CN104394390A - Diversity reception method for satellite digital television - Google Patents

Abstract

The invention relates to a diversity receiving method of satellite digital TV, which is suitable for receiving satellite digital TV broadcast signals on a moving carrier. If the traditional satellite receiving system is installed on a mobile carrier, when there is an obstruction between the receiving antenna and the satellite, the signal will be interrupted. The present invention sets multiple receiving antennas to receive digital TV signals from satellites from different positions through the method of space diversity, demodulates the signals from multiple antennas respectively, and marks, aligns and merges the demodulated outputs to eliminate occlusion interference The resulting output data error. Under the existing satellite receiving framework, the method of the invention improves the receiving performance of the receiving system by marking, aligning, merging and choosing the outputs of multiple channel demodulation modules, and achieves the purpose of stably receiving digital TV broadcasting signals.

Description

A Diversity Receiving Method for Satellite Digital TV

technical field

The invention belongs to the technical field of satellite digital television reception, and relates to a diversity reception method of satellite digital television.

Background technique

The satellite digital TV broadcasting system usually uses the transponder of the communication satellite in the geosynchronous orbit to forward the uplink digital TV signal from the earth, and the satellite digital TV receiver uses the satellite receiving antenna to receive the digital TV signal transmitted by the satellite. If the traditional satellite receiving system is installed on a mobile carrier, when there is an obstruction between the receiving antenna and the satellite, the signal will be interrupted. For example, when the satellite receiver is installed on a train, the satellite receiving antenna is in a moving state, although technical means can Ensure that the antenna is always pointing to the communication satellite in geosynchronous orbit, but due to the operation of the train, the satellite signal between the receiving antenna and the satellite will inevitably be blocked by tunnels, tree crowns, etc., resulting in a short interruption of digital TV reception.

Contents of the invention

The invention provides a diversity receiving method for satellite digital TV, which can set multiple receiving antennas on a moving carrier to receive digital TV signals from satellites from different positions through the method of space diversity, and separate signals from multiple antennas Perform demodulation, mark, align, and combine the demodulated output, eliminate output data errors caused by occlusion interference, and achieve the purpose of stably receiving digital TV broadcasts.

The present invention adopts a plurality of channel demodulation modules to respectively demodulate signals from a plurality of antennas in different positions, and the demodulation module can adopt an existing channel demodulation module. Since the processing delay brought by each demodulation module of the satellite signal may be different, the TS packet sequence output by the demodulation module will also have a certain time stagger. In order to solve the time stagger of the TS packet sequence, the present invention first TS packets need to be marked.

The present invention is applicable to the digital television system that adopts the TS stream of MPEG standard as the data transmission format. The TS stream is composed of a series of fixed-length TS packets continuous in time. The demodulation module receives the satellite signal and completes demodulation to send out the TS stream. Provide the error indication information TS_ERR of each data packet simultaneously, when this information is 0, represent that corresponding TS bag does not have receiving error, when this information is 1, represent that corresponding TS bag has receiving error, TS_ERR will be by the present invention The TS packet merging module is used in order to eliminate erroneous data packets. In addition, according to the requirements of the MPEG standard, the sending end will periodically select some TS packets in the TS stream to carry program clock reference information (PCR), and the location information where the PCR occurs will be used by the present invention to mark each TS packet so that each TS streams output by channel demodulation are aligned.

The present invention first marks each TS packet contained in the TS streams output by each receiver for the output of each channel demodulation module respectively, then performs TS packet alignment on the marked TS packets according to the marks, and then aligns the TS packets after alignment The TS packets are selected and combined according to the error indication signal of the TS stream itself, and finally the TS stream formed by the combined TS packets is sent to the subsequent information source decoding module for decoding processing, and the decoding method follows the traditional method.

Implementation steps of the present invention are as follows:

Step 1. Dispersively install n satellite receiving antennas Ant(1), Ant(2),...,Ant(n) and n channel demodulation modules Dem(1), Dem(2),...,Dem on the mobile carrier (n), the number of satellite receiving antennas and channel demodulation modules is the same; wherein the channel demodulation module adopts existing modules;

Step 2, mark the output TS stream of each channel demodulation module together with the error indication TS_err, the marking method is:

Step (1), setting a marker counter corresponding to each channel demodulation module: C(1), C(2),...,C(n);

Step (2), initialize C(1), C(2), ..., C(n) to 0;

Step (3), according to each TS packet update marker counter C (i) in the output TS flow of each channel demodulation module, i=1,2,...,n, the method of updating C (i) is: as The current TS packet contains PCR, and the corresponding C(i) of this packet is cleared to 0; if the current TS packet does not contain PCR, the corresponding C(i) of this packet is increased by 1;

Step 3, adding the value of the updated mark counter C(i) to the end of the corresponding TS packet;

Step 4, aligning the input data streams from each channel demodulation module in time according to the count value added at the end of each TS packet, the basis of alignment is that the count value added at the end of the TS packet of each input data stream after alignment is consistent;

Step 5. Check the error indication signal TS_err of the TS packets with the same tag value in the aligned TS streams: if the error indication signal TS_err is 0 in the TS packets with the same tag value, directly set the TS packet with TS_err to 0 Send out the TS packet as the tag value, and ignore the TS packets with the same tag sent on other channels, and at the same time set the error indication signal TS_err_out of the tag value in the final output data stream to 0; if the TS packets with the same tag value All error indication signals TS_err are 1, indicating that all packets have errors, select any TS packet corresponding to the tag value as the TS packet of the tag value, and ignore the TS packets with the same tag on other data paths, and at the same time Set the flag value error indication signal TS_err_out of the final output data stream to 1;

Step 6. Operate according to step 5 for each TS packet with the same tag value in each TS stream, and delete the count value inserted at the end of each TS packet after merging to form the final TS stream TS_out;

Step 7. Send the TS stream TS_out to the source decoding module for decoding to obtain audio and video information. The source decoding module adopts an existing module.

The invention has the advantage that under the existing satellite receiving framework, the receiving performance of the receiving system is improved by marking, aligning, combining and choosing the outputs of multiple channel demodulation modules. The used channel demodulation module and source decoding module can adopt existing software and hardware.

Description of drawings

Fig. 1 is a block diagram of the present invention;

Fig. 2 is a block diagram of an embodiment of the present invention;

Figure 3 is a schematic diagram of TS streams and error indications before TS packet marking in the embodiment;

FIG. 4 is a schematic diagram of TS streams and error indications after TS packets are marked in the embodiment;

FIG. 5 is a schematic diagram of aligned TS streams and error indication signals, and a combined TS stream and error indication signal in an embodiment.

Detailed ways

Steps of the present invention are as shown in Figure 1, below in conjunction with accompanying drawing, select a representative satellite digital television receiving system and illustrate the specific implementation of the present invention, the present embodiment adopts the European second generation satellite receiving standard of the present invention DVBS2 satellite TV receiving system, 3 channel demodulation modules are set in the system, the specific implementation steps are as follows:

Step 1, as shown in Figure 2, 3 satellite receiving antennas Ant (1), Ant (2), Ant (3), 3 channel demodulation modules Dem (1), Dem (2), Dem(3), the number of satellite receiving antennas and channel demodulation modules is the same; wherein the channel demodulation module adopts existing modules;

Step 2, mark the output TS stream of each channel demodulation module together with the error indication TS_err, the marking method is:

Step (1), setting a flag counter corresponding to each channel demodulation module: C(1), C(2), C(3);

Step (2), initialize C(1), C(2), C(3) to 0;

Step (3), according to each TS package update mark counter C (i) in the output TS flow of each channel demodulation module, i=1,2,3, the method for updating C (i) is: as current TS If the packet contains PCR, the corresponding C(i) of this packet is cleared to 0; if the current TS packet does not contain PCR, the corresponding C(i) of this packet is increased by 1;

The various TS streams and error indication signals before the TS packet marking in this embodiment are as shown in Figure 3, in the figure:

When TS_err1 is high, it means that the corresponding package in TS1 contains errors;

When TS_err2 is high, it means that the corresponding package in TS2 contains errors;

When TS_err3 is high, it means that the corresponding package in TS3 contains errors;

The shaded packets in each TS stream contain PCR;

Step 3, adding the value of the updated mark counter C(i) to the end of the corresponding TS packet;

In this embodiment, the TS streams and error indication signals of each path after the TS packet marking are shown in Figure 4, in the figure: the value of the marking technology device C (i) is added at the end of each TS packet, and the end of the packet including PCR is appended The value of the mark counter of is 0;

Step 4, align the input data streams from each channel demodulation module in time according to the count value added at the end of each TS packet, and the basis for alignment is that the count value added at the end of the TS packet of each input data stream after alignment is consistent; this implementation The aligned 3-way TS streams in the example are shown in Figure 5, where:

TS1', TS2', TS3' are the aligned TS streams respectively;

TS_err1', TS_err2', TS_err3' are error indication signals corresponding to TS1', TS2', TS3' respectively;

Step 5. Check the error indication signal TS_err of the TS packets with the same tag value in the aligned TS streams: if the error indication signal TS_err is 0 in the TS packets with the same tag value, directly set the TS packet with TS_err to 0 Send out the TS packet as the tag value, and ignore the TS packets with the same tag sent on other channels, and at the same time set the error indication signal TS_err_out of the tag value in the final output data stream to 0; if the TS packets with the same tag value All error indication signals TS_err are 1, indicating that all packets have errors, select any TS packet corresponding to the tag value as the TS packet of the tag value, and ignore the TS packets with the same tag on other data paths, and at the same time Set the flag value error indication signal TS_err_out of the final output data stream to 1;

In the present embodiment shown in FIG. 5, the merging process of each TS stream is as follows:

The three TS packets with a tag value of 854 are TS1(2), TS2(0), and TS3(3). According to the corresponding error indications TS_err1', TS_err2', and TS_err3', it can be known that TS1(2), TS2(0) are not Including errors, select TS1(2) and send it to TS_out, and set TS_err_out corresponding to this package to 0;

The three TS packets with the mark value of 0 are TS1(3), TS2(1), and TS3(4). According to the corresponding error indications TS_err1', TS_err2', and TS_err3', it can be seen that TS2(1), TS3(4) are both If it does not contain errors, select TS2(1) and send it to TS_out, and set TS_err_out corresponding to this package to 0;

The three TS packets with a flag value of 1 are TS1(4), TS2(2), and TS3(5). According to the corresponding error indications TS_err1', TS_err2', and TS_err3', it can be known that these three packets contain errors and are randomly selected. TS1(4) is sent to TS_out, and TS_err_out corresponding to this packet is set to 1;

The three TS packets with a tag value of 2 are TS1(5), TS2(3), and TS3(6). According to the corresponding error indications TS_err1', TS_err2', and TS_err3', it can be seen that TS3(6) does not contain errors, so select TS3 (6) Send to TS_out, and set TS_err_out corresponding to this packet to 0;

The three TS packets with a tag value of 3 are TS1(6), TS2(4), and TS3(7). According to the corresponding error indications TS_err1', TS_err2', and TS_err3', it can be known that these three packets do not contain errors. Select TS1(6) and send it to TS_out, and set TS_err_out corresponding to this packet to 0;

Step 6. Operate according to step 5 for each TS packet with the same tag value in each TS stream, delete the count value inserted at the end of each TS packet after merging, and form the final TS stream TS_out as shown in Figure 5;

Step 7. Send the TS stream TS_out to the source decoding module for decoding to obtain audio and video information. The source decoding module adopts an existing module.

It should be understood that the above examples are only descriptions of the present invention, rather than limitations of the present invention, and any inventions that do not exceed the spirit of the present invention fall within the protection scope of the present invention.

Claims (1)

1. a diversity receiving method of satellite digital television, is characterized in that the method concrete steps are: Step 1. Dispersively install n satellite receiving antennas Ant(1), Ant(2),...,Ant(n) and n channel demodulation modules Dem(1), Dem(2),...,Dem on the mobile carrier (n), the number of satellite receiving antennas and channel demodulation modules is the same; Step 2, mark the output TS stream of each channel demodulation module together with the error indication TS_err, the marking method is: Step (1), setting a marker counter corresponding to each channel demodulation module: C(1), C(2),...,C(n); Step (2), initialize C(1), C(2), ..., C(n) to 0; Step (3), according to each TS packet update marker counter C (i) in the output TS flow of each channel demodulation module, i=1,2,...,n, the method of updating C (i) is: as The current TS packet contains PCR, and the corresponding C(i) of this packet is cleared to 0; if the current TS packet does not contain PCR, the corresponding C(i) of this packet is increased by 1; Step 3, adding the value of the updated mark counter C(i) to the end of the corresponding TS packet; Step 4, aligning the input data streams from each channel demodulation module in time according to the count value added at the end of each TS packet, the basis of alignment is that the count value added at the end of the TS packet of each input data stream after alignment is consistent; Step 5. Check the error indication signal TS_err of the TS packets with the same tag value in the aligned TS streams: if the error indication signal TS_err is 0 in the TS packets with the same tag value, directly set the TS packet with TS_err to 0 Send out the TS packet as the tag value, and ignore the TS packets with the same tag sent on other channels, and at the same time set the error indication signal TS_err_out of the tag value in the final output data stream to 0; if the TS packets with the same tag value All error indication signals TS_err are 1, indicating that all packets have errors, select any TS packet corresponding to the tag value as the TS packet of the tag value, and ignore the TS packets with the same tag on other data paths, and at the same time Set the flag value error indication signal TS_err_out of the final output data stream to 1; Step 6. Operate according to step 5 for each TS packet with the same tag value in each TS stream, and delete the count value inserted at the end of each TS packet after merging to form the final TS stream TS_out; Step 7. Send the TS stream TS_out to the source decoding module for decoding to obtain audio and video information.