CN109813963B - Method and device for realizing frequency spectrum scanning by single chip microcomputer - Google Patents
Method and device for realizing frequency spectrum scanning by single chip microcomputer Download PDFInfo
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- CN109813963B CN109813963B CN201910085981.7A CN201910085981A CN109813963B CN 109813963 B CN109813963 B CN 109813963B CN 201910085981 A CN201910085981 A CN 201910085981A CN 109813963 B CN109813963 B CN 109813963B
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Abstract
The invention relates to a method and a device for realizing frequency spectrum scanning by a singlechip, which mainly comprise the following steps: setting a local oscillation frequency of a current frequency point, and collecting voltage value data of a plurality of signals under the current local oscillation frequency; setting filtering parameters according to the required bandwidth, carrying out root mean square calculation on the voltage value data of a plurality of signals after filtering the voltage value data, carrying out logarithmic calculation on the root mean square voltage value to obtain the signal intensity of the current frequency point, and setting the local oscillation frequency of the next frequency point; and repeating the steps S2-S4 until the signal intensity of all the frequency points is obtained, thereby obtaining the signal spectrum. The invention realizes the frequency spectrum scanning with variable bandwidth through the singlechip, and has high precision on the same cost.
Description
Technical Field
The invention relates to the field of satellite televisions, in particular to a method and a device for realizing frequency spectrum scanning by a single chip microcomputer.
Background
At present, a set top box of many families receives satellite television signals, a satellite receiving pot is required to be installed to receive the signals, and the satellite receiving pot can normally receive the signals at a small angle. Therefore, it is difficult to accurately install the star finder without a professional. The frequency spectrograph is an important and convenient function in a professional star finder, and the design is extremely convenient, so that the cost is the lowest under the condition of meeting the requirement of basic installation precision. The spectrometer on the star finder is different from the professional spectrometer on the market, the cost of the spectrometer on the star finder is low, and the performance only needs to meet the requirement of installing a receiving pot; in the prior art, a set top box TUNER IC is mainly used, software adjusts AGC gain of TUNER by fixing the output signal intensity of the TUNER IC, and thus, a signal intensity ratio value is obtained through AGC; but its accuracy is low because the gain of AGC is not linearly changed and thus the absolute strength of the signal cannot be correctly displayed; because the bandwidth of the filter is fixed, if a plurality of bandwidths are required to be realized, a plurality of stages of filters are required to be added, and the cost is increased. In addition, in the scheme of the general frequency spectrograph, a plurality of mixers, local oscillators, filters, AD sampling and digital signal processors are adopted, so that the precision is high but the cost is higher, and the precision is not required when a satellite television receiving pot is installed.
Disclosure of Invention
The invention provides a method and a device for realizing frequency spectrum scanning by a single chip microcomputer aiming at the defects of the prior art, realizes frequency spectrum scanning with variable bandwidth by the single chip microcomputer, and has high precision on the same cost.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a method for realizing frequency spectrum scanning by a single chip microcomputer comprises the following steps:
s1: setting the local oscillation frequency of the current frequency point through the singlechip;
s2: controlling the ADC to collect voltage value data of a plurality of signals under the current local oscillation frequency;
s3: the single chip microcomputer sets filtering parameters according to the required bandwidth, and after voltage value data of the signals are filtered, the root mean square voltage value is obtained through calculation according to the following formula:
wherein, VrmsIs the root mean square voltage value, N is the number of signals, VnVoltage value data for each signal after filtering;
s4: carrying out logarithmic calculation on the root mean square voltage value to obtain the signal intensity of the current frequency point, and setting the local oscillation frequency of the next frequency point;
s5: and repeating the steps S2-S4 until the signal intensity of all the frequency points is obtained, thereby obtaining the signal spectrum.
Further, the formula of the logarithmic calculation is as follows: s is 20log (V)rms) Where S represents signal strength.
Further, the step S2 further includes: the RF signal is subjected to frequency reduction processing by a frequency reduction device and then is transmitted to the ADC.
Furthermore, the acquisition speed of the ADC is more than twice the bandwidth of a low-pass filter in the frequency reduction device.
Further, the frequency demultiplier comprises: the local oscillator, a low pass filter and a mixer, wherein the RF signal is delivered to the low pass filter via the mixer.
Further, the single chip microcomputer is provided with an IIR filter, and the required bandwidth is smaller than that of the low-pass filter.
An apparatus for implementing the above scanning method includes: the frequency reduction device, the ADC and the single chip microcomputer, wherein,
the frequency reducing device is used for reducing the frequency of an input RF signal;
the ADC is connected with the frequency reduction device and is used for collecting RF signals;
the single chip microcomputer is respectively connected with the frequency reduction device and the ADC and used for setting the local oscillation frequency of the frequency reduction device and processing the collected RF signals to obtain the signal intensity, so that the signal frequency spectrum is obtained.
Further, the method also comprises the following steps: and the CPU is connected with the singlechip and is used for displaying the signal frequency spectrum.
Further, the frequency demultiplier comprises: the RF signal is transmitted to the low-pass filter through the frequency mixer, the local oscillator is connected with the frequency mixer, and the low-pass filter is connected with the ADC.
The beneficial effects of the invention at least comprise: the invention has simple circuit, realizes the frequency spectrograph with variable bandwidth through software, can make the bandwidth smaller, has the best precision under the same cost, and is more suitable for the requirement of installing a satellite television receiving pot.
Drawings
FIG. 1 is a flow chart of the method of the present invention.
FIG. 2 is a block diagram of the apparatus of the present invention.
Detailed Description
In order to make the technical solutions of the present invention better understood by those skilled in the art, the present invention will be further described in detail with reference to specific examples. The following examples are illustrative only and are not to be construed as limiting the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications.
Fig. 1 is a flow chart of the method of the present invention, and referring to fig. 1, the method of the present invention for realizing the scanning of the frequency spectrum by the single chip microcomputer mainly includes the following steps.
S1: and setting the local oscillation frequency of the current frequency point through the singlechip.
S2: and controlling the ADC to collect voltage value data of a plurality of signals under the current local oscillation frequency.
The step S2 may further include: the RF signal is processed by the frequency-reducing device and then transmitted to the ADC (analog-to-digital converter), the acquisition speed of the ADC is more than twice the bandwidth of a low-pass filter in the frequency-reducing device, and specific numerical values are not limited, for example, the bandwidth of the low-pass filter is 4MHz, and the acquisition speed of the ADC is 18 MHz.
The frequency reducing device comprises: the local oscillator, a low pass filter and a mixer, wherein the RF signal is delivered to the low pass filter via the mixer. In addition, it should be understood that the frequency down device of the present invention may be a TUNER IC of an existing set-top box or other components capable of implementing the frequency down function.
S3: the single chip microcomputer sets filtering parameters according to the required bandwidth, and after voltage value data of the signals are filtered, the root mean square voltage value is obtained through calculation according to the following formula:
wherein, VrmsIs the root mean square voltage value, N is the number of signals, VnVoltage value data for each signal after filtering.
It can be understood that the invention can be adjusted by the single chip according to the required bandwidth, thus realizing the variable bandwidth; and because the number of signals collected by the invention is very large, the specific number is not limited, for example: and N is 1024, in order to improve the data accuracy, the conventional root mean square formula is deformed to a certain extent to obtain the formula of the invention, and compared with the conventional formula, the data accuracy obtained by the invention is higher.
The single chip microcomputer is provided with an IIR filter, the IIR filter is obtained by software design, namely the filtering function of the IIR filter is obtained by writing a program, in addition, the required bandwidth is smaller than the bandwidth of the low-pass filter, namely the software can adjust the variable bandwidth to be smaller than the bandwidth of the low-pass filter, and specific numerical values are not limited, for example: the bandwidth of the low-pass filter is 4MHz, and the adjustable bandwidth is 10KHz-4 MHz.
S4: carrying out logarithmic calculation on the root-mean-square voltage value, wherein the logarithmic calculation formula is as follows: 20log SdbuV (V)rmsand/uV), wherein S represents the signal intensity, the signal intensity of the current frequency point is obtained, and the local oscillation frequency of the next frequency point is set.
S5: and repeating the steps S2-S4 until the signal intensity of all the frequency points is obtained, thereby obtaining the signal spectrum.
In addition, fig. 2 is a block diagram of the apparatus of the present invention, and referring to fig. 2, the present invention provides an apparatus for implementing the scanning method, including: the frequency reduction device, the ADC and the single chip microcomputer, wherein the frequency reduction device is used for carrying out frequency reduction processing on an input RF signal; the ADC is connected with the frequency reduction device and is used for collecting RF signals; the single chip microcomputer is respectively connected with the frequency reduction device and the ADC and used for setting the local oscillation frequency of the frequency reduction device and processing the collected RF signals to obtain the signal intensity, so that the signal frequency spectrum is obtained.
Meanwhile, the device of the invention can also comprise: the CPU is connected with the singlechip and is used for displaying the signal frequency spectrum; the single chip microcomputer sets local oscillation frequency, RF signals are input into the frequency mixer to be subjected to frequency reduction and then are output to the ADC to be sampled, the single chip microcomputer receives a sampling result and then performs data analysis, the specific analysis refers to the steps S1-S5, and final frequency spectrum data obtained through analysis are transmitted to the CPU to be displayed.
The frequency reducing device of the invention comprises: the local oscillator, the low-pass filter and the mixer, wherein the RF signal is transmitted to the low-pass filter through the mixer, the local oscillator is connected with the mixer, and the low-pass filter is connected with the ADC; the local oscillator, the mixer and the low-pass filter can be a TUNER IC of the existing set-top box or other components capable of realizing the frequency reduction function.
In summary, the invention has simple circuit, realizes the spectrogram with variable bandwidth through software, can make the bandwidth smaller, has higher precision under the same cost, and is more suitable for the requirement of installing a satellite receiving pot.
In the present invention, unless otherwise expressly stated or limited, the terms "connected" and "connected" are to be construed broadly, e.g., as meaning either a fixed connection or a removable connection, or an integral part; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Although embodiments of the present invention have been shown and described, it is understood that the embodiments are illustrative and not restrictive, that various changes, modifications, substitutions and alterations may be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (8)
1. A method for realizing frequency spectrum scanning by a single chip microcomputer is characterized by comprising the following steps:
s1: setting the local oscillation frequency of the current frequency point through the singlechip;
s2: controlling the ADC to collect voltage value data of a plurality of signals under the current local oscillation frequency;
s3: the single chip microcomputer sets filtering parameters according to the required bandwidth, and after voltage value data of the signals are filtered, the root mean square voltage value is obtained through calculation according to the following formula:
wherein, VrmsIs the root mean square voltage value, N is the number of signals, VnVoltage value data for each signal after filtering;
s4: performing a logarithmic calculation on the root mean square voltage value, the logarithmic meterThe formula of the calculation is as follows: s is 20log (V)rms) Obtaining the signal intensity S of the current frequency point, and setting the local oscillation frequency of the next frequency point;
s5: and repeating the steps S2-S4 until the signal intensity of all the frequency points is obtained, thereby obtaining the signal spectrum.
2. The scanning method according to claim 1, characterized in that said step S2 further comprises: the RF signal is subjected to frequency reduction processing by a frequency reduction device and then is transmitted to the ADC.
3. The scanning method according to claim 2, wherein the acquisition speed of said ADC is greater than twice the bandwidth of the low pass filter in the down conversion means.
4. The scanning method according to claim 3, characterized in that said down-conversion means comprises: the local oscillator, a low pass filter and a mixer, wherein the RF signal is delivered to the low pass filter via the mixer.
5. A scanning method according to claim 3, characterized in that said single-chip microcomputer is provided with an IIR filter, and said required bandwidth is smaller than the bandwidth of said low-pass filter.
6. An apparatus for implementing the scanning method according to any one of claims 1 to 5, comprising: the frequency reduction device, the ADC and the single chip microcomputer, wherein,
the frequency reducing device is used for reducing the frequency of an input RF signal;
the ADC is connected with the frequency reduction device and is used for collecting RF signals;
the single chip microcomputer is respectively connected with the frequency reduction device and the ADC and used for setting the local oscillation frequency of the frequency reduction device and processing the collected RF signals to obtain the signal intensity, so that the signal frequency spectrum is obtained.
7. The apparatus of claim 6, further comprising: and the CPU is connected with the singlechip and is used for displaying the signal frequency spectrum.
8. The apparatus of claim 6, wherein the frequency down-conversion means comprises: the RF signal is transmitted to the low-pass filter through the frequency mixer, the local oscillator is connected with the frequency mixer, and the low-pass filter is connected with the ADC.
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| CN111565081A (en) * | 2020-04-28 | 2020-08-21 | 深圳中科国威信息系统技术有限公司 | Method, medium, terminal and device for scanning white spectrum frequency band in cognitive radio |
| CN116298513B (en) * | 2023-03-01 | 2024-03-12 | 扬州宇安电子科技有限公司 | Broadband spectrum monitoring system with multiple scanning modes |
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