CN103117759A - Digital down converter and method for underwater acoustic communication receiver and method - Google Patents

Abstract

The invention relates to a digital down converter and a method for an underwater acoustic communication receiver. The digital down converter comprises a first subcircuit, a second subcircuit and a merging module, wherein the first subcircuit is used for generating down-conversion real part data according to received passband signals, the second subcircuit is used for generating down-conversion imaginary part data according to the passband signals, and the merging module is used for generating complex base band data according to the down-conversion real part data and the down-conversion imaginary part data. According to the digital down converter and the method for the underwater acoustic communication receiver, aiming at digital down conversion of the underwater acoustic communication receiver, a novel processing method is put forward, thus the step of orthogonal mixing process is eliminated, calculated quantity is lowered, and power consumption is reduced.

Description

A kind of digital down converter and method for the underwater sound communication receiver

Technical field

The present invention relates to the communications field, relate in particular to a kind of digital down converter for the underwater sound communication receiver and method.

Background technology

Underwater acoustic communication set is usually used in ocean environment observation the occasions such as transfer of data, the general mode that adopts from charged pool, and power consumption becomes an important topic.Digital Down Convert functional module in the underwater sound communication receiver that the employing digital form is realized, high sampling rate passband signal after realization is sampled from AD (analog-digital conversion), conversion to the low sampling rate baseband signal, this transfer process amount of calculation is larger, the power consumption that expends is larger, affects the use of receiver.

Fig. 1 is underwater sound communication receiver schematic diagram in prior art.It adopts traditional digital down converter method, namely adopts the method based on the quadrature mixing, realizes the conversion from the passband signal to the complex baseband signal.This method need to be done following processing to the received signal: receiving belt pass filter, quadrature mixing, low-pass filtering and extraction.Wherein, low-pass filtering and extract need to be to the real part after the quadrature mixing and imaginary component other places reason.Receiving belt pass filter and quadrature mixing must be processed under high sampling rate, can not with the withdrawal device combination, thereby total amount of calculation is larger.

Summary of the invention

For the problems referred to above, the embodiment of the present invention is processed for the Digital Down Convert in the underwater sound communication receiver, proposes new algorithm, can save quadrature Frequency mixing processing process, greatly save the amount of calculation of processing procedure, thereby effectively reduce the power consumption that solves the underwater sound communication receiver.

In first aspect, the embodiment of the present invention proposes a kind of digital down converter for the underwater sound communication receiver, its described digital down converter comprises the first branch road, the second branch road and merges module, and described the first branch road is used for generating down-conversion real part data according to the passband signal that receives; Described the second branch road is used for generating the down-conversion imaginary data according to described passband signal; Described merging module generates complex radical band data according to described down-conversion real part data and down-conversion imaginary data.

In second aspect, the embodiment of the present invention proposes a kind of digital down converter method for the underwater sound communication receiver, and described method comprises: generate down-conversion real part data according to the passband signal that receives; Generate the down-conversion imaginary data according to described passband signal; Generate complex radical band data according to described down-conversion real part data and down-conversion imaginary data.

The embodiment of the present invention proposes a kind of new processing method for the Digital Down Convert in the underwater sound communication receiver, saves quadrature Frequency mixing processing step, has reduced amount of calculation, is conducive to reduce power consumption.

Description of drawings

Fig. 1 is underwater sound communication receiver schematic diagram in prior art;

Fig. 2 is based on the spectrum diagram of signals at different levels in the down-converted of Hilbert filtering;

Fig. 3 is a kind of schematic diagram of the communication control processor Digital Down Convert structure of the embodiment of the present invention;

Fig. 4 is the Digital Down Convert structural correspondence real part of the embodiment of the present invention, the impulse response schematic diagram of two branch filters that imaginary part is used;

Fig. 5 is the down-conversion structural entity amplitude-frequency response schematic diagram of the embodiment of the present invention;

Fig. 6 is the another kind of schematic diagram of filtering part in the communication control processor Digital Down Convert structure of the embodiment of the present invention.

Embodiment

Below by drawings and Examples, the technical scheme of the embodiment of the present invention is described in further detail.

The purpose of the embodiment of the present invention is to provide a kind of underwater sound communication digital receiver down conversion method and corresponding communication control processor of low amount of calculation, satisfying the requirement of underwater acoustic communication set low-power consumption, thereby facilitating the use of communication control processor---same at least battery can be strengthened for the flying power of this communication control processor.

The underwater sound communication receiver can be sampled to underwater sound signal when work, and sample rate is generally the integral multiple of underwater sound signal centre frequency.For ease of narration, in the embodiment of the present invention, the underwater sound signal centre frequency is set to 8kHz, and sample rate is 64kHz.Be noted that this is only a kind of operative scenario, just for convenient narration and understanding, can not consist of any restriction to the embodiment of the present invention.

Suppose that receiving signal is r (n), it is processed through receiving filter, removes the out of band signal component.The unit impact response sequence of supposing described receiving filter is h ₁(n).Pass through so after receiving filter signal should for

Symbol wherein The convolution of two signals is asked in expression.r ₁(n) obtain signal through after delay filter $r_2^I\left(n\right)=r_1\left(n\right)\⊗\mathrm{\δ}(n-m).$

Simultaneously with r ₁(n) through hilbert filter h ₂(n), obtain signal

H wherein ₂(n) retardation equals M.According to the character of Hilbert filtering, can know real signal r ₁(n) corresponding analytic signal is $r_2\left(n\right)=r_2^I\left(n\right)+j{r}_2^Q\left(n\right),$ Wherein $j=\sqrt{-1}.$

Described reception signal r (n), the signal r after accepting filter ₁(n), analytic signal r ₂(n), three's frequency spectrum is as (a) in Fig. 2 (b) as shown in (c).r ₂(n) and there is following relation in spectrum concentration near centre frequency:

$r_2\left(n\right)=r\left(n\right)\⊗{\[h}_1\left(n\right)\⊗\mathrm{\δ}(n-m)+\mathrm{jr}\left(n\right)n\⊗{\[h}_1\left(n\right)\⊗h_2\left(n\right)\]---\left(1\right)$

As seen, receive signal through the analytic signal r after receiving filter ₂(n) real part can obtain by the filter that band pass filter and delayer cascade form, and analytic signal r ₂(n) imaginary part can obtain by the cascading filter of bandpass filtering and hilbert filter.Be noted that in concrete practice, the filter that described band pass filter and delayer cascade form can be also a filter, and it possesses the function that described band passes to and postpones simultaneously.

If with analytic signal r ₂(n) carry out complex frequency and be mixed to zero intermediate frequency, obtain

Carry out the extraction of 8 times of speed, the complex baseband signal that obtains after reduce sampling frequency is again

$r_3\left(m\right)=r_2\left(n\right)\exp \{-j2\mathrm{\π}\frac{8\mathrm{kHz}}{64\mathrm{kHz}}n\}{|}_{n=8m}=r_2\left(8m\right)\exp \{-j2\mathrm{\π}\frac{8\mathrm{kHz}}{64\mathrm{kHz}}8m\}=r_2\left(8m\right)$

As seen, can be with r ₂(n) directly carry out 8 times of extractions and obtain complex baseband signal, namely

r ₃(m)＝r ₂(n) _n＝8m (2)

r ₃(m) frequency spectrum is as shown in (d) in Fig. 2.

As seen of the prior artly will receive that signal accepts filter, the processing procedure of quadrature mixing, reduce sampling frequency, pass through formula (1) and the formula (2) that are equivalent to the embodiment of the present invention are completed to be processed by r (n) and are obtained r ₃(m) processing procedure.The processing procedure of formula (1) and formula (2) only comprises filtering and extraction process, realizes block diagram as shown in Figure 3, greatly simplifies with respect to traditional method amount of calculation.

In practice, can utilize the windowing algorithm design to go out reception bandpass filter h ₁(n) and Hilbert filtering h ₂(n), operation can obtain in formula (1) through simple convolutional

With

Two filters, their unit impact response as shown in Figure 4.The amplitude-frequency response of the whole filter that in Fig. 3, up and down two branch filter parallel joins obtain as shown in Figure 5, can find out, the amplitude-frequency response of down-converted filter to surpassing 60dB with outer inhibition, can satisfy the requirement of underwater acoustic communication set receiver fully at this moment.Be noted that in concrete practice, described band pass filter and hilbert filter can be also a filter on physical form, and it possesses simultaneously, and described band passes to and the Hilbert filter function.

Especially, as shown in Figure 6, the filter that relates in two branch roads in up and down in the Digital Down Convert structure chart can be respectively merges with the withdrawal device of rear class, the structure that adopts multiphase filter to realize, in Fig. 6, the filtering extraction front signal is equivalent to 64KHz sample rate passband signal in Fig. 3, and after filtering extraction, signal is equivalent to 8KHz complex baseband signal in Fig. 3.Multiphase filter coefficient in Fig. 6 value respectively is:

d _k(n)＝h(k+8n),k＝0,1,2,...,7 (3)

Wherein h (n) sequence value is

Sequence or

Sequence is respectively used to realize two filters that real part in Fig. 3 or imaginary part are processed.Adopt Fig. 6 structure, amount of calculation further is simplified, and does not affect handling property.

The embodiment of the present invention proposes a kind of new processing method for the Digital Down Convert in the underwater sound communication receiver, saves quadrature Frequency mixing processing step, has reduced amount of calculation, is conducive to reduce power consumption.

Those skilled in the art should further recognize, each exemplary module and algorithm steps in conjunction with embodiment description disclosed herein, can realize with electronic hardware, computer software or combination both, for the interchangeability of hardware and software clearly is described, composition and the step of each example described in general manner according to function in the above description.These functions are carried out with hardware or software mode actually, depend on application-specific and the design constraint of technical scheme.Those skilled in the art can specifically should be used for realizing described function with distinct methods to each, but this realization should not thought the scope that exceeds the application.

The method of describing in conjunction with embodiment disclosed herein or the step of algorithm can use the software module of hardware, processor execution, and perhaps both combination is implemented.Software module can be placed in the storage medium of any other form known in random asccess memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable ROM, register, hard disk, moveable magnetic disc, CD-ROM or technical field.

It is to be noted, these are only preferred embodiment of the present invention, be not to limit practical range of the present invention, technical staff with professional knowledge base can realize the present invention by above embodiment, therefore every any variation, modification and improvement according to making within the spirit and principles in the present invention, all covered by the scope of the claims of the present invention.Namely, above embodiment is only unrestricted in order to technical scheme of the present invention to be described, although with reference to preferred embodiment, the present invention is had been described in detail, those of ordinary skill in the art is to be understood that, can modify or be equal to replacement technical scheme of the present invention, and not break away from the spirit and scope of technical solution of the present invention.

Claims (10)

1. a digital down converter that is used for the underwater sound communication receiver, is characterized in that, described digital down converter comprises the first branch road, the second branch road and merging module,

Described the first branch road is used for generating down-conversion real part data according to the passband signal that receives;

Described the second branch road is used for generating the down-conversion imaginary data according to described passband signal;

Described merging module generates complex radical band data according to described down-conversion real part data and down-conversion imaginary data.

2. digital down converter as claimed in claim 1, is characterized in that,

Described the first branch road comprises the first band pass filter, delay filter and the first withdrawal device, and described the first band pass filter, delay filter and the first withdrawal device are connected successively;

Described the second branch road comprises the second band pass filter, hilbert filter and the second withdrawal device, and described the second band pass filter, hilbert filter and the second withdrawal device are connected successively.

3. digital down converter as claimed in claim 1, is characterized in that,

Described the first branch road comprises the first multiphase filter, and described the first multiphase filter comprises a plurality of filter branch, and each filter branch is comprised of unit delay device, branch road withdrawal device and branch road filtration module;

Described the second branch road comprises the second multiphase filter, and described the second multiphase filter comprises a plurality of filter branch, and each filter branch is comprised of unit delay device, branch road withdrawal device and branch road filtration module.

4. digital down converter as claimed in claim 2, is characterized in that, described the first band pass filter is identical with the coefficient of the second band pass filter.

5. digital down converter as claimed in claim 2, is characterized in that, described the first withdrawal device is identical with the extracting multiple of the second withdrawal device.

6. a digital down converter method that is used for the underwater sound communication receiver, is characterized in that, described method comprises:

Generate down-conversion real part data according to the passband signal that receives;

Generate the down-conversion imaginary data according to described passband signal;

Generate complex radical band data according to described down-conversion real part data and down-conversion imaginary data.

7. digital down converter method as claimed in claim 6, it is characterized in that, described according to described passband signal generation down-conversion real part data, be specially: utilize the first band pass filter, delay filter and the first withdrawal device to generate down-conversion real part data according to described passband signal, described the first band pass filter, delay filter and the first withdrawal device are connected successively; Described according to described passband signal generation down-conversion imaginary data, be specially: utilize the second band pass filter, hilbert filter and the second withdrawal device to generate the down-conversion imaginary data, described the second band pass filter, hilbert filter and the second withdrawal device are connected successively.

8. digital down converter method as claimed in claim 6, it is characterized in that, described according to described passband signal generation down-conversion real part data, be specially: utilize the first multiphase filter to generate down-conversion real part data, described the first multiphase filter comprises a plurality of filter branch, each filter branch is comprised of unit delay device, branch road withdrawal device and branch road filtration module, and the coefficient of each branch road filtration module generates according to the coefficient of the first band pass filter; Described according to described passband signal generation down-conversion imaginary data, be specially: utilize the second multiphase filter to generate the down-conversion imaginary data, described the second multiphase filter comprises a plurality of filter branch, each filter branch is comprised of unit delay device, branch road withdrawal device and branch road filtration module, and the coefficient of each branch road filtration module generates according to the coefficient of the second band pass filter and the coefficient of described hilbert filter.

9. digital down converter method as claimed in claim 7, is characterized in that, described the first band pass filter is identical with the coefficient of the second band pass filter.

10. digital down converter method as claimed in claim 7, is characterized in that, described the first withdrawal device is identical with the extracting multiple of the second withdrawal device.

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