摘要:
An approach for immediate channel assignment in a wireless communications system involves receiving a channel request message from a wireless transceiver, the channel request message including a dialed party number; forming an immediate assignment message including a channel assignment; transmitting the immediate assignment message to the wireless transceiver; and establishing a communications channel between the wireless transceiver and a called party by establishing a channel between the wireless transceiver and the called party.
摘要:
During multipath fading in a terrestrial digital radio system, off-axis arrival of signals excites higher-order modes in a horn reflector antenna. In the disclosed system specified ones of these higher-order modes and the fundamental mode are allowed to propagate in a main waveguide connected to the antenna. At least one of the higher-order modes is abstracted from the main waveguide and fed to a standby receiver while the fundamental mode is propagated intact to a main receiver.Error occurrences in the fundamental and higher-order modes due to multipath fading are substantially uncorrelated. Hence, upon detecting an error in the signals delivered to the main receiver, the system switches to the standby receiver thereby to provide in a single-antenna a significant improvement in performance against multipath fading.
摘要:
The present invention relates to a hybrid mode waveguide or feedhorn antenna for transforming the TE.sub.11 mode into the HE.sub.11 mode. The waveguide or antenna comprises a first waveguide section of uniform cross-section at the TE.sub.11 mode entrance port which in the antenna arrangement changes to a second section which flares outward toward the antenna mouth, and a spiro-helical projection bonded with a dielectric layer to the inner surface of the waveguide or antenna. The spiro-helical projection comprises a closely spaced helically wound wire structure formed of dielectrically coated wires which in the first section decrease in gauge size in small adjacent portions thereof as the helix progresses away from the TE.sub.11 mode entrance port and in the remainder of the helical projection, the same or decreasing gauge wire in adjacent portions can be used.
摘要:
The present invention relates to a small hybrid mode feed for dual frequency band use. In the present feed, a helically wound wire structure (10) is bonded to the inner surface of a hollow conducting waveguide structure (12) by a layer (14) of low-loss dielectric material having a predetermined thickness to permit a first frequency band to propagate. Embedded in the dielectric layer between the helically wound wire structure and the inner wall of the waveguide is a periodic tuned grid structure (16) disposed at a predetermined depth from the helical wire structure to permit a second frequency band to propagate. The periodic tuned grid structure can comprise, for example, a Jerusalem Cross grid arrangement.
摘要:
A first transmitting device is used to transmit a first signal on a first carrier frequency to a relay device. The relay device receives the signal by demodulating the first carrier frequency. Subsequently, the relay device retransmits the signal by modulating a second and/or a third carrier frequency. The signal is then recovered at one or more receiving devices by demodulating the second and/or third carrier frequencies. Further, a second transmitting device transmits a second signal on a fourth carrier frequency and the relay device retransmits the signal by modulating a fifth and/or a sixth carrier frequency. The signal is then recovered at one or more receiving devices by demodulating the fifth and/or sixth carrier frequencies. The transmitting and/or receiving devices are preferably voice terminals, such as a wireless telephones or data terminals, such as portable computers. The transmitting and/or receiving devices are optionally coupled to a communications network, such as a public switched telephone network or the Internet. The relay device is preferably a multiple beam satellite and/or a ground station covering several distinct geographical regions.
摘要:
A first transmitting device is used to transmit a first signal on a first carrier frequency to a relay device. The relay device receives the signal by demodulating the first carrier frequency. Subsequently, the relay device retransmits the signal by modulating a second and/or a third carrier frequency. The signal is then recovered at one or more receiving devices by demodulating the second and/or third carrier frequencies. Further, a second transmitting device transmits a second signal on a fourth carrier frequency and the relay device retransmits the signal by modulating a fifth and/or a sixth carrier frequency. The signal is then recovered at one or more receiving devices by demodulating the fifth and/or sixth carrier frequencies. The transmitting and/or receiving devices are preferably voice terminals, such as a wireless telephones or data terminals, such as portable computers. The transmitting and/or receiving devices are optionally coupled to a communications network, such as a public switched telephone network or the Internet. The relay device is preferably a multiple beam satellite and/or a ground station covering several distinct geographical regions.
摘要:
A first transmitting device is used to transmit a first signal on a first carrier frequency to a relay device. The relay device receives the signal by demodulating the first carrier frequency. Subsequently, the relay device retransmits the signal by modulating a second and/or a third carrier frequency. The signal is then recovered at one or more receiving devices by demodulating the second and/or third carrier frequencies. Further, a second transmitting device transmits a second signal on a fourth carrier frequency and the relay device retransmits the signal by modulating a fifth and/or a sixth carrier frequency. The signal is then recovered at one or more receiving devices by demodulating the fifth and/or sixth carrier frequencies. The transmitting and/or receiving devices are preferably voice terminals, such as a wireless telephones or data terminals, such as portable computers. The transmitting and/or receiving devices are optionally coupled to a communications network, such as a public switched telephone network or the Internet. The relay device is preferably a multiple beam satellite and/or a ground station covering several distinct geographical regions.
摘要:
In a TDM/TDMA portable radio communications system, a portable handset is compatible for operation in both a frequency-division duplexing (FDD) mode for communication in the licensed portion of the Emerging Technologies frequency band, and in a time-division duplexing (TDD) mode for communication in the unlicensed portion of the Emerging Technologies frequency band. In the FDD mode, different frequencies are used to separate a downlink transmission to a portable from a port from an uplink transmission from a port to a portable. In the TDD mode, uplink and downlink transmissions are separated in different time-slots, but at the same frequency. The handset includes common transmit and receive circuitry that operates at fixed IF frequencies that are separated in frequency by the fixed FDD frequency difference between corresponding uplink and downlink signals. In the FDD mode, therefore, a frequency synthesizer (301), which is used to tune to transmit and receive at different frequencies from different ports, does not have to switch its frequency between transmitting and receiving a burst to and from a single port. In the TDD mode, however, even though uplink and downlink signals are at the same frequency, the synthesizer is switched in frequency between transmitting uplink and receiving downlink.
摘要:
A mode coupler for vertically polarized modes comprises a first waveguide (32) having a relatively small rectangular cross-section and a second waveguide (22) having a relatively large rectangular cross-section. The first small cross-section waveguide has a wall (300) formed in common with a portion (400) of a wall (200) of the second large cross-section waveguide. The common wall portion contains a series of circular apertures (202) extending in a longitudinal direction of both waveguides. The centers of the apertures are displaced a first distance (.tau..sub.1) from a center line of a wall of the first waveguide and a second distance (.tau..sub.2) from a center line of the wall of the second waveguide. In this case, a fundamental TE.sub.01S mode of the first waveguide is in phase synchronism and couples equally to the two degenerate TE.sub.11L and TM.sub.11L higher order vertically polarized modes of the second waveguide.