EP1391058A4 - Liaison de communication a ondes millimetriques - Google Patents

Liaison de communication a ondes millimetriques

Info

Publication number
EP1391058A4
EP1391058A4 EP02766896A EP02766896A EP1391058A4 EP 1391058 A4 EP1391058 A4 EP 1391058A4 EP 02766896 A EP02766896 A EP 02766896A EP 02766896 A EP02766896 A EP 02766896A EP 1391058 A4 EP1391058 A4 EP 1391058A4
Authority
EP
European Patent Office
Prior art keywords
antenna
transceiver
antennas
ghz
camera
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02766896A
Other languages
German (de)
English (en)
Other versions
EP1391058A1 (fr
Inventor
Randall B Olsen
Louis Slaughter
John Lovberg
Kenneth Y Tang
Vladimir Kolinko
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Trex Enterprises Corp
Original Assignee
Trex Enterprises Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US09/847,629 external-priority patent/US6556836B2/en
Priority claimed from US09/872,542 external-priority patent/US20020164958A1/en
Priority claimed from US09/872,621 external-priority patent/US20020164959A1/en
Priority claimed from US09/882,482 external-priority patent/US6665546B2/en
Priority claimed from US09/952,591 external-priority patent/US6714800B2/en
Priority claimed from US09/965,875 external-priority patent/US20030022694A1/en
Priority claimed from US10/046,348 external-priority patent/US20030027586A1/en
Priority claimed from US10/001,617 external-priority patent/US20020165001A1/en
Priority claimed from US09/992,251 external-priority patent/US20020164960A1/en
Priority claimed from US10/000,182 external-priority patent/US20020164946A1/en
Priority claimed from US10/025,127 external-priority patent/US20020176139A1/en
Priority claimed from US10/041,083 external-priority patent/US6611696B2/en
Application filed by Trex Enterprises Corp filed Critical Trex Enterprises Corp
Publication of EP1391058A1 publication Critical patent/EP1391058A1/fr
Publication of EP1391058A4 publication Critical patent/EP1391058A4/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/112—Line-of-sight transmission over an extended range
    • H04B10/1123—Bidirectional transmission
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V8/00—Prospecting or detecting by optical means
    • G01V8/005—Prospecting or detecting by optical means operating with millimetre waves, e.g. measuring the black losey radiation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/125—Means for positioning
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
    • H01Q19/10—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/26—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
    • H01Q3/2682—Time delay steered arrays
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/3805—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving with built-in auxiliary receivers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114—Indoor or close-range type systems
    • H04B10/1149—Arrangements for indoor wireless networking of information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/40—Transceivers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0408—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas using two or more beams, i.e. beam diversity

Definitions

  • the present invention relates to wireless communications links and specifically to high data rate point-to-point links.
  • Wireless communications links using portions of the electromagnetic spectrum, are well known. Most such wireless communication at least in terms of data transmitted is one way, point to multi-point, which includes commercial radio and television. However there are many examples of point-to-point wireless communication. Mobile telephone systems that have recently become very popular are examples of low-data- rate, point-to-point communication. Microwave transmitters on telephone system trunk lines are another example of prior art, point-to-point wireless communication at much higher data rates. The prior art includes a few examples of point-to-point laser communication at infrared and visible wavelengths.
  • trunk lines to serve as parts of communication links for their point-to-point customers. These trunk lines typically carry hundreds or thousands of messages simultaneously using multiplexing techniques. Thus, high volume trunk lines must be able to transmit in the gigabit (billion bits, Gbits, per second) range. Most modern trunk lines utilize fiber optic lines. A typical fiber optic line can carry about 2 to 10 Gbits per second and many separate fibers can be included in a trunk line so that fiber optic trunk lines can be designed and constructed to carry any volume of information desired virtually without limit. However, the construction of fiber optic trunk lines is expensive (sometimes very expensive) and the design and the construction of these lines can often take many months especially if the route is over private property or produces environmental controversy.
  • Bandwidth-efficient modulation schemes allow, as a general rule, transmission of data at rates of 1 to 10 bits per Hz of available bandwidth in spectral ranges including radio wave lengths to microwave wavelengths. Data transmission requirements of 1 to tens of Gbps thus would require hundreds of MHz of available bandwidth for transmission.
  • Equitable sharing of the frequency spectrum between radio, television, telephone, emergency services, military and other services typically limits specific frequency band allocations to about 10% fractional bandwidth (i.e., range of frequencies equal to about 10% of center frequency).
  • AM radio at almost 100% fractional bandwidth (550 to 1650 GHz) is an anomaly; FM radio, at 20% fractional bandwidth, is also atypical compared to more recent frequency allocations, which rarely exceed 10% fractional bandwidth.
  • Reliability typically required for wireless data transmission is very high, consistent with that required for hardwired links including fiber optics.
  • Typical specifications for error rates are less than one bit in ten billion (10 " '° bit-error rates), and link availability of 99.999% (5 minutes of down time per year). This necessitates all- weather link operability, in fog and snow, and at rain rates up to 100 mm/hour in many areas.
  • weather-related attenuation limits the useful range of wireless data transmission at all wavelengths shorter than the very long radio waves.
  • Typical ranges in a heavy rainstorm for optical links are 100 meters and for microwave links, 10,000 meters.
  • Atmospheric attenuation of electromagnetic radiation increases generally with frequency in the microwave and millimeter-wave bands.
  • excitation of rotational transitions in oxygen and water vapor molecules absorbs radiation preferentially in bands near 60 and 118 GHz (oxygen) and near 23 and 183 GHz (water vapor).
  • Rain which attenuates through large-angle scattering, increases monotonically with frequency from 3 to nearly 200 GHz.
  • millimeter- wave frequencies i.e., 30 GHz to 300 GHz corresponding to wavelengths of 1.0 millimeter to 1.0 centimeter
  • rain attenuation in very bad weather limits reliable wireless link performance to distances of 1 mile or less.
  • link distances to 10 miles can be achieved even in heavy rain with high reliability, but the available bandwidth is much lower.
  • High frequency, large antennas are typically designed to produce very narrow beams which must be very accurately aligned. Because of the narrow beams, both transmit and receive antennas must be precisely pointed at each other. Gimbals for these antennas are typically designed with two pointing angles; therefore, the process of aligning two antennas is essentially a 4 dimensional search. Since the antennas of the instant invention (such as a four-foot diameter antenna) can have narrow beams in the range of 0.15 degrees or less and are capable of thousands of discrete positions in each dimension, there are an extremely large number of four-dimensional alignments over which to search. As will be shown below, a complete search of this four- dimensional space could theoretically consume many years.
  • the present invention provides a point-to-point wireless gigabit millimeter wave communications link. Preferred embodiments provide a backup link.
  • each of two communicating antennas is equipped with a telescopic camera connected to a processor programmed to recognize landscape images. The processors are programmed to remember the pattern of the landscape as it appears when the antennas are aligned. Each of the cameras then view the landscape periodically or continuously and if the landscape in view changes by more than a predetermined amount a signal is provided to indicate a misalignment. An operator can then take corrective action or alternatively the antenna system can be configured for remote or automatic realignment based of feedback from the camera.
  • the antennas are initially aligned by substituting a narrow band oscillator power source for the signal transmitting electronics associated with a first antenna and a power detector is substituted for the signal receiving electronics of associated with a second antenna.
  • a first alignment procedure is performed, the procedure is repeated with an oscillator power source connected to the second antenna and a power detector connected to the first antenna.
  • the antennas are pre-aligned using a signaling mirror or a narrow beam searchlight or laser.
  • the transceiver electronics are reconnected.
  • communication link operates within the 92 to 95 GHz portion of the millimeter spectrum and provides data transmission rates in excess of 155 Mbps.
  • a first transceiver transmits at a first bandwidth and receives at a second bandwidth both within the above spectral range.
  • a second transceiver transmits at the second bandwidth and receives at the first bandwidth.
  • the transceivers are equipped with antennas providing beam divergence small enough to ensure efficient spatial and directional partitioning of the data channels so that an almost unlimited number of transceivers will be able to simultaneously use the same spectrum.
  • Antennas and rigid support towers are described to maintain beam directional stability to less than one-half the half-power beam width.
  • the first and second spectral ranges are 92.3- 93.2 GHz and 94.1-95.0 GHz and the half power beam width is about 0.15 degrees or less.
  • FIG. 1 is a schematic diagram of a millimeter-wave transmitter of a prototype transceiver system built and tested by Applicants.
  • FIG. 2 is a schematic diagram of a millimeter-wave receiver of a prototype transceiver system built and tested by Applicants.
  • FIG. 3 is measured receiver output voltage from the prototype transceiver at a transmitted bit rate of 200 Mbps.
  • FIG. 4 is the same waveform as FIG. 3, with the bit rate increased to 1.25 Gbps.
  • FIGS. 5A and 5B are schematic diagrams of a millimeter-wave transmitter and receiver in one transceiver of a preferred embodiment ofthe present invention.
  • FIG. 6A and 6B are schematic diagrams of a millimeter-wave transmitter and receiver in a complementary transceiver of a preferred embodiment ofthe present invention.
  • FIGS. 7 A and 7B show the spectral diagrams for a preferred embodiment of the present invention.
  • FIG. 8 is a layout showing an installation using a preferred embodiment ofthe present invention.
  • FIGS. 9 and 9 A show a preferred hollow steel tube antenna support structure (diameter of 24 inches) rigid enough for use in a preferred embodiment ofthe present invention.
  • FIG. 10 shows how very slight directional instability can interfere with transmission.
  • FIG. 11 shows how narrow a beam is when produced by a diffraction-limited 4- foot diameter antenna operating at 94 GHz.
  • FIGS. 12A and 12B diagrammatically show how a signaling device is used to aid in the preliminary alignment ofthe telecommunications link.
  • FIG. 13 is a schematic of an alignment system comprising a Gunn oscillator power source and a power detector.
  • FIG. 14 is a schematic ofthe millimeter-wave power detector.
  • FIG. 15A and 15B illustrate the positions of a power source and a power detector relative to the first and second antennas during the fine alignment procedures.
  • FIG. 16 shows an alignment assurance camera mounted to a sighting telescope mounted to an antenna operating at millimeter wave frequencies.
  • FIG. 17 shows a scene as observed from the position of the alignment assurance camera location.
  • FIGS. 18A and 18B show two images of a magnified portion of the scene of FIG. 13 at different times (before and after the antenna has suffered an alignment shift).
  • FIG. 19 is a schematic diagram of an out-of-band signaling system for communicating antenna alignment information to a NOC. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
  • FIGS. 1 to 4 A prototype demonstration of the millimeter-wave transmitter and receiver useful for the present invention is described by reference to FIGS. 1 to 4. With this embodiment the Applicants have demonstrated digital data transmission in the 93 to 97 GHz range at 1.25 Gbps with a bit error rate below 10 "12 .
  • FIG. 1 The circuit diagram for the millimeter-wave transmitter is shown in FIG. 1.
  • Voltage- controlled microwave oscillator 1, Westec Model VTS133/V4 is tuned to transmit at 10 GHz, attenuated by 16 dB with coaxial attenuators 2 and 3, and divided into two channels in two-way power divider 4.
  • a digital modulation signal is pre-amplified in amplifier 7, and mixed with the microwave source power in triple-balanced mixer 5, Pacific Microwave Model M3001HA.
  • the modulated source power is combined with the un-modulated source power through a two-way power combiner 6.
  • a line stretcher 12 in the path of the un-modulated source power controls the depth of modulation of the combined output by adjusting for constructive or destructive phase summation.
  • the amplitude-modulated 10 GHz signal is mixed with a signal from a 85-GHz source oscillator 8 in mixer 9 and high-pass filtered in waveguide filter 13 to reject the 75 GHz image band.
  • the resultant, amplitude-modulated 95 GHz signal contains spectral components between 93 and 97 GHz, assuming unfiltered 1.25 Gbps modulation.
  • a rectangular WR-10 wave guide output of the high pass filter is converted to a circular wave guide 14 and fed to a circular horn 15 of 4 inches diameter, where it is transmitted into free space. The horn projects a half-power beam width of 2.2 degrees.
  • the circuit diagram for the receiver is shown in FIG. 2.
  • the antenna is a circular horn 1 of 6 inches in diameter, fed from a waveguide unit 14R consisting of a circular W- band wave-guide and a circular-to-rectangular wave-guide converter which translates the antenna feed to WR-10 wave-guide which in turn feeds heterodyne receiver module 2R.
  • This module consists of a monolithic millimeter-wave integrated circuit (MMIC) low-noise amplifier spanning 89-99 GHz, a mixer with a two-times frequency multiplier at the LO port, and an IF amplifier covering 5-15 GHz.
  • MMIC millimeter-wave integrated circuit
  • the local oscillator 8R is a cavity-tuned Gunn oscillator operating at 42.0 GHz (Spacek Model GQ410K), feeding the mixer in module R2 through a 6 dB attenuator 7.
  • a bias tee 6 at the local oscillator input supplies DC power to receiver module 2R.
  • a voltage regulator circuit using a National Semiconductor LM317 integrated circuit regulator supplies +3.3V through bias tee 6.
  • An IF output ofthe heterodyne receiver module 2R is filtered at 6- 12 GHz using bandpass filter 3 from K&L Microwave.
  • Receiver 4R that is an HP Herotek Model DTM 180AA diode detector, measures total received power.
  • the voltage output from the diode detector is amplified in two-cascaded microwave amplifiers 5R from MiniCircuits, Model 2FL2000.
  • the baseband output is carried on coax cable to a media converter for conversion to optical fiber, or to a Bit Error-Rate Tester (BERT) IOR.
  • BERT Bit Error-Rate Tester
  • this embodiment has demonstrated a bit-error rate of less than 10 " for digital data transmission at 1.25 Gbps.
  • the BERT measurement unit was a Microwave Logic, Model gigaBERT.
  • the oscilloscope signal for digital data received at 200 Mbps is shown in FIG. 3.
  • oscilloscope bandwidth limitations lead to the rounded bit edges seen in FIG. 4.
  • Digital levels sustained for more than one bit period comprise lower fundamental frequency components (less than 312 MHz) than those which toggle each period (622 MHz), so the modulation transfer function of the oscilloscope, which falls off above 500 MHz, attenuates them less.
  • the link hardware consists of a millimeter-wave transceiver pair including a pair of millimeter- wave antennas and a microwave transceiver pair including a pair of microwave antennas.
  • the millimeter wave transmitter signal is amplitude modulated and single-sideband filtered, and includes a reduced-level carrier.
  • the receiver includes a heterodyne mixer, phase-locked intermediate frequency (IF) tuner, and IF power detector.
  • Millimeter-wave transceiver A (FIGS. 5 A and 5B) transmits at 92.3-93.2 GHz as shown at 60 in FIG. 7 A and receives at 94.1-95.0 GHz as shown at 62
  • millimeter-wave transmitter B (FIGS. 6A and 6B) transmits at 94.1-95.0 GHz as shown at 64 in FIG/ 7B and receives at 92.3-93.2 GHz as shown at 66.
  • transmit power is generated with a cavity-tuned Gunn diode 21 resonating at 93.15 GHz.
  • This power is amplitude modulated using two balanced mixers in an image reject configuration 22, selecting the lower sideband only.
  • the source 21 is modulated at 1.25 Gbps in conjunction with Gigabit-Ethernet standards.
  • the modulating signal is brought in on optical fiber, converted to an electrical signal in media converter 19 (which in this case is an Agilent model HFCT-5912E) and amplified in preamplifier 20.
  • the amplitude- modulated source is filtered in a 900 MHz-wide passband between 92.3 and 93.2 GHz, using a bandpass filter 23 on microstrip.
  • a portion of the source oscillator signal is picked off with coupler 38 and combined with the lower sideband in power combiner 39, resulting in the transmitted spectrum shown at 60 in FIG. 7A.
  • the combined signal propagates with horizontal polarization through a waveguide 24 to one port of an orthomode transducer 25, and on to a four- foot diameter Cassegrain dish antenna 26, where it is transmitted into free space with horizontal polarization.
  • the receiver unit at Station A as shown on FIGS 5B1 and 5B2 is fed from the same Cassegrain antenna 26 as is used by the transmitter, at vertical polarization (orthogonal to that of the transmitter), through the other port of the orthomode transducer 25.
  • the received signal is pre-filtered with bandpass filter 28 A in a passband from 94.1 to 95.0 GHz, to reject back scattered return from the local transmitter.
  • the filtered signal is then amplified with a monolithic MMW integrated- circuit amplifier 29 on indium phosphide, and filtered again in the same passband with bandpass filter 28B.
  • This twice filtered signal is mixed with the transmitter source oscillator 21 using a heterodyne mixer-do wnconverter 30, to an IF frequency of 1.00-1.85 GHz, giving the spectrum shown at 39A in FIG. 7A.
  • a portion ofthe IF signal, picked off with coupler 40, is detected with integrating power detector 35 and fed to an automatic gain control circuit 36.
  • the fixed-level IF output is passed to the next stage as shown in FIG. 5B2.
  • a quadrature-based (I Q) phase-locked synchronous detector circuit 31 is incorporated, locking on the carrier frequency of the remote source oscillator.
  • the loop is controlled with a microprocessor 32 to minimize power in the "Q" channel while verifying power above a set threshold in the "I” channel.
  • Both “I” and “Q” channels are lowpass-filtered at 200 MHz using lowpass filters 33A and 33B, and power is measured in both the “I” and Q channels using square-law diode detectors 34.
  • the baseband mixer 38 output is pre-amplified and fed through a media converter 37, which modulates a laser diode source into a fiber-optic coupler for transition to optical fiber transmission media.
  • transmit power is generated with a cavity-tuned Gunn diode 41 resonating at 94.15 GHz.
  • This power is amplitude modulated using two balanced mixers in an image reject configuration 42, selecting the upper sideband only.
  • the source 41 is modulated at 1.25 Gbps in conjunction with Gigabit-Ethernet standards.
  • the modulating signal is brought in on optical fiber as shown at 80, converted to an electrical signal in media converter 60, and amplified in preamplifier 61.
  • the amplitude-modulated source is filtered in a 900 MHz- wide passband between 94.1 and 95.0 GHz, using a bandpass filter 43 on microstrip.
  • a portion ofthe source oscillator signal is picked off with coupler 48 and combined with the higher sideband in power combiner 49, resulting in the transmitted spectrum shown at 64 in FIG. 7B.
  • the combined signal propagates with vertical polarization through a waveguide 44 to one port of an orthomode transducer 45, and on to a four- foot Cassegrain dish antenna 46, where it is transmitted into free space with vertical polarization.
  • the receiver is fed from the same Cassegrain antenna 46 as the transmitter, at horizontal polarization (orthogonal to that ofthe transmitter), through the other port of the orthomode transducer 45.
  • the received signal is filtered with bandpass filter 47 A in a passband from 92.3 to 93.2 GHz, to reject backscattered return from the local transmitter.
  • the filtered signal is then amplified with a monolithic MMW integrated- circuit amplifier on indium phosphide 48, and filtered again in the same passband with bandpass filter 47B.
  • This twice filtered signal is mixed with the transmitter source oscillator 41 using a heterodyne mixer-downconverter 50, to an IF frequency of 1.00-1.85 GHz, giving the spectrum shown at 39B in FIG. 7B.
  • the fixed-level IF output is passed to the next stage as shown on FIG. 6B2.
  • a quadrature-based (I/Q) phase-locked synchronous detector circuit 51 is inco ⁇ orated, locking on the carrier frequency of the remote source oscillator.
  • the loop is controlled with a microprocessor 52 to minimize power in the "Q” channel while verifying power above a set threshold in the "I” channel.
  • Both "I” and “Q” channels are lowpass-filtered at 200 MHz using a bandpass filters 53A and 53B, and power is measured in each channel using a square- law diode detector 54.
  • the baseband mixer 58 output is pre-amplified and fed through a media converter 57, which modulates a laser diode source into a fiber-optic coupler for transition to optical fiber transmission media.
  • a dish antenna of four- foot diameter projects a half-power beam width of about 0.15 degrees at 94 GHz.
  • the full-power beamwidth (to first nulls in antenna pattern) is narrower than 0.45 degrees. This suggests that about 800 independent beams could be projected azimuthally around an equator from a single transmitter location, without mutual interference, from an array of 4-foot dishes.
  • two receivers placed 400 feet apart can receive independent data channels from the same transmitter location.
  • two receivers in a single location can discriminate independent data channels from two transmitters ten miles away, even when the transmitters are as close as 400 feet apart. Larger dishes can be used for even more directivity.
  • a communication beam having a half-power beam width of only about 0..15 degrees requires an extremely stable antenna support.
  • Prior art antenna towers such as those used for microwave communication typically are designed for angular stability of about 0.6 to 1.1 degrees or more. Therefore, the present invention requires much better control of beam direction.
  • the receiving antenna should be located at all times within the half power foot print ofthe transmitted beam. At 10 miles the half power footprint of a 0.15 -degree beam is about 150 feet.
  • the support for the transmitter antenna should be rigid enough so that the beam direction does not change enough so that the receiving transceiver antenna is outside the half- power footprint.
  • the transmitting antenna should be directionally stable to within +/- 0.09 degrees.
  • This rigid support of the antenna not only assures continued communication between the two transceivers as designed but the narrow beam widths and rigid antenna support reduces the possibility of interference with any nearby links operating in the same spectral band.
  • FIG. 10 shows the effect of a 0.74-degree deflection of a 0.36-degree beam.
  • the 0.74 degree deflection moves the beam axis 682 feet at 10 miles so that the receive antenna is clearly outside the beam 332 foot half power footprint. This angular variation would almost certainly disrupt communication between the millimeter wave links described above. However, similar calculations made for a solidly mounted 24-inch diameter, 40 feet tall hollow carbon steel monopole tower shows that the deflection in a 90 mile per hour wind would be only 0.11 degrees. This structure is shown in FIG 10.
  • the 24-inch tube 700 supports radome 720 enclosing antenna 740, antenna mount 760 and transceiver 750.
  • Flange 710 is welded to the bottom of tube 700 and is bolted with bolts 800 encased in reinforced concrete base 820 which is buried mostly below ground level 730.
  • antennas of about 2 feet diameter are mounted on solidly mounted reinforced concrete monopole towers having heights of 40 feet or less as shown in FIG. 9.
  • antennas could be rigidly mounted on the side or top of stable buildings. Steel trussed towers could be used or monopoles with high tension guide wires. In each case however the designer should determine using reliable codes or actual testing that these alternate supports are adequate to maintain the needed directional stability.
  • a backup communication link is provided which automatically goes into action whenever a predetermined drop-off in quality transmission is detected.
  • a preferred backup system is a microwave transceiver pair operating in the 10.7-11.7 GHz band. This frequency band is already allocated by the FCC for fixed point-to- point operation. FCC service rules parcel the band into channels of 40-MHz maximum bandwidth, limiting the maximum data rate for digital transmissions to 45 Mbps full duplex.
  • Transceivers offering this data rate within this band are available off-the-shelf from vendors such as Western Multiplex Co ⁇ oration (Models Lynx DS- 3, Tsunami 100BaseT), and DMC Stratex Networks (Model DXR700 and Altium 155).
  • the digital radios are licensed under FCC Part 101 regulations.
  • the microwave antennas are Cassegrain dish antennas of 24-inch diameter. At this diameter, the half- power beamwidth of the dish antenna is 3.0 degrees, and the full-power beamwidth is 7.4 degrees, so the risk of interference is higher than for MMW antennas. To compensate this, the FCC allocates twelve separate transmit and twelve separate receive channels for spectrum coordination within the 10.7-11.7 GHz band. Sensing of a millimeter wave link failure and switching to redundant microwave channel is an existing automated feature of the network routing switching hardware available off-the-shelf from vendors such as Cisco, Foundry Networks and Juniper Networks.
  • the narrow antenna beam widths afforded at millimeter-wave frequencies allow for geographical portioning of the airwaves, which is impossible at lower frequencies. This fact eliminates the need for band parceling (frequency sharing), and so enables wireless communications over a much larger bandwidth, and thus at much higher data rates, than were ever previously possible at lower RF frequencies.
  • An preferred antenna for long-range communication at frequencies above 70 GHz has gain in excess of 50 dB, 100 times higher than direct-broadcast satellite dishes for the home, and 30 times higher than high-resolution weather radar antennas on aircraft.
  • antennas with dB gains of 40 to 45 may be preferred.
  • the prime-focus antenna places the receiver directly at the focus of the parabola.
  • the Cassegrainian antenna places a convex hyperboloidal secondary reflector in front of the focus to reflect the focus back through an aperture in the primary to allow mounting the receiver behind the dish. (This is convenient since the dish is typically supported from behind as well.)
  • the Gregorian antenna is similar to the Cassegrainian antenna, except that the secondary mirror is a concave ellipsoid placed in back of the parabola's focus. An offset parabola rotates the focus away from the center of the dish for less aperture blockage and improved mounting geometry.
  • Cassegrainian, prime focus, and offset parabolic antennas are the preferred dish geometries for the MMW communication system.
  • a preferred primary dish reflector is a conductive parabola.
  • the preferred surface tolerance on the dish is about 15 thousandths of an inch (15 mils) for applications below 40 GHz, but closer to 5 mils for use at 94 GHz.
  • Typical hydroformed aluminum dishes give 15 -mil surface tolerances, although double-skinned laminates (using two aluminum layers surrounding a spacer layer) could improve this to 5 mils.
  • the secondary reflector in the Cassegrainian geometry is a small, machined aluminum "lollipop" which can be made to 1-mil tolerance without difficulty.
  • Mounts for secondary reflectors and receiver waveguide horns preferably comprise mechanical fine-tuning adjustment for in-situ alignment on an antenna test range.
  • a flat-panel slot array antenna such as that described by one ofthe present inventors and others in U.S. Patent No. 6,037,908, issued 14 March 2000 which is hereby inco ⁇ orated herein by reference.
  • That antenna is a planar phased array antenna propagating a traveling wave through the radiating aperture in a transverse electromagnetic (TEM) mode.
  • a communications antenna would comprise a variant of that antenna inco ⁇ orating the planar phased array, but eliminating the frequency-scanning characteristics of the antenna in the prior art by adding a hybrid traveling-wave/co ⁇ orate feed.
  • Flat plates holding a 5-mil surface tolerance are substantially cheaper and easier to fabricate than parabolic surfaces.
  • Planar slot arrays utilize circuit-board processing techniques (e.g. photolithography), which are inherently very precise, rather than expensive high- precision machining.
  • Pointing a high-gain antenna requires coarse and fine positioning. Coarse positioning can be accomplished initially using a visual sight such as a bore-sighted rifle scope or laser pointer. The antenna is locked in its final coarse position prior to fine-tuning. The fine adjustment is performed with the remote transmitter turned on. A power meter connected to the receiver is monitored for maximum power as the fine positioner is adjusted and locked down. At gain levels above 50 dB, wind loading and tower or building flexure can cause an unacceptable level of beam wander. A flimsy antenna mount could not only result in loss of service to a wireless customer; it could inadvertently cause interference with other licensed beam paths. In order to maintain transmission only within a specific "pipe,” some method for electronic beam steering may be required.
  • Phased-array beam combining from several ports in the flat-panel phased array could steer the beam over many antenna beam widths without mechanically rotating the antenna itself.
  • Sum-and-difference phase combining in a mono-pulse receiver configuration locates and locks on the proper "pipe.”
  • a rotating, slightly unbalanced secondary (“conical scan") could mechanically steer the beam without moving the large primary dish.
  • a multi-aperture e.g. quad-cell floating focus could be used with a selectable switching array.
  • beam tracking is based upon maximizing signal power into the receiver.
  • the common aperture for the receiver and transmitter ensures that the transmitter, as well as the receiver, is correctly pointed.
  • FIG. 8 is a map layout of a proposed application of the present invention. This map depicts a sparsely populated section of the island, Maui in Hawaii. Shown are communication facility 70 which is connected to a major communication trunk line from a communication company's central office 71, a technology park 72 located about 2 miles from facility 70, a relay station 76 located about 6 miles from facility 70 and four large ocean-front hotels 78 located about 3 miles from relay station 76. Also shown is a mountaintop observatory 80 located 13 miles from facility 70 and a radio antenna tower 79 located 10 miles from facility 70. As indicated in FIG. 8, the angular separation between the radio antenna and the relay station is only 4.7 degrees.
  • type-A transceiver units are positioned at facility 70, each comprising a transmitter and receiver unit as described in FIGS. 5A and 5B. These units are directed at corresponding type-B transceiver units positioned at the technology park, the relay station, the observatory, and the radio tower. Millimeter wave transceiver units with back-up microwave units as described above are also located at the hotels and are in communication with corresponding units at the relay station. In a preferred embodiment the 1.25 GHz spectrum is divided among the four hotels so that only one link needs to be provided between facility 70 and relay station 76. This system can be installed and operating within a period of about one month and providing the most modern communication links to these relatively isolated facilities. The cost of the system is a very small fraction of the cost of providing fiber optic links offering similar service.
  • the microwave backup links operate at approximately eight times lower frequency (8 times longer wavelength) than the millimeter wave link.
  • the microwave antennas have broader beam widths than the millimeter-wave antennas, again wider by about 8 times.
  • a typical beam width from a 2-foot antenna is about 7.5 degrees. This angle is wider than the angular separation of four service customers (hotels) from the relay tower and it is wider than the angular separation of the beam between the relay station and the radio antenna.
  • the minimum angular separation between hotels from the relay station is 1.9 degrees.
  • the angular separation between receivers at radio antenna tower 79 and relay station 76 is 4.7 degrees as seen from a transmitter at facility 70.
  • these microwave beams cannot be separated spatially; however, the FCC Part 101 licensing rules mandate the use of twelve separate transmit and twelve separate receive channels within the microwave 10.7 to 11.7 GHz band, so these microwave beams can be separated spectrally.
  • the FCC sponsored frequency coordination between the links to individual hotels and between the links to the relay station and the radio antenna will guarantee non-interference, but at a much reduced data rate.
  • the FCC has appointed a Band Manager, who oversees the combined spatial and frequency coordination during the licensing process.
  • FIG. 11 shows how narrow a beam is when produced by a diffraction-limited 4 foot diameter antenna operating at 94 GHz.
  • An 8-degree by 8-degree field of view is indicated by the surrounding square 170.
  • the tiny circles, which are less than 0.15 degrees in diameter correspond to the full-width, half-maximum power beam-width produced by a diffraction-limited 4 foot diameter antenna operating at 94 GHz i.e. 94 GHz beam-width 174.
  • the larger circles 178 (a little larger than 2 degrees) indicate the full-width, half-maximum power beam-width produced by a diffraction-limited 4-foot diameter antenna operating at 5.8 GHz.
  • the corresponding FWHM footprint of a 0.15-degree beam is 40 meters (140 feet) at sixteen kilometers (ten miles) compared to a footprint of 560 meters (1800 feet) at ten miles for a 2- degree beam.
  • a simple method of establishing such a co-alignment is to use the signal from one antenna as an alignment aid for its companion antenna. With relatively broad beams, such as a 5.8 GHz beams, this simple method of co-alignment can work. However, this simple method does not work well when applied to narrow millimeter wave beams emanating from large aperture antennas.
  • One major problem with aligning two very narrow beam antennas is that one of the antennas has to be approximately aligned first before the second antenna can use the first antenna's signal as an alignment aid.
  • FIGS. 12A and 12B diagrammatically show how a signaling device is used to aid in the preliminary alignment of the telecommunications link.
  • FIG. 12A shows a first installer 220 near a first antenna 222 (e.g. corresponding to location 70 of FIG. 8) holding a first rescue signaling mirror 224 available from Outback Gear, Niles, OH, an example of a signaling device.
  • First rescue signaling mirror 224 reflects sunlight 229 toward second antenna 232 (e.g. corresponding to location 76 of FIG. 8).
  • Second installer 230 looks through a second sighting scope 238 that has been previously aligned with the beam axis of second antenna 232.
  • Second installer 230 adjusts second mount 235 of second antenna 232 to point second sighting scope 238, and thereby also second antenna 232, toward first rescue signaling mirror 224.
  • These little mirrors (about 2 inches by 3 inches) produce narrow beams (but with relatively large footprints at a distances of 10 miles), and the installers can scan the beams so the reflected sun light covers a large enough range to easily encompass the opposite antenna location.
  • the signaling mirror's output is easily distinguishable against the background light because the beam's brightness is essentially equal to the sun's brightness (though the signaling mirror's angular extent is much smaller).
  • FIG. 12B shows second installer 230 near second antenna 232 holding a second rescue signaling mirror 234.
  • Second rescue signaling mirror 234 reflects sunlight 239 toward first antenna 222.
  • First installer 220 looks through a first sighting scope 228 that has been previously aligned with the beam axis of first antenna 222.
  • First installer 220 adjusts a first mount 225 of first antenna 222 to point first sighting scope 228, and thereby also first antenna 222, toward second rescue signaling mirror 234.
  • pre-alignment After pre-alignment with signaling mirrors has been performed, the antennas are aligned to within about 1 degree or better. With such an optical pre-alignment a large reduction in the alignment search space has been accomplished. Instead of an 8 degree by 8 degree (for antenna one) by 8 degree by 8 degree (for antenna two) 15 year search, the problem is reduced to a 4-dimensional 1 degree search. In other words, the search space has been reduced by a factor of 8 4 (4096). (An alternative to the reflecting mirror, pre-alignment can also be accomplished using a narrow beam light source such as a searchlight or laser. In this case it may be desirable to do the pre-alignment in the early evening or at night.
  • the first side lobes will contain 13 dB to 40 dB less power than the primary beam (the smaller diminution corresponds to a uniformly illuminated aperture while the greater reduction corresponds to a very tapered illumination).
  • the antennas are not even looking at each other's first side lobe, but rather at a second, third or still higher order side lobe.
  • the amount of power transferred between two antennas pre-aligned to a seemingly accurate 1 -degree level of precision is likely several orders of magnitude smaller than for a well-aligned pair.
  • FIG. 13 is a simplified schematic of an alignment system comprising a Gunn oscillator power source 310 and a millimeter- wave power detector 320.
  • Gunn oscillator power source 310 and millimeter-wave power detector 320 replace the radio transceiver pairs illustrated in FIGS. 5 and 6 during the alignment procedure.
  • Gunn oscillator power source 310 and millimeter- wave power detector 320 are attached to antennas 26 and 46 as shown in FIG. 13. By comparison with the radios that the power source and the power detector replace, the later are much more sensitive and have much greater dynamic range.
  • the Gunn oscillator 310 uses a gallium arsenide diode as its millimeter-wave power source and is available, for example, from Spacek Labs Santa Barbara, California.
  • the Gunn oscillator 310 benefits by a factor of 2 in power (3 dB) on average compared to a radio by virtue of the fact that it is always turned on.
  • the Gunn oscillator benefits by a factor of 5 in power (7 dB) compared to a radio because the Gunn oscillator does not have to suffer the conversion loss of the modulator.
  • the Gunn oscillator can contribute about a factor of 10 (10 dB) improvement in sensitivity relative to radio sets.
  • FIG. 14 is a schematic ofthe millimeter-wave power detector.
  • a first low noise amplifier (LNA) 410 available, for example, from HRL Malibu, California, amplifies a signal received by antenna 46 (FIG. 13) then sends the amplified signal to a bandpass filter 420, with about 1 GHz bandwidth (centered at millimeter-wave frequency ofthe Gunn oscillator 310) available, for example, from Quinstar Torrance, California.
  • LNA low noise amplifier
  • the twice amplified and once filtered signal is then converted by detector diode and integrating capacitor 440 to a voltage that is proportional to the original millimeter-wave signal power detected with a detector diode, available, for example as Model HP 9161, from Hewlett-Packard Santa Rosa, California.
  • a post detection "integrating" capacitor is used which can result in overall bandwidth as narrow as 10 MHz or even as narrow as 1 kHz.
  • the improvement stems from the ability to narrow the bandwidth (and hence noise power) of the detector. This is possible since we are only interested in detecting and measuring power in the case of aligning a link as contrasted with the requirements that prevail when sending data at extraordinarily high data rates.
  • An additional aid provided by the alignment system of FIG. 13 is the audio output device 330 that allows hands-free and eyes-free adjustments to a given antenna while the installer listens for improvements in the link alignment.
  • a voltage proportional to the detected power level is generated in the millimeter wave detector 320 and sent to the voltage controlled oscillator (VCO) 332.
  • the oscillating output of VCO 332 is amplified by amplifier 334 then converted from electrical signal to auditory signal by speaker 336.
  • FIG. 13 shows a visual feedback by means of the voltage meter 340.
  • the voltage meter 340 is useful for making comparison of power over relatively longer time frames, say minutes or longer, while the audio output device 330 is more useful for making comparisons of power over relatively shorter time frames such a few seconds or less. Therefore, both methods of feedback are useful and desirable.
  • FIGS. 15A and B describe a preferred alignment method.
  • FIG. 15A illustrates the positions of a power source A 510 and a power detector A 520 relative to first antenna 26 and second antenna 46 during the fine alignment procedure for the second antenna 46.
  • a first installer 517 turns on power source A 510.
  • the emitted power is directed toward second antenna 46 as a result of the prior preliminary alignment that was performed with the aid of signaling mirrors.
  • a second installer 527 monitors the power detected by power detector A 520 while making small angular perturbations on the second antenna. Due to the prior preliminary alignment of both antennas, and the enhanced sensitivity of the alignment aids, the power detector A 520 is assured of receiving sufficient signal immediately upon initiating this fine alignment procedure. In other words, the second installer does not need to do any angular scan searching to acquire the signal. It is instantly on. The acquired signal has sufficient strength to be readily distinguished from background noise.
  • Second installer 527 continues to monitor the power detected by power detector A 520 while using small angular perturbations on the second antenna 46 to increase the strength of the received signal. Angular perturbations are continued along one axis until a maximum received signal is found. Then angular perturbations are performed along the other axis until a new, and larger, maximum received signal is found. This procedure is repeated, alternating between the two axes until a global maximum is found which corresponds to the best alignment orientation for second antenna 46. Once the orientation has been optimized for second antenna 46 it is time for aligning first antenna 26.
  • FIG. 15B illustrates the positions of a power source B 560 and a power detector B 570 relative to first antenna 26 and second antenna 46 during the fine alignment procedure for the first antenna 46.
  • first installer 517 removes power source A from first antenna 26 and replaces it with power detector B 570. Simultaneous with this removal and replacement a similar procedure is performed at the second antenna 46. Second installer 527 removes power detector A from second antenna 46 and replaces it with power source B 560.
  • Second installer 527 turns on power source B 560.
  • the emitted power is directed toward first antenna 515 as a result of the fine alignment just performed.
  • First installer 517 monitors the power detected by power detector B 570 while using small angular perturbations on the first antenna 26 to increase the strength of the received signal. Angular perturbations are continued along one axis until a maximum received signal is found. Then angular perturbations are performed along the other axis until a new, and larger, maximum received signal is found. This procedure is repeated, alternating between the two axes until a global maximum is found which corresponds to the best alignment orientation for first antenna 26.
  • an installation team could align both antennas while using only one set of power source and power detector (e.g. Set A comprising power source A and power detector A). This may seem a good way to minimize equipment cost for the installation team. There are at least two ways this could be done.
  • the first half of the procedure (alignment of second antenna 46) would be identical with the procedure described above. Then to align the first antenna 26, the installation team could use cell phones to talk information from the power detector A 520 over to first installer 517 during the second half of the procedure (alignment of first antenna 26).
  • This procedure has been performed by the inventors, but is deemed awkward due the need for the second installer 527 to read meter 340 and speak via a cell phone to the first installer 517. This feedback mechanism is less desirable due to time delays and errors involved in the process.
  • power source A and power detector A can be used for the second half of the procedure (alignment of first antenna 515) as well as for the first half of the procedure (alignment of second antenna 46).
  • this would necessitate and additional step of transporting the equipment a potentially long distance (up to 10 miles or more) to swap the locations of these alignment aids.
  • Such a swap would overcome the feedback awkwardness just described for the first case alternative procedure, but the labor time cost of such a step is substantial and therefore should be avoided.
  • FIG. 16 shows an alignment assurance camera 200 mounted to a sighting telescope 210 mounted to an antenna 220 operating at millimeter wave frequencies.
  • Sighting telescope 210 and alignment assurance camera 200 are rigidly mounted to antenna 220 so that a disturbance in the orientation of the axis of antenna 220 produces the same effect on the alignment of sighting telescope 210.
  • Alignment assurance camera 200 can operate in the visual band or in the infrared. For the pu ⁇ oses of monitoring during the night, infrared enhancement is preferred and can be provided at low cost by a wide variety of silicon-based CCD cameras or by newer silicon-based CMOS cameras. In some installations it may be desirable to use an image-intensified camera to assure that distinct images are received even during darkness.
  • Sighting telescope 210 can be, for example, a Model SPS20X40RD, with a fixed power 20 times magnification, objective diameter equal to 40mm and a field of view of 1.5 degrees, available from BSA Optics, Ft. Lauderdale, FL.
  • the alignment assurance camera 200 can be, for example, a Model XCam2 available from XlO Wireless Technology, Inc. Seattle, WA.
  • the XCam2 with XRay Vision software allows the user to transmit live color video to a computer and send digital snapshots to any remote computer via the Internet.
  • the software can be set (locally or remotely) to update new images every 10 seconds or every 2 hours.
  • the software can also be set to have the camera take a snapshot only if it detects motion either within the image or a shift of the entire image.
  • the NOC operators can use a remote viewer on their local computer or they can have the software update a web site with new images or email the images to the NOC or elsewhere.
  • FIG. 17 shows a scene as observed from the position of the alignment assurance camera location.
  • sighting telescope 210 will be aligned parallel with the axis of antenna 220 and therefore be useful not only be useful for alignment assurance but also useful in the process of the initial alignment itself.
  • the primary pu ⁇ ose ofthe alignment assurance system is for the ongoing monitoring of alignment and the aiding in rapid reacquisition of alignment should realignment be needed.
  • the sighting telescope 210 may be desirable or even necessary, for the sighting telescope 210 to point in a direction other than directly toward the antenna at the other end of the data link (i.e. companion antenna).
  • a primary reason this may be the case is that what is most important for the ongoing maintenance ofthe orientation ofthe antenna direction is a clear and distinct image be monitored by alignment assurance camera 200.
  • a clear and distinct image may be difficult to obtain in the direction pointing directly toward the companion antenna.
  • the companion antenna may be sighted on the top of a mountain in an area often obscured by clouds.
  • FIGS. 18A and 18B show two images of a magnified portion of the scene of FIG. 17 at different times (before and after the antenna has suffered an alignment shift).
  • FIG. 18 A shows an original, antenna-aligned image
  • FIG. 18B indicates a new image after the antenna has been rotated slightly out of alignment.
  • the procedure for assuring proper antenna pointing is very simple.
  • An original digital image is stored that corresponds to the output of alignment assurance camera 200 when the antenna 220 is properly aligned.
  • recent electronic images are constantly acquired by alignment assurance camera 200 and transmitted to a network operations center (NOC) for processing.
  • the recent images are compared with the original image to make sure that the recent images do not show evidence of any shift (which would correspond to a rotation in the mounting of antenna 220).
  • NOC computer can alert the operator that a misalignment has occurred.
  • a non-NOC computer can do the image analysis and alert a repair crew.
  • each of the antennas have their own alignment assurance camera 200 mounted on them. As a result, if one antenna is somehow knocked out of alignment, that particular antenna can be rapidly identified. This is important because if a communication link goes down, it is known that there is a problem with at least one end of the link, but it would not otherwise be known in which end of the link the problem had occurred. With alignment assurance cameras 200 installed at both ends of the link, the culprit end can be rapidly and easily identified.
  • This advanced feature of the instant invention is particularly valuable since the data links herein can be very long, up to 10 miles long or more. With this feature a potentially large repair cost can be avoided. The potentially large repair cost is associated with time delays of repair crews traveling back and forth between the widely separated end points of a communication link just to isolate which end of the link has experienced the disruptive failure.
  • the alignment assurance cameras help repair crews determine if alignment is or is not the cause of the link disruption. Furthermore, if alignment is to blame, the alignment assurance cameras can be used to direct repair crews as to both the direction and extent that realignment needs be done.
  • FIG. 19 is a schematic diagram of an out-of-band signaling system for communicating antenna alignment information to a NOC.
  • An alignment telescope and camera system 510 are mounted to an antenna 505 and send image information to a frame grabber circuit 515 which in turn sends digital image data to a computer 520.
  • computer 520 When the data- link is operating normally, computer 520 then sends image information to a switch/router 530 which then passes the image information via a transceiver 540 and antenna 505 through a network 550 and onward to a NOC 560.
  • Computer 520 is also provided with other transceiver performance data by an electrical diagnostics system 522. This other transceiver performance data is also sent to switch/router 530 which then passes the other transceiver performance data via transceiver 540 and antenna 505 through network 550 and finally to NOC 560.
  • FIG. 15 shows an example of an out-of-band communications system that uses a cell phone network 570.
  • computer 520 sends image information via a modem 572 and cell phone 574 to cell phone network 570 that then passes the image information to NOC 560.
  • computer 520 processes the digital image data from the alignment telescope and camera system 510 to determine if the recent images match the original image as described earlier.
  • computer 520 is again provided with other transceiver performance data by electrical diagnostics system 522. This other transceiver performance data is also sent via modem 572 and cell phone 574 to cell phone network 570 that then passes the image information to NOC 560.
  • any of the several currently-allocated microwave bands, including 5.2-5.9 GHz, 5.9-6.9 GHz, 10.7-11.7 GHz, 17.7-19.7 GHz, and 21.2-23.6 GHz can be utilized for the backup link.
  • the modulation bandwidth of both the MMW and microwave channels can be increased, limited again only by FCC spectrum allocations.
  • any flat, conformal, or shaped antenna capable of transmitting the modulated carrier over the link distance in a means consistent with FCC emissions regulations can be used. Horns, prime focus and offset parabolic dishes, and planar slot arrays are all included.
  • Transmit power may be generated with a Gunn diode source, an injection-locked amplifier or a MMW tube source resonating at the chosen carrier frequency or at any sub-harmonic of that frequency.
  • Source power can be amplitude, frequency or phase modulated using a PIN switch, a mixer or a biphase or continuous phase modulator. Modulation can take the form of simple bi-state AM modulation, or can involve more than two symbol states; e.g. using quantized amplitude modulation (QAM).
  • Double- sideband (DSB), single-sideband (SSB) or vestigial sideband (VSB) techniques can be used to pass, suppress or reduce one AM sideband and thereby affect bandwidth efficiency.
  • Phase or frequency modulation schemes can also be used, including simple FM, bi-phase, or quadrature phase-shift keying (QPSK). Transmission with a full or suppressed carrier can be used. Digital source modulation can be performed at any date rate in bits per second up to eight times the modulation bandwidth in Hertz, using suitable symbol transmission schemes. Analog modulation can also be performed. A monolithic or discrete-component power amplifier can be inco ⁇ orated after the modulator to boost the output power. Linear or circular polarization can be used in any combination with carrier frequencies to provide polarization and frequency diversity between transmitter and receiver channels. A pair of dishes can be used instead of a single dish to provide spatial diversity in a single transceiver as well.
  • QPSK quadrature phase-shift keying
  • the MMW Gunn diode and MMW amplifier can be made on indium phosphide, gallium arsenide, or metamo ⁇ hic InP-on-GaAs.
  • the MMW amplifier can be eliminated completely for short-range links.
  • the detector can be made using silicon or gallium arsenide.
  • the mixer/downconverter can be made on a monolithic integrated circuit or fabricated from discrete mixer diodes on doped silicon, gallium arsenide, or indium phosphide.
  • the phase lock loop can use a microprocessor- controlled quadrature (I/Q) comparator or a scanning filter.
  • the detector can be fabricated on silicon or gallium arsenide, or can comprise a heterostructure diode using indium antimonide.
  • the backup transceivers can use alternate bands 5.9-6.9 GHz, 17.7-19.7 GHz, or 21.2- 23.6 GHz; all of which are covered under FCC Part 101 licensing regulations.
  • the antennas can be Cassegrainian, offset or prime focus dishes, or flat panel slot array antennas, of any size appropriate to achieve suitable gain.

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Abstract

L'invention concerne une liaison de communication sans fil point à point à ondes millimétriques et à très haut débit (de l'ordre du gigabit). Des modes de réalisation préférés permettent d'obtenir un prolongement terrestre. Dans d'autres modes de réalisation, chaque antenne de communication (220) est équipée d'une caméra télescopique (200) connectée à un processeur programmé pour reconnaître des images de paysage. Lesdits processeurs sont programmés pour se souvenir de la forme du paysage, comme il apparaît, lorsque les antennes sont alignées. Chaque caméra (200) affiche ensuite le paysage périodiquement ou continuellement. Si des changements se produisent au niveau de l'affichage, et si ces changements sont supérieurs à une quantité de changement prédéterminée, un signal est envoyé pour indiquer un mauvais alignement. Un opérateur peut ensuite prendre une action corrective ou éventuellement, le système d'antenne peut être configuré pour obtenir un réalignement éloigné ou automatique par rapport au retour de la caméra (200). Dans un mode de réalisation préféré, les antennes sont initialement alignées par le biais de la substitution d'une source d'alimentation d'oscillateur à bande étroite par un système électronique d'émission de signal, associé à une première antenne, et un détecteur de puissance est substitué par le système électronique recevant le signal associé à une seconde antenne.
EP02766896A 2001-05-02 2002-05-01 Liaison de communication a ondes millimetriques Withdrawn EP1391058A4 (fr)

Applications Claiming Priority (25)

Application Number Priority Date Filing Date Title
US41083 1993-04-01
US09/847,629 US6556836B2 (en) 2001-05-02 2001-05-02 Point-to-point, millimeter wave, dual band free space gigabit per second communication link
US847629 2001-05-02
US09/872,621 US20020164959A1 (en) 2001-05-02 2001-06-02 Point-to-point, millimeter wave, free space narrow beam width communication link
US872542 2001-06-02
US872621 2001-06-02
US09/872,542 US20020164958A1 (en) 2001-05-02 2001-06-02 Millimeter wave and copper pair communication link
US882482 2001-06-14
US09/882,482 US6665546B2 (en) 2001-05-02 2001-06-14 High speed, point-to-point, millimeter wave dated communication system
US952591 2001-09-14
US09/952,591 US6714800B2 (en) 2001-05-02 2001-09-14 Cellular telephone system with free space millimeter wave trunk line
US965865 2001-09-28
US09/965,875 US20030022694A1 (en) 2001-05-02 2001-09-28 Communication system with multi-beam communication antenna
US46348 2001-10-25
US10/046,348 US20030027586A1 (en) 2001-05-02 2001-10-25 Wireless communication network with tracking dish antenna
US1617 2001-10-30
US10/001,617 US20020165001A1 (en) 2001-05-02 2001-10-30 Wireless communication network with tracking flat-panel antenna
US09/992,251 US20020164960A1 (en) 2001-05-02 2001-11-13 Conference area network
US992251 2001-11-13
US182 2001-12-01
US10/000,182 US20020164946A1 (en) 2001-05-02 2001-12-01 Conference area network with multibeam antenna
US10/025,127 US20020176139A1 (en) 2001-05-02 2001-12-18 SONET capable millimeter wave communication system
US25127 2001-12-18
US10/041,083 US6611696B2 (en) 2001-05-02 2002-01-05 Method and apparatus for aligning the antennas of a millimeter wave communication link using a narrow band oscillator and a power detector
PCT/US2002/013800 WO2002089357A1 (fr) 2001-05-02 2002-05-01 Liaison de communication a ondes millimetriques

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EP1391058A4 true EP1391058A4 (fr) 2006-01-25

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EP3493323B8 (fr) * 2017-12-04 2022-06-15 Rohde & Schwarz GmbH & Co. KG Système de mesure d'antenne et procédé pour positionner une antenne

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