Satellite signal frequency translation and stacking
View Patent ↗An outdoor satellite receiving unit (ODU) receives several independent satellite signals, selects two signals with a switch matrix, downconverts the two signals to a bandstacked signal with a high and a low band signal, and outputs the bandstacked signal on the same cable to receiver units. Several satellite signals can be selected in groups of two or more and output to independent receiver units. Signal selecting is performed at the received radio frequency (RF) and bandstacking is performed with a single downconversion step to an intermediate frequency (IF). Channel stacking on the same cable of more than two channels from several satellites can be achieved by using frequency agile downconverters and bandpass filters prior to combining at the IF output. A slow transitioning switch minimizes signal disturbances when switching and maintains input impedance at a constant value.
1. A device for processing satellite signals comprising:
a first amplifier chain that receives a first RF signal having a first frequency;
a second amplifier chain that receives a second RF signal having a second frequency;
a first bandpass filter coupled to the output of the first amplifier chain;
a second bandpass filter coupled to the output of the second amplifier chain;
a matrix switch coupled to the outputs of the first bandpass filter and the second bandpass filter, wherein the matrix switch comprises:
an input port;
an output port;
an internal termination having an impedance value of Z;
a first switch element having first variable impedance Z 3 coupled between the input port and the internal termination;
a second switch element having second variable impedance Z 2 coupled between the input port and the output port; and
means of controlling impedance values of both the first switch element and the second switch element, and wherein the matrix switch has a constant input impedance and performs on-frequency signal routing at the first frequency and the second frequency;
the device further comprising:
a frequency converter block coupled to the outputs of the matrix switch that outputs frequency converted signals; and
a combiner coupled to the output of matrix switch that combines the frequency converted signals and produces a frequency stacked IF output wherein a single frequency conversion is performed between the RF input signals and the frequency stacked IF output.
2. The device for processing satellite signals of claim 1 , wherein the frequency converter block comprises at least one oscillator wherein the oscillator is a phase-locked loop oscillator.
3. The device for processing satellite signals of claim 1 , wherein the frequency converter block comprises at least one oscillator wherein the oscillator is a dielectric-resonator oscillator.
4. The device of processing satellite signals of claim 1 , wherein the frequency converter block comprises at least one oscillator wherein the frequency of the oscillator is fixed.
5. The device of processing satellite signals of claim 1 , wherein the frequency converter block comprises at least one oscillator wherein the frequency of the oscillator is changeable.
6. A method for processing satellite RF signals comprising:
amplifying the RF satellite signals having a frequency;
filtering the amplified RF satellite signals;
selecting the desired filtered amplified RF satellite signals using a matrix switch capable of switching at RF, wherein the matrix switch comprises:
an input port;
an output port;
an internal termination having an impedance value of Z;
a first switch element having first variable impedance Z 3 coupled between the input port and the internal termination;
a second switch element having second variable impedance Z 2 coupled between the input port and the output port; and
means of controlling impedance values of both the first switch element and the second switch element and wherein the matrix switch has a constant input impedance and performs on-frequency signal routing at the frequency;
downconverting the selected satellite signals to IF; and
combining the frequency converted signals and producing a frequency stacked IF output wherein a single frequency conversion is performed between the satellite RF input signals and the frequency stacked IF output.
7. The method of claim 6 , wherein the satellite RF signals are signals from a single satellite.
8. The method of claim 6 , wherein the satellite RF signals are signals from multiple satellites.
9. The device of processing satellite signals of claim 1 , wherein the upper sideband products of the conversion in the frequency conversion block fall in a frequency range of 23 to 27 GHz.
10. The device of processing satellite signals of claim 1 , wherein the frequency conversion block comprises a set of downconverters, and the number of the downconverters is equal to the number of the matrix switch outputs.
11. The device of processing satellite signals of claim 1 , wherein the impedance relationship substantially achieved is described by the equation Z 3 ·Z 2 =Z 2 .
12. The device of processing satellite signals of claim 1 , wherein the means of controlling impedance is a switch control circuit, the switch control circuit generates a time varying control signal having a controllable rate of change to achieve impedance values of the impedances Z 3 and Z 2 , and the switch transition between states is slowed down to allow tracking loops in a system receiving a switched signal to track out the signal change caused by the switching.
13. The method of claim 6 , wherein the step of downconverting is performed by a frequency conversion block comprising a set of downconverters, and the number of the downconverters is equal to the number of the matrix switch outputs.
14. The method of claim 6 , wherein the impedance relationship substantially achieved is described by the equation Z 3 Z 2 =Z 2 .
15. The method of claim 6 , wherein the means of controlling impedance is a switch control circuit, the switch control circuit generates a time varying control signal having a controllable rate of change to achieve impedance values of the impedances Z 3 and Z 2 , and the switch transition between states is slowed down to allow tracking loops in a system receiving a switched signal to track out the signal change caused by the switching.