JPH04150331A - Spread spectrum receiver - Google Patents

Abstract

PURPOSE:To eliminate a disturbance wave by detecting an input signal while being separated into three band channels or over and turning off a switch of a channel in which an adjacent level difference of a detected value is larger than a prescribed value. CONSTITUTION:An input signal is inputted to a narrow band filter group 11. Part of outputs is selected by a filter selection circuit (MPX) 12 and inputted to a detection circuit 13. The circuit 12 decides a filter selected by a comparison discrimination circuit 15. The other output is inputted to a synthesizer 17 via a switch circuit 16. A detection signal from the circuit 13 is inputted to the circuit 15 through an integration circuit 14, the circuit 15 compares and discriminates an output energy of the filter group 11 to control the circuit 16. The circuit 16 turns on/off each switch in response to the control information obtained from the circuit 15. Outputs of the circuit 16 are synthesized by the synthesizer 17, resulting that a spread spectrum signal from which a disturbing wave is eliminated is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spread spectrum receiver, and more particularly to an improvement in means for removing interference waves from an input signal in the receiver.

[Summary of the Invention] In a spread spectrum receiver, an input signal is separated into at least three band channels, the magnitude of each separated band signal is detected, and the level difference between detected values of adjacent channels is detected. The interference wave is removed from the input signal by comparing it with a predetermined value and removing and combining the signals of channels whose level difference is greater than the predetermined value.

[Prior Art] The present inventor previously proposed patent application No. 1-313 as a technology for removing interference waves from an input signal in a spread spectrum receiver.
No. 813 was filed.

[Problems to be Solved by the Invention] Although the technology of the above-mentioned prior application relates to a basic method for effectively removing a large number of interference waves, there are still problems that should be improved as described below.

In other words, when there is no interference wave or there is a small level of interference wave as shown in Figs. , which results in the removal of the vicinity of the center frequency. This leads to deterioration of the S/N ratio, which in turn results in deterioration of the performance of the spread spectrum receiver.

Further, when there are many high-level interference waves as shown in FIG. 3, only the band in which the interference wave with the highest energy exists is reduced, and other interference waves cannot be removed.

[Object of the Invention] Therefore, an object of the present invention is to provide a spread spectrum receiver that can obtain a good received signal even when interference waves of any power level are mixed.

[Means for Solving the Problems] In order to achieve the above object, the spread spectrum receiver of the present invention is a reception system that separates a spread spectrum reception signal including interference waves into at least three or more band channels having different center frequencies. A signal separating means, a switch group provided for each band channel to turn on/off the output thereof, a combiner combining the outputs of each channel obtained through the switch group, Detection means for detecting the magnitude of each band signal, and a level difference between a detection value from the detection means corresponding to each channel and a detection value from the detection means corresponding to a channel adjacent to that channel, respectively. Comparing a calculation means and a level difference corresponding to each channel by the calculation means with a predetermined value,
a comparison judgment circuit comprising comparison means for turning off the switch of the channel corresponding to the channel in which the level difference is larger than the predetermined value, and determining the band in which the interference wave exists and controlling on/off of the switch group; The main point is that the system is equipped with the following.

[Operation] The input signal is separated into at least three or more band channels, the band signals of each channel are detected, and the level difference between the detected values of adjacent channels is compared with a predetermined value, and the band determined to be larger is detected. The channel is switched off and the interference is removed.

[Examples] The present invention will be described below with reference to examples shown in the drawings. FIG. 4 shows the main part (input part) of an embodiment of the spread spectrum receiver according to the present invention. In the figure, 11 is a group of narrowband filters, 12 is a filter selection circuit (MPX),
13 is a detection circuit, 14 is an integration circuit, 15 is a comparison/judgment circuit, 16 is a switch circuit, and 17 is a synthesizer.

In FIG. 11, a received signal (human input signal) in which a spread spectrum signal is mixed with an interference wave is input to a group of narrowband filters 11 having different center frequencies. The filter group 11 is composed of n (for example, 10) bandpass filters BPF having different center frequencies for the band of the spread spectrum signal.

The output of each filter is divided into two systems, one of which is selected by a filter selection circuit (IVIPX) 12 and input to a detection circuit 13 . The MPX circuit 12 determines the filter to be selected by the comparison/judgment circuit 15.

In addition, the other switch circuit 1 is provided for each band.
6 and then input to the synthesis circuit.

The detection signal from the detection circuit 13 is inputted to the comparison/determination circuit 15 through the integration circuit 14, and the comparison/determination circuit compares and determines the output energy from each filter in the following procedure, and controls the switch circuit 16.

That is, the magnitude of energy between adjacent bands is compared and the difference is determined. Next, a band in which this difference exceeds a certain threshold value is detected. Since such a band is considered to be a band in which interference waves that have a large influence on the desired wave obviously exist, the switch circuit 16 is controlled to remove such a band.

For example, as shown in Figure 5, two types of energy difference A
- Find B. Here, the energy difference A is (MPX I
+]) - (MPX I), the energy difference B is (MPX
I)-(MPX r+1). As can be seen from the figure, one or more 10's symbols are added to bands where interference exists.

Therefore, using the example in FIG. 5, band numbers (I) and (1
It becomes clear that interference waves exist in the +1) band.

The switch circuit 16 turns on/off each switch according to the control information obtained from the comparison/judgment circuit 15. For example, in the example shown in FIG. 5, switches Si and Si+1 are turned off. Each output of the switch circuit 16 is combined by a combiner 17,
As a result, a spread spectrum signal from which interfering waves have been removed is obtained.

In this way, as shown in FIGS. 1 and 2, even if the energy difference between each band is significant or not, it is no longer necessary to remove the necessary spectrum spread signal.

FIG. 6 shows a specific configuration example of the above embodiment, in which the filter group 11
is composed of six filters Fl-F6, the filter selection circuit 12 is composed of six switches 81 to S6, and the switch circuit 16 is also composed of six switches Sl' to S6'. The comparison and determination circuit 15 also includes a comparison control section 18, a storage section 1 such as a RAM-ROM, etc.
9. Consists of a determining section 2°.

In FIG. 6, an input signal is input to each of the filters F1 to F6 of the filter group 11, and each band is divided into six bands having different center frequencies. Each filter output becomes an input signal to each switch Sl' to 86' of the switch circuit 16 and each switch Sl to S6 of the filter selection circuit 12.

The filter selection circuit 12 turns on the switch designated by the comparison/judgment circuit 15 to pass only one band.

Thereafter, the output signal from the filter selection circuit is detected, integrated, and input to the comparison control section 18.

In this way, in the comparison control section 18, the filter selection circuit 12
Each switch sequentially reads each filter output. At this time, when reading the previous MPX output and the current MPX output value, calculate the difference between the output of the Si output S3 and store each value in the storage unit 19 (for example, when reading the filter output value of the switch S4, Calculate the output of Si - the output of 83 and the output of S4 of 83).

''--, all MPX outputs are read, and the comparison control section 18 calculates the energy difference between each band. In the determination unit 20, if either of these two energy difference values is larger than the set threshold,
It is determined that there is an interference wave, and the switch circuit 16 is instructed to turn off the switch for that band and turn on the other switches.

In the synthesizer 17, each switch circuit of the switch circuit 16 ~
Since the outputs of S6' are combined, an output signal from which unnecessary bands have been removed can be obtained.

7 and 8 are flowcharts showing the operation of the apparatus of FIG. 6. In the figure, tables A and B contain the contents of difference tables calculated by the comparison control section 18 and stored in the storage section 19 as described below.

Contents of Difference Table Flowchart 1 in FIG. 7 shows the operation of the comparison control section 18. First, clear the RAM of the storage unit 19 in step 5T.
l), turn on the switch s of MPx12 and step S
T,), and the output value (initial value) of the integrating circuit 14 is held in the RAM (step ST,).

After loading the initial value (measured data D,) into the RAM in this way, turn on each switch of MPX12 in sequence,
The data to be imported into table A and table B is repeated until i=6 (step ST).

~ST,).

Next, a flowchart 2 in FIG. 8 shows the operation of the comparison control section 18 and the determination section 20, and the step ST.

In step ST, the calculation values read out from tables A and B are given to the determination unit 20 by the comparison control unit 18.
A comparison with a threshold value is performed in ST, , and the switch circuit 12 is turned on and off according to the result (steps ST, , ST, , ).

This operation is executed until j=6 (step ST
,,,ST,,).

[Effects of the Invention] As explained above, according to the present invention, a spread spectrum receiver can eliminate a large number of interference waves at any level, and the structure is relatively simple and inexpensive. Nasatsuru.

[Brief explanation of the drawing]

Figure 1 shows a spread spectrum signal with no interference waves, Figure 2 shows a spread spectrum signal with small level interference waves, and Figure 3 shows a spread spectrum signal with many large level interference waves. A diagram showing a spread spectrum signal, FIG. 4 is a block diagram showing an embodiment of the present invention, FIG. 5 is a diagram showing an example of calculating an energy difference, and FIG. 6 is a concrete diagram of the embodiment of FIG. 4. A block diagram showing a configuration example, FIG. 7 is a flow chart 1 showing the operation of the above block diagram, and FIG. 8 is a flow chart 1 and 2 showing the operation of the above block diagram. 11... Filter group, 12...
...Filter selection circuit, 13...Detection circuit, 14...Integrator circuit, 15...
...Comparison/judgment circuit, 16...Switch circuit, 17...Synthesizer, 18...
. . . Comparison control section, 19 . . . Storage section, 20 . . . Determination section.

Claims (1)

[Claims] Received signal separation means for separating a spread spectrum received signal including interference waves into at least three band channels having different center frequencies, and a switch provided for each band channel to turn on/off its output. a combiner for combining the outputs of each channel obtained through the switch group, a detection means for respectively detecting the magnitude of each band signal separated by the separation means, and the above detection corresponding to each channel. Calculating means for calculating the level difference between the detected value from the detecting means and the detected value from the detecting means corresponding to a channel adjacent to the channel, and comparing the level difference corresponding to each channel by the calculating means with a predetermined value. and a comparison/judgment circuit comprising comparison means for turning off the switch of the channel corresponding to the channel in which the level difference is larger than the predetermined value, and determining the band in which the interference wave exists and controlling on/off of the switch group. A spread spectrum receiver comprising: and.