terminal was demonstrated, aiming not only for geostationary earth orbit (GEO)-LEO links but also for ground-to-LEO optical links. This paper presents the results of Phase-1, Phase-2 and Phase-3 KODEN experiments.

Optical LEO downlinks from the Japanese OICETS to the optical ground station built by the German Aerospace Center (DLR) near Munich have been performed. This was the first optical LEO downlink on European grounds. The ground station received a 50-Mbit/s OOK signal at 847 nm on its 40-cm Cassegrain telescope and sent two spatially displaced beacon beams towards OICETS. Five out of eight trials could be performed successfully while the other three were hindered by cloud blockage. A BER of 10-6 has been reached. The elevation angle above the horizon ranged between 2° and 45°. The Fried parameter and the scintillation were measured with instruments inside the ground station. The beacon power received by the LUCE Terminal onboard OICETS has also been recorded. This paper describes the setup of the experiment and highlights the results of the measurement trials.

Ground-to-satellite laser communication experiments between the optical ground station developed by the National Institute of Information and Communications Technology (NICT) located in Koganei, Tokyo and a low-earth-orbit (LEO) satellite, the Optical Inter-orbit Communications Engineering Test Satellite (OICETS) called "Kirari" developed by the Japan Aerospace Exploration Agency (JAXA), were successfully performed in March and May, 2006. The Kirari optical communication demonstration experiments with the NICT optical ground station (KODEN) were conducted as a cooperative experiment between JAXA and NICT

Ground-to-satellite laser communication experiments between the optical ground station located in Koganei of downtown Tokyo and a low earth orbit (LEO) satellite, the Optical Inter-orbit Communications Engineering Test Satellite (OICETS) called "Kirari", were successfully performed in March and May, 2006. The optical communication demonstration experiment at the optical ground station was conducted in cooperation between the Japan Aerospace Exploration Agency (JAXA) and the National Institute of Information and Communications Technology (NICT). Ten trials over the course of two months were conducted during the test campaign. Acquisition and tracking of the satellite were successful on seven days out of the assigned test days. The tests were unsuccessful during three out of the four days when it was cloudy or rainy, but they were successful on all six of the days when partly clear skies were predominant. For the uplink, the fluctuation of the received signal power was well minimized by using multi-beam laser transmissions. The bit error ratio (BER) on the downlink was measured to be as low as 10-5. The applicability of the onboard optical terminal was demonstrated, aiming not only for geostationary earth orbit (GEO)-LEO links but also for ground-to-LEO optical links.

The initial verification results of the in-orbit free-space laser communication functions equipped on the Optical Inter-orbit Communications Engineering Test Satellite (OICETS) are presented. The operation system for OICETS is introduced with some characteristics on the radio-frequency communication links which connects OICETS to the ground facilities and satellites. The verification procedures of optical functions are carried out with a scenario that begins with measurements of optical devices' responses and moves to confirmations of automatic sequences in acquisition and tracking stars. Finally, all the OICETS functions required for the in-orbit laser communications with ARTEMIS are found to be in good conditions. We describe here the story of the initial verifications with typical examples measured by these tests.

We present the results of the on-orbit free-space laser communications between the Optical Inter-orbit Communications Engineering Test Satellite (OICETS) and the Advanced Relay and Technology Mission (ARTEMIS) geostationary satellite. We first introduce the history of developing OICETS and add some descriptions on characteristics of OICETS, where the performance of the optical communication terminal named the Laser Utilizing Communications Equipment (LUCE) is also stated. We summarize the on-orbit investigation results of LUCE's function and finally make a report on the inter-orbit laser communication experiment carried out by ARTEMIS and OICETS.

Free-space laser communication systems offer many advantages such as high data rate, small sized equipment, low consumption electric power and others. There are, however, many development factors to construct a realistic laser communication system in space. Precise Acquisition, Tracking, and Pointing (ATP) functions are key issue to establish the laser communication system in space. OICETS (Optical Inter-orbit Communications Engineering Test Satellite) has been developed by National Space Development Agency of Japan (NASDA) to verify an optical data link technology in space. ATP functions of the OICETS satellite for a laser inter-orbit link system must be controlled with an angular accuracy better than a few micro radian under vibrational disturbances of the host satellite. The microvibrational disturbances continually come from the satellite subsystem operations such as reaction wheels, solar paddle motors, scan sensors and so on. NASDA performed an on-ground microvibration test to evaluate vibration characteristics of the OICETS satellite and to verify laser tracking performances of the ATP system. The test was carried out by using a simulated OICETS satellite that consists of a mechanical structure model and an engineering model of the laser communication terminal. The mechanical structure model is equipped with some flight components and mass dummy components. The satellite is suspended from a lifting tackle by four straps and the free-free configuration was simulated using a suspension device. As a result, the incremental residual tracking error of 0.19 micro radians was measured due to the microvibration of the disturbing sources from the satellite platform.

The average bit error rate (BER) of optical communication systems is considered in the presence of random angular pointing jitter. The received power and the BER in the absence of jitter are reviewed and then the average BER is obtained in the presence of circularly symmetric, normally distributed jitter by using the probability density function of the optical signal. By minimizing the power penalty for average BER, the optimum ratio of the divergence angle of the laser beam to the random angular jitter at the desired BER is obtained. The derived approximation is used to determine the beam divergence angle easily against the random pointing jitter. As an example, the optimum link budget for both optical tracking and communication channels is designed in the presence of fluctuated optical signal due to random pointing jitter.

An optical downlink is a method for high data-rate communication for downloading data acquired by a satellite to terrestrial networks. However, directing a laser beam at the ground may not be safe for the eyes of human observers when such irradiance is higher than the maximum permissible exposure (MPE). The MPE is an index of acceptable irradiance for eye safety as a function of the duration that human eyes are exposed to a laser beam. The hazard level of free-space laser communication systems should be examined with regard to eye safety. The probability that irradiance exceeds the MPE can be considered statistically based on the characteristics of the laser tracking and transmission system in the acquisition and tracking phases. As an example, the probabilities calculated from the results of a thermal vacuum test with the laser communications terminal onboard the OICETS satellite were used to assess the risk of impairing eye safety. As a result, the irradiance of the laser beam directed from the satellite to the ground can be evaluated relative to the permissible irradiance level for the eyes of general human observers.

Optical Inter-orbit Communications Engineering Test Satellite (OICETS) is under development by NASDA to verify the laser communications technology in space. The in-orbit experiment will be done by establishing inter-orbit communication between the OICETS and European geostationary satellite ARTEMIS in cooperation with ESA. These satellites will be launched in to the orbit in 2000. Laser communications system in space is a promising technology for future space activities, but it has many research matters. Acquisition tracking and pointing system of a laser terminal performs a prominent role to keep the laser communication. This paper describes the ATP system strategy of the laser terminal.

OICETS (Optical Inter-orbit Communications Engineering Test Satellite) is under development by NASDA to verify the optical data link technology. The experiment in orbit will be done establishing optical link between the OICETS and ARTEMIS (Advanced Relay and Technology Mission Satellite) in cooperation with ESA. This presentation explains current OICETS Laser Terminal (LUCE: Laser Utilizing Communications Equipment) development status. The LUCE EM (Engineering Model) is under assembling phase and the test will be finished in 997. LUCE uses two 200 mW LD's (Laser Diodes) for transmitting. Selection procedure of the flight parts and some of the performance requirements are also presented.

Optical free-space communications is a promising technology for future space activities. National Space Development Agency of Japan (NASDA) began developing the Optical Inter-orbit Communications Engineering Test Satellite (OICETS). OICETS carries an optical communications equipment named Laser Utilizing Communications Equipment (LUCE) and will be launched in 1998. NASDA plans to conduct an inter-orbit optical communications experiment which will be performed under the international collaboration between NASDA and European Space Agency (ESA). Communications system of LUCE employs the IMDD technique which uses LD as a transmission device and APD as a detection device. The preliminary design of OICETS including LUCE has been completed. The paper describes the result of design and planned experiments for optical communications system of OICETS.

Angular microvibrations of platform jitter on the optical inter-orbit communications engineering test satellite are measured in space during ground-to-satellite laser communication links. The microaccelerations are measured by the onboard accelerometers at a sampling rate of 2048 Hz. The angular microvibrations are estimated from the measured microaccelerations using the tracking characteristics of the laser communications terminal and the conversion factor on the basis of microvibration data obtained from ground-based tests. The power spectral density (PSD) of the satellite microvibrations is analyzed by using the fast Fourier transform analysis and the data length is examined according to the frequency resolution of the PSD. The in-orbit measurements of the PSDs are compared with those obtained from the ground test. The angular microvibrational base motion is estimated and a PSD up to 1024 Hz is additionally provided as a database of the real measurement results with previously obtained in-orbit measurements. The measured results will contribute to the angular jitter estimation and the design of a tracking control loop for space laser communication systems in the future.

The average bit error rate (BER) of optical communication systems is considered in the presence of random angular jitter. First, the received power and the BER in the absence of jitter are reviewed. Then the average BER is obtained in the presence of circularly symmetric, normally distributed jitter by using the probability density function of the optical signal. By minimizing the power penalty for average BER, the optimum ratio of the divergence angle of the laser beam to the random angular jitter at the desired BER is obtained. An analytic approximation of the optimum ratio is derived as a function of the desired average BER. The results can be used for designing the link budget of optical communication and tracking channels in the presence of jitter.

This report deals with a feasibility study of a wide-beam tanker (L/B=5) with respect to ship-controllability.The report consists of the following three parts ; 1) To estimate the indices of manoeuvring characteristics of the ship by the method of series tests using similar models which are 4 m, 10 m and 30 m in length.2) To check whether or no the ship is unstable in course keeping mainly owing to so-called unusual phenomena.3) To check the feeling of control of the ship which has the manoeuvring characteristics estimated by item 1), by the method of simulation apparatus of ship manoeuvre.The results hereby obtained show that if a big large wide-beam tanker has an enough large rudder area ratio, the ship is feasible in the viewpoint of ship-controllability.

Coherent optical receivers have the following features: shot-noise-limited receiver sensitivity with sufficient local oscillator (LO) power; high frequency resolution at the intermediate frequency or baseband stage in highly dense frequency division multiplexed channels; improved receiver sensitivity compared with that of intensity modulation/direct detection (IMDD) systems; and active realization of multilevel signal transmission using not only intensity but also phase, frequency, and polarization states. With the advent of coherent binary phase shift keying (BPSK) receivers in orbit, it is absolutely imperative to establish interoperability between the different optical communications systems. A bread board model (BBM) of an optical receiver that can demodulate both IMDD and coherent optical signals for free-space laser communications has been developed. In this receiver, the carrier phase is recovered after homodyne detection by means of digital signal processing (DSP), which is implemented using a field programmable gate array (FPGA) for both estimating the carrier phase and recovering the payload data. The first BBM of the optical coherent receiver has the ability to demodulate 3-Gbit/s coherent BPSK and 6-Gbit/s quadrature phase-shift keying (QPSK) signals. In this paper, preliminary experimental results of the real-time coherent BPSK communication performance at the OC-48c data rate in the laboratory are presented.