The present invention generally relates to radio broadcasting receivers. More specifically, the present invention relates to a system and method for minimizing acquisition time in DRM (Digital Radio Mondiale) receivers.
Broadcasting is a process of distribution of audio and/or video to dispersed audience through various electronic mass communication mediums. In recent days, digital radio broadcasting has become more popular because of its audio quality compared to traditional analog radio broadcasting. The digital radio broadcasting exists in frequency bands such as used by AM, FM bands and also in other bands for data transmission and reception. It may include several channels that contain audio, informational data, diagnostic parameters and other data.
Digital Radio Mondiale (DRM) is a broadcasting standard at AM bands below 30 MHz and VHF bands above 30 MHz. It is a high quality digital replacement for analogue radio broadcasts of AM and FM frequency. The DRM digital radio stream contains three channels namely a Main Service Channel (MSC), a Fast Access Channel (FAC), and a Service Description Channel (SDC). The MSC may contain an audio or informational data, depending on the type of service being broadcast. The FAC may contain transmission frame id, type of modulation of SDC & MSC, number of services, type of services and part information on how to decode MSC. The SDC may contain information about the received DRM digital radio stream, such as a radio station identifier, geographic location, time, date, and other information including additional information to decode MSC.
DRM has the following features,
Further, DRM has different robustness modes used under different propagation conditions. Robustness Modes A, B, C and D are used for transmissions under 30 MHz and Robustness Mode E is used in VHF bands. Modulation parameters are different for different Robustness Modes.
One of the major performance differentiator of DRM Receivers is the acquisition time taken by the receiver. Acquisition time is the time taken by the receiver to output the audio signal after receiving the DRM radio signal i.e. after tuning to a frequency. The radio data stream (both audio and data) is contained in the MSC. To start MSC processing, receiver needs SDC channel information. Based on first received transmission frame, acquisition time will change. Following are the three conditions on reception of the transmission frames.
Conventionally, many systems and methods are known in the existing art that have been proposed to overcome the problems associated with the time taken to execute the data frames at the receiver end.
Japanese Patent Application No. 2007088923 to Alpine Electronics Inc, entitled “Receiver and reception frequency detecting method” deals with a receiver and reception frequency detection method to search receivable frequencies in a short period of time in Digital Radio Mondiale system. A broadcast schedule creation unit creates a broadcast schedule list based on the detected schedule information and stores schedule list in the memory and during seek operation the reception frequency is searched in the list thereby eliminating the need of searching unnecessary frequencies.
However, the above solution does not overcome the delay caused during the processing of frames. Hence, further developments have been proposed to avoid time delay in processing of frames using memory units.
U.S. Pat. No. 7,974,338 to Harman Becker Automotive Systems GmbH, entitled “System for decoding a digital radio stream” deals with a method for improving user experience in DRM by outputting data contained in Fast Access Channel (FAC) and Service Description channel (SDC) without waiting for the Main Service Channel (MSC) decoding to finish. The DRM channels (FAC, SDC, MSC) decoded data is stored in a memory and reused to improve acquisition time.
European Patent Document No. 1104138 to Robert Bosch Gmbh, entitled “Descrambling of data frames” discloses a method for reducing audio decoding delay in Digital Radio systems like Digital Radio Mondiale (DRM). By selecting the most likely frame configuration for a frequency and by filling the memory of de-interleaver with demodulated data before the control channel is decoded; parallel processing of information has been performed and thereby delay time is reduced in the receiver side.
Though the above existing systems and methods disclose storing of decoded DRM signal data in memory unit for reducing delay in Digital Radio Mondiale (DRM) receiver, still there exists time delay for reception and processing of frames during frame execution or during incorrect selection of configuration
To overcome these problems and thereby to improve user experience, the present invention proposes a system and method to improve the acquisition time by storing the demodulated data on memory unit. After identifying the first frame id by decoding FAC, the stored demodulated data from memory is re-split to get MSC channel data. This MSC data is stored in memory unit and once SDC is available, MSC data stored in memory unit is decoded.
An objective of the present invention is to propose an effective system and method for improving the acquisition time of a DRM (Digital Radio Mondiale) receiver, in order to enhance the user experience.
In the present invention, the DRM receiver system comprises: a) an antenna, b) a tuner, c) a processor with internal components arrangement, d) one or more memory/storage unit and e) output devices. The processor of the present invention comprises: a) an asynchronous sample rate converter (ASRC), b) a demodulator, c) a channel splitter, d) a channel decoder and e) middleware and applications.
According to the present invention, a DRM (Digital Radio Mondiale) signal from the transmission station is received through the antenna. The receiver is tuned to a frequency using the tuner and is fed to the processor. In the processor unit, the received signal is converted to demodulator sample rate, demodulated and stored in the memory unit. Also, the demodulated signal is split into Fast Access Channel (FAC), Service Description Channel (SDC) and Main Service Channel (MSC). The channel split data is decoded by the channel decoder. Middleware parses the channel decoded data and process as audio and data. Application sends processed data to output devices such as speaker & display.
In accordance with the present invention, the DRM demodulator output is stored in memory for reuse in case of reception of Frame-0 without SDC or Frame-1 or Frame-2. If the first received frame is Frame-0 without SDC or Frame-1 or Frame-2, the channel splitter re-splits the data stored in memory-1 and stores MSC data in memory-2. Once SDC is available, MSC data stored in memory-2 is decoded. This solution avoids the additional time taken in waiting for MSC data after receiving SDC data to decode MSC data when Frame-0 (without the first one or two symbols), Frame-1 or Frame-2 is received. Thus, the acquisition time of DRM signal is improved.
The objective and advantages of the present invention will become more evident from the following detailed description when taken in conjunction with the accompanying drawings.
The objective of the present invention will now be described in more detail with reference to the accompanying drawings, in which:
The present invention proposes an effective system and method for improving the acquisition time of the DRM signal at DRM receiver in order to enhance the user experience.
In general, Digital Radio Mondiale (DRM) is a digital radio standard used in all frequency bands (AM and VHF) above and/or below 30 MHz. The DRM is a high quality digital replacement of analogue radio broadcasts in AM and FM bands. One of the major performance differentiator of DRM Receiver is the acquisition time.
The present invention provides a system for improving the acquisition time in DRM receiver (100). The system comprises components such as: a) an antenna (10) to receive radio signal from a transmission station, b) a tuner (20) to tune the receiver (100) to a frequency, c) a processor (30) to process the tuned signal, d) one or more memory/storage units (40) to store the signal data and e) one or more output devices (50) (such as display/speaker) to output the processed data and audio.
According to the present invention, the signal from any of the transmission stations is received by the antenna (10) located at the receiver end (100) which is tuned to receive the desired frequency. The obtained DRM signal is processed by a processor which comprises: a) an asynchronous sample rate converter (ASRC) (31) to convert the sample rate of input signal to demodulator sample rate, b) a demodulator (32) to demodulate the information/data for further processing, c) a channel splitter (33) to split the demodulated data into Fast Access Channel (FAC), Service Description Channel (SDC) and Main Service Channel (MSC), d) a channel decoder (34) to decode the information from each channel and e) a middleware (351) to parse the decoded channel data and process as audio and data and applications (352) to send processed data to output devices (50) such as speaker and display.
Referring to
There are three conditions that exists during the reception of the transmission frames, namely (i) the first received transmission frame is Frame-0, (ii) the first received transmission frame is Frame-1 and (iii) the first received transmission frame is Frame-2.
According to
Hence, the present solution avoids the additional time taken of a) 1146 ms-1150 ms used in condition (i), where the first received transmission frame is Frame-0 without SDC, b) 800 ms used in condition (ii), where the first received transmission frame is Frame-1 and c) 400 ms used in condition (iii), where the first received transmission frame is Frame-2 in case of long interleaving depth as DRM channel splitter (33) stores the demodulator (32) output in memory (40). In case of short interleaving, a similar method is adapted and delay of up to 400 ms is reduced. If the first received frame is other than Frame-0 (i.e. Frame-1 or Frame-2), then on next loop the channel splitter (33) re-splits the data stored in memory (40) and starts MSC channel decoding after obtaining SDC parameters, thus enhancing the user experience by improving the acquisition time.
While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed.
Number | Date | Country | Kind |
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201841014795 | Apr 2018 | IN | national |
Number | Name | Date | Kind |
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5195109 | Bochmann | Mar 1993 | A |
7221720 | Robinson | May 2007 | B2 |
7974338 | Becker | Jul 2011 | B2 |
8138915 | Milbar | Mar 2012 | B2 |
8737532 | Green | May 2014 | B2 |
20080072259 | Seo | Mar 2008 | A1 |
20080279314 | Liu | Nov 2008 | A1 |
Number | Date | Country |
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10-304012 | Nov 1998 | JP |
Entry |
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Office Action for related Indian Patent Application No. 201841014795 dated Apr. 16, 2019. |
Number | Date | Country | |
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20190327009 A1 | Oct 2019 | US |