Patent Application
20100060520
The present invention generally relates to a receiver device, and more particularly, a receiver device that receives multiple signals transmitted at substantially the same frequency.
Generally, vehicles can be equipped with satellite radio receivers as an alternative to, or in combination with, common traditional terrestrial radio receivers. Additionally, satellite radio receivers can be used in places other than vehicles, such as handheld devices. Generally, satellite radio systems are designed, such that the receiver receives a satellite radio frequency (RF) signal from a satellite and a terrestrial RF signal from a terrestrial repeater or a transponder, which typically provides system redundancy.
The current systems in operation in the U.S. generally use double redundant information to enable high signal availability to receivers. These systems typically use time and spatial redundancy for the satellite signals, such that the signal is transmitted from two sources. Typically, in urban areas, terrestrial repeaters can provide a third signal source. Generally, such systems use different frequencies for the satellite signal and the terrestrial repeater signal. This architecture generally reduces the bandwidth efficiency of the system by one-third (⅓), while increasing overall availability.
Due to current European regulations, the European satellite radio system currently has twenty-three (23) contiguous frequencies across a forty megahertz (40 MHz) frequency band. Generally, there are seven (7) frequencies that are designated for hybrid systems only, which include the transmission of the satellite RF signal and the terrestrial RF signal. Typically, the current European satellite radio system is constrained to frequency bandwidths of 1.712 MHz.
With multiple satellites, it can be a problem to receive signals from one satellite and then receive signals from another satellite at the same frequency due to the differing locations of the satellites with respect to the receiver. One exemplary system generally includes a receiver having an antenna element that receives signals at the same frequency, wherein the antenna element has a very high gain (e.g., beam steered). By including such a high gain antenna element, the signals can be separated, along with polarization. Typically, such an exemplary system transmits satellite television signals that are received by the antenna element.
According to one aspect of the present invention, a receiver device includes at least one antenna element and circuitry in communication with the at least one antenna element. The at least one antenna element is configured to receive at least a first signal having a first polarization and a second signal having a second polarization, wherein the first polarization is different than the second polarization. The circuitry is configured to process and emit an output based upon at least one of the received first and second signals, wherein the first signal is received at a reception elevation angle with respect to the at least one antenna element that is greater than a reception elevation angle of the second signal with respect to the at least one antenna element, and the first and second signals are transmitted at substantially the same frequency.
According to another aspect of the present invention, a receiver device includes at least one antenna element and circuitry in communication with the at least one antenna element. The at least one antenna element is configured to receive at least a first signal that is one of right hand circularly polarized (RHCP) and left hand circularly polarized (LHCP), and a second signal that is the other of RHCP and LHCP, wherein at least one of the antenna elements is an omni directional antenna element without beam steering capabilities. The circuitry is configured to process and emit an output based upon at least one of the received first and second signals, wherein the first signal is transmitted from a first satellite having a first reception elevation angle with respect to the at least one antenna element that is greater than a second reception elevation angle of a satellite transmitting the second signal, and the first and second signals are transmitted at substantially the same frequency.
According to yet another aspect of the present invention, a method of receiving a plurality of signals includes the steps of receiving a first signal having a first polarization by at least one antenna element, and receiving a second signal having a second polarization that is different than the first polarization, wherein the first signal is received at a first reception elevation angle with respect to the at least one antenna element that is greater than a second reception elevation angle of the second signal with respect to the at least one antenna element. The method further includes the step of emitting an output based upon at least one of the received first and second signals, wherein the first and second signals are transmitted at substantially the same frequency.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
In regards to
According to one embodiment, the first and second signals are transmitted by a transmitter 14, such that the first signal is received and re-transmitted by a first satellite 16A, and the second signal is received and re-transmitted by a second satellite 16B (i.e., rising and/or falling satellite). With respect to
In regards to
The receiver device 12 can further include a polarization selector 24 in communication with the antenna element A1. Typically, the polarization selector 24 alters the polarization of the antenna element A1, such that the antenna element A1 is adapted to receive either the first signal having the first polarization or the second signal having the second polarization. By way of explanation and not limitation, the polarization selector 24 can select the polarization of the antenna element A1 based upon the content desired by a user of the receiver device 12, such that the output varies based upon whether the first or second signal is received.
According to one embodiment, the first polarization is one of right hand circular polarization (RHCP) and left hand circular polarization (LHCP), and the second polarization is the other of RHCP and LHCP. However, it should be appreciated by those skilled in the art that other suitable polarizations can be implemented so long as the at least one antenna element (A1,A2, . . . AN) can be configured to cross-polarize reject at least one of the first and second signals when it is desired to receive only one of the first and second signals.
Additionally, the receiver device 12 can include at least one down converter 26 and at least one analog-to-digital (A/D) converter 28. Typically, the down converter 26 down converts or reduces a frequency of a radio frequency (RF) signal that is received by the antenna element A1 to a lower frequency for transmission through the receiver device 12, and the A/D converter 28 converts the analog signal received by the antenna element A1 to a digital signal. The receiver device can further include a demodulator 30 in communication with the A/D converter 28 that is configured to demodulate the signal received by the antenna element A1. Further, a decoder 32 can be in communication with the demodulator 30 and be configured to decode an output received from the demodulator 30, and a source decoder 34 can receive and decode an output of the decoder 32, such that the output 22 is emitted based upon the signal received by the antenna element A1.
With respect to
The receiver device 12′ can include circuitry 20′ that processes the received one or more signals and emits the output 22, according to one embodiment. The first signal having the first polarization can be communicated from the first antenna element A1′ to a first down converter 26A, and to a first A/D converter 28A. Additionally, the second signal having the second polarization received by the second antenna element A2′ is communicated from the second antenna element A2′ to a second down converter 26B and a second A/D converter 28B. The receiver device 12′ can include a combiner 36 that receives the outputs from the first A/D converter 28A and the second A/D converter 28B.
According to one embodiment, the combiner 36 is a multiple-input and multiple-output (MIMO) combiner. Typically, the use of the MIMO combiner 36 results in multiple antennas being used to transmit the first and second signals and multiple antennas being used to receive the first and second signals. In such an embodiment, the use of the MIMO combiner 36 requires the data transmitted in the first and second signals to be precoded, spatially multiplexed, and diversity coded. Typically, when the first and second signals are precoded, the first and second signals are formed to increase the signal gain from constructive combining reduced multipath fading effects. The first and second signals are spatially multiplexed such that the high rate signals split into multiple lower rate streams, wherein each stream is transmitted into multiple lower rate streams, and each stream is transmitted from a different transmitted antenna into the same frequency channel. Thus, the first antenna element A1′ and second antenna element A2′ can be configured to receive the first and second signals having different polarizations, respectively, substantially simultaneous, and the MIMO combiner 36 can be configured to combine each of the satellite signals so that the output 22 can be emitted. The receiver device 12′ can also include the demodulator 30, the decoder 32, and the source decoder 34.
With respect to
Typically, the first satellite 16A having the greater elevation angle with respect to the at least one antenna element (A1,A2, . . . AN) transmits the high priority data, and the second satellite 16B having the lower elevation angle with respect to the at least one antenna element (A1,A2, . . . AN) transmits the low priority data. The first antenna element A1,A1′ can have good cross-polarization rejection and higher gain due to the first signal having a different polarization and the reception elevation angle, and thus, the second single can be transmitted by the rising and/or falling second satellite 16B,16B′, wherein the first and second signals have minimal interference with one another.
According to one embodiment, the first and second signals are broadcast or transmitted substantially simultaneously at substantially the same frequency. Thus, communications system 10 communicates additional data, while minimizing the frequency spectrum that is being occupied when compared to a communications system that transmits the high priority data and low priority data at different frequencies. It should be appreciated by those skilled in the art that the substantially the same frequency can be a single frequency or range of frequencies.
In regards to
However, if it is determined at decision step 104 that both the first and second signals can be received substantially simultaneously, then the method 100 proceeds to step 114. At step 114, both the first and second signals are received. At step 116, the received first and second signals are combined, and an output is emitted at step 110 based upon the combined first and second signals. The method 100 then ends at step 112.
By way of explanation and not limitation, the receiver device 12,12′ can be used with a vehicle 38 (
Advantageously, the receiver device 12,12′ and method 100 can receive the data transmitted in the first signal and the data transmitted in the second signal to enhance the output 22 without increasing the frequencies of the frequency spectrum that are being used by the communications system 10. Further, by using the second satellite 16B to transmit the second signal, which typically transmits the lower priority data, the user obtains the benefit of receiving the data transmitted in the second signal, wherein the second satellite 16B would otherwise be turned off due to the orbital location of the second satellite 16B in the orbital path 18. It should be appreciated by those skilled in the art that there may be additional or alternative advantages of the communications system 10 and method 100. It should further be appreciated by those skilled in the art that the above elements of the communications system 10 and receiver device 12,12′ can be combined in alternative ways.
The above description is considered that of preferred embodiments only. Modifications of the invention will occur to those skilled in the art and to those who make or use the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and not intended to limit the scope of the invention, which is defined by the following claims, as interpreted according to the principles of patent law, including the doctrine of equivalents.
