U.S. patent application number 15/155860 was filed with the patent office on 2017-01-26 for systems and methods for selecting digital content channels using low noise block converters including digital channelizer switches.
The applicant listed for this patent is Entropic Communications, LLC. Invention is credited to Tommy Yu.
Application Number | 20170026059 15/155860 |
Document ID | / |
Family ID | 46516416 |
Filed Date | 2017-01-26 |
United States Patent
Application |
20170026059 |
Kind Code |
A1 |
Yu; Tommy |
January 26, 2017 |
SYSTEMS AND METHODS FOR SELECTING DIGITAL CONTENT CHANNELS USING
LOW NOISE BLOCK CONVERTERS INCLUDING DIGITAL CHANNELIZER
SWITCHES
Abstract
Systems and methods in accordance with embodiments of the
invention include converting satellite signals to an intermediate
frequency signal for content decoding, and selecting modulated
digital data within the satellite signals for content decoding
using digital signal processing. One embodiment includes a system
configured to select at least one content channel from an input
signal including a plurality of content channels modulated onto a
carrier, the system including: a digital channelizer switch
including: a high speed analog to digital converter configured to
digitize an intermediate frequency signal; a digital channelizer
configured to digitally tune a content channel from the digitized
intermediate frequency signal; and a high speed digital to analog
converter configured to generate an analog output signal using the
content channel digitally tuned from the digitized intermediate
frequency signal by the digital channelizer.
Inventors: |
Yu; Tommy; (Orange,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Entropic Communications, LLC |
Carlsbad |
CA |
US |
|
|
Family ID: |
46516416 |
Appl. No.: |
15/155860 |
Filed: |
May 16, 2016 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13355413 |
Jan 20, 2012 |
9344262 |
|
|
15155860 |
|
|
|
|
61435119 |
Jan 21, 2011 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 5/06 20130101; H04B
1/16 20130101; H04B 7/18513 20130101; H04B 1/001 20130101; H04L
27/2634 20130101 |
International
Class: |
H04B 1/00 20060101
H04B001/00; H04L 27/26 20060101 H04L027/26; H04B 7/185 20060101
H04B007/185; H04B 1/16 20060101 H04B001/16; H04L 5/06 20060101
H04L005/06 |
Claims
1-10. (canceled)
11. A system configured to receive a radio frequency (RF) band, the
system comprising: a first analog-to-digital converter (ADC)
configured to digitize the RF band; and a digital channelizer
configured to digitally select one or more content channels from
the digitized RF band, where the digital channelizer comprises: a
demultiplexer configured to sequentially distribute samples of the
digitized RF band to N paths, an N-points Fast Fourier Transform
(FFT) configured to receive the N paths comprising samples of the
digitized RF band, a plurality of selectors, wherein each selector
is operable to select, among a plurality of outputs of the N-points
FFT, one or more FFT outputs corresponding to a particular content
channel of the one or more content channels, and a plurality of
digital mixers, each digital mixer being operable to adjust a
frequency of an output of a corresponding one of the plurality of
selectors, wherein the adjustment is according to a signal from a
direct digital frequency synthesis.
12. The system of claim 11, wherein the RF signal is transmitted by
a satellite.
13. The system of claim 11, wherein a sample rate of the first ADC
is less than a lowest frequency of the RF band.
14. The system of claim 11, wherein the system comprises a second
ADC, configured to digitize the RF band, the first ADC being
operably coupled to a vertical polarization antenna, the second ADC
being operably coupled to a horizontal polarization antenna.
15. The system of claim 14, wherein a sample rate of the second ADC
is less than a lowest frequency of the RF band.
16. The system of claim 11, wherein the output of each digital
mixer is operably coupled to a decimation circuit.
17. The system of claim 11, wherein the output of each digital
mixer is operably coupled to a combiner.
18. The system of claim 17, wherein the output of the combiner is
operably coupled to a digital to analog converter (DAC).
19. The system of claim 11, wherein the output of each digital
mixer is operably coupled to a digital to analog converter
(DAC).
20. The system of claim 11, wherein the output of each digital
mixer is at an intermediate frequency (IF).
21. A method for receiving a radio frequency (RF) band, the method
comprising: digitizing the RF band; and digitally selecting one or
more content channels from the digitized RF band, wherein digitally
selecting comprises: sequentially distributing samples of the
digitized RF band to N paths, performing a Fast Fourier Transform
(FFT) across the N paths that comprise samples of the digitized RF
band, selecting one or more FFT outputs corresponding to the one or
more content channels, and adjusting a frequency of the selected
one or more FFT outputs according to a signal from a direct digital
frequency synthesis.
22. The method of claim 21, wherein the RF signal is transmitted by
a satellite.
23. The method of claim 21, wherein digitizing the RF band is at a
sample rate less than a lowest frequency of the RF band.
24. The method of claim 21, wherein digitizing the RF band utilizes
a first analog-to-digital converter (ADC) and a second ADC, the
first ADC being operably coupled to a vertical polarization
antenna, the second ADC being operably coupled to a horizontal
polarization antenna.
25. The method of claim 24, wherein a sample rate of the second ADC
is less than a lowest frequency of the RF band.
26. The method of claim 21, wherein the method comprises decimating
the one or more frequency adjusted FFT outputs.
27. The method of claim 21, wherein method comprises combining the
one or more frequency adjusted FFT outputs.
28. The method of claim 27, wherein the method comprises converting
the combined one or more frequency adjusted FFT outputs to an
analog signal.
29. The method of claim 21, wherein the method comprises converting
the output of each digital mixer to an analog signal.
30. The method of claim 21, wherein the output of each digital
mixer comprises an intermediate frequency (IF).
Description
RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application 61/345119 filed Jan. 21, 2011, the entirety of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to conversion of satellite
signals to an intermediate frequency (IF) for content decoding and
selection of data within satellite signals for content
decoding.
BACKGROUND OF THE INVENTION
[0003] Content may be transmitted by a geosynchronous satellite
communication network to users for decoding and playback. A system
diagram of a typical satellite download link is illustrated in FIG.
1. The satellite downlink 100 includes a satellite antenna 102
connected to a low noise block converter (LNB) 104. The LNB is
connected to a satellite receiver/decoder 106. The satellite can
transmit signals including content channels modulated on a carrier.
The content channels can be analog content channels or digital
content channels. In many systems, data is modulated onto the same
carrier using different polarizations. Where digital content
channels are modulated onto a carrier, the digital data modulated
on the carrier can include a plurality of digital content channels,
each of which typically includes at least one video and/or audio
stream.
[0004] In many instances, a signal containing multiple content
channels is transmitted to a satellite network from an uplink
facility. A transponder on the satellite then transmits a signal
that can be received by a number of satellite antennas 102. The
received signal is then passed to a LNB 104, which down converts
the signal to an intermediate frequency (IF). Lastly, the IF signal
is passed to a satellite receiver/decoder 106, such as a set top
box, where the signal containing content is demodulated and decoded
(i.e. audio and/or video) for playback.
[0005] In this way, information transmitted as relatively high
frequency satellite signals, usually as microwave signals, may be
converted to similar signals at a much tower frequency, usually
known as an intermediate frequency (IF) compatible with the
electronics of the decoding device and/or cabling used to connect
an LNB to a satellite receiver/decoder. A content channel is the
digital data modulated onto a carrier frequency within the IF
signal. Users may then receive selected content channels as IF
signals for decoding and use. Representations of the frequency
spectra of signals during various stages in the down-conversion of
satellite communication signals is illustrated FIGS. 2A, 2B and
2C.
[0006] Radio frequency (RF) signals are typically transmitted by a
satellite to a receiver at high frequencies. A typical satellite
radio frequency (RF) signal for downlinking is illustrated in FIG.
2A. As illustrated, the signal is transmitted at high frequencies,
spanning from 11 GHz to 12 GHz. A satellite signet when received by
a satellite signal receiver is usually weak after traveling great
distances during transmission and is of a relatively high
frequency. When signals are sent through coaxial cables, the higher
the frequency, the greater the losses that occur in the cable per
unit of length.
[0007] A LNB may be used to amplify and convert these high
frequency signals to a lower, more manageable frequency. The
frequency spectrum of satellite signals processed by a LNB is
illustrated in FIGS. 2B and 2C. In Europe, the frequency spectrum
of LNB processed signals may be from 950 MHz to 2150 MHz (see FIG.
2B). In the United States (U.S.), the frequency spectrum of LNB
processed signals may be from 950 MHz to 1450 MHz (see FIG.
2C).
[0008] Signals containing content received from a satellite
typically include multiple content channels in the frequency band
of the carrier signal. Typical frequency spectrum for carrier
frequencies of channels of encoded digital data carried by the IF
signal processed by a typical LNB is illustrated in FIG. 2D. Here,
the frequency band spans from 950 MHz to 2150 MHz or 1450 MHz and
there are multiple 36/55 MHz content channels in this frequency
band. In order for a user to decode selected media, an L-band tuner
may be used to select the desired channel. For example, a certain
carrier frequency may be selected where a 36/55 MHz band may be
transferred to a receiver/decoder for use by the user.
[0009] LNBs can be implemented in many ways using many different
LNB architectures. FIG. 3 illustrates a diagram of a typical
universal LNB architecture with dual outputs. In this architecture,
the LNB receives two RF input signals from the satellite. One
signal is for the vertical polarization antenna 302 and the other
is for the horizontal polarization antenna 304. For example, the
frequency band of both signals may be from 10.7-12.75 GHz. The LNB
first separates the signal into two bands with two band pass
fitters, a low band 306 (10.7-11.7 GHz) and a high band 308
(11.7-12.75 GHz). Low band signals are mixed down to 950-1950 MHz
with local oscillator (LO) 310 at 9.75 GHz. The LO is the frequency
used in the LNB to block convert the frequency of the satellite
signal, or transponder frequency, to a lower frequency band. High
band signals are mixed down to 1100-2150 MHz with LO 312 at 10.6
GHz. Output signals are selected from the four down converted
L-band signals with a 4:2 multiplexer 314 in response to request
for specific channels from the decode device. Using the Universal
LNB illustrated in FIG. 3, viewers can only tune to content on two
of the 1 GHz L-band channels at any time. Additional cables are
required for users to watch content from one of the other two 1 GHz
L-band channels.
[0010] Single cable LNB architectures have been developed to reduce
the amount of cabling involved in providing a system that can
provide content from all four of the 1 GHz L-band signals produced
by the LNB. A diagram of a typical single cable LNB design
supporting up to four satellite content channels in one cable is
illustrated in FIG. 4. In the illustrated single cable LNB
architecture, the LNB receives two RF input signals from the
satellite in a manner similar to FIG. 3. One is for the vertical
polarization antenna 402 and the other is for the horizontal
polarization antenna 404. In many systems, the frequency band of
both signals may be from 10.7-12.75 GHz. The LNB first separates
the signal into two bands with two band pass fitters, a low band
406 (10.7-11.7 GHz) and a high band 408 (11.7-12.75 GHz). Low band
signals are mixed down to 950-1950 MHz with a LO 410 at 9.75 GHz.
High band signals are mixed down to 1100-2150 MHz with a LO 412 at
10.6 GHz. Four content channels (i.e. a channel within the L-band
signal containing digital data modulated onto a specific carrier
frequency) from these four L-band signals are selected with a
multiplexer 414 and mixed to four new carrier frequencies using
four mixers. Four surface acoustic wave (SAW) fitters 416 are then
used to remove the unselected channels in the band.
SUMMARY OF THE INVENTION
[0011] Systems and methods in accordance with embodiments of the
invention include converting satellite signals to an IF frequency
signal for content decoding, and selecting modulated digital data
within the satellite signals for content decoding using digital
signal processing. One embodiment includes a system configured to
select at least one content channel from an input signal including
a plurality of content channels modulated onto a carrier, the
system including: an input configured to receive an input signal
comprising a plurality of content channels modulated on a carrier;
a mixer configured to down convert the plurality of content
channels to an intermediate frequency signal; a digital channelizer
switch including: a high speed analog to digital converter
configured to digitize the intermediate frequency signal; a digital
channelizer configured to digitally tune a content channel from the
digitized intermediate frequency signal, and a high speed digital
to analog converter configured to generate an analog output signal
using the content channel digitally tuned from the digitized
intermediate frequency signal by the digital channelizer.
[0012] In a further embodiment, the mixer includes a local
oscillator.
[0013] In another embodiment, the content channel includes a
digital content channel.
[0014] In a still further embodiment, the content channel includes
an analog content channel.
[0015] In still another embodiment, the frequency of the input
signal is in the range from 10.7 GHz to 12.75 GHz.
[0016] In a yet further embodiment, the frequency of the
intermediate frequency signal is in the range from 0.2 GHz to 2.25
GHz.
[0017] In yet another embodiment, the frequency of the analog
output signal is in the range from 950 MHz to 2150 MHz.
[0018] In a further embodiment again, the frequency of the analog
output signal is in the range from 950 MHz to 1450 MHz.
[0019] In another embodiment again, the high speed analog to
digital converter is configured to sample the intermediate
frequency signal at a frequency at least twice the highest
frequency of the intermediate frequency signal.
[0020] A further additional embodiment includes a system configured
to select at Least one content channel from a plurality of input
signals, where each input signal includes a plurality of content
channel modulated on a carrier, the system including: a plurality
of inputs, where each of the plurality of inputs is configured to
receive an input signal including a plurality of content channels
modulated on a carrier; a plurality of mixers, where each mixer is
connected to an input and is configured to down convert the content
channels to an intermediate frequency signal, a digital channelizer
switch including: a plurality of high speed analog to digital
converters, where each high speed analog to digital converter is
configured to digitize an intermediate frequency signal generated
by one of the mixers; a plurality of digital channelizers, where
each digital channelizer is configured to digitally tune a content
channel from a digitized intermediate frequency signal generated by
one of the high speed analog to digital converters; a multiplexer
configured to select digitized intermediate frequency signals
generated by the plurality of high speed analog to digital
converters as inputs to the plurality of digital channelizers; and
at toast one high speed digital to analog converter, where each
high speed digital to analog converter is configured to generate an
analog output signal using a content channel digitally tuned from
one of the at least one digitized intermediate frequency signals by
a digital channelizer.
[0021] In another additional embodiment, the digital channelizer
switch further includes a common combiner configured to digitally
combine a plurality of content channels digitally tuned from at
least one of the digitized intermediate frequency signals by the
plurality of digital channelizers: and one of the at least one high
speed digital to analog converters is configured to generate an
analog output signal using the output of the common combiner.
[0022] In a still yet further embodiment, the mixer comprises a
local oscillator.
[0023] In still yet another embodiment, the content channel
comprises a digital content channel.
[0024] In a stilt further embodiment again, the content channel
comprises an analog content channel.
[0025] In a still another embodiment again, the frequency of the
input signal is in the range from 10.7 GHz to 12.75 GHz.
[0026] In a still further additional embodiment, the frequency of
the intermediate frequency signal is in the range from 0.2 GHz to
2.25 GHz.
[0027] In stilt another additional embodiment, the frequency of the
analog output signal is in the range from 950 MHz to 2150 MHz.
[0028] In a yet further embodiment again, the frequency of the
analog output signal is in the range from 950 MHz to 1450 MHz.
[0029] In yet another embodiment again, the high speed analog to
digital converter is configured to sample the intermediate
frequency signal at a frequency at least twice the highest
frequency of the intermediate frequency signal
[0030] A yet further additional embodiment includes a method of
selecting at least one content channel from at least one input
signal, where each input signal includes a plurality of content
channels modulated on a carrier, the method including: receiving at
least one input signal, where each input signal includes a
plurality of content channels modulated on a carrier; down
converting the plurality of content channels on each of the at
least one input signals to an intermediate frequency signal using
at least one mixer; digitizing each of the intermediate frequency
signals using at least one high speed analog to digital converter;
digitally tuning at least one content channel from the at least one
digitized intermediate frequency signals using at least one digital
channelizer and generating at least one analog output signal from
at least one digital content channel digitally tuned from a
digitized intermediate frequency signal using at least one digital
to analog converter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 illustrates a system diagram of a typical satellite
downlink.
[0032] FIG. 2A illustrates a typical satellite radio frequency (RF)
signal for downlinking.
[0033] FIG. 2B illustrates the frequency spectrum of satellite
signals when processed by a LNB in accordance with European
standards.
[0034] FIG. 2C illustrates the frequency spectrum of satellite
signals when processed by a LNB in accordance with U.S.
standards.
[0035] FIG. 2D illustrates typical frequency spectrum for modulated
digital data on a plurality of content channels within an L-Band IF
signal generated by a LNB.
[0036] FIG. 3 illustrates typical universal LNB architecture with
dual outputs.
[0037] FIG. 4 illustrates typical single cable LNB architecture
configured to generate an output signal with up to four content
channels re-modulated to different frequencies.
[0038] FIG. 5 illustrates a single cable LNB with a digital
channelizer switch in accordance with an embodiment of the
invention.
[0039] FIG. 6 illustrates a universal LNB including a digital
channelizer switch in accordance with an embodiment of the
invention.
[0040] FIG. 7 illustrates a single cable LNB including a digital
channelizer switch with four digital channelizers in accordance
with an embodiment of the invention.
[0041] FIG. 8 illustrates a single cable LNB including a digital
channelizer switch with twelve digital channelizers in accordance
with an embodiment of the invention.
[0042] FIG. 9 illustrates a digital channelizer switch with
multiple RF inputs, digital channelizers and outputs in an
embodiment of the invention.
[0043] FIG. 10 illustrates a LNB including a digital channelizer
switch with multiple satellite RF inputs, 24 channelizers and a
single output in accordance with an embodiment of the
invention.
[0044] FIG. 11 illustrates a digital channelizer switch with a
single input for an arbitrary number of channels in accordance with
an embodiment of the invention.
DETAILED DISCLOSURE OF THE INVENTION
[0045] Turning now to the drawings, systems and methods for
converting satellite signals to an IF frequency signal for content
decoding, and selecting modulated digital data within the satellite
signals for content decoding using digital signal processing are
disclosed in accordance with embodiments of the invention. In
various embodiments, analog circuitry is utilized to generate an IF
signal that is then digitized to enable selection of the modulated
digital data within the received satellite signal to provide to a
satellite receiver/decoder using digital signal processing
techniques. Once selection is performed using digital signal
processing, the selected modulated digital data is converted back
to an analog signal and output by the LNB. In several embodiments,
a digital channelizer of a digital channelizer switch is used to
separate or digitally tune the content of a single content channel
digital data modulated onto a specific carrier frequency) from the
signals received via the satellite downlink. A digital channelizer
switch can include at least one digital channelizer, which when
used in conjunction with a multiplexer, enables selection of
content from a digitized intermediate frequency signal. Digital
channelizer switches can be utilized in a variety of LNB
architectures, including a universal LNB architecture or a single
cable LNB architecture. LNBs in accordance with many embodiments of
the invention can utilize analog to digital converters (ADC) and
digital to analog converters (DAC) such as the ADCs and DACs
developed by Mobius Semiconductor Inc. of Irvine, Calif., which can
sample at multiple GHz and dissipate less power than the
traditional RF mixer based tuner. Down converted satellite band
signals may typically be between 950-2150 MHz. The sample rate
needs to be at least two times the maximum frequency. Therefore,
certain embodiments use an ADC or DACs developed by Mobius
Semiconductor Inc. with a maximum sample rate of 6 GHz.
[0046] In a number of embodiments, utilizing a high frequency low
power analog to digital converter to digitize L-band signals, a
digital channelizer to select modulated digital data from the
digitized signal, and a digital to analog converter to generate an
analog output signal can significantly reduce the power consumption
and component cost of the LNB. In addition, content channel
switching may be done instantaneously without settling time due to
usage of digital circuitry. Furthermore, the use of digital
components can result in an LNB architecture that is easily
scalable allowing the construction of single cable LNBs that are
powered by the decoder device via the coaxial cable and that can
mix a number of content channels onto an output signal that is only
constrained by the requirements of the application (e.g. mixing the
modulated digital data of 24 content channels onto a single L-band
output signal). In this way, LNBs can be constructed in accordance
with embodiments of the invention that overcome power and cost
constraints that may be imposed by the use of analog components.
LNBs and the use of high speed low power analog to digital
converters, and digital channelizers in accordance with embodiments
of the invention are discussed further below.
General LNB Architecture with Digital Channelizer Switch
[0047] Digital channelizer switches can be integrated into any of a
variety of LNB architectures, including commonly used architectures
such as universal LNBs or single cable LNBs. A general LNB
architecture including a digital channelizer switch in accordance
with an embodiment of the invention is illustrated in FIG. 5. In
many embodiments, the LNB receives two RF input signals 502 from a
satellite. One signal is for the vertical polarization antenna and
the other is for the horizontal polarization antenna. For example,
the frequency band of both signals may be from 10.7-12.75 GHz. In
other embodiments, the frequency band of the signals is the C-band
(4-6 GHz), the X-band (8 GHz), the Ka-band (20-30 GHz) and/or any
other band appropriate to a specific application. The RF input
signals are connected to two amplifiers 508. The two amplifiers are
each connected to different mixers 510. Both mixers 510 are
connected with a LO 512. In the illustrated embodiment, both
frequency bands are mixed down with a LO at 10.5 GHz. In other
embodiments, another LO appropriate to the requirements of the
application can be utilized. Each mixer 510 is also connected to
different ADCs 504. Each down converted signal is sampled by an ADC
504 with sample frequency at 6 GHz. Both ADCs 504 are connected to
a digital channelizer switch 506. The digital channelizer switch
506 is connected to a digital to analog converter (DAC) 508. The
DAC 508 is connected to an amplifier 514. The desired content
channel within the satellite signal is selected with the digital
channelizer switch 506 and converted to an L-band signal with a
high speed DAC 508 sampled at 6 GHz. In this example, there may be
4 or 6 output frequencies or content channels selected by the
digital channelizer 506. However, the output frequencies and number
of content channels can be arbitrary. Although a specific
configuration is illustrated in FIG. 5, any of a variety of
architectures can be utilized appropriate to the characteristics of
the signal received by the LNB.
Universal LNB Architecture
[0048] Digital channelizer switches in accordance with many
embodiments of the invention may be integrated into a universal
LNB. A universal LNB including an ADC based digital channelizer
switch in accordance with an embodiment of the invention is
illustrated in FIG. 6. In the illustrated universal LNB
architecture, an input for the vertical antenna 602 and an input
for the horizontal antenna 604 are each connected to different RF
amplifiers 612. Each of the RF amplifiers 612 is connected to a
different image band pass fitter (BPF) 614. Each band pass fitter
614 is connected to a different mixer 616. Each mixer 616 is
associated to a common LO 618. Each mixer 616 is connected to a
digital channelizer switch 620 via a respective input to different
low noise amplifiers (LNA) 622. Each LNA 622 is connected to a
different analog to digital converter (ADC) 606. Each ADC 606 is
connected to a common multiplexer, or multiplexer selector (Mux
Sel) 624. For ease of discussion, the terms multiplexers and
multiplexer selectors are interchangeably used. The Mux Sel 624 is
connected to two different digital channelizers 626. Each
channelizer 626 is connected to a different DAC 610. Each DAC 610
is connected to different IF amplifiers 630. Each IF amplifier 630
is connected to a different output 632.
[0049] In many embodiments, the LNB receives two RF input signals
from the satellite. One signal is for the vertical polarization
antenna 602 and the other is for the horizontal polarization
antenna 604. For example, the frequency band of both signals may be
from 10.7-12.75 GHz. Both frequency bands are mixed down to
0.2-2.25 GHz with one mixer at 10.5 GHz. Each down converted signal
is sampled by an ADC 606 with sample frequency at 6 GHz. The
desired content channel for the output frequency band is selected
with digital circuitry 608 through use of channelizers 626 and
converted to an L-band signal with a high speed DAC 610 sampled at
6 GHz. Although this illustrated embodiment employs two outputs, an
arbitrary number of outputs can be achieved in embodiments of the
invention by adding corresponding channelizers to serve the desired
number of outputs.
[0050] Although the generation of two L-band outputs from two down
converted satellite signals is shown in FIG. 6, ADC based
channelizer switches in accordance with embodiments of the
invention can be utilized to generate any number of L-band output
signals from any number of IF input signals including but not
limited to generating four L-band output signals from two IF input
signals, generating two L-band output signals from four IF input
signals, selecting four L-band output signals from four IF input
signals, and selecting eight L-band output signals from four IF
input signals,
[0051] In many embodiments, digital circuitry 608 takes the place
of functions performed by analog circuitry in conventional LNB
architectures. For example, the number of analog circuits, such as
RF mixers, local oscillators, and band pass filters, are reduced in
comparison with the equivalent analog circuitry shown in FIG. 3.
Replacement of analog components with digital components can
provide savings in power and cost. Analog RF switching circuitry
can also have a settling time when switching between different
inputs. An equivalent digital implementation in accordance with an
embodiment of the invention may have switching times of the order
of one clock cycle, which may be in the nanosecond range. The fast
switching time can provide a more seamless user experience.
Single Channel LNB Architecture
[0052] Digital channelizer switches in accordance with many
embodiments of the invention may be integrated into a single
channel LNB. A single cable LNB including a digital channelizer
switch in accordance with an embodiment of the invention is
illustrated in FIG. 7. In many embodiments, an input for the
vertical antenna 702 and an input for the horizontal antenna 704
are each connected to different RF amplifiers 712. Each of the RF
amplifiers 712 is connected to a different image band pass fitter
MPH 714. Each band pass fitter 714 is connected to a different
mixer 716. Each mixer 716 is associated to a common LO 718. Each
mixer 716 is connected to a channelizer switch 720 via a respective
input to different low noise amplifiers (LNA) 722. Each LNA 722 is
connected to a different analog to digital converter (ADC) 706.
Each ADC 706 is connected to a common multiplexer selector (Mux
Sel) 724. The Mux Sel 724 is connected to four different
channelizers 708. Each channelizer 708 is connected to a single
common combiner 726. In certain embodiments, a common combiner is a
digital summer (adder) that sums up all of the channelizer outputs.
The common combiner 726 is connected to a DAC 710. The DAC is
connected to an IF amplifier 728 and the IF amplifier 728 is
connected to an output 730.
[0053] In embodiments of the invention, the LNB receives two RF
input signals from the satellite similar to the signals described
above with respect to FIG. 3. One is for the vertical polarization
antenna 702 and the other is for the horizontal polarization
antenna 704. In many systems, the frequency band of both signals
may be from 10.7-12.75 GHz. Both frequency bands are nixed down to
0.2-2.25 GHz with one mixer at 10.5 GHz. Each down converted signal
is sampled by an ADC 706 with sample frequency at 6 GHz. The
desired content channels are digitally tuned with digital
channelizers 708 and converted to L-band signals with a high speed
DAC 710 sampled at 6 GHz.
[0054] Single cable LNB architectures capable of utilizing a
digital channelizer switch in accordance with many embodiments of
the invention can utilize an arbitrary number of channelizers to
allow output of an arbitrary number of content channels. A single
cable LNB including a digital channelizer switch with twelve
digital channelizers 808 in accordance with an embodiment of the
invention is illustrated in FIG. 8. In many embodiments, an input
for the vertical antenna 802 and an input for the horizontal
antenna 804 are each connected to different RF amplifiers 812. Each
of the RF amplifiers 812 are connected to a different image band
pass fitter (BPF) 814. Each band pass fitter 814 is connected to a
different mixer 816. Each mixer 816 is associated to a common LO
818. Each mixer 816 is connected to a channelizer switch 820 via a
respective input to different low noise amplifiers (LNA) 822. Each
LNA 822 is connected to a different analog to digital converter
(ADC) 806. Each ADC 806 is connected to a common multiplexer
selector (Mux Sel) 824. The Mux Sel 824 is connected to twelve
different channelizers 808. Each channelizer 808 is connected to a
single common combiner 826. The common combiner 826 is connected to
a DAC 810. The DAC 810 is connected to an IF amplifier 828. The IF
amplifier 828 is connected to an output 830.
[0055] In embodiments of the invention, similar to FIG. 7, digital
channelizers are used to select the desired content channels, which
then can be converted into an analog L-band signal including each
of the selected channels using a digital to analog converter and
received by a satellite receiver/decoder. However, here there are
twelve channelizers 808 rather than four and therefore twelve
content channels may be selected out of the satellite signal, and
converted into an analog L-band signal including each of the
selected channels using a digital to analog converter and received
by a satellite receiver/decoder. Although twelve channelizers 808
are illustrated in FIG. 8, any number of channelizers can be
utilized as appropriate to a specific application in accordance
with embodiments of the invention.
[0056] In many embodiments, use of digital channelizers can enhance
scalability of single cable LNB architectures compared to
traditional single cable LNB implementations. LNBs in accordance
with embodiments of the invention can provide for the output of an
arbitrary number of content channels with the addition of
additional digital channelizers. Traditional implementations
typically utilize an additional tuner and SAW fitter per content
channel output. Also, embodiments with the digital channelizer can
pack content channels for output closer together than in an all
analog LNB due to the imitations imposed on analog LNBs by analog
fitter roll-off and the fact that sharp fitters can be implemented
in the digital circuit.
Multiple RF Inputs with Multiple Outputs
[0057] Digital channelizer switches in accordance with many
embodiments of the invention can be implemented in situations that
require multiple RF inputs and multiple outputs. A digital
channelizer switch with multiple RF inputs in an embodiment of the
invention is illustrated in FIG. 9. In many embodiments, the RF
inputs 902 are each connected to different LNAs 908. Each LNA 908
is connected to different ADCs 910. Each ADC 910 is connected to a
common Mux Sel 912. The Mux Sel 912 is connected to twenty four
different digital channelizers 906. Each channelizer 906 is
connected to a single common combiner 914. The first channelizer
916 is connected also to a multiplexer (mux) 918. The second to
eighth channelizers are also connected to different DACs 922. The
single common channel 914 is connected to the mux 918. The mux 918
is connected to another different DAC 922. AU DACs 922 are
connected to a digital satellite equipment control (DiseqC
Interface) 924. All DACs 922 are also connected to different
outputs 904. The DiseqC Interface 924 is connected to a micro
controller (uController) 926. The microcontroller 926 may be
connected to elements outside of the channelizer switch. The
microcontroller is connected to a Single Wire Multi-switch (SWM)
control interface or a satellite master antenna TV (SMATV) control
interface 928. The SWM/SMATV 928 control interface may be connected
to the DACs 922 or the outputs 904 or the DiseqC interface 924.
[0058] In many embodiments, the digital channelizer switch includes
five RF inputs 902 and eight IF outputs. Also, there are twenty
four channelizers 906 which can digitally tune up to twenty four
content channels for output on any single IF output. Although there
are five inputs in this embodiment, any number of inputs can be
utilized as appropriate to a specific application in accordance
with embodiments of the invention. Similarly, although there are
eight outputs in this embodiment, any number of outputs can be
utilized as appropriate to a specific application in accordance
with embodiments of the invention.
[0059] Digital channelizer switches in accordance with many
embodiments of the invention can be utilized in a variety of LNB
architectures, including processing multiple IF signals converted
from multiple RF signals. A LNB including an ADC based channelizer
switch and multiple satellite RF inputs in accordance with an
embodiment of the invention is illustrated in FIG. 10. In many
embodiments, fourteen inputs 1002 from five satellites with
different polarization and frequency bands are connected to
different RF amplifiers 1012. Each RF amplifier 1012 is connected
to different band pass fitters 1010. Each band pass fitter 1010 is
connected to different mixers 1008. Each mixer 1008 may also be
connected to a corresponding LO 1014. A certain number of mixers
1008 may be combined with different channels 1016. Each channel
1016 is connected to a channelizer switch 1018 via different LNAs
1020. Each LNA 1020 is connected to different ADCs 1022. Each ADC
1022 is connected to a common Mux Sel 1024. The Mux Sel 1024 is
connected to twenty four different channelizers 1006. Each
channelizer 1006 is connected to a single combiner 1026 in the
channelizer switch 1018. The combiner 1026 in the channelizer
switch 1018 is connected to a DAC 1028. The DAC 1028 is connected
to an IF amplifier 1030. The IF amplifier 1030 is connected to an
output 1004.
[0060] In many embodiments, fourteen inputs 1002 from five
satellites with different polarization and frequency bands are
received by the LNB. There is also one IF output 1004 with up to
twenty four content channels digitally tuned by twenty four
channelizers 1006. Aspects of this embodiment are compatible with
the Single Wire Multi-switch technology of DirecTV in El Segundo,
Calif. Although fourteen inputs from five satellites are featured
in the illustrated embodiment, any number of inputs from any number
of satellites can be utilized as appropriate to a specific
application in accordance with embodiments of the invention. In
addition, the number of content channels digitally tuned using
digital channelizers can be determined by the requirements of a
specific application.
[0061] The 14 satellite RF inputs 1002 can receive signals having
different polarization and frequency bands such as the Ku-band at
12.2-12.7 GHz, Ka-band to at 18.3-18.8 GHz and Ka-band hi at
19.7-20.2 GHz. These satellite signals are first filtered by
band-pass fillers 1010 for each RF input signal and down converted
with mixers 1008, for example the Ku-band may use a LO at 11.25 GHz
and the Ka-band may use a LO at 18.05 GHz. For the Ku-band, the
down converted frequency band may be 950-1450 Mhz. For Ka-band to,
the down converted signal may be between 250-750 MHz. For Ka-band
hi, the down converted signal may be between 1650-2150 MHz. Three
down converted signals are then combined with a summer to produce a
signal at 250-2150 MHz. That combined signal from the summer is
received by the channelizer switch and sampled by an ADC at 6
GS/sec.
Channelizer Switch with a Single RF Input
[0062] Digital channelizer switches in accordance with many
embodiments of the invention can utilize a single RF input for
digital selection of any number of channels from the RF input. A
channelizer switch in accordance with an embodiment of the
invention is illustrated in FIG. 11. In many embodiments, an RF
input 1110 is connected to an LNA 1112. The LNA 1112 is connected
to an ADC 1114. The ADC 1114 is connected to a demultiplexer
(demux) 1116. The demux 1116 is connected to poly-phase fitters
1118. Each poly-phase fitter 1118 is connected to an input of one
N-point FFT 1102. The N-points FFT 1102 is connected to two
multiplexers, or multiplexer selectors (Mux Sel) 1104. Each Mux Sel
1104 is connected to a different mixer 1120. Each mixer 1120 is
also connected with a different Direct Digital Frequency Synthesis
(DNS) 1106 along with different N-stage decimation 1108. Each
N-stage decimation 1108 is connected to a low pass fitter (LPF)
1122. Each LPF 1122 is connected to a decimator 1124 for down
sampling by two. Each decimator 1124 is connected to a different
Variable Gain Amplifier (VGA) 1126. Each VGA 1126 is connected to
separate channel outputs 1128. Both VGAs 1126 and both channel
outputs 1128 are controlled with an automatic gain control (AGC)
1130.
[0063] In many embodiments a Fast Fourier Transform (FFT) based
channelizer 1102 is used for coarse frequency tuning. For example,
the outputs may be N_fft/2 overlapped channels at 2.7 GHz/M (i.e.
where M in FIG. 11 is chosen to be N_fft/4). There may be two
choices for N_fft: 32 and 64. A poly-phase filter may be used for
better pass-band and stop-band response of the fitter bank. One
example of a polyphase fitter design is the Chebyshev window. The
window length may be equal to N_fft for a simple implementation. In
other embodiments, any of a number of different fitters can be
utilized in the band pass littering of the channels. Given a real
input, only half of the FFT outputs are needed. The FFT Channelizer
1102 outputs to the multiplexer selectors (Mux Sel) 1104. For
example, there may be 32 mux for selecting N_fft/2 channelizer
outputs for each desired channel. There may also be direct digital
frequency synthesis (DNS) 1106 based fine frequency tuning for each
content channel where each fine frequency tuning block includes one
complex multitier and one DDFS running at 2.7 GHz/M. The
illustrated embodiment also features decimation filters 1108 and
Adjacent Channel Interference (ACI) rejection filters. There may be
multiple stages of decimation by two filters to bring the sample
rate down to 10.547 MHz. There may also be three types of
decimation by two fitters used in this design. Also, four fix
coefficients fitters may be used for ACI rejection. For example, a
hall-band (default for eight MHz channels), band, third-band
(default for six MHz channels), and a quarter-band. Lastly, this
embodiment features a variable gain stage and automatic gain
control (AGC), where variable gain may be at the output stage and a
single AGC processing unit is used for all 32 channels output gain
control.
[0064] Therefore, the channelizer switch illustrated in FIG. 11 is
able to take an RF input 1110 and digitally select a number of
content channels within a satellite signal from the RF input 1110
for content decoding. Although a specific embodiment of a
channelizer switch is illustrated in FIG. 11, any of a variety
digital signal processing circuits can be utilized to digitally
select one or more content channels within a digitized satellite
signal in accordance with embodiments of the invention.
[0065] Although the present invention has been described in certain
specific embodiments, many additional modifications and variations
would be apparent to those skilled in the art. It is therefore to
be understood that the present invention may be practiced otherwise
than specifically described, including various changes in the size,
shape and materials, without departing from the scope and spirit of
the present invention. Thus, embodiments of the present invention
should be considered in all respects as illustrative and not
restrictive.
* * * * *