CN109729398A - A kind of originator filter, receiving end filter and method for upgrading system - Google Patents
A kind of originator filter, receiving end filter and method for upgrading system Download PDFInfo
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- CN109729398A CN109729398A CN201711040938.6A CN201711040938A CN109729398A CN 109729398 A CN109729398 A CN 109729398A CN 201711040938 A CN201711040938 A CN 201711040938A CN 109729398 A CN109729398 A CN 109729398A
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Abstract
The invention discloses a kind of originator filter, receiving end filter and method for upgrading system, wherein, originator filter Tx1 includes link control unit, filter Tx2 and compensating filter CT, and link control unit is used to control input signal and exports after filter Tx2 and compensating filter CT processing or export after filter Tx2 processing；Filter Tx2 and filter compensating filter CT in series and filter Rx0 constitute a pair of of matched filter；Receiving end filter Rx1 includes link control unit, filter Rx2 and compensating filter CR, and link control unit is used to control input signal and exports after filter Rx2 and compensating filter CR processing or export after filter Rx2 processing；Filter and Tx2 and CT Rx2 and CR in series filter in series constitutes a pair of of matched filter.The present invention provides the scheme that new set-top box gradually replaces old set-top box, make it possible system upgrade.
Description
Technical field
The invention proposes a kind of broadcast transmitters for promoting radio data system (DVB-C) performance and set-top box to connect
The front end filter and method for upgrading system of receipts machine；It is used under the scene that the present invention can also be similar in other systems.
Background technique
Many decades are deployed in the world based on DVB-C standard radio and television set-top box, and set-top box quantity reaches
To as many as several hundred million, square root cosine (SRRC) filter is set to its sending/receiving filter by standard.All due to various filters
There are frequency intermediate zones, thus its availability of frequency spectrum decreases, and DVB-C standard specifies the band efficiency of filter to only have
77%.There is the filter of some more dominance energy in industry in recent years, these Novel Filters can significantly promote frequency spectrum benefit
With rate, other indices are better than existing DVB-C standard, and computation complexity also decreases.Theory analysis and experimental result table
Bright, the DVB-C system performance based on Novel Filter has very big promotion than existing system.
However, Nyquist criteria requires originator filter and receiving end filter for a communication system
Common response results to meet the requirement of not intersymbol interference.In addition, in order to reach best noise robustness, sending and receiving end is answered
This is a pair of of matched filter.Therefore, if the filter of existing DVB-C system to be upgraded to the filter of novel high-performance,
It must be carried out simultaneously in sending and receiving end.It, can be with since transmitter quantity is relatively small for the broadcast system as the DVB-C
Very fast carry out upgrading.However, the receiver of DVB-C system is the set-top box in huge number of be currently running,
Replace original set-top box needs to take an undesirably long time the set-top box with Novel Filter, this period is known as
Transitional period.In this transitional period, if transmitting terminal uses novel filter, newly deployed set-top box can normal work
Make, and original set-top box can not work normally.If instead then new set-top box can not be normal using original transmitter
Work.Therefore, it is necessary to provide a kind of filter of transitional emittor/receiver to design embodiment, make new and old two machine
Top box can be properly received the signal of transmitting, and signal quality will meet the requirement of DVB-C standard.Up to the present, also
There is no feasible scheme, causes DVB-C system and other similar systems that can not carry out upgrading.
Summary of the invention
The present invention gives using improve the availability of frequency spectrum as the transmitter of the DVB-C system of target and other similar systems/
Receive end filter upgrading embodiment.It is original that the solution of the present invention will use new transmitter and new set-top box to replace
Equipment, gradually replace the transitional period of old set-top box in new set-top box, two set-top box coexists, and the scheme that the present invention provides is not
Only guarantee that new set-top box works normally, the performance of original set-top box is not affected because of the change of transmitting signal, makes
All there is optimal system performance under transitional period new and old filter coexistence scenario.
Technical solution of the present invention: DVB-C transmitter/set-top box front-end filter design scheme, step include:
1. transmitter/set-top box filter of existing DVB-C system is set as Tx0 and Rx0, what new and old set-top box coexisted
Transitional originator/receiving end filter is set as Tx1 and Rx1, after the transitional period new transmitter/set-top box filter be Tx2 and
Rx2.Wherein Tx0 and Rx0 is a pair of of matched filter, and Tx2 and Rx2 are a pair of of matched filters.If originator uses old filtering
Device Tx0 and receiving end use new filter Rx2, then are unmatched.Similarly Tx2 and Rx0 is also unmatched.In the transitional period,
Tx1 first has to match with Rx0, to guarantee that old set-top box can work normally.Tx1 will also be matched with Rx1 simultaneously, new to guarantee
Set-top box work normally, and gradually replace old set-top box, as shown in Figure 1.Tx1 and Rx1 are designed thus.
2.Tx1 transmitter filter consists of three parts, and a part is Tx2 filter, it is therefore an objective to when had been friends in the past set-top box
After being all substituted, originator filter is converted directly into Tx2；Another part is compensating filter CT, and effect is the sound to Tx2
It answers function to compensate, matches Tx2 with the coefficient result of CT with Rx0, to guarantee the signal of new filter Tx2 transmitting
It can be properly received by the Rx0 of original set-top box；Some is the link control unit (chain switched over to two states
For controlling, input signal exports road control unit after the filter Tx2 and compensating filter CT processing or input is believed
Number through the filter Tx2 processing after export；For example can be a controllable switch K), as shown in the transmitting terminal in Fig. 2, filter
Tx2 is connect with controllable switch K, and switch K can connect compensating filter CT or straight-through, to constitute transitional period filter Tx1；
Filter Tx2 and filter compensating filter CT in series and filter Rx0 constitute a pair and meet Nyquist criterion
Matched filter.
3. the receptance function of originator compensating filter can be derived under Nyquist criterion qualifications, specific real
Example is applied to provide in the next section.Using the structure of new filter and originator compensating filter, it is ensured that new originator filter
The matching of the filter Rx0 of Tx1 and original set-top box.
4. receiving end filter Rx1 includes three parts, a part is new filter Rx2, it is therefore an objective to when had been friends in the past machine top
For box all by after new substitution, receiving end filter only uses Rx2；Another part is receiving end compensating filter CR, for compensate by
In Rx2 and the originator unmatched problem of filter Tx1, receiving end filter Rx1 is matched with originator filter Tx1；Some
It is that (link control unit is for controlling input signal through the filter for the link control unit that switches over to two states
It is exported after Rx2 and compensating filter CR processing or input signal exports after filter Rx2 processing；Such as it can be for one can
Control switch K), as shown in the receiving end in Fig. 2；Filter Rx2 is connect with controllable switch K, and switch K can connect compensating filter
CR is straight-through, to constitute transitional period filter Rx1；The filter that filter Rx2 and compensating filter CR are connected and composed with
Filter Tx1 constitutes the matched filter that a pair meets Nyquist criterion.
5. the receptance function of receiving end compensating filter can be derived under Nyquist criterion qualifications, such as following
Shown in given specific embodiment.Using the structure of new filter and originator compensating filter, it is ensured that new set-top box
The matching of filter Rx1 and new originator filter Tx1.
6. in the case of there is Rx0 in a network, the controllable switch K in Tx1/Rx1 is connect with port 1, originator/receiving end benefit
Repay filter work；When all Rx0 disappear, i.e., after old set-top box is all replaced by new set-top box, controllable switch K and port
2 connections, compensating filter are bypassed, and system uses Tx2 and Rx2, complete transitional transformation process.
7. such as Fig. 2, in transitional period controllable switch K connectivity port 1, originator filter Tx1 is collectively formed by Tx2 and CT, is received
End filter Rx1 is collectively formed by Rx2 and CR, and the Rx0 and new set-top box Rx1 in old set-top box coexist, Tx1 with both
Matching.When the set-top box being had been friends in the past be replaced by it is new after, controllable switch K is connect with port 2, at this moment only new filtering
Device Tx2 and Rx2 work, CT and CR are ineffective, the upgrading so as to complete new set-top box to old set-top box.
In order to guarantee performance required by DVB-C standard, either the Tx1 that uses of transitional period and Rx1 and transition are completed
The Tx2 and Rx2 used afterwards, will meet following requirement:
A. deployed old set-top box and newly deployed set-top box should be able to coexist in escalation process.In this way, new
Set-top box can gradually come into operation, until old set-top box is completely replaced.
B. theoretically, transmitter will meet Nyquist criterion with the cascade of the filter of corresponding set-top box response.
C. theoretically, originator filter and receiving end filter should be a pair of of matched filters, to obtain maximum signal to noise ratio,
Realize optimum reception.
D. the availability of frequency spectrum of new filter is higher than the availability of frequency spectrum of existing DVB-C system.
E. in view of the equipment that set-top box is cost sensitivity, the computation complexity of filter will be lower than old filter.
F. all indexs will meet DVB-C standard, such as stopband attenuation (SBA) should be greater than 43dB.
G. it completes to be also required to from transitional period to final updated simple and easy.
Compared with prior art, the positive effect of the present invention are as follows:
The filter design scheme that the present invention provides is guaranteeing that new transmitter filter and new set-top box filter are mutual
Under matching condition, moreover it is possible to guarantee being mutually matched for new transmitting end filter and existing set-top box, make original set-top box work
Make normal.In addition, new transmitting/reception end filter indices are all satisfied the requirement of DVB-C standard.With existing DVB-C
System is compared, and spectrum utilization efficiency can be improved 18%, system complexity also significant reduction.In addition to this, the present invention can also be
It is used under similar scene in other systems.
Detailed description of the invention
Fig. 1 is the new and old set-top box coexistence scenario System describe block diagram of the present invention；
Fig. 2 is new and old set-top box coexistence scenario filter solutions example in the present invention；
Fig. 3 is design embodiment of the invention compared with without using the performance of this programme.
Specific embodiment
The present invention is further illustrated below by the mode of embodiment, but does not therefore limit the present invention to the reality
It applies among a range.
A kind of solution of the filter upgrading of DVB-C transmitting terminal and set-top box is provided in the embodiment of the present invention,
In the solution, emphasis is solved under transitional period new and old two kinds of set-top box coexistence scenarios, and the filter of new transmitter is implemented
The embodiment of scheme and new filter for receiver, target are guaranteed in a kind of transmitter, two different receiver
In the case where new and old two receiver normal work, and meet the requirement of existing DVB-C standard.
The design embodiment carries out the design of transitional period transmitter filter first, carries out reception machine filter on this basis
The design of wave device.Specific embodiment is as follows:
1. the emission filter design that the transitional period is new:
If the transmitting of original old set-top box/reception end filter frequency response function is Tx0 (ω)/Rx0 (ω), mistake
Transmitting/reception end filter the frequency response function for crossing the set-top box of phase is Tx1 (ω)/Rx1 (ω), new after the completion of transition
The transmitting of set-top box/reception end filter frequency response function is Tx2 (ω)/Rx2 (ω).
According to the requirement of Fig. 1, the transformation of transmitter filter will meet the requirement of original set-top box filtering first.For this
It invents transitional period Tx1 (ω)/Rx1 (ω) for providing and realizes block diagram as shown in Fig. 2, originator/receiving end compensating filter here
Frequency response function is respectively CT(ω) and CR(ω)。
During transition, the connectivity port by-pass switch controllable switch K 1, the frequency response function of Tx1 are as follows:
Tx1 (ω)=Tx2 (ω) CT(ω) (1)
As newly deployed square of root nyquist filter, it is as follows that Tx2 and Rx2 meet Nyquist criterion:
Rx2 (π-ω)=1 (2) Tx2 (ω) Rx2 (ω)+Tx2 (π-ω)
Basic demand to Tx1 is, when replacing existing running old Tx0 with it, old set-top box without
Original performance indicator is kept in the case where any transformation.In other words, the cascade response of Tx1 and Rx0 will meet Nyquist
Criterion, i.e.,
Rx0 (π-ω)=1 (3) Tx1 (ω) Rx0 (ω)+Tx1 (π-ω)
For the degree that reduces that the device is complicated, originator/receiving end compensating filter amplitude response is each designed to about pi/2 pair
Claim, then have:
CT(ω)=CT(π-ω) (4)
CR(ω)=CR(π-ω) (5)
Formula (1), (2) and (4) is substituted into (3), the frequency response function of compensating filter CT can be exported:
The frequency response function C of the derived originator compensating filter of above formulaT(ω), can guarantee cascade response Tx1 with
Rx0 meets Nyquist criterion, i.e., the introducing of new Tx1 emission filter does not influence the receptivity of original set-top box.
2. the receiving filter design that the transitional period is new:
After transmitting signal uses new emission filter, it is desirable that the set-top box newly introduced can also work normally.
The structure proposed according to fig. 2, frequency domain response Rx1 (ω) are given by:
Rx1 (ω)=Rx2 (ω) CR(ω) (7)
The cascade response of the filter Rx1 and new transmitter filter Tx1 of new set-top box should also meet Nyquist standard
Then, it may be expressed as:
Rx1 (π-ω)=1 (8) Tx1 (ω) Rx1 (ω)+Tx1 (π-ω)
It brings formula (1), (5) into formula (8), obtains:
The receptance function C for the receiving end filter that above formula providesR(ω) can guarantee new set-top box filter Rx1 and originator
Tx1 forms a pair of of matched filter, and new set-top box is made to can satisfy the standard of DVB-C.
Note that in Tx1 (ω)/Rx1 (ω) derivation process, it is assumed that original originator/receiving end filter and final updated
Originator afterwards/receiving end filter is a pair of of matched filter, it may be assumed that
Tx0 (ω)=Rx0 (ω) (10)
Tx2 (ω)=Rx2 (ω) (11)
Knot is implemented in the design of the receptance function of the transitional originator and receiving end filter that provide according to embodiments of the present invention
Fruit, it is ensured that
A. the introducing of new transmitting equipment does not influence the normal work of existing old set-top box,
B. new set-top box can be worked together with new transmitting equipment
C. after it is new set-top box that the set-top box being had been friends in the past, which all substitutes, as long as by originator/receiving end compensating filter
Controllable switch K is connected to port 2, can terminate the transitional period, completes the upgrading of DVB-C system.
Performance evaluation
Here performance evaluation has been carried out to embodiments of the present invention.In accordance with existing DVB-C standard, here to embodiment
In the key index that provides carried out simulating, verifying, actual test.The result shows that the embodiment provided meets DVB-C standard
It is required that performance is higher than the index of old set-top box filter.
A. spectrum efficiency is analyzed
Assuming that it is Rs that DVB-C system, which gives symbol rate under bandwidth, between signal(-) carrier frequency and its first adjacent channel
Difference is channel spacing D, then it is normalizing transition band α can be to indicate with channel spacing relationship are as follows:
D=(1+2 α) Rs
It is equal to 0.15 existing DVB-C standard for α, obtains D=1.3Rs, i.e., bandwidth shared by old system is theoretical bandwidth
1.3 times.And Novel Filter Tx2, the D=1.1Rs for being 0.05 for intermediate zone, i.e., bandwidth shared by updated system are reason
By 1.1 times of bandwidth.The system of upgrading occupies less frequency band than standard DVB-C system.
Defining spectrum utilization efficiency η is
Due to the reduction of intermediate zone, the availability of frequency spectrum of DVB-C system is increased to 91% from 77%.With DVB-C standard phase
Than the availability of frequency spectrum of the solution of the present invention improves 18%.Frequency spectrum is carried out to DVB-C system based on this data to advise again
It draws, more broadcasting channels can be obtained.
B. minimum stop-band attenuation is analyzed:
According to the standard of DVB-C, minimum stop-band attenuation 43dB.The present invention by the stop band attenuation of the system provided into
Actual test is gone, result 43.94dB has 1dB or so gain compared to original old system.
C. error rate of system (BER) is analyzed
Fig. 3 gives bit error rate performance (BER) and compares.It can be seen from the chart, BER of the invention and notional result are extremely
It is close, reach the optimum of system.If designed as a comparison, also giving here without the transitional period of the invention,
But original Tx0 directly is replaced using new filter Tx2 in transmitting terminal, and receiving end still uses old set-top box,
In this case BER penalty, old set-top box can not work normally.It can be seen that the necessity for the method that the present invention provides
Property, and the performance of method provided.
D. analysis of complexity:
Table 1 gives the comparison result of filter complexity and time delay, and wherein Tx0/Rx0 is old transmitter and set-top box
Index, Tx1/Rx1 is transitional index, and Tx2/Rx2 is the index of the completely new system after the completion of the transitional period.For with product
The directly related hardware realization complexity index of price, industry is generally using multiplier number as benchmark.In old Tx0/
In Rx0 system, multiplier number is 163, and considers Tx1/Rx1 and the final updated completion of compensating filter resource
The complexity of Tx2/Rx2 be respectively less than old system.Time delay relatively in, the time delays of transitional Tx1/Rx1 are slightly less than
Tx0/Rx0, and final completely new Tx2/Rx2, time delay are greatly reduced than original old system.
Table 1 be original DVB-C system, transitional period system, in new system filter complexity and time delay comparison sheet
It, can be with more importantly the scheme that the present invention provides can be applied not only to the upgrading of DVB-C system
The upgrading of filter for any running system is changed with solving old system with filter upgrading under new system Coexistence Situation
The problem of making.
Although specific embodiments of the present invention have been described above, it will be appreciated by those of skill in the art that these
It is merely illustrative of, protection scope of the present invention is defined by the appended claims.Those skilled in the art is not carrying on the back
Under the premise of from the principle and substance of the present invention, many changes and modifications may be made, but these are changed
Protection scope of the present invention is each fallen with modification.
Claims (10)
1. a kind of originator filter, which is characterized in that including link control unit, filter Tx2 and for filter Tx2
The compensating filter CT that compensates of receptance function, the link control unit is for controlling input signal through the filter
It is exported after Tx2 and compensating filter CT processing or input signal exports after filter Tx2 processing；The filter
Tx2 and the filter compensating filter CT in series and filter Rx0 constitute that a pair meets Nyquist criterion
With filter；Wherein, the filter Tx2 is the originator filter after upgrading, and the filter Rx0 is the receiving end filter before upgrading
Wave device.
2. originator filter as described in claim 1, which is characterized in that be derived by under Nyquist criterion qualifications
The receptance function of the compensating filter CT.
3. originator filter as described in claim 1, which is characterized in that the link control unit is a controllable switch K.
4. a kind of receiving end filter, which is characterized in that including link control unit, filter Rx2 and for filter Rx2
The compensating filter CR that compensates of receptance function, the link control unit is for controlling input signal through the filter
It is exported after Rx2 and compensating filter CR processing or input signal exports after filter Rx2 processing；The filter
The filter Rx2 and compensating filter CR in series and filtering filter Tx2 and compensating filter CT in series
Device constitutes the matched filter that a pair meets Nyquist criterion；Wherein, the filter Rx2 is the receiving end filtering after upgrading
Device, the filter Tx2 are the originator filter after upgrading, and the compensating filter CT is for the sound to filter Tx2
Answer the compensating filter that function compensates.
5. receiving end filter as claimed in claim 4, which is characterized in that be derived by under Nyquist criterion qualifications
The receptance function of the compensating filter CR.
6. receiving end filter as claimed in claim 4, which is characterized in that the link control unit is a controllable switch K.
7. a kind of method for upgrading system, step include:
In the originator deployment originator filter Tx1 of system；The originator filter Tx1 includes link control unit, filter Tx2
With the compensating filter CT compensated for the receptance function to filter Tx2, the link control unit is for controlling
Input signal exports after the filter Tx2 and compensating filter CT processing or input signal is through the filter Tx2
It is exported after processing；The filter Tx2 and the filter compensating filter CT in series and filter Rx0 constitute a pair of
Meet the matched filter of Nyquist criterion；
Receiving end filter Rx1 is disposed in the receiving end of system；The receiving end filter Rx1 includes link control unit, filter Rx2
With the compensating filter CR compensated for the receptance function to filter Rx2, the link control unit is for controlling
Input signal exports after the filter Rx2 and compensating filter CR processing or input signal is through the filter Rx2
It is exported after processing；The filter Rx2 and the filter compensating filter CR in series and filter Tx1 constitute a pair of
Meet the matched filter of Nyquist criterion；
Wherein, the filter Tx2 is the originator filter after upgrading, and the filter Rx0 is the receiving end filter before upgrading；
The filter Rx2 is the receiving end filter after upgrading, and filter Tx0 is the originator filter before upgrading；The filter
Tx2, the filter Rx2 are the matched filter that a pair meets Nyquist criterion, the filter Tx1, the filter
Rx1 is that a pair meets the matched filter of Nyquist criterion, the filter Tx0, the filter Rx0 be it is a pair of meet how
The matched filter of Qwest's criterion；When the originator filter Tx1, the receiving end filter Rx1 deployment in system finish
Before, the link control unit control input signal in the originator filter Tx1 is through the filter Tx2 and the benefit
It is exported, described in the link control unit control input signal warp in the receiving end filter Rx1 after repaying filter CT processing
It is exported after filter Rx2 and compensating filter CR processing, as the originator filter Tx1 in system, receiving end filter
After wave device Rx1 deployment finishes, the link control unit control input signal in the originator filter Tx1 is through the filter
It is exported after wave device Tx2 processing, the link control unit control input signal in the receiving end filter Rx1 is through the filtering
It is exported after device Rx2 processing.
8. the method for claim 7, which is characterized in that the frequency response function of the filter Tx0 be Tx0 (ω),
The frequency response function of the filter Rx0 is Rx0 (ω), and the frequency response function of the filter Tx1 is Tx1 (ω), institute
The frequency response function for stating filter Rx1 is Rx1 (ω), and the frequency response function of the filter Tx2 is Tx2 (ω), described
The frequency response function of filter Rx2 is Rx2 (ω), and the frequency response function of the compensating filter CT is CT(ω), it is described
The frequency response function of compensating filter CR is CR(ω)；Link control unit control in the originator filter Tx1
When input signal exports after the filter Tx2 and compensating filter CT processing, Tx1 (ω)=Tx2 (ω) CT(ω),The link control unit in the receiving end filter Rx1
When control input signal exports after the filter Rx2 and compensating filter CR processing, Rx1 (ω)=Rx2 (ω) CR
(ω),
9. the method for claim 7, which is characterized in that the link control unit is a controllable switch K.
10. the method as described in claim 7 or 8 or 9, which is characterized in that the system is radio data system；The originator
Filter is the filter in the transmitter of radio data system；The receiving end filter is in the set-top box of radio data system
Filter.
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| CN201711040938.6A CN109729398A (en) | 2017-10-31 | 2017-10-31 | A kind of originator filter, receiving end filter and method for upgrading system |
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| CN201711040938.6A CN109729398A (en) | 2017-10-31 | 2017-10-31 | A kind of originator filter, receiving end filter and method for upgrading system |
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Application publication date: 20190507 |