CN105763497A

CN105763497A - Zynq-based multichannel AM and FM demodulation method

Info

Publication number: CN105763497A
Application number: CN201610214262.7A
Authority: CN
Inventors: 邓永国; 莫舸舸; 张笑语
Original assignee: CHENGDU HUARI COMMUNICATION TECHNOLOGY Co Ltd
Current assignee: CHENGDU HUARI COMMUNICATION TECHNOLOGY Co Ltd
Priority date: 2016-04-07
Filing date: 2016-04-07
Publication date: 2016-07-13

Abstract

The invention discloses a Zynq-based multichannel AM and FM demodulation method. The method comprises the following steps of command issuing and data collection, digital down conversion and AM demodulation or FM demodulation. Four demodulation channels are provided, and AM/FM modulation signals in four channels can be demodulated at the same time. As digital down conversion and signal demodulation which require a large amount of logic resources are put in an FPGA for operation, the FPGA has a parallel processing capability and provides special DSP resources, the demodulation data rate for the FPGA is theoretically only limited by the clock rate of the FPGA (Zynq can reach 300 MHz or above), and as the FPGA has the parallel processing capability, the signal precision (data bit width) is improved as much as possible when digital down conversion and demodulation are carried out, the FPGA operation speed is not influenced in a condition in which the resources are met, and real-time processing of multichannel signals can be met completely.

Description

Multichannel AM and FM demodulation method based on Zynq

Technical field

The present invention relates to digital receiver demodulation techniques field, be specifically related to a kind of multichannel AM based on Zynq and FM demodulation method.

Background technology

AM and FM demodulation is function essential to digital receiver, and in demodulating process, data bit width (precision) will directly affect quality and the resource occupation degree of demodulation；Existing receiver realizes the mode of demodulation and gathers signal acquisition I/Q component mainly by FPGA, then I/Q component is sent to computer terminal, is demodulated by the mode of software, namely adopts " FPGA+ computer " framework.In order to obtain higher demodulation accuracy, the bit wide of I/Q data should be improved as far as possible, and bit wide improves and computer resource will be made to take increase rapidly, cause that CPU processing speed sharply declines, thus causing that computer cannot take into account the demand of other application.

Summary of the invention

Instant invention overcomes the deficiencies in the prior art, it is provided that a kind of multichannel AM based on Zynq and FM demodulation method.

For solving above-mentioned technical problem, the present invention by the following technical solutions:

A kind of multichannel AM based on Zynq and FM demodulation method, described method comprises the following steps:

Step one, order issue and data collection

Demodulation carrier frequency value needed for issuing numeral DDC mixing by AXI bus, filtering bandwidth parameter, AM or FM demodulate Selection parameter；

Step 2, Digital Down Convert

The signal received and carrier signal are mixed, signal are moved base band, and it is filtered and extracts reduction data rate, obtain baseband I/Q signal；

Step 3, AM demodulation or FM demodulation

When carrying out AM demodulation, extract the amplitude information of i/q signal, according to quadrature demodulation principle, modulation signal m (n)=sqrt (I*I+Q*Q)；

When carrying out FM demodulation, extract the phase information of i/q signal, and it is carried out derivation operation, m (n)=φ (n)-φ (n-1)；Wherein φ (n)=arctg (Q/I).

Further technical scheme is also to include:

Step 4, audio frequency are play

Collect through the FPGA demodulating data processed by AXI bus, and by ARM, the voice data after demodulating is delivered to speaker plays out.

Further technical scheme is that step one also includes: ARM arranges the radio frequency center frequency point and the bandwidth that comprise four channels by AXI bus, obtains intermediate-freuqncy signal.

Further technical scheme is that step one also includes: be respectively provided with bandwidth and the center frequency point of four channels.

The present invention is directed to computer when cannot take into account for demodulation accuracy and data processing speed, it would be desirable to consume the demodulation of a large amount of calculation resources and be also put in FPGA in the lump and process, only final demodulating data need to be delivered to computer terminal.Be equivalent to " FPGA+ computer " framework owing to Zynq being integrated with FPGA and ARM resource, possess high-speed parallel disposal ability and efficient process scheduling ability, and adopt Zynq platform can conveniently realize the data interaction between FPGA and ARM.The operation needing a large amount of computings is put in FPGA, and ARM has only to carry out order control and data receiver and broadcasting, thus improve the disposal ability to data stream；Described on end, this application selects to realize on Zynq platform, it is provided that four-way AM/FM signal demodulates.

Compared with prior art, the invention has the beneficial effects as follows: the present invention provides four tunnel demodulation passages, and the AM/FM that can simultaneously demodulate four channels modulates signal.Digital Down Convert and signal demodulation owing to needing a large amount of logical resource are all put into computing in FPGA, and FPGA possesses parallel processing capability and provides special DSP resource, the data rate that FPGA is demodulated in theory is limited solely by the clock rate (Zynq is up to more than 300MHz) of FPGA；And because of its parallel processing capability, signal accuracy (data bit width) can be improved carrying out Digital Down Convert reconciliation timing as far as possible, without influence on the speed of FPGA computing under resource meets situation, fully meet the real-time process of multiple signals.

Accompanying drawing explanation

The method that Fig. 1 is one embodiment of the invention realizes schematic diagram.

Fig. 2 is audio volume control figure after the demodulation of first passage in one embodiment of the invention.

Fig. 3 is audio volume control figure after the demodulation of second channel in one embodiment of the invention.

Detailed description of the invention

All features disclosed in this specification, or the step in disclosed all methods or process, except mutually exclusive feature and/or step, all can combine by any way.

This specification (include any accessory claim, summary and accompanying drawing) disclosed in any feature, unless specifically stated otherwise, all can by other equivalences or there is the alternative features of similar purpose replaced.That is, unless specifically stated otherwise, each feature is an example in a series of equivalence or similar characteristics.

Below in conjunction with drawings and Examples, the specific embodiment of the present invention is described in detail.

As it is shown in figure 1, according to one embodiment of present invention, the present embodiment discloses a kind of multichannel AM based on Zynq and FM demodulation method, and the realization of the method includes four parts: order issues and data collection section (ARM)；Digital Down Convert part (DDC)；Demodulation part；Audio frequency plays part.

Wherein, order issues part and data collection section: this part is arranged in the ARM of Zynq, being attached by AXI bus and fpga logic, the demodulation carrier frequency value needed for issuing numeral DDC mixing by AXI bus, filtering bandwidth parameter, AM/FM demodulate Selection parameter；Collected through the FPGA demodulating data processed by AXI bus simultaneously, and speaker is delivered in demodulation play out.

Digital Down Convert part: the signal received and carrier signal are mixed, signal are moved base band, and it is filtered and extracts reduction data rate, obtain baseband I/Q signal.

Demodulation part: when AM demodulates, extracts the amplitude information of i/q signal, according to quadrature demodulation principle, modulation signal m (n)=sqrt (I*I+Q*Q)；When FM demodulates, extract the phase information of i/q signal, and it is carried out derivation operation, m (n)=φ (n)-φ (n-1)；Wherein φ (n)=arctg (Q/I).

Audio frequency plays part: the voice data after demodulation is delivered to speaker by ARM and played out by this part.

Concrete, the present embodiment is as follows based on the multichannel AM of Zynq and the control flow of FM demodulation method:

The first step, ARM arranges the radio frequency center frequency point and the bandwidth that comprise four channels by AXI bus, obtains intermediate-freuqncy signal.

Second step, is respectively provided with bandwidth and the center frequency point of four channels.

3rd step, selects demodulation mode (AM/FM).

4th step, demodulating data is sent in ARM by AXI bus.

5th step, ARM delivers to speaker and plays after demodulating data is carried out respective handling.

Concrete, if selected intermediate frequency is 70MHz in the present embodiment, arranging first passage demodulation pattern is AM demodulation, and mid frequency is 1116KHz, and bandwidth is 8KHz, and after demodulation, audio volume control is as shown in Figure 2；It is FM demodulation that closedown first passage arranges second channel demodulation pattern, and mid frequency is 89.4MHz, and bandwidth is set to 250KHz, and after demodulation, audio volume control is as shown in Figure 3.If the multiple channels that need to demodulate are included in a radio frequency bandwidth, then can open four paths simultaneously and be demodulated.

Owing to FPGA is possessed parallel processing capability at a high speed, it is suitable for processing data stream at a high speed；ARM possesses task scheduling ability flexibly, is suitable for controlling with order.Zynq is integrated with FPGA and ARM resource simultaneously and is more conducive to both mutual, and the present invention adopts Zynq to demodulate while realizing four channels；FPGA in Zynq undertakes all of digital signal processing tasks, and including Digital Down Convert and demodulation, ARM realizes order and issues and Audio Processing and broadcasting, can be convenient, flexible meet every application.

" embodiment ", " another embodiment ", " embodiment " spoken of in this manual etc., refer to the specific features, structure or the feature that describe in conjunction with this embodiment and include at least one embodiment that the application generality describes.Multiple local appearance statement of the same race is not necessarily refer to same embodiment in the description.Furthermore, it is understood that when describing a specific features, structure or feature in conjunction with any one embodiment, what advocate is also fall within the scope of the present invention to realize this feature, structure or feature in conjunction with other embodiments.

Although reference be made herein to invention has been described for the multiple explanatory embodiment invented, but, it should be understood that those skilled in the art can be designed that a lot of other amendments and embodiment, these amendments and embodiment will drop within spirit disclosed in the present application and spirit.More specifically, in disclosure scope of the claims, it is possible to building block and/or layout to theme composite configuration carry out multiple modification and improvement.Except the modification that building block and/or layout are carried out and improvement, to those skilled in the art, other purposes also will be apparent from.

Claims

1. the multichannel AM based on Zynq and FM demodulation method, it is characterised in that: described method comprises the following steps:

Step one, order issue and data collection

Step 2, Digital Down Convert

Step 3, AM demodulation or FM demodulation

2. the multichannel AM based on Zynq according to claim 1 and FM demodulation method, it is characterised in that also include:

Step 4, audio frequency are play

3. the multichannel AM based on Zynq according to claim 1 and FM demodulation method, it is characterised in that described step one also includes: ARM arranges the radio frequency center frequency point and the bandwidth that comprise four channels by AXI bus, obtains intermediate-freuqncy signal.

4. the multichannel AM based on Zynq according to claim 3 and FM demodulation method, it is characterised in that described step one also includes: be respectively provided with bandwidth and the center frequency point of four channels.