Solar cell forced shunting circuit for satellite

Abstract

The invention relates to a solar cell forced shunting circuit for a satellite, and belongs to the field of electricity. Comprising a solar cell power supply unit, a shunting unit, an isolation unit, a filtering unit, a modulation signal unit and a forced shunting signal unit. The solar cell circuit power supply unit is used for providing electric energy for the satellite through the isolation unit and the filtering unit; the shunting unit is used for shunting redundant electric energy supplied by the solar cell to the ground; the modulation signal unit is used for generating a modulation signal and controlling the shunting unit to work through the driving unit; the forced shunting signal unit is used for enabling the shunting unit to be in a shunting mode according to an external signal. According to the invention, the requirements of light-weight and high-power load power distribution can be met.

Description

Technical Field

[0001] The invention belongs to the field of electricity and relates to a circuit for forced current diversion of a solar cell for a satellite. Background Art

[0002] In the satellite power supply system, solar cells are the main energy source for satellite power supply. As the various working conditions of the satellite change, it is necessary to force the solar cells to be diverted. At present, the control of solar cells for satellites is all carried out in a closed-loop form, and the energy of solar cells cannot be controlled by external instructions and circuits. The closed-loop logic of the current solar cell energy control system can no longer meet the needs of the mission.

[0003] At the same time, with the rapid development of satellite technology, satellites have more and more strategies for controlling solar cell energy, and conventional closed-loop logic control can no longer meet the mission requirements of satellites. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a circuit for forced current diversion of satellite solar cells. Under the premise of not affecting the closed-loop control strategy of satellite solar cell energy, the energy of satellite solar cells can be forced to be controlled by external signals to meet the open-loop and closed-loop control requirements of solar cell energy.

[0005] The solution of the present invention is:

[0006] A satellite solar cell forced shunting circuit comprises a solar cell power supply unit, an isolation unit, a filtering unit, a shunting unit, a modulation signal unit, a forced shunting signal unit and a driving unit, wherein:

[0007] The solar cell power supply unit converts space solar energy into electrical energy, and sequentially supplies power to the satellite through the isolation unit and the filter unit;

[0008] The isolation unit is used to unidirectionally isolate the solar cell power supply unit from the filter unit;

[0009] The filtering unit is used to filter the electric energy after unidirectional isolation by the isolation unit, so as to provide stable electric energy for the satellite;

[0010] The shunt unit modulates and shunts the electric energy of the solar cell under the control of the driving unit; when no signal from the driving unit is received, the shunt unit is in a cut-off state;

[0011] The driving unit drives the shunt unit to modulate the electric energy of the solar cell according to the modulation signal of the modulation signal unit, and drives the shunt unit to shunt all the electric energy of the solar cell to the ground according to the shunt control signal of the forced shunt signal unit;

[0012] The modulation signal unit generates a modulation signal according to the power demand of the satellite and inputs the modulation signal to the driving unit;

[0013] The forced shunt signal unit generates a forced shunt signal according to an external signal. The forced shunt signal includes a shunt control signal and a modulation drive shutdown signal. The shunt control signal is input to the drive unit, and the modulation drive shutdown signal is used to shut down the modulation signal of the modulation signal unit.

[0014] Preferably, under normal satellite power demand state:

[0015] When no external signal is received, the modulation signal unit generates a square wave modulation signal with adjustable output width according to the power demand of the satellite and sends it to the driving unit, which controls the state of the shunt unit through the driving unit to adjust the power provided by the solar cell power supply unit to the satellite;

[0016] When an external signal is received, that is, when the external signal is at a high level, the forced shunt signal unit generates a shunt control signal and a modulation drive shutdown signal, and the modulation drive shutdown signal forces the modulation signal of the modulation signal unit to be at a low level; the shunt control signal is sent to the drive unit, and the drive unit controls the shunt unit to be turned on, thereby realizing forced full shunt of the solar cell electric energy;

[0017] When the satellite does not need power:

[0018] The forced shunt signal unit is triggered by an external signal to generate a shunt control signal and a modulation drive shutdown signal, and the modulation drive shutdown signal forces the modulation signal of the modulation signal unit to be a low level; the shunt control signal is sent to the drive unit, and the drive unit controls the shunt unit to be in an on state, thereby completely shunts the energy of the solar cell power supply unit.

[0019] Preferably, the solar cell power supply unit is composed of solar cell circuit monomers connected in series and parallel.

[0020] Preferably, the isolation unit comprises a diode D3, an anode of the diode D3 is connected to the positive electrode of the solar cell power supply unit, and a cathode of the diode D3 is connected to the positive electrode of the filter unit.

[0021] Preferably, the filtering unit comprises a capacitor C2, the positive electrode of C2 is connected to the anode of the isolation unit diode D3 as a satellite power output positive line, and the negative electrode of C2 is connected to the ground as a satellite power output return line.

[0022] Preferably, the shunting unit comprises a transistor Q1;

[0023] The gate of the transistor Q1 is connected to the output signal of the driving unit, the source of the transistor Q1 is connected to the ground, and the drain of the transistor Q1 is connected to the positive electrode of the solar cell power supply unit.

[0024] Preferably, the modulation signal unit includes resistors R1, R2, R3, capacitor C1, operational amplifier U1, comparator U2, transistors Q2, Q3;

[0025] One end of the resistor R1 is connected to the positive power output line of the circuit, and the other end is simultaneously connected to one end of the resistor R2 and the positive input terminal of the operational amplifier U1;

[0026] The other end of the resistor R2 is connected to the ground, the negative input end of the operational amplifier U1 is connected to the reference voltage and one end of the capacitor C1 at the same time, the other end of the capacitor C1 is connected to the resistor R3, the other end of the resistor R3 is connected to the output end of the operational amplifier U1, the output end of the operational amplifier U1 is connected to the positive input end of the comparator U2, the negative input end of the comparator U2 is connected to the reference triangular wave carrier, the output end of the comparator U2 is connected to the base of the transistor Q2 and the base of Q3 at the same time, the collector of the transistor Q2 is connected to the power output positive line of the circuit, the collector of the transistor Q3 is connected to the ground, and the emitter of the transistor Q2 is connected to the emitter of the transistor Q3 as the output end of the modulation signal unit.

[0027] Preferably, the driving unit includes a capacitor C3, a diode D4, a voltage regulator tube D1, and resistors R6 and R7;

[0028] One end of the capacitor C3 is connected to the output end of the modulation signal unit and the positive electrode of the diode D4, and the other end of the capacitor C3 is connected to the negative electrode of the voltage regulator tube D1, one end of the resistor R7 and the negative electrode of the diode D4;

[0029] The positive electrode of the voltage regulator tube D1 is connected to the ground, and the other end of the resistor R7 is connected to one end of the resistor R6 and the signal input end of the shunt unit at the same time; the other end of the resistor R6 is connected to the ground.

[0030] Preferably, the forced shunt signal unit includes resistors R4, R5, a diode D2, and transistors Q4, Q5;

[0031] One end of the resistor R4 is connected to the external signal, and the other end is connected to the anode of the diode D2 and the base of the transistor Q4;

[0032] The cathode of the diode D2 is connected to one end of the resistor R5, and the other end of the resistor R5 is connected to the cathode of the voltage regulator tube D1 of the driving unit;

[0033] After the collector of transistor Q4 is connected to the collector of transistor Q5, it is connected to the output end of the modulation signal unit, the emitter of transistor Q4 is connected to the base of transistor Q5; the emitter of transistor Q5 is connected to the ground.

[0034] Preferably, the external signal is a signal provided by a rocket or a separated signal from a satellite.

[0035] The beneficial effects of the present invention compared with the prior art are:

[0036] Under the premise of not affecting the closed-loop control strategy of satellite solar cell energy, the function of forcibly shunting the energy of satellite solar cells through external signals is realized. For example, current satellites have begun to be launched in a way that the active segment is not powered. When the rocket completes the separation of the fairing during flight, the satellite's solar cells are exposed to sunlight to provide power for the satellite. However, because the satellite has not yet separated from the rocket, the power demand of the satellite is greater than the power provided by the solar cells, making it very likely that the satellite is in an abnormal undervoltage state. The present invention can completely shunt the energy of solar cells exposed to sunlight through external signals. The signal can be provided by the rocket or by the separation signal of the satellite, so that before the separation of the satellite and the rocket, regardless of whether the satellite solar cells are exposed to sunlight, a path is provided through the forced shunting mode to release the satellite solar cell energy to the ground.

[0037] For example, when a satellite is performing a mission and the solar cells generate excess energy, the energy generated by the solar cells can be diverted through signals sent by the satellite itself.

[0038] Compared with the traditional satellite solar cell control strategy, the present invention can further effectively control the energy of the solar cell without affecting the control strategy of the satellite solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The schematic diagram of the principle of a circuit for forced current diversion of a solar cell for satellite according to the present invention;

[0040] Figure 2 The present invention is a schematic diagram of the specific structure of a circuit for forced current diversion of a solar cell for satellite use. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the accompanying drawings.

[0042] The invention discloses a satellite solar cell forced shunting circuit, which can realize the function of forcibly shunting the satellite solar cell energy through an external signal without affecting the satellite solar cell energy closed-loop control strategy.

[0043] The basic structure of a satellite solar cell forced current shunting circuit of the present invention is as follows: Figure 1 As shown, the circuit includes: a solar cell power supply unit 110 , an isolation unit 120 , a filtering unit 130 , a shunt unit 140 , a modulation signal unit 150 , a forced shunt signal unit 160 and a driving unit 170 .

[0044] The solar cell power supply unit 110 is used to provide electric energy to the satellite through the isolation unit 120 and the filter unit 130 in sequence, and can also shunt all the energy through the shunt unit 140. The solar cell power supply unit converts space solar energy into electric energy, thereby providing energy input for the satellite.

[0045] The isolation unit isolates the solar cell power supply unit from the filter unit in one direction. The filter unit stabilizes the modulated solar power supply and provides stable power to the satellite. The shunt unit shunts or cuts off the power of the solar cell according to the power demand of the satellite.

[0046] The modulation signal unit 150 is connected to the satellite power output and the driving unit 170 , and is used to form a first signal (modulation signal) according to the satellite power demand and send it to the driving unit 170 .

[0047] The first signal is an electrical signal generated by the modulation signal unit according to the power output condition, and the electrical signal is a voltage signal. The first signal can have a high level state and a low level state, and the high level state is different from the low level state. For example, the first signal corresponding to the high level state is higher than the reference level, and the first signal corresponding to the low level state is lower than the reference level. It is further explained that the high level state and the low level state here are level states relative to the reference level.

[0048] The forced shunt signal unit 160 is connected to the external signal and the driving unit 170, and is used to generate a second signal (shunt control signal) and a third signal (modulation drive shutdown signal) simultaneously according to the external signal. The second signal is sent to the driving unit 170 to determine whether the driving unit is forced to shunt; the third signal forces the first signal to be in a low level state.

[0049] The second signal and the third signal are both electrical signals generated by the forced shunt signal unit. The electrical signal is a voltage signal. The second signal and the third signal have a high level state and a low level state, and the high level state is different from the low level state. For example, the second signal and the third signal corresponding to the high level state are lower than the reference level, and the second signal and the third signal corresponding to the low level state are higher than the reference level. It is further explained that the high level state and the low level state here are level states relative to the reference level.

[0050] The driving unit 170 is connected to the shunt unit 140, the modulation signal unit 150, and the forced shunt signal unit 160, and generates a fourth signal according to the first signal, the second signal, and the third signal, for controlling the opening or closing or opening state of the shunt unit.

[0051] The fourth signal is an electrical signal generated by the driving unit. The electrical signal is a voltage signal. The fourth signal has a high level state and a low level state, and the high level state is different from the low level state. For example, the fourth signal corresponding to the high level state is higher than the reference level, and the fourth signal corresponding to the low level state is lower than the reference level. It is further explained that the high level state and the low level state here are level states relative to the reference level.

[0052] The shunt unit 140 is connected to the solar cell power supply unit 110, the isolation unit 120, and the driving unit 170. According to the fourth signal generated by the driving unit 170, it is determined whether the shunt unit forcibly shunts the solar cell power supply energy or provides power output to the satellite. The shunt unit has a modulation state, a shunt state, and a cut-off state. Among them, the modulation state is that the shunt unit is in a square wave state with an adjustable output width, and the output of the solar cell power is achieved through the adjustable square wave to meet the power required by the satellite; the shunt state is that the shunt unit is in a fully conductive state, and all the solar cell power is shunted to the ground; the cut-off state is that the shunt unit is in a shut-off state, and all the solar cell power is output.

[0053] When no external signal is sent for forced shunt, the first signal generates a square wave modulation signal according to the power demand of the satellite to provide stable power supply to the satellite; when an external signal is sent for forced shunt, the second signal generates a high level and forces the first signal to be turned off, thereby realizing the function of forced shunt of the solar cell.

[0054] When the satellite requires power, the modulation signal unit generates a first signal, controls the state of the shunt unit through the driving unit, and adjusts the solar cell power supply unit, the isolation unit, and the filter unit to provide power to the satellite.

[0055] When the satellite is in a normal power demand state, the first signal outputs a modulation signal with adjustable width, and the second signal outputs a low level state.

[0056] The external control signal is in a high level state, forcing the shunt signal unit to output the second signal as a high level, and at the same time the third signal forces the first signal output by the modulation signal unit to be in a low level state.

[0057] When the satellite does not need power, the forced shunt signal unit is triggered by an external signal to generate a high level, and the modulation signal unit is turned off at the same time. The driving unit controls the shunt unit to be in the on state, and the energy of the solar cell power supply unit is completely shunt.

[0058] The solar cell forced shunting circuit provided by the present invention can realize the function of forcibly shunting the satellite solar cell energy through an external signal without affecting the satellite solar cell energy closed-loop control strategy.

[0059] In order to explain the above circuit structure in more detail, the present invention also provides a specific example structure of the power supply control circuit. The specific structure of the circuit is as follows: Figure 2 shown.

[0060] The circuit includes: a solar cell power supply unit 110 , an isolation unit 120 , a filtering unit 130 , a shunt unit 140 , a modulation signal unit 150 , a forced shunt signal unit 160 and a driving unit 170 .

[0061] The solar cell power supply unit 110 is used to provide electric energy to the satellite through the isolation unit 120 and the filter unit 130 in sequence, and can also shunt all the energy through the shunt unit 140.

[0062] The solar cell power supply unit 110 is formed by connecting a plurality of solar cell monomers in series and parallel.

[0063] The positive output electrode of the solar cell power supply unit 110 is connected to the anode of the diode D3 of the isolation unit 120, and the negative output electrode of the solar cell power supply unit 110 is connected to the ground.

[0064] The isolation unit 120 includes a diode D3, wherein D3 can also be designed for reliability in series-parallel connection. The present invention uses a single diode as an example. The anode of the diode D3 is connected to the positive output of the solar cell power supply unit 110, and the cathode of the diode D3 is connected to the filter unit 130.

[0065] The filtering unit 130 includes a capacitor C2, wherein the capacitor C2 can also be a plurality of capacitors connected in series or parallel for reliability design, and the present invention example takes a single capacitor as an example. The positive electrode of the capacitor C2 is connected to the cathode of the diode D3 of the isolation unit 120 as the satellite power output positive line, and the negative electrode of the capacitor C2 is connected to the ground as the satellite power output return line.

[0066] The shunt unit 140 includes a transistor Q1 . The gate of the transistor Q1 is connected to the fourth signal generated by the driving unit 170 , the source of the transistor Q1 is connected to the ground, and the drain of the transistor Q1 is connected to the anode of the diode D3 of the isolation unit diode 120 .

[0067] It should be noted that the transistor Q1 in the present invention can be a circuit element such as a metal-oxide-semiconductor (MOS) field effect transistor, an insulated gate bipolar transistor (IGBT), etc. The embodiment of the present invention takes a MOS transistor as an example.

[0068] The modulation signal unit 150 includes resistors R1, R2, R3, capacitor C1, operational amplifier U1, comparator U2, transistors Q2, Q3;

[0069] One end of the resistor R1 is connected to the positive line of the power output, and the other end is simultaneously connected to one end of the resistor R2 and the positive input of the operational amplifier U1;

[0070] The other end of the resistor R2 is connected to the ground, the negative input end of the operational amplifier U1 is connected to the reference voltage and is connected to one end of the capacitor C1, the other end of the capacitor C1 is connected to the resistor R3, the other end of the resistor R3 is connected to the output end of the operational amplifier U1, the output end of the operational amplifier U1 is connected to the positive input pin of the comparator U2, the negative input end of the comparator U2 is connected to the reference triangular wave carrier, the output end of the comparator U2 is connected to the bases of transistors Q2 and Q3, the collector of the transistor Q2 is connected to the power output positive line, the collector of the transistor Q3 is connected to the ground, and the emitter of the transistor Q2 is connected to the emitter of the transistor Q3 as the output end of the first signal.

[0071] The driving unit 170 includes a capacitor C3, a diode D4, a voltage regulator D1, and resistors R6 and R7;

[0072] One end of the capacitor C3 is connected to the first signal generated by the modulation signal unit 150 and is also connected to the anode of the diode D4. The other end of the capacitor C3 is also connected to the cathode of the voltage regulator tube D1, one end of the resistor R7 and the cathode of the diode D4.

[0073] The positive electrode of the voltage regulator D1 is connected to the ground, the other end of the resistor R7 is connected to one end of the resistor R6 to form a fourth signal and is also connected to the gate of the transistor Q1 of the shunt unit 140, and the other end of the resistor R6 is connected to the ground.

[0074] The forced current shunting signal unit 160 includes resistors R4, R5, a diode D2, and transistors Q4, Q5;

[0075] The external signal is connected to one end of the resistor R4, and the other end of the resistor R4 is connected to the anode of the diode D2 and the base of the transistor Q4;

[0076] The cathode of the diode D2 is connected to one end of the resistor R5, and the other end of the resistor R5 is connected to the cathode of the voltage regulator tube D1 of the driving unit to form a second signal;

[0077] The collector of transistor Q4 is connected to the collector of transistor Q5 to form a third signal and is also connected to the output terminal of the debugging signal unit. The emitter of transistor Q4 is connected to the base of transistor Q5; the emitter of transistor Q5 is connected to the ground.

[0078] It should be noted that the transistors Q2, Q3, Q4, and Q5 in the present invention may be circuit elements such as metal-oxide-semiconductor (MOS) field effect transistors and bipolar junction transistors (BJT). The present invention takes the BJT as an example.

[0079] The present invention can meet the demand for light-weight and high-power load power distribution.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention.

Claims

1. A circuit for forced current diversion of solar cells for satellites, characterized in that: It includes a solar cell power supply unit, an isolation unit, a filtering unit, a shunt unit, a modulation signal unit, a forced shunt signal unit and a driving unit, wherein: The solar cell power supply unit converts space solar energy into electrical energy, and sequentially supplies power to the satellite through the isolation unit and the filter unit; The isolation unit is used to unidirectionally isolate the solar cell power supply unit from the filter unit; The filtering unit is used to filter the electric energy after unidirectional isolation by the isolation unit, so as to provide stable electric energy for the satellite; The shunt unit modulates and shunts the electric energy of the solar cell under the control of the driving unit; when no signal from the driving unit is received, the shunt unit is in a cut-off state; The driving unit drives the shunt unit to modulate the electric energy of the solar cell according to the modulation signal of the modulation signal unit, and drives the shunt unit to shunt all the electric energy of the solar cell to the ground according to the shunt control signal of the forced shunt signal unit; The modulation signal unit generates a modulation signal according to the power demand of the satellite and inputs the modulation signal to the driving unit; The forced shunt signal unit generates a forced shunt signal according to an external signal. The forced shunt signal includes a shunt control signal and a modulation drive shutdown signal. The shunt control signal is input to the drive unit, and the modulation drive shutdown signal is used to shut down the modulation signal of the modulation signal unit.

2. A satellite solar cell forced current shunting circuit according to claim 1, characterized in that: Under normal satellite power demand state: When no external signal is received, the modulation signal unit generates a square wave modulation signal with adjustable output width according to the power demand of the satellite and sends it to the driving unit, which controls the state of the shunt unit through the driving unit to adjust the power provided by the solar cell power supply unit to the satellite; When an external signal is received, that is, when the external signal is at a high level, the forced shunt signal unit generates a shunt control signal and a modulation drive shutdown signal, and the modulation drive shutdown signal forces the modulation signal of the modulation signal unit to be at a low level; the shunt control signal is sent to the drive unit, and the drive unit controls the shunt unit to be turned on, thereby realizing forced full shunt of the solar cell electric energy; When the satellite does not need power: The forced shunt signal unit is triggered by an external signal to generate a shunt control signal and a modulation drive shutdown signal, and the modulation drive shutdown signal forces the modulation signal of the modulation signal unit to be a low level; The shunt control signal is sent to the driving unit, and the driving unit controls the shunt unit to be in an on state, so that all the energy of the solar cell power supply unit is shunt.

3. A satellite solar cell forced current shunting circuit according to claim 1, characterized in that: The solar cell power supply unit is composed of solar cell circuit monomers connected in series and parallel.

4. A satellite solar cell forced current shunting circuit according to claim 1, characterized in that: The isolation unit comprises a diode D3, an anode of the diode D3 is connected to the positive electrode of the solar cell power supply unit, and a cathode of the diode D3 is connected to the positive electrode of the filter unit.

5. A satellite solar cell forced current shunting circuit according to claim 4, characterized in that: The filtering unit comprises a capacitor C2, the positive electrode of C2 is connected to the anode of the isolation unit diode D3 as a satellite power output positive line, and the negative electrode of C2 is connected to the ground as a satellite power output return line.

6. A satellite solar cell forced current shunting circuit according to claim 1, characterized in that: The shunt unit includes a transistor Q1; The gate of the transistor Q1 is connected to the output signal of the driving unit, the source of the transistor Q1 is connected to the ground, and the drain of the transistor Q1 is connected to the positive electrode of the solar cell power supply unit.

7. A satellite solar cell forced current shunting circuit according to claim 1, characterized in that: The modulation signal unit includes resistors R1, R2, R3, capacitor C1, operational amplifier U1, comparator U2, transistors Q2, Q3; One end of the resistor R1 is connected to the positive power output line of the circuit, and the other end is simultaneously connected to one end of the resistor R2 and the positive input terminal of the operational amplifier U1; The other end of the resistor R2 is connected to the ground, the negative input end of the operational amplifier U1 is connected to the reference voltage and one end of the capacitor C1 at the same time, the other end of the capacitor C1 is connected to the resistor R3, the other end of the resistor R3 is connected to the output end of the operational amplifier U1, the output end of the operational amplifier U1 is connected to the positive input end of the comparator U2, the negative input end of the comparator U2 is connected to the reference triangular wave carrier, the output end of the comparator U2 is connected to the base of the transistor Q2 and the base of Q3 at the same time, the collector of the transistor Q2 is connected to the power output positive line of the circuit, the collector of the transistor Q3 is connected to the ground, and the emitter of the transistor Q2 is connected to the emitter of the transistor Q3 as the output end of the modulation signal unit.

8. A satellite solar cell forced current shunting circuit according to claim 1, characterized in that: The driving unit includes a capacitor C3, a diode D4, a voltage regulator tube D1, and resistors R6 and R7; One end of the capacitor C3 is connected to the output end of the modulation signal unit and the positive electrode of the diode D4, and the other end of the capacitor C3 is connected to the negative electrode of the voltage regulator tube D1, one end of the resistor R7 and the negative electrode of the diode D4; The positive electrode of the voltage regulator tube D1 is connected to the ground, and the other end of the resistor R7 is connected to one end of the resistor R6 and the signal input end of the shunt unit at the same time; the other end of the resistor R6 is connected to the ground.

9. A satellite solar cell forced current shunting circuit according to claim 8, characterized in that: The forced current shunting signal unit includes resistors R4, R5, a diode D2, and transistors Q4, Q5; One end of the resistor R4 is connected to the external signal, and the other end is connected to the anode of the diode D2 and the base of the transistor Q4; The cathode of the diode D2 is connected to one end of the resistor R5, and the other end of the resistor R5 is connected to the cathode of the voltage regulator tube D1 of the driving unit; After the collector of transistor Q4 is connected to the collector of transistor Q5, it is connected to the output end of the modulation signal unit, the emitter of transistor Q4 is connected to the base of transistor Q5; the emitter of transistor Q5 is connected to the ground.

10. A satellite solar cell forced current shunting circuit according to any one of claims 1 to 9, characterized in that: The external signal is a signal provided by the rocket or a separation signal from the satellite.

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