Title of Invention	APPARATUS FOR VERIFYING A LOW NOISE BLOCK OUTPUT VOLTAGE
Abstract	The present invention relates to system diagnostic circuitry for antenna systems with active antenna components. More specifically, the present invention discloses an apparatus comprising a connection (710) between an antenna and a power supply conducting a first DC voltage, a source of a pulse width modulated signal (730), a lowpass filter for converting (R3, Cl) the pulse width modulated signal to a second DC voltage, and a comparator for comparing (740) the first DC voltage and the second DC voltage and generating an output signal responsive to the difference between the first DC voltage and the second DC voltage.

Title of Invention

APPARATUS FOR VERIFYING A LOW NOISE BLOCK OUTPUT VOLTAGE

Abstract

The present invention relates to system diagnostic circuitry for antenna systems with active antenna components. More specifically, the present invention discloses an apparatus comprising a connection (710) between an antenna and a power supply conducting a first DC voltage, a source of a pulse width modulated signal (730), a lowpass filter for converting (R3, Cl) the pulse width modulated signal to a second DC voltage, and a comparator for comparing (740) the first DC voltage and the second DC voltage and generating an output signal responsive to the difference between the first DC voltage and the second DC voltage.

Full Text	APPARATUS FOR VERIFY NG A LOW NOISE BLOCK OUTPUT VOLTAGE Field of the Invention The present invention relates active antenna components. to system diagnostic circuitry for antenna systems with Background of the Invention Satellite television receiving systems receiving antenna and a "block" con processing section. The block convejrter frequency RF signals transmitted by frequencies. usually comprise an "outdoor unit" including a dish-like erter, and an "indoor unit" including a tuner and a signal converts the entire range ("block") of relatively high a satellite to a more manageable, lower range of In a conventional satellite television in analog form and the RF signals tn GHz) and Ku (e.g., 11.7 to 14.2 GHz antenna of the receiving system are to 2000 MHz). An RF filter section o; signals received from the block converter mixer/local oscillator section of the t intermediate frequency (IF) range fo ransmission system, television information is transmitted nsmitted by the satellite are in the C (e.g., 3.7 to 4.2 bands. The RF signal received from the satellite by the converted by the block converter to the L band (e.g., 900 the tuner of the indoor unit selects the one of the RF corresponding to the selected channel, and a ner converts the selected RF signal to a lower, filtering and demodulation. In newer satellite television systems Corporation of California, television are transmitted by the satellite in the the L band. The frequency range of smaller (e.g., between 12.2 and 12.7 such as the DirecTv™ operated by the Hughes iformation is transmitted in digital form. The RF signals Ku band, and are converted by the block converter to ie RF signals transmitted by the satellite is somewhat GHz) than that for the analog satellite television system, and the frequency range of RF sign somewhat smaller (e.g., between 95 In a digital satellite television broadc compressed and organized into a se respective video, audio, and data po modulated on to a RF carrier signal Keying) modulation and the RF sign is retransmitted back to the earth. In QPSK modulation, the phases of response to the bits of respective dig degrees (.degree.) in response to a in response to a high logic level ("1" combined and the result transmitted each symbol of the modulated QPSh and 11 s produced by the block converter is accordingly and 1450 MHz). st system, the television information is digitized, ies or stream of data packets corresponding to tions of the television information. The digital data is what is known as QPSK (Quaternary Phase Shift is transmitted to a satellite in earth orbit, from which it vo quadrature phase signals, I and Q, are controlled in tal data streams. For example, the phase is set to 0 w logic level ("0"), and the phase is set to 1 SO.degree. The phase shift modulated I and Q signals are is a QPSK modulated RF carrier signal. Accordingly, carrier indicates one of four logic states, i.e., 00, 01,10 The conversion stage of the block supplied by the indoor unit. The sa the subscriber's residence. When a service provider to be able to remote] y possibly avoiding having to send a s simple enough, instructions can be remedied. If the problem is too com equipment failure, advanced informal on technician, thereby allowing the tech cc nverter of the outdoor unit is powered by a DC voltage ellite television signal receivers are typically located at roblem with the system occurs, it is desirable for the diagnose the problems with the receiver, thereby rvice technician to the remote location. If the problem is ven to the subscriber, and the problem immediately ex for the subscriber to remedy, or there is an on the problem can be provided to the service ician to bring the required parts or equipment to the subscriber's location. Among the pa line voltage. In addition to s are used to select between different There are defined ranges for each o kinds of problems in the receiving sy what voltage is being presented on t Having greater knowledge of the volt and effect of problems in the receiving somewhere between or very, very cl than just an indication of the voltage setting. applying operating ameters desirable to be diagnosed remotely is the LNB power to the LNB, different LNB line voltages signals or polarizations of signals received by the LNB. the two allowed voltages. In order to diagnose certain item, it is desirable to know with reasonable accuracy e antenna connector at the back of the indoor unit, age allows better decision-making in determining cause system. Knowing that the LNB line voltage is se to one limit of allowable voltage is more desirable s higher than the allowable band for the lower voltage Summary of the Invention In order to solve the problems addre voltage measurement system and m described in detail with reference to sed above, the present invention concerns an LNB line (thod. This and other aspects of the invention will be accompanying drawings. tie lary embodiment of a digital satellite broadcast system, lary embodiment of a multiple LNB configuration for use Brief Description of the Drawings Fig. 1 is a block diagram of an exem Fig 2. is a block diagram of an exemj in a digital satellite broadcast system Fig. 3 is an exemplary circuit diagrar i of a first exemplary embodiment of an LNB line voltage measurement system. Fig. 4 is a flow chart of the system rojuting for measuring an LNB line voltage using the circuitry of Fig. 3. of a second exemplary embodiment of an LNB line Fig. 5 is an exemplary circuit diagran voltage measurement system. Fig. 6 is a flow chart of the system routing for measuring an LNB line voltage using the circuitry of Fig. 5. Fig. 7 is an exemplary circuit diagrarin of a third exemplary embodiment of an LNB line uting for measuring an LNB line voltage using the voltage measurement system. Fig. 8 is a flow chart of the system re circuitry of Fig. 7. Detailed Description of the Preferrec Embodiment The exemplifications set out herein i such exemplifications are not to be manner. lustrate preferred embodiments of the invention, and donstrued as limiting the scope of the invention in any Referring to Fig. 1, a diagram of an shown. Fig. 1 shows a transmitting noise block (130), a digital satellite s !xemplary embodiment of a satellite television system is satellite (110), a parabolic dish antenna (120) with a low et-top box (140) and a television monitor (150). A satellite broadcast system operate s area. In a digital television broadcast from a geosynchronous satellite (11 once each day and sits at approxim a digital television broadcast satellit remains in the same position with receiving antenna (120) to maintain to broadcast microwave signals to a wide broadcast system, this is accomplished by transmitting the signals )). A geosynchronous satellite (110) orbits the earth ttely 35,786 kilometers above the earths surface. Since (110) generally orbits around the equator it constantly rejspect to positions on the ground. This allows a satellite a fixed look angle. A digital television transmitting satel ite (110) receives a signal from an uplink transmitter and then rebroadcasts the signal back to earth. The altitude of the transmitting satellite (110) allows subscribers in a wide geographical area to receiving the signal. However, the distance from the earth and the seve result in a weak signal being receivec e power conservation requirements of the satellite also by the subscriber. It is therefore critical that the signal be amplified as soon as possible after it is received by the antenna. This requirement is achieved through the placement of a parabolic dish antenna (120). ow noise block (LNB) (130) at the feed horn of the Referring to Fig. 2, a diagram of an exemplary embodiment of a satellite television receiver configuration is shown. Fig. 2 shows switch (240), an indoor unit (250), a f a first LNB (210), a second LNB (220), a third LNB, a rst transmission cable (270), a second transmission cable (260), a third transmission cable (280) and a fourth transmission cable (280). The dish structure of a parabolic ante nna, (120) of Fig. 1 operates in a manner to reflect an incident plane wave such that the en 3rgy from the reflected wave is focused at a point proximate to the surface of the reflec of the parabolic antenna. The distan determined by the radius of the curve :or structure. This point is referred to as the focal point ;e between the reflector structure and the focal point is of the reflector surface. The reflector surface is optimally configured when all the ene rgy focused at the focal point is in phase. This essentially occurs when the energy incident travels an identical distance from the satellite to the focal point. The position of the fecal point can also change depending on the angle of the reflection compared to the incident wave. Exploiting this opportunity to move the focal point allows antenna designers to receive signals from multiple satellites by using a single reflector with multiple LNBs. Each LNB is placed at the resulting focal point for each of the satellite signals incident on the reflector. The exemplary satellite television sigpal signals from three different satellites receiver shown in Fig. 2 is configured to receive using a different LNB (210, 220, 230) at each of the three resulting focal points. Each therefore only the operation of the f the LNBs (210, 220, 230) operate in the same manner, rst LNB (210) will be described. An LNB (210) is positioned at the signal desired. A digital television { frequency range between 12.2 and feed horn integral to the LNB (210) of the signal is increased. The ami frequency RF signal between 950 transmission cable (270) to a switcl connected by a separate transmiss indoor unit (250) the switch routes transmission cable (260) to the i switch 240 has three inputs, each television receiver can operate with can operate with a large number of surface to receive the signal from a fc cal point of the reflector (120) of Fig.1, for the satellite ignal that is transmitted by a satellite is typically in the Ku 12.7 GHz. This signal from the satellite is received by a passed to a low noise RF amplifier where the amplitude F lified signal is then downconverted to a relatively lower end tie indc or 1450 MHz. This signal is then conducted by a (240). The switch (240) has a plurality of inputs each on cable to a plurality of LNBs. As determined by the signal from the desired LNB through a second unit (250). IN the exemplary embodiment shown, the connected to one of three LNBs (210, 220, 230). A digital a single LNB, in which case no switch is required, or it LNBs, each positioned with respect to the reflector single satellite. To provide power to the selected LljJB transmission cable (260), via the suHtch finally to the selected LNB (210). The the LNB (210) by a number of low pjass referred to as the LNB line voltage. , the indoor unit provides a DC voltage to the second (240), via the first transmission cable (270), and DC signal is isolated both at the indoor unit (250) and and high pass filters. This DC voltage is commonly The satellite television signal receivers When a problem with the system oc remotely diagnose the problems with are typically located at the subscriber's residence, curs, it is desirable for the service provider to be able to the receiver, thereby possibly avoiding having to send a service technician to the remote loca be given to the subscriber, and the p complex for the subscriber to remedj ion. If the problem is simple enough, instructions can oblem immediately remedied. If the problem is too , or there is an equipment failure, advanced information on the problem can be provided to the service technician, thereby allowing the technician to bring the required parts or equipmen to the subscriber's location. Among the parameters desirable to be diagnosed remotely in the LNB line voltage. Referring to Fig.3, a LNB Line voltag comprises a first comparator (320), a } test system is shown. The LNB line voltage system second comparator (330), an LNB voltage supply line (310), a first input (340), a second input (350), a first output (345) and a second output (355). In this exemplary embodiment, the fi to a first reference voltage. The LNB divided using a conventional voltage reference voltage. If the desired LNE output (345) of the first comparator ( second input (350) of the second voltage. If the desired LNB line voltage (355) of the second comparator (330 employed indicating the output voltage second threshold voltage. For the vicinity of 13 and 18 volts. When microprocessor of the indoor unit (25J) ifiist st input (340) of the first comparator (320) is connected line voltage on the LNB voltage supply line (310) is divider network R1 ,R2 and compared to the first line voltage is below the first set threshold, the first 20) will indicate a fault condition data bit. Similarly, the comparator (330) is connected to a second reference is below the second set threshold, the second output will indicate a fault condition data bit. Two data bits are is below the first threshold voltage and/or below the exemplary embodiment, the two thresholds are set in the verification of the LNB line voltage is required, the system of Fig. 2) will follow the test sequence shown in Fig. 4. Referring to Fig. 4 shows a test sequence followed by the system microprocessor of the indoor unit (250 of Fig. 2) when verifii ation of the LNB line voltage is required. First the system microprocessor sets the LNB Bine voltage to 13 volts. (410) Then the microprocessor checks the first output (345) of the f second comparator (355) to ensure rst comparator (320) and the second output (355) of the that the LNB line voltage exceeds 13 volts but is less than 18 volts. (420) If the two outpit data bits indicate that neither the 13 volt threshold has been met or the 18 volt threshold, tt LNB, indicating a fault condition anc is indicates that no 13 volt power is being supplied to the either the subscriber or the service provider is notified. (430) If both the 13 volt threshold a id the 18 volt threshold are exceeded, this indicates that the LNB line voltage is stuck at 18 volts indicating a fault condition and either the subscriber or the service provider is notified. (440) If the 13 volt threshold is exceeded but not the 18 volt threshold, the micro sets the LNB line voltage to 18 volts. (450) The microprocessor then tests the LNB voltage to ensure that it exceeds 18 volts. (460) If the 13 volt threshold is exceeded but not the 18 volt threshold his indicates that no 13 volt power is being supplied to the LNB, indicating a fault condition and either the subscriber or the service provider is notified. (470) If both the 13 volt threshold and the 18 volt threshold are exceeded/both voltages are within desired range ar d the LNB voltage test is concluded. (480) Some of the benefits of the LNB line minimal hardware and software to i range of interest, there is shared ha voltage test system shown in Fig. 3 are that it requires implement, it has reasonable accuracy over a limited dware over multiple LNBs. Referring to Fig. 5, a second exemp test system. The LNB line voltage C1, a first resistor R1, a second supply voltage line (510), a second input (580), a third input output voltage measurement circuit conversion method which translates the width of which is measured by tifSt resi >tor ary circuit configuration is shown for an LNB line voltage system shown in Fig. 5 comprises a timing capacitor R2, a first transistor (520), a first input (530), an LNB comparator (550) (570) tre , a third resistor R3, a fourth resistor R4, a a fifth resistor R5, and an output (560). The LNB i shown in Fig. 5, implements an Analog to Digital the LNB power supply voltage (510) into a digital pulse, system microprocessor. The microprocessor sets the first input (530) to high. This has the (520), thereby draining any stored ch effect of applying a voltage to the base of the transistor jrge from the timing capacitor C1. Applying a voltage to the base of the transistor (520) also r as the setting the collector voltage of the transistor (520) to essentially zero volts, which s the voltage seen at the inverting input of the ,. comparator (550). Since the non invorting terminal of the comparator (550) is not higher in potential than the inverting terminal, tie output (560) is set to high. To measure the LNB line voltage (510), the microprocessor sets the first input to low and captures the starts a counter. When the capacitor C1 has charged up to a level above the reference voltage (580), the output of the comparator (550) will tr« nsition from high to low. The microprocessor will stop the counter at the point when the comparator (550) transitions from high to low. This counter value is then converted to an appropniate voltage value by either computation of table lookup. The microprocessor can calculate the LNB voltage from the time measured and known component values in accordance witf Vc = VLNB(1-e Where VLNB is the LNB regulator volt? causing the comparator (550) to tran! the standard charge formula. (Equation 1) t/R2C1K Equation 1 ge being measured, t is the time to charge C1 to Vref ition from high to low, and Vc is the LNB output voltage. Referring to Fig. 6 shows a test sequ ?nce followed by the system microprocessor of the microprocessor starts a counter (630 the output (560) remains high (650). indoor unit (250 of Fig. 2) when verification of the LNB line voltage is required. The microprocessor sets the LNB voltage to the desired test level, either 13 or 18 volts. (610) The microprocessor then sets the value of the first input to zero volts. (620) The and increments that counter (640) for every cycle that When the output (560) transitions to low, the microprocessor calculates the LNB line voltage using the counter value. (660) The microprocessor then compares the a ilculated LNB line voltage with the desired test level. (670). If the value is out of a predete mined range, indicating a fault condition and either the subscriber or the service provider is r otified. 680 If the value is within the predetermined range, the microprocessor sets the normal program flow. (695) 3vel of the first input 530 to high 690 and returns to Referring to Fig. 7, a second exemp test system. The LNB line voltage t voltage line (710), a first input (730) (740), a first resistor R1, a second r first capacitor C1. The LNB line digital conversion of the scaled LNB employed to produce the pulse-widt i system microprocessor of the indoo PWM signal to the first input (730). results in a lower DC value for lowe At a 100% PWM duty cycle the gres microprocessor Vcc value. If it is dc to a value less than Vcc for compari and the second resistor R2 make comparison value below Vcc. This through a low pass filter C1, R3, to the resistor or capacitor values of wave modulated signal ripple, but d as the worst case ripple is smaller (740) compares the scaled LNB line pulse width modulated signal. The (750). The system microprocessor which indicates if the converted PW voltage. (710) Successive voltage ary circuit configuration is shown for an LNB line voltage sst system shown in Fig. 7 comprises an LNB supply a second input (720), a first output (750), a comparator sistor R2, a third resistor R4, a fifth resistor R5, and a test system shown in Fig. 7 performs an analog to line voltage (710). Typically a microprocessor would be modulation (PWM) signal, such as for example, the unit (250 of Fig. 2). The microprocessor applies the Changing the duty cycle of pulse width modulated signal duty cycles and higher DC values for higher duty cycles. :est voltage possible on the inverting input of 740 is the sirable in the application to have the LNB voltage scaled on as in the exemplary embodiment, the first resistor R1 a voltage divider to scale the LNB voltage to a F ulse width modulated (PWM) signal is then passed onvert the signal to an effective DC value. Variations in the low pass filter C1, R3 affect only the removal of pulse not reduce the overall measurement accuracy as long than approxin ation one half LSB of the conversion. The comparator voltage (710) to the DC value of the low pass filtered dpmparator (740) applies an output data bit to the output f the indoor unit (250 of Fig. 2) then reads this output bit vl DC value is higher or lower than the scaled LNB line , ramp method, or other methods are used to discover the closest comparison point of the scaled LNB voltage (710). When the A to D conversion cycle is complete, the fin? I percentage of pulse width modulated duty cycle is then multiplied by the pulse width modulated amplitude or system microprocessor PIO Vcc to indicate the scaled value of the measured LNB voltage (710). The actual LNB voltage (710) is this value multiplied by the scaling actor of the first resistor R1 and the second resistor R2. LNB voltage limits are read from memory accessible to the system microprocessor and the system program reports the LNB volt ige status to the subscriber or the service provider. To keep the comparator circuit from switching point hysteresis is added to the positive feedback of R4. qscillating when the comparison voltage is at or near the the comparator circuit. The hysteresis is achieved with Referring to Fig. 8 a test sequence is is followed by the system microprocei shown using the ramp method of approximation which >sor of the indoor unit (250 of Fig. 2) when verification of the LNB line voltage is required using the circuitry shown in Fig. 7. When required to test the LNB line voltage, the system microprocessor of the indoor unit (250 of Fig. 2) sets the pulse width modulated signal applied to the microprocessor then reads the outpui first input (730 of Fig. 7) to a 0% duty cycle. (810) The (750 of Fig. 7) of the comparator (740 of Fig. 7). (820). If the output is low, this indicates that (the scaled LNB voltage does not exceed the effective DC value of the filtered PWM signal. If the output is low, the system microprocessor increments the PWM duty cycle by a predetermined amount 830. The system microprocessor then rereads the output (750 of Fig. 7) of the comparator (740 of Fig. 7). (820) This process is repeated until tine comparator output 750 indicates a high state. At this point, the high state of the output indicates that the scaled LNB voltage does exceeds the effective DC value of the filtered PWfV the LNB line voltage based on the val signal. The system microprocessor then calculates je of the duty cycle used during the last increment. (840). The measured LNB line voltage can be calculated by taking the product of the duty cycle, the PWM signal amplitude and any scaling factors. While the present invention has been described in terms of a specific embodiment, it will be appreciated that modifications may be made which will fall with in the scope of the invention. Ule 1 . An apparatus comprising: a connection between an ante nna and a power supply conducting a first DC voltage; a source of a pulse width moc ulated signal; a lowpass filter for converting pe pulse width modulated signal to a second DC voltage; and a comparator for comparing tt e first DC voltage and the second DC voltage and generating an output signal rejsponsive to the difference between the first DC voltage and the second DC voltage. 2. The apparatus of claim 1 width modulated signal and further comprising a microprocessor for generating the pulse receiving the output signal. 3. The apparatus of claim 2 further comparator and a plurality of comparison of said plurality of comprising a switch connected between the IpC voltages wherein said switch facilitates the DC voltages with said pulse width modulated signal. 4. The apparatus of claim 1 whe ein said first DC voltage is a low noise block power supply voltage. 5. An apparatus comprising: a connection between an antehna and a power supply conducting a first power supply signal; a first lowpass filter for conver DC voltage; a source of a pulse width mod ing said first power supply signal to a first substantially jlated signal; first substantially DC voltage and the second generating an output signal responsive to the difference ally voltage and the second substantially DC voltage. itre a second lowpass filter for converting the pulse width modulated signal to a second substantially DC voltage; and a comparator for comparing substantially DC voltage and between the first DC substant 6. The apparatus of claim 5 further width modulated signal and receiving comprising a microprocessor for generating the pulse the output signal. 7. The apparatus of claim 6 furtHer comparator and a plurality of comparison of said plurality of DC comprising a switch connected between the voltages wherein said switch facilitates the DC voltages with said pulse width modulated signal. 8. The apparatus of claim 1 whe block power supply voltage. ein said first substantially DC voltage is a low noise 9. An apparatus comprising: a first source of a first DC a second source of a a source of a pulse width a lowpass filter for convert voltage; a switch with an output for second DC voltage and a comparator for comparinb generating an output signa voltage and the 3rd DC vo oltage; second DC voltage; rjiodulated signal; ng the pulse width modulated signal into a third DC electing the first DC voltage and alternatively the ou putting a selected DC voltage; and the selected DC voltage and the third DC voltage and responsive to the difference between the selected DC age. 10. The apparatus of claim 9 furthler width modulated signal and re comprising a microprocessor for generating the pulse ceiving the output signal. 11. The apparatus of claim 9 whe supply voltage 12. The apparatus of claim 9 whei supply voltage. ein said first DC voltage is a low noise block power ein said second DC voltage is a low noise block power 13. A method of measuring an applying a pulse width modulated processing said pulse width comparing said effective DC voltage has an amplitude; adjusting the characteristics o predetermined relationship between is met; and calculating said amplitude of pulse modulated waveform. LN3 line voltage comprising the steps of: waveform to a first input; mjodulated waveform to produce an effective DC voltage; voltage to said LNB line voltage wherein said LNB line said pulse width modulated waveform until a said effective DC value and said LNB line voltage skid LNB line voltage using the characteristics of said 14. The method of claim 13 wherein the duty cycle of the pulse width modulated waveform is adjusted until a p value and said LNB line voltag edetermined relationship between said effective DC e is met. 15. The method of claim 13 whe waveform is adjusted until a value and said LNB line volteige ein the amplitude of the pulse width modulated jredetermined relationship between said effective DC is met. 16. The method of claim 13 whe a lowpass filter. ein the pulse width modulated signal is processed using 17. The method of claim 13 whe said LNB line voltage whereifi the characteristics of said pu relationship between said eff performed subject to a ramp ein the steps of comparing said effective DC voltage to said LNB line voltage has an amplitude and adjusting se width modulated waveform until a predetermined active DC value and said LNB line voltage is met are Tiethod of approximation. 18. The method of claim 13 whei said LNB line voltage whereii the characteristics of said pu relationship between said by successive approximation ein the steps of comparing said effective DC voltage to said LNB line voltage has an amplitude and adjusting se width modulated waveform until a predetermined effective DC value and said LNB line voltage is performed

Full Text

APPARATUS FOR VERIFY

NG A LOW NOISE BLOCK OUTPUT VOLTAGE

Field of the Invention
The present invention relates active antenna components.

to system diagnostic circuitry for antenna systems with

Background of the Invention Satellite television receiving systems receiving antenna and a "block" con processing section. The block convejrter frequency RF signals transmitted by frequencies.
usually comprise an "outdoor unit" including a dish-like erter, and an "indoor unit" including a tuner and a signal converts the entire range ("block") of relatively high a satellite to a more manageable, lower range of

In a conventional satellite television in analog form and the RF signals tn GHz) and Ku (e.g., 11.7 to 14.2 GHz antenna of the receiving system are to 2000 MHz). An RF filter section o; signals received from the block converter mixer/local oscillator section of the t intermediate frequency (IF) range fo
ransmission system, television information is transmitted nsmitted by the satellite are in the C (e.g., 3.7 to 4.2 bands. The RF signal received from the satellite by the converted by the block converter to the L band (e.g., 900 the tuner of the indoor unit selects the one of the RF
corresponding to the selected channel, and a ner converts the selected RF signal to a lower, filtering and demodulation.

In newer satellite television systems Corporation of California, television are transmitted by the satellite in the the L band. The frequency range of smaller (e.g., between 12.2 and 12.7

such as the DirecTv™ operated by the Hughes iformation is transmitted in digital form. The RF signals Ku band, and are converted by the block converter to ie RF signals transmitted by the satellite is somewhat GHz) than that for the analog satellite television system,

and the frequency range of RF sign somewhat smaller (e.g., between 95
In a digital satellite television broadc compressed and organized into a se respective video, audio, and data po modulated on to a RF carrier signal Keying) modulation and the RF sign is retransmitted back to the earth.
In QPSK modulation, the phases of response to the bits of respective dig degrees (.degree.) in response to a in response to a high logic level ("1" combined and the result transmitted each symbol of the modulated QPSh and 11

s produced by the block converter is accordingly and 1450 MHz).
st system, the television information is digitized, ies or stream of data packets corresponding to tions of the television information. The digital data is what is known as QPSK (Quaternary Phase Shift is transmitted to a satellite in earth orbit, from which it
vo quadrature phase signals, I and Q, are controlled in tal data streams. For example, the phase is set to 0 w logic level ("0"), and the phase is set to 1 SO.degree. The phase shift modulated I and Q signals are is a QPSK modulated RF carrier signal. Accordingly, carrier indicates one of four logic states, i.e., 00, 01,10

The conversion stage of the block supplied by the indoor unit. The sa the subscriber's residence. When a service provider to be able to remote] y possibly avoiding having to send a s simple enough, instructions can be remedied. If the problem is too com equipment failure, advanced informal on technician, thereby allowing the tech
cc nverter of the outdoor unit is powered by a DC voltage ellite television signal receivers are typically located at roblem with the system occurs, it is desirable for the diagnose the problems with the receiver, thereby rvice technician to the remote location. If the problem is ven to the subscriber, and the problem immediately ex for the subscriber to remedy, or there is an
on the problem can be provided to the service ician to bring the required parts or equipment to the

subscriber's location. Among the pa line voltage. In addition to s are used to select between different There are defined ranges for each o kinds of problems in the receiving sy what voltage is being presented on t Having greater knowledge of the volt and effect of problems in the receiving somewhere between or very, very cl than just an indication of the voltage setting.
applying operating
ameters desirable to be diagnosed remotely is the LNB power to the LNB, different LNB line voltages signals or polarizations of signals received by the LNB. the two allowed voltages. In order to diagnose certain item, it is desirable to know with reasonable accuracy e antenna connector at the back of the indoor unit, age allows better decision-making in determining cause
system. Knowing that the LNB line voltage is se to one limit of allowable voltage is more desirable s higher than the allowable band for the lower voltage

Summary of the Invention In order to solve the problems addre voltage measurement system and m described in detail with reference to

sed above, the present invention concerns an LNB line (thod. This and other aspects of the invention will be accompanying drawings.
tie

lary embodiment of a digital satellite broadcast system, lary embodiment of a multiple LNB configuration for use
Brief Description of the Drawings
Fig. 1 is a block diagram of an exem
Fig 2. is a block diagram of an exemj
in a digital satellite broadcast system
Fig. 3 is an exemplary circuit diagrar i of a first exemplary embodiment of an LNB line
voltage measurement system.
Fig. 4 is a flow chart of the system rojuting for measuring an LNB line voltage using the
circuitry of Fig. 3.
of a second exemplary embodiment of an LNB line
Fig. 5 is an exemplary circuit diagran
voltage measurement system.

Fig. 6 is a flow chart of the system routing for measuring an LNB line voltage using the
circuitry of Fig. 5.
Fig. 7 is an exemplary circuit diagrarin of a third exemplary embodiment of an LNB line
uting for measuring an LNB line voltage using the
voltage measurement system. Fig. 8 is a flow chart of the system re circuitry of Fig. 7.
Detailed Description of the Preferrec Embodiment

The exemplifications set out herein i such exemplifications are not to be manner.
lustrate preferred embodiments of the invention, and donstrued as limiting the scope of the invention in any

Referring to Fig. 1, a diagram of an shown. Fig. 1 shows a transmitting noise block (130), a digital satellite s

!xemplary embodiment of a satellite television system is satellite (110), a parabolic dish antenna (120) with a low et-top box (140) and a television monitor (150).

A satellite broadcast system operate s area. In a digital television broadcast from a geosynchronous satellite (11 once each day and sits at approxim a digital television broadcast satellit remains in the same position with receiving antenna (120) to maintain
to broadcast microwave signals to a wide broadcast system, this is accomplished by transmitting the signals )). A geosynchronous satellite (110) orbits the earth ttely 35,786 kilometers above the earths surface. Since (110) generally orbits around the equator it constantly rejspect to positions on the ground. This allows a satellite a fixed look angle.

A digital television transmitting satel

ite (110) receives a signal from an uplink transmitter and

then rebroadcasts the signal back to earth. The altitude of the transmitting satellite (110) allows subscribers in a wide geographical area to receiving the signal. However, the

distance from the earth and the seve result in a weak signal being receivec

e power conservation requirements of the satellite also by the subscriber. It is therefore critical that the signal

be amplified as soon as possible after it is received by the antenna. This requirement is

achieved through the placement of a parabolic dish antenna (120).

ow noise block (LNB) (130) at the feed horn of the

Referring to Fig. 2, a diagram of an exemplary embodiment of a satellite television receiver

configuration is shown. Fig. 2 shows switch (240), an indoor unit (250), a f

a first LNB (210), a second LNB (220), a third LNB, a rst transmission cable (270), a second transmission

cable (260), a third transmission cable (280) and a fourth transmission cable (280).

The dish structure of a parabolic ante nna, (120) of Fig. 1 operates in a manner to reflect an incident plane wave such that the en 3rgy from the reflected wave is focused at a point

proximate to the surface of the reflec of the parabolic antenna. The distan determined by the radius of the curve

:or structure. This point is referred to as the focal point ;e between the reflector structure and the focal point is of the reflector surface. The reflector surface is

optimally configured when all the ene rgy focused at the focal point is in phase. This essentially occurs when the energy incident travels an identical distance from the satellite to the focal point. The position of the fecal point can also change depending on the angle of the reflection compared to the incident wave. Exploiting this opportunity to move the focal point

allows antenna designers to receive

signals from multiple satellites by using a single reflector

with multiple LNBs. Each LNB is placed at the resulting focal point for each of the satellite signals incident on the reflector.

The exemplary satellite television sigpal signals from three different satellites

receiver shown in Fig. 2 is configured to receive using a different LNB (210, 220, 230) at each of the

three resulting focal points. Each therefore only the operation of the f

the LNBs (210, 220, 230) operate in the same manner, rst LNB (210) will be described.

An LNB (210) is positioned at the signal desired. A digital television { frequency range between 12.2 and feed horn integral to the LNB (210) of the signal is increased. The ami frequency RF signal between 950 transmission cable (270) to a switcl connected by a separate transmiss indoor unit (250) the switch routes transmission cable (260) to the i switch 240 has three inputs, each television receiver can operate with can operate with a large number of surface to receive the signal from a
fc cal
point of the reflector (120) of Fig.1, for the satellite ignal that is transmitted by a satellite is typically in the Ku 12.7 GHz. This signal from the satellite is received by a passed to a low noise RF amplifier where the amplitude F lified signal is then downconverted to a relatively lower
end
tie
indc or
1450 MHz. This signal is then conducted by a (240). The switch (240) has a plurality of inputs each on cable to a plurality of LNBs. As determined by the signal from the desired LNB through a second unit (250). IN the exemplary embodiment shown, the connected to one of three LNBs (210, 220, 230). A digital a single LNB, in which case no switch is required, or it LNBs, each positioned with respect to the reflector single satellite.

To provide power to the selected LljJB transmission cable (260), via the suHtch finally to the selected LNB (210). The the LNB (210) by a number of low pjass referred to as the LNB line voltage.
, the indoor unit provides a DC voltage to the second (240), via the first transmission cable (270), and
DC signal is isolated both at the indoor unit (250) and and high pass filters. This DC voltage is commonly

The satellite television signal receivers When a problem with the system oc remotely diagnose the problems with
are typically located at the subscriber's residence, curs, it is desirable for the service provider to be able to the receiver, thereby possibly avoiding having to send a

service technician to the remote loca
be given to the subscriber, and the p complex for the subscriber to remedj

ion. If the problem is simple enough, instructions can oblem immediately remedied. If the problem is too , or there is an equipment failure, advanced information

on the problem can be provided to the service technician, thereby allowing the technician to

bring the required parts or equipmen

to the subscriber's location. Among the parameters

desirable to be diagnosed remotely in the LNB line voltage.

Referring to Fig.3, a LNB Line voltag comprises a first comparator (320), a

} test system is shown. The LNB line voltage system second comparator (330), an LNB voltage supply line

(310), a first input (340), a second input (350), a first output (345) and a second output (355).

In this exemplary embodiment, the fi to a first reference voltage. The LNB divided using a conventional voltage reference voltage. If the desired LNE output (345) of the first comparator ( second input (350) of the second voltage. If the desired LNB line voltage (355) of the second comparator (330 employed indicating the output voltage second threshold voltage. For the vicinity of 13 and 18 volts. When microprocessor of the indoor unit (25J)
ifiist
st input (340) of the first comparator (320) is connected line voltage on the LNB voltage supply line (310) is divider network R1 ,R2 and compared to the first line voltage is below the first set threshold, the first 20) will indicate a fault condition data bit. Similarly, the comparator (330) is connected to a second reference
is below the second set threshold, the second output will indicate a fault condition data bit. Two data bits are is below the first threshold voltage and/or below the exemplary embodiment, the two thresholds are set in the verification of the LNB line voltage is required, the system of Fig. 2) will follow the test sequence shown in Fig. 4.

Referring to Fig. 4 shows a test sequence followed by the system microprocessor of the

indoor unit (250 of Fig. 2) when verifii

ation of the LNB line voltage is required. First the

system microprocessor sets the LNB Bine voltage to 13 volts. (410) Then the microprocessor

checks the first output (345) of the f second comparator (355) to ensure

rst comparator (320) and the second output (355) of the that the LNB line voltage exceeds 13 volts but is less

than 18 volts. (420) If the two outpit data bits indicate that neither the 13 volt threshold has

been met or the 18 volt threshold, tt LNB, indicating a fault condition anc

is indicates that no 13 volt power is being supplied to the either the subscriber or the service provider is notified.

(430) If both the 13 volt threshold a id the 18 volt threshold are exceeded, this indicates that the LNB line voltage is stuck at 18 volts indicating a fault condition and either the subscriber or the service provider is notified. (440) If the 13 volt threshold is exceeded but not the 18 volt threshold, the micro sets the LNB line voltage to 18 volts. (450) The microprocessor then tests the LNB voltage to ensure that it exceeds 18 volts. (460) If the 13 volt threshold is exceeded but not the 18 volt threshold his indicates that no 13 volt power is being supplied to

the LNB, indicating a fault condition

and either the subscriber or the service provider is

notified. (470) If both the 13 volt threshold and the 18 volt threshold are exceeded/both voltages are within desired range ar d the LNB voltage test is concluded. (480)

Some of the benefits of the LNB line minimal hardware and software to i range of interest, there is shared ha
voltage test system shown in Fig. 3 are that it requires implement, it has reasonable accuracy over a limited dware over multiple LNBs.

Referring to Fig. 5, a second exemp test system. The LNB line voltage C1, a first resistor R1, a second supply voltage line (510), a second input (580), a third input output voltage measurement circuit conversion method which translates the width of which is measured by
tifSt
resi >tor
ary circuit configuration is shown for an LNB line voltage system shown in Fig. 5 comprises a timing capacitor R2, a first transistor (520), a first input (530), an LNB
comparator (550)
(570)
tre
, a third resistor R3, a fourth resistor R4, a a fifth resistor R5, and an output (560). The LNB i shown in Fig. 5, implements an Analog to Digital the LNB power supply voltage (510) into a digital pulse, system microprocessor. The microprocessor sets the

first input (530) to high. This has the (520), thereby draining any stored ch

effect of applying a voltage to the base of the transistor jrge from the timing capacitor C1. Applying a voltage to

the base of the transistor (520) also r as the setting the collector voltage of the transistor

(520) to essentially zero volts, which

s the voltage seen at the inverting input of the

,.
comparator (550). Since the non invorting terminal of the comparator (550) is not higher in potential than the inverting terminal, tie output (560) is set to high. To measure the LNB line voltage (510), the microprocessor sets the first input to low and captures the starts a counter.
When the capacitor C1 has charged up to a level above the reference voltage (580), the

output of the comparator (550) will tr«

nsition from high to low. The microprocessor will stop

the counter at the point when the comparator (550) transitions from high to low. This counter value is then converted to an appropniate voltage value by either computation of table lookup. The microprocessor can calculate the LNB voltage from the time measured and known

component values in accordance witf
Vc = VLNB(1-e Where VLNB is the LNB regulator volt? causing the comparator (550) to tran!

the standard charge formula. (Equation 1)
t/R2C1K
Equation 1
ge being measured, t is the time to charge C1 to Vref ition from high to low, and Vc is the LNB output voltage.

Referring to Fig. 6 shows a test sequ

?nce followed by the system microprocessor of the

microprocessor starts a counter (630 the output (560) remains high (650).
indoor unit (250 of Fig. 2) when verification of the LNB line voltage is required. The microprocessor sets the LNB voltage to the desired test level, either 13 or 18 volts. (610) The microprocessor then sets the value of the first input to zero volts. (620) The
and increments that counter (640) for every cycle that
When the output (560) transitions to low, the
microprocessor calculates the LNB line voltage using the counter value. (660) The microprocessor then compares the a ilculated LNB line voltage with the desired test level.

(670). If the value is out of a predete

mined range, indicating a fault condition and either the

subscriber or the service provider is r otified. 680 If the value is within the predetermined

range, the microprocessor sets the normal program flow. (695)

3vel of the first input 530 to high 690 and returns to

Referring to Fig. 7, a second exemp test system. The LNB line voltage t voltage line (710), a first input (730) (740), a first resistor R1, a second r first capacitor C1. The LNB line digital conversion of the scaled LNB employed to produce the pulse-widt i system microprocessor of the indoo PWM signal to the first input (730). results in a lower DC value for lowe At a 100% PWM duty cycle the gres microprocessor Vcc value. If it is dc to a value less than Vcc for compari and the second resistor R2 make comparison value below Vcc. This through a low pass filter C1, R3, to the resistor or capacitor values of wave modulated signal ripple, but d as the worst case ripple is smaller (740) compares the scaled LNB line pulse width modulated signal. The (750). The system microprocessor which indicates if the converted PW voltage. (710) Successive
voltage
ary circuit configuration is shown for an LNB line voltage sst system shown in Fig. 7 comprises an LNB supply a second input (720), a first output (750), a comparator sistor R2, a third resistor R4, a fifth resistor R5, and a test system shown in Fig. 7 performs an analog to line voltage (710). Typically a microprocessor would be modulation (PWM) signal, such as for example, the unit (250 of Fig. 2). The microprocessor applies the Changing the duty cycle of pulse width modulated signal duty cycles and higher DC values for higher duty cycles. :est voltage possible on the inverting input of 740 is the sirable in the application to have the LNB voltage scaled on as in the exemplary embodiment, the first resistor R1 a voltage divider to scale the LNB voltage to a
F ulse
width modulated (PWM) signal is then passed
onvert the signal to an effective DC value. Variations in
the
low pass filter C1, R3 affect only the removal of pulse
not reduce the overall measurement accuracy as long
than
approxin ation
one half LSB of the conversion. The comparator voltage (710) to the DC value of the low pass filtered dpmparator (740) applies an output data bit to the output f the indoor unit (250 of Fig. 2) then reads this output bit vl DC value is higher or lower than the scaled LNB line , ramp method, or other methods are used to

discover the closest comparison point of the scaled LNB voltage (710). When the A to D

conversion cycle is complete, the fin?

I percentage of pulse width modulated duty cycle is

then multiplied by the pulse width modulated amplitude or system microprocessor PIO Vcc to indicate the scaled value of the measured LNB voltage (710). The actual LNB voltage (710)

is this value multiplied by the scaling

actor of the first resistor R1 and the second resistor R2.

LNB voltage limits are read from memory accessible to the system microprocessor and the system program reports the LNB volt ige status to the subscriber or the service provider.

To keep the comparator circuit from switching point hysteresis is added to the positive feedback of R4.
qscillating when the comparison voltage is at or near the the comparator circuit. The hysteresis is achieved with

Referring to Fig. 8 a test sequence is is followed by the system microprocei

shown using the ramp method of approximation which >sor of the indoor unit (250 of Fig. 2) when verification of

the LNB line voltage is required using the circuitry shown in Fig. 7. When required to test the LNB line voltage, the system microprocessor of the indoor unit (250 of Fig. 2) sets the pulse

width modulated signal applied to the microprocessor then reads the outpui

first input (730 of Fig. 7) to a 0% duty cycle. (810) The (750 of Fig. 7) of the comparator (740 of Fig. 7). (820).

If the output is low, this indicates that (the scaled LNB voltage does not exceed the effective DC value of the filtered PWM signal. If the output is low, the system microprocessor increments the PWM duty cycle by a predetermined amount 830. The system microprocessor then rereads the output (750 of Fig. 7) of the comparator (740 of Fig. 7). (820) This process is repeated until tine comparator output 750 indicates a high state. At this point, the high state of the output indicates that the scaled LNB voltage does exceeds the

effective DC value of the filtered PWfV
the LNB line voltage based on the val

signal. The system microprocessor then calculates je of the duty cycle used during the last increment.

(840). The measured LNB line voltage can be calculated by taking the product of the duty cycle, the PWM signal amplitude and any scaling factors.
While the present invention has been described in terms of a specific embodiment, it will be appreciated that modifications may be made which will fall with in the scope of the invention.

Ule

1 . An apparatus comprising: a connection between an ante

nna and a power supply conducting a first DC voltage;

a source of a pulse width moc ulated signal;
a lowpass filter for converting pe pulse width modulated signal to a second DC

voltage; and
a comparator for comparing tt

e first DC voltage and the second DC voltage and

generating an output signal rejsponsive to the difference between the first DC voltage and the second DC voltage.

2. The apparatus of claim 1 width modulated signal and
further comprising a microprocessor for generating the pulse receiving the output signal.

3. The apparatus of claim 2 further comparator and a plurality of comparison of said plurality of
comprising a switch connected between the IpC voltages wherein said switch facilitates the DC voltages with said pulse width modulated signal.

4. The apparatus of claim 1 whe ein said first DC voltage is a low noise block power
supply voltage.
5. An apparatus comprising:
a connection between an antehna and a power supply conducting a first power supply signal;

a first lowpass filter for conver
DC voltage;
a source of a pulse width mod

ing said first power supply signal to a first substantially
jlated signal;

first substantially DC voltage and the second generating an output signal responsive to the difference ally voltage and the second substantially DC voltage.
itre
a second lowpass filter for converting the pulse width modulated signal to a second substantially DC voltage; and a comparator for comparing substantially DC voltage and between the first DC substant

6. The apparatus of claim 5 further width modulated signal and receiving
comprising a microprocessor for generating the pulse the output signal.

7. The apparatus of claim 6 furtHer comparator and a plurality of comparison of said plurality of
DC
comprising a switch connected between the voltages wherein said switch facilitates the DC voltages with said pulse width modulated signal.

8. The apparatus of claim 1 whe block power supply voltage.

ein said first substantially DC voltage is a low noise

9. An apparatus comprising:
a first source of a first DC a second source of a a source of a pulse width a lowpass filter for convert voltage;
a switch with an output for second DC voltage and a comparator for comparinb generating an output signa voltage and the 3rd DC vo
oltage;
second
DC voltage; rjiodulated signal; ng the pulse width modulated signal into a third DC
electing the first DC voltage and alternatively the ou putting a selected DC voltage; and
the selected DC voltage and the third DC voltage and responsive to the difference between the selected DC age.

10. The apparatus of claim 9 furthler width modulated signal and re
comprising a microprocessor for generating the pulse ceiving the output signal.

11. The apparatus of claim 9 whe
supply voltage
12. The apparatus of claim 9 whei
supply voltage.

ein said first DC voltage is a low noise block power
ein said second DC voltage is a low noise block power

13. A method of measuring an applying a pulse width modulated processing said pulse width comparing said effective DC voltage has an amplitude; adjusting the characteristics o predetermined relationship between is met; and
calculating said amplitude of pulse modulated waveform.
LN3
line voltage comprising the steps of:
waveform to a first input;
mjodulated waveform to produce an effective DC voltage; voltage to said LNB line voltage wherein said LNB line
said pulse width modulated waveform until a
said effective DC value and said LNB line voltage
skid LNB line voltage using the characteristics of said

14. The method of claim 13 wherein the duty cycle of the pulse width modulated

waveform is adjusted until a p value and said LNB line voltag

edetermined relationship between said effective DC e is met.

15. The method of claim 13 whe waveform is adjusted until a value and said LNB line volteige
ein the amplitude of the pulse width modulated jredetermined relationship between said effective DC is met.

16. The method of claim 13 whe a lowpass filter.

ein the pulse width modulated signal is processed using

17. The method of claim 13 whe said LNB line voltage whereifi the characteristics of said pu relationship between said eff performed subject to a ramp
ein the steps of comparing said effective DC voltage to said LNB line voltage has an amplitude and adjusting se width modulated waveform until a predetermined active DC value and said LNB line voltage is met are Tiethod of approximation.

18. The method of claim 13 whei said LNB line voltage whereii the characteristics of said pu relationship between said by successive approximation
ein the steps of comparing said effective DC voltage to said LNB line voltage has an amplitude and adjusting se width modulated waveform until a predetermined effective DC value and said LNB line voltage is performed

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Patent Number

268588

Indian Patent Application Number

6974/DELNP/2006

PG Journal Number

37/2015

Publication Date

11-Sep-2015

Grant Date

04-Sep-2015

Date of Filing

21-Nov-2006

Name of Patentee

THOMSON LICENSING

Applicant Address

46,QUAI A LE GALLO F-92100 BOULOGNE BILLANCOURT FRANCE

Inventors:

#	Inventor's Name	Inventor's Address
1	FITZPATRICK JOHN JAMES	3903 JUNCO CIRCLE INDIANAPOLIS INDIANA 46228 USA
2	SCHMIDT ROBERT WARREN	5019 WESTWOOD DRIVE INDIANAPOLIS INDIANA 46033,USA
3	PITSCH,ROBERT ALAN	246 BOULDER CT CARMEL INDIANA 46032,USA
4	CURTIS JOHN JOSEPH	121 SCARBOROUGHT CIRCLE NOBLESVILLE INDIANA 46060 USA

PCT International Classification Number

H04N 7/20

PCT International Application Number

PCT/US2004/016864

PCT International Filing date

2004-05-27

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	PCT/US04/016864	2004-05-27	France