MXPA06000550A - Method and system for converting streaming digital data to fm modulated data - Google Patents

Abstract

A system ( 10 ) for converting streaming digital data to frequency modulated data includes a digital decoder ( 12 ) providing content and associated data, a system controller ( 14 ) for formatting the associated data into frequency modulated sub-carrier data, and a frequency modulator ( 20 ) for modulating ( 24 ) the content and combining ( 25 ) the modulated content with a buffered version of the frequency modulated sub-carrier data. The streaming digital data can come from a satellite digital audio radio system receiver and the associated data can include at least one among a channel name, a channel number, an artist name, a song title, and traffic information. The system controller can format the associated data into an RDS Message format. The frequency modulator can include an RDS physical layer ( 32 ) and an RDS data link layer ( 30 ) that can generate a checksum. The frequency modulator can also include a register or buffer ( 28 ).

Description

METHOD AND SYSTEM TO CONVERT A CURRENT DIGITAL DATA TO MODULATED FREQUENCY DATA CROSS REFERENCE WITH RELATED REQUESTS (NOT APPLICABLE) FIELD OF THE INVENTION This invention relates generally, to a method and an apparatus, for providing a source signal and the data associated with a radio frequency receiver and, more particularly, to a method and an apparatus for wirelessly providing a signal source. providing wirelessly a source signal and the associated data through a signal sub-carrier to a radio frequency receiver.

BACKGROUND OF THE INVENTION Satellite radio operators provide broadcasting services for digital radio that cover the entire United States. These services offer approximately 100 channels, of which about 50 channels have their own configuration that supplies music; and the remaining stations offer news, sports, voice and data channels. In summary, the service provided by the XM Radio satellite includes a satellite X-band link for two satellites that offer frequency translation to the S-band, for retransmission to radio receivers on the ground within its area of coverage. The radio frequency bearers from one of the satellites are also received by the terrestrial repeaters. The content received in the repeaters is retransmitted to a different carrier S-band, for the same radios that are within their respective coverage areas. These terrestrial repeaters facilitate reliable reception in geographic areas, where reception from satellites is obscured by tall buildings, hills, tunnels and other obstacles. The signals transmitted by satellites and repeaters are received by SDARS (satellite digital audio radio service) receivers, which can be located in cars, in portable or stationary units for domestic or office use. SDARS receivers are designed to receive one or both signals from the satellite, in addition to the signals emitted from the terrestrial repeaters and to combine or select one of the signals as the output of the receiver. The FM radio receivers (frequency modulated) or other existing FM radio receivers can be improved to receive the digital radio signal from the satellite and allow to listen to the programming through an FM frequency not used with the use of an RF modulator. (radio frequency). As shown in Figure 1, an audio system 3 may include an FM modulator 5, which is connected to the end unit 6 with its corresponding FM antenna 7, through a coaxial cable 9 or a line of transmission to allow a frequency response. To receive the digital audio radio transmission of the satellite, the audio system 3 further needs a satellite antenna 4 and an antenna module 2, coupled to the satellite receiver 1, by means of another coaxial cable 8 or transmission line. The cable required for installation in an automotive environment, as shown in Figure 1, may cause slight discomfort because it includes an additional cost since it requires additional wiring. In addition, the transmission of associated data transmitted in the satellite signal, through an FM modulator, to any FM receiver, is typically lost unless additional cable is adapted; and encoding and decoding is offered between the satellite receiver and the FM receiver. FM radio stations of the FM transmitter and FM receiver equipment providers have introduced a Radio Data System (RDS) that provides a method for sending additional information together with VHF / FM radio services (very high frequency / frequency modulated), for the appropriate receiver equipment without affecting the normal FM radio programming. Since most FM radio stations do not use all of their broadband, the RDS takes advantage of the remaining bandwidth by transmitting low bit-rate digital data over the remaining broadband with the use of an FM sub-carrier. The RDS signal is modulated within the signal of the radio station and is transmitted together with the signal of the radio station. No satellite radio system, takes advantage of the capabilities of the RDS in the current FM receivers, to provide associated data through a sub-carrier, with the use of an FM modulation scheme.

BRIEF DESCRIPTION OF THE INVENTION The transmission of a signal source having a content of data and associated data through an FM modulator can combine the data and data associated with the use of a sub-ported signal. In a first embodiment according to the present invention, a system for converting a digital data stream into frequency modulation data includes a digital decoder that supplies the content and associated data, a system controller for formatting the data associated in frequency modulated sub-carrier data and a frequency modulator to modulate the content and combine the modulated content with a memorized version of the frequency modulated sub-carrier data. The digital data in current can come from the receiver of the digital audio radio system of the satellite and the associated data can include at least one between a channel name, a channel number, an artist name, a song title and information of traffic. The system controller can format the associated data in an RDS message format. The frequency modulator can include an RDS physical layer and an RDS data link layer that can generate a revision sum. The system controller can control the operation of the RDS physical layer. The frequency modulator may also include a register or a buffer. In a second embodiment, a method for converting digital data into FM modulated data, may include the steps of decoding a digital data source into content data and associated data, formatting the associated data for transmission of FM sub-carrier , modulate the frequency of the content data and combine the modulated frequency content data, with the data formatted in the frequency modulated sub-carrier. The formatting of the associated data will be carried out by formatting the associated data in an RDS message format. Additionally, the method may include the step of memorizing the associated data in the RDS message format. When the RDS is used, the method can also include the steps to generate the revision sum, apply a displacement word to the revision sum, allow RDS processing of the associated data, generate an interruption to format the associated data formatted RDS, for an FM modulator and execute the functions of the RDS physical layer, such as, receive a 19 kHz input and provide a modulated RDS output. In a third embodiment, a receiver system may include a receiver such as a satellite receiver having a decoder, to decode a digital stream into content data and associated data, a processor coupled to the receiver to process associated data and provide data processed associates; and a frequency modulator coupled to the decoder and the processor, wherein, the frequency modulator combines the content data with the associated data processed in a sub-bearer. In addition, the system may include an antenna for transmitting the combined content data and the associated data processed from the frequency modulator.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram of an existing satellite digital audio radio receiver system. Figure 2 illustrates a radio system having an FM modulator, combining content data and associated data according to an embodiment of the present invention. Figure 3 is a block diagram of a radio system using an RDS physical layer, in accordance with one embodiment of the present invention. Figure 4 is a block diagram of a satellite digital audio radio receiver system in a vehicle according to an embodiment of the present invention. Figure 5 is a block diagram of a portion of the satellite receiver system of Figure 4, which also details the coupling network, in accordance with one embodiment of the present invention. Figure 6 is an illustration describing the structure of an RDS packet, in accordance with one embodiment of the present invention. Figure 7 is an illustration describing a revision sum and word generation of displacement in a link layer of the FM modulator of Figure 2, in accordance with one embodiment of the present invention. Figure 8 is an illustration describing the position of the scroll word, in accordance with one embodiment of the present invention. Figure 9 is a flow diagram, illustrating a method, in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION As mentioned above, there is no satellite radio system that takes advantage of the RDS, or of the sub-carrier signaling available on VHF / FM frequencies, to avoid additional physical wiring, which could otherwise be necessary to transmit associated data from a satellite receiver to an FM modulator, for eventual audio output from an FM receiver. The FM modulator proposed here presents consumers to receive satellite radio programming and data association data within vehicles or elsewhere. With reference to Figure 2, a digital satellite audio radio system 10 may include a satellite receiver 11 having a signal decoder 12, for decoding the contents (such as songs, voice, shows, etc.). and associated data (such as channel names, channel numbers, song titles, artist names, information traffic, weather information, etc.). The content is sent from the decoder 12 to an FM modulator 20, which has a data converter 22 and a stereo FM modulator 24, to convert the content within the left and right channels and modulate the content for stereo reception by a FM receiver (not shown). The associated data is sent to a processor or controller system 14. In the case of an XM satellite receiver, the controller system 14, in addition, can include a stack 16 for storing the associated data and a formatter 18 for converting the associated data of the XM satellite, to the RDS message format. The FM modulator 20 may additionally include a register 28 for receiving the associated data in RDS format, after providing an interrupt signal to the system controller 18, an RDS data link layer 30, and a RDS physical layer 32 to provide an data signal which is combined with the FM stereo modulated content signal with the use of an adder 25. A phase lock circuit 34 finally helps to transmit the content over an FM channel and the associated data in a sub-carrier FM. With reference to Figure 3, a more detailed view of the RDS physical layer is illustrated, together with several external components in a system 40. The signals of the stereo program (content) can be modulated to FM, by the encoder / modulator 24. stereo that provides a multiplexed signal to the adder 25. The encoder / modulator also provides a 19 kHz pilot tone reference signal for the physical layer 32 RDS. The RDS signal is modulated to a sub-carrier of 57 kHz with the use of an oscillator 51. To minimize the audible interference on an FM radio station or on an FM channel, the data rate must be kept low, so , a data rate of 1187.5 bits / second is used. This number was chosen because it can be easily derived from the carrier signal, by dividing by 48, by using a divisor 52 of twenty-four and dividing by two divisors 53. In an RDS scheme, the associated data signal is processed through an encoder 54 differential, a two-phase symbol generator 56 and mixed in a mixer 58, with a signal of 57 kHz, before being combined with the signal (content) multiplexed in the adder 25. The combined signal can be transmitted through a transmitter 52 and antenna 51. With reference to Figure 4, another system SDARS 50 is shown as used, in a vehicle 31, which includes a satellite receiving unit 21, and an external antenna 33 (used with the FM modulator 20), which serves both for the external broadcast antenna and for an SDARS receiving antenna for receiving satellite signals, from at least one satellite 41. The FM modulator 20 can convert the SDARS signal into a to FM. The antenna cable 33 can be coupled to the satellite receiver such as a radio receiving unit 11 of the XM, through a coupling network 26. As will be explained later in detail with respect to Figure 5, the coupling network 26 allows the use of a single antenna to transmit FM signals and receive signals from the satellite. Optionally, separate antennas can be used to receive only signals from the XM satellite (without the coupling network 26 being required), as well as to broadcast or transmit the FM modulated signal through a second optional antenna. The receiving unit 11 may also have a decoder 12 and a system controller 14 as described with respect to Figure 2. The receiving unit 21 can be turned on through a power source 42 that can be supplied by the automobile 31, or in another way. It should be noted that the automobile 31 may be factory installed, or installed after purchasing an AM / FM radio 43 (modulated amplitude / frequency modulation) that includes a 36 FM receiver, a control head 37, an RF converter 38 to audio, some speakers 39 and an FM receiving antenna 35. In this mode, the receiver 36 can decode the RDS signaling (the associated data) and the control head 37 can display the associated data. As previously noted, the FM receiving antenna 35 is normally placed outside or embedded in the glass 33, either in the windshield or in the medallion. With this distribution, the satellite receiver unit 21 provides optimum FM reception for any car having an antenna configured for FM without using additional cable. With reference to Figure 5, the satellite receiver system 60 is shown in greater detail, which includes the satellite receiver 11, the radio frequency modulator 20 and the coupling network 26. As shown, the values of the inductor and the capacitor for the components shown are supplied in such a way that the reception path of the satellite is seen as a short circuit for the satellite signals in the S-band and as an open circuit for the satellite. FM signal received. Similarly, the inductor and capacitor values for the FM transmission path components essentially create a short circuit for the FM transmitted signals and an open circuit for the satellite signals in the S-band. using a single antenna 33 to receive both signals from the satellite in the S-band and transmit FM-modulated signals, as is fully detailed in U.S. Application No. 10 / XXX.XXX, incorporated herein by reference. With reference to Figure 6, the structure of an RDS package is illustrated. In this mode, a 26-bit block contains a word with 16-bit information and a 10-bit checkword. Each 104-bit group in the RDS package structure contains four 26-bit blocks. The information word can come from the formatted message, generated by the controller 14 of the system of Figure 2. The check word can be generated by the data link layer 30. It should be noted that the RDS register 28, in the FM modulator 20, of Figure 2, may consist of 4 x 16 bit information words. With reference to Figure 7, a shift word generation and checksum generation scheme of the RDS data link layer is illustrated. In Figure 8, further details of the information word and the structure of the check word and the structure of the check word including the position of the word of travel are illustrated. Within a block, an information word may include a 4-bit group of the code type (A), a version code (B), a traffic program code and additional codes (PTY). The version code can indicate which offset version to use in a particular block.

With reference to Figure 9, a flow chart illustrates a method 90 for converting digital data into FM modulated data, can include step 91 of decoding a digital data source into content data and associated data, formatting associated data for the transmission of the FM sub-bearer in step 92, frequency modulating the content data in step 94 and combining the frequency modulated content data with the formatted data of the frequency modulated sub-bearer in step 95. formatting of the associated data can be done by formatting the associated data in an RDS message format, as shown in optional step 93. Method 90 can further include the optional step 96 of storing the associated data in the message format RDS. When the RDS is used, the method 90 may further include the steps of generating a checksum, applying a scrolling word for the checksum, enabling the RDS processing of the associated data, generating an interruption for the formatting of the data. associated formatted RDS for an FM modulator and carry out the functions of the RDS physical layer such as, receive a 19 kHz input and supply an RDS modulated output, as shown in block 97. The above description is intended to be considered by way of example and not as to limit the present invention, in any manner, except as set forth in the following claims.

Claims (21)

1. A system for converting digital data into current in frequency modulated data, characterized in that it comprises: a digital decoder that provides content and associated data; a system controller for formatting the associated data in frequency modulated sub-carrier data; a frequency modulator for modulating the content and combining the modulated content with a memorized version of the frequency modulated sub-carrier data.

The system according to claim 1, characterized in that the digital data in current comes from a receiver of the digital audio radio system.

The system according to claim 1, characterized in that the associated data includes at least one channel name, a channel number, an artist name, a song title and traffic information.

The system according to claim 1, characterized in that the system controller formats the associated data in an RDS message format.

5. The system according to claim 1, characterized in that the frequency modulator further comprises an intermediate memory.

6. The system according to claim 1, characterized in that the frequency modulator generates a checksum.

The system according to claim 6, characterized in that the checksum is generated in the RDS data link layer.

The system according to claim 1, characterized in that the frequency modulator is an FM frequency modulator, which includes RDS physical layers.

The system according to claim 8, characterized in that the system controller controls the operation of the physical layer of the RDS.

10. A method for converting digital data into FM modulated data, characterized in that it comprises the following steps: decoding the source of digital data into content data and associated data; format the associated data for the transmission of the FM sub-carrier; Modulate the frequency of the content data; combining the modulated frequency content data with the formatted data of the frequency modulated sub-carrier.

11. The method according to claim 10, characterized in that the step of formatting the associated data comprises formatting the associated data within an RDS message format.

12. The method according to claim 11, characterized in that the method also comprises the step of storing the associated data in the RDS message format.

The method according to claim 11, characterized in that the method also comprises the step of generating a checksum.

The method according to claim 11, characterized in that the method also comprises the step of developing the functions of the RDS physical layer.

The method according to claim 14, characterized in that the RDS physical layer receives an input of 19 kHz and provides an RDS modulated output.

The method according to claim 10, characterized in that the method also comprises the step of enabling the RDS processing of the associated data.

The method according to claim 10, characterized in that the method also comprises the step of causing an interruption in the formatting of the associated data formatted RDS for an FM modulator.

18. The method according to claim 10, characterized in that the method also comprises the step of applying a displacement word in the checksum.

19. A receiver system characterized in that it comprises: a receiver having a decoder for decoding a digital current in content data and associated data; a processor coupled to the receiver for processing the associated data to supply the associated processed data. a frequency modulator coupled with the decoder and with the processor, wherein the frequency modulator combines the content data with the associated data processed in a sub-bearer. The receiving system according to claim 19, characterized in that the system also comprises an antenna for transmitting the combined content data and the associated processed data. The receiving system according to claim 19, characterized in that the receiver comprises a satellite receiver having a satellite antenna to receive the digital current.