MXPA06010216A - Verifying 22khz tone operation in a set-top box - Google Patents

Abstract

A set top box arrangement includes transmitting circuitry for transmitting a message and an emulated reply to the message, and receiver circuitry for receiving the control message and comparing the control message to the emulated reply to the message. The transmitted message and emulated reply message are each a digital satellite equipment control message. The emulated reply message that was received is compared with the reply that was transmitted to verify 22kHz tone operation of a low noise block downconverter power supply.

Description

VERIFICATION OF OPERATION OF TONE AT 22 KHz IN A TRANSCODIFIER FIELD OF THE INVENTION The present invention relates in general to satellite communications and more particularly to the verification of the 22 kHz tone operation of a satellite transcoder.

BACKGROUND OF THE INVENTION The control of open digital satellite equipment (DiSEqC) is based on the switching of a 22 kHz tone quickly on and off. In this way, a specially designed receiver can communicate with several control devices, which can be connected to a low noise block (LNB) down converter. DiSEqC messages are sent as sequences of short bursts of a 22 kHz tone modulated in the LNB power supply carried by the coaxial cable from the input to the receiver (the master) to the LNB and / or other devices. The messages comprise a number of digital bytes of nine bits each (8 data bits + 1 odd parity bit). Each bit occupies a specific time and the proportion of that time is filled with the 22 kHz burst and determines if that bit is a 1 or a 0. It is a simple scheme of pulse width modulation. The DiSEqC system has been designed primarily to solve the problem of multi-satellite systems and / or multiple bands with ease. It has commands to switch between inputs, change frequencies between devices and many others, as well as allow custom commands to be used in systems. The first byte of the DiSEqC protocol is the framed byte.

The first five bits of this byte follow the "11100" pattern to allow sound devices (slaves) to synchronize with the signal. Some bit definitions can change with the latest DiSEqC versions also allow you to use custom data definitions. The sixth bit is set to "0" when the message is a command from the master or "1" when it is a response from the slave. Bit seven is set to "1" when a response is required or "0" when it is not. The last framed bit indicates if this message is a re-transmission of a message for which no response was received. The second byte indicates the family of devices to which the message belongs. The first half (four bits) indicates the type of device (LNB, switch, positioner, etc.) and the second half the particular type. On each half of this address byte a value of "0" means that the message is open to all. Next comes the command byte. This actually dictates to listening devices their function. This is followed by the number of bytes of data to be passed in numbers relevant to the command (such as the required angle from a separate polarizer). For the control of simple switches that do not necessarily require support for the extension of the DiSEqC protocol with the protocol known as tone burst. A burst of 12.5ms of a continuous 22 kHz tone is used to select the "A" position on the switch and the nine-bit DiSEqC sequence is used to select the "B" position. When attempting to start an installation of the user's transcoder, it would be useful to solve some problems when the transcoder hardware can develop a self-test procedure. Simple detection circuits consist of one or two transistors and few separate components can be implemented to perform the test. This additional circuitry adds cost and may fail and falsely indicate a problem with the transcoder while the LNB supply of the transcoder is operating correctly. Accordingly, there is a need to determine whether or not a 22 kHz portion of an LNB power supply of the transcoder is functioning correctly and is within specification without requiring additional hardware.

BRIEF DESCRIPTION OF THE INVENTION A transcoder arrangement includes transmitting circuitry for transmitting a message and receiving circuitry for receiving the control message and comparing the control message with the transmitted message. The transmitted message may be a control message of digital satellite equipment.

In an alternative embodiment, a transcoder array includes transmitting circuitry for transmitting a message, a controlled input terminal for emulating a response to the transmitted message, and circuitry for comparing the simulated response with the received message. A method for verifying a tone operation at 22 kHz in a satellite transcoder includes the steps of sending a control message of digital satellite equipment with a transmitter, changing the control of the transmitter on a controlled input pin, pressing the pin of input to send a simulated response to the control message, and compare the simulated response with the received response to verify the operation.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the present invention can be obtained after considering the following description together with the drawings, in which: Figure 1 is a block diagram of a principal end arrangement of an exemplary satellite transcoder to carry out the invention; Figure 2 is a block diagram of an exemplary method for verifying the tone operation 22 kHz according to the invention.

DETAILED DESCRIPTION OF THE INVENTION As part of the satellite transcoder, the LNB power supply may include the generation of a 22 kHz tone or a pulse-width modulated 22 kHz tone for communication to the LNB or other peripherals, such as a multi- switch, which can be connected to the transcoder. This invention allows the transcoder to determine whether this 22 kHz portion of the transcoder's power supply LNB is functioning correctly with the use of the hardware in the transcoder, which is used for communication to and from the LNB and / or peripherals. The invention is a methodology for determining whether or not the portion of an LNB power supply of the transcoder is functioning correctly and within specifications without the need for additional hardware. Figure 1 shows a block diagram 100 for a main end configuration of a satellite transcoder (STB). The satellite signal is carried from an outdoor unit (ODU) (not shown) consisting of the LNB and / or multiple switches and / or other accessories to the 101 input of the STB satellite through! coaxial cable. The radio frequency (RF) signal passes to the satellite tuner 102. The 22 kHz tone and / or DiSEqC messages are passed to a DiSEqC receiver 105. The tone is displayed on the 105 DIseqC receiver regardless of whether it originates in the LNB power supply or in the ODU. The LNB power supply 103 is responsible for passing the control and DC signals to the ODU through the same coaxial cable that carries the RF radio frequency signal to the STB. The control signal may consist of DiSEqC messages or a scheme of modulated messages of similar pulse width or a continuous tone. When it is necessary to diagnose a problem, why satellite signals do not reach the STB, many things can be wrong. It can be from a loose connection or a broken cable to a problem with the circuitry in the STB. Testing the 22 kHz to verify that this portion of the LNB power supply is operating correctly helps solve the problem and possibly avoid "fixing" a wrong problem. This can be achieved with a small circuit designed for this purpose, which consists of several transistors and few separate components. However, when the STB already has the circuitry to implement the 22 kHz (bidirectional) for control of the ODU, the existing circuitry can be used to verify that the 22 kHz tone portion of the LNB power supply is operating correctly. The 22 kHz can be verified with the use of transmitter circuitry of the DiSEqC transmitter 104 not only to transmit an original DiSEqC message, but to simulate the response that will occur in a device in the DiSEqC busbar as an LNB or a multi-switch. Depending on the design of the LNB supply and the DiSEqC circuitry, it may be possible that the receiving portion of the circuit "receives" exactly what is transmitted. The received data can be compared with the transmitted data and the 22 kHz operation is verified. When the DiSEqC circuitry and the LNB supply are designed in such a way that they do not allow the receiving portion to "receive" exactly what is transmitted (ie, it ignores what is sent), then the 22 kHz can be verified by simulating a response in the busbar. This can be done by "copying the bits" of the response through the LNB power supply with the use of a general purpose input / output (GPIO) plug under the control of software in the STB to create the DiSEqC message . The received data is then compared to the simulated response expected to verify the 22 kHz tone. Here, other things come into play. The 22 kHz tone from the STB may have sufficient amplitude to control the ODU correctly. This may be different than expected in the DiSEqC busbar. It may be possible to verify the amplitude, given the design of the DiSEqC receiver that allows adjustments in the amplitude threshold. Several problems may arise when testing 22 kHz with the simulated response. There may be devices in the DiSEqC busbar that actually respond to the original signal transmitted. When the format and timing of the response are appropriate and expected, it also verifies that the 22 kHz transmission works well. However, when the response is not exactly what is expected, then the simulated response will need to verify that the 22 kHz tone operates correctly. However, the simulated response can "contend" with the response from the ODU in the busbar and both messages will be compromised. This contention can be eliminated with the careful selection of the original transmitted DiSEqC message. For example, the original transmitted DiSEqC command may be a "sleep" command. This can put all devices in the busbar in sleep mode and may not respond to other commands until the "wake up" command is received. The "wake up" command will have to be transmitted after completing the tests, so that the devices in the DiSEqC bus bar can resume operation. Another example to avoid contention in the busbar may be to send a DiSEqC command for which no response is expected. A "reset" command can be an example of such a command. Another example to try to avoid contention in the busbar will be to make the original command transmitted an "unknown" command: For example, the first group of an appropriate DiSEqC message always consists of the binary bits "1", "1", "1", "0" In this way, an unknown command will have a first group of a bit pattern that does not match this pattern. Figure 2 is an exemplary flow chart 200 of the way to verify the 22 kHz tone upon receiving a simulated response. The text in bold in the diagram offers the hexadecimal commands that are sent in the DiSEqC busbar. The original DiSEqC message is sent with the transmitter 201 followed by a sufficient waiting period for the bus 202 to be released. This first message is sent to release the bus to a known state and is optional. At this point, the voltage thresholds of the DiSEqC receiver circuit can be adjusted 203 when such control exists. This step is also optional. The DiSEqC message is then sent with the transmitter 204. The control of the DiSEqC transmitter is changed with the general purpose input / output pin 205 (GPIO). At least 15 milliseconds of silence in the bus is necessary before sending the simulated response. The GPIO plug is pressed in high and low to create the 22 kHz tone or a 22 kHz tone envelope, depending on the design of the LNB power supply to send a simulated "response" 207. The byte to be sent back is selected in arbitrary way to be a sequence of bytes plus the appropriate odd parity bit, that is, 0x45 + "1". Sufficient time is allowed for the receiver to receive the complete message 208. The received byte is compared to the expected byte sequence, 0x45 + "1", 209. When the received message is identical to the wait byte sequence, then the tone 22 kHz operates correctly 210. When the received message is not identical or when the message is not received, and the comparison 209 was the first attempt, then another command 213 is sent. When the comparison test was not the first attempt, then the 22 kHz tone does not operate well 212. The number of re-attempts is arbitrary and is selected based on the probability of the collision of the bus bar and / or the user's preference. Although various embodiments embodying the teachings of the present invention have been shown, those skilled in the art will be able to contemplate other modalities that also incorporate these teachings.

Claims (13)

1. A transcoder arrangement characterized in that it comprises: transmitting circuitry (104) for transmitting a message; and receiver circuitry (105) for receiving a control message and comparing the control message with the received message.

2. The transcoder according to claim 1, characterized in that the message is a control message of digital satellite equipment.

3. The transcoder according to claim 1, characterized in that the message is a 22 kHz digital satellite equipment control message.

4. The transcoder according to claim 1, characterized in that it further comprises a supply (103) of downward conversion energy LNB with low noise block. The transcoder according to claim 4, characterized in that each of the message and the response is a control message of digital satellite equipment to verify the operation of a tone operation at 22 kHz of the power supply (103) of LNB . 6. A transcoder arrangement, characterized in that it comprises: transmitter circuitry (104) for transmitting a message; a controlled input terminal to simulate a response to a transmitted message; circuitry to receive a message; and circuitry (103) for comparing the simulated response with the received message. The method according to claim 6, characterized in that the message is a control message of digital satellite equipment. The method according to claim 6, characterized in that each of the message and the response are a control message of digital satellite equipment at 22 kHz. The method according to claim 6, characterized in that the circuitry for comparing the response with the transmitted message comprises an energy supply of down converter LNB with low noise block. The method according to claim 9, characterized in that the circuitry for comparison verifies the tone operation at 22 kHz of the power supply LNB. 11. A method for verifying a tone operation at 22 kHz in a satellite transcoder characterized in that it comprises the steps of: sending a control message of digital satellite equipment with a transmitter; change the control of the transmitter on the controlled input pin; press the input pin to send a simulated response to the control message; and compare the simulated response with a response received based on the control message to verify the operation. The method according to claim 11, characterized in that the controlled input pin comprises a general input / output (GPIO) pin in a satellite transcoder. The method according to claim 11, characterized in that the step of verifying the operation comprises verifying the operation of the tone at 22 kHz of a down converter energy supply with low noise block.