JPS5947858A - Receiving circuit of spread spectrum communication - Google Patents

Abstract

PURPOSE:To simplify the circuit constitution, by applying a PSK demodulation at first to obtain a binary-coding signal and processing the signal with a digital circuit such as correlation circuit or the like. CONSTITUTION:A PSK demodulation circuit 1 mixes a spread spectrum signal S(t) and a carrier component cosomegact and demodulates a mixed signal d(t).p(t) of the information d(t) and a PN code p(t). The correlation circuit 3 obtains the correlation between the signal d(t).p(t) and the PN code at the receiving side from a PN code generating section 2. A sample circuit 4 samples an output of the circuit 3 in the specific timing of the PN code. Since this receiving circuit applies PSK demodulation to a broad band signal at first from the local view point, the error rate of data due to the demodulation seems to be larger slightly, but the error rate of information data is improved with the correlation circuit, then the substantial error rate is improved significantly.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of the Invention The present invention relates to a receiving circuit in spread spectrum communication.

(The conventional technology and the spread spectrum signal in the spread spectrum communication have the information data +l (L) (-1-1 or -1
].

The PN code is l) (t) (-1-1 or -1],
Assuming that the carrier wave is e08ωCt.

S (mu) = d (mu)・11 (mo) ' 1
i08 0IcA, but mc”
270f (represented by ;. This Nubek 1-
``Tsum spread Ai word S (shi) is sent ゛, so receive 1:
In the i' i rule, there is a decision to demodulate the information data in response to this i1 No. S (c).

Therefore, the receiver 11-7 circuit of the conventional Spec I/RAM diffusion communication is the same as the 9 sender side as shown in Figure 1.
(L) is locally oscillated, and first, this p (shi) +7j and Uke 1□11-1υS (also) are mixed to generate the PSK father, υ "'
−j skin (+I (L)・01181 mountain・1.) is obtained, and this signal・′f:PSK demodulation is performed to create the ・1 condolence data+I
(L) (I'm trying to get r. That is, receiving L1
Circuit (-1, broadband 21r as shown in Figure 2(a)
'i'1it-S; Add the same PN code 1) as the sending side to S (+,) (Figure 2 (1))
The father was introduced to the narrow band features as shown in
Demodulated information data d(t)? In a circuit of this type, the signal component is emphasized and m'1.11'+
Since the component is reduced, the trace 1j'k is always strong against noise. 'J' can be.

However, the circuit of the above-mentioned viC is
Lamb diffusion 1d No. S (also) first P N V + F No. p (
t), and then PSK demodulation is performed to obtain the carrier wave a
oso no c1. 'i is removed and the information data d (t) is obtained. Since the analog A and A circuit are taken in advance at the last dimension of the circuit, the circuit (, 4 components are 1, 1 and 1. There is a drawback.

(c) Purpose of the invention The purpose of this invention is to eliminate the drawbacks of the conventional circuit described above.

It is an object of the present invention to provide a receiving circuit with a relatively small circuit configuration that can be realized in one piece at low cost and has a spec.

B) Structure and Effects of the Invention In order to achieve the above-mentioned object r, the receiving circuit of the Nuvectrum spread communication according to the invention is as shown in FIG.

After receiving the Nuvectorum spread signal S (t), the Nuvectorum spread signal S (v) and the carrier wave component cos 0Jct
f mix.

Mixture of information d (1,) and PN i J−° p (mu) 1
PSKtM′A that demodulates the word d(t)′>P(L)
Circuit 1, the PN code source 2 which generates the PN code on the receiving side, and the mixed code (1 (Mo'I j) (L) and P N (:]υjC11 The correlation with the PN code from part 2 is J〈4'll relation 1LI8
3 and this correlation circuit 5'f) output as P N <:4-
Number ζ is sampled at a fixed timing and is composed of jl''7 from ``1'1t4''.

The reception of Nubek 1-ram amnesty i1d '1i-i of this invention (, 1 time: itt? (・This is Nubek 1-ram prayer <
l Makii [No. 1 S (+,) is first subjected to PSK demodulation and the binarization information υ is 11-), and the subsequent No. 111 processing is performed by digital circuits such as correlation circuits, so the overall digital circuit is The regeneration of the circuit j with the circuit of iMl'rl'.

(E) Description of Examples This invention will be further explained in 11 nights and 11 below using examples.

FIG. 4-: This is a block diagram of a receiving circuit for Nupekullam spread communication showing one embodiment of the present invention. As shown in the figure, the PSK demodulation circuit is
5. Square circuit that squares the received signal. Hand vanu filter 6.
+2 (, jU function, a binary counter 7 which outputs a cosine component, a mixer 8 which mixes the received signal S(t) and a cosoidL component from the binary counter 7.
The low-pass filter 9 and the binarization circuit 10 are also constructed.

Further, the PN code death/life section 2 includes a tsuji counter 11 and a PN code generation circuit 12, each having a function of C6p (1) CL acid component sequence ÷K1m. Note that K is the carrier frequency and PN
The sign υ° is the ratio of the clock, and the binary counter 11 is 4.1
j li i! : Clock input terminal of 1j path C), C2
Input clock number 3.

A.11 The circuit 3 must be a shift register type circuit.

From PSK demodulation circuit 1 to dl, )・P at the D1 input terminal
(t)'s L pitch 1- data is added, D2 human power 1
iii1i to fi PN ii, J-υ death and life circuit 12 yosu L
Bit PN I, J-No. 1) (RI, υ, 1, 1, 'I'l' relationship between both is taken, and positive A
''(If there are 4 gates, +1. Negative i (1 gate 7b and -1
is output.

The sample circuit section 4 receives P from the PN code generation circuit 12.
A decoder 16 that receives the signal and outputs the sample timing. 2-suppressing device that doubles the output of the correlation circuit 6
A decoder 16 receives the outputs of each 14 and the binarization circuit 14.
It consists of a flip-flop ball tip 15 that performs a sample operation in the same way as sample quimming.

Next, with reference to the waveform time chart A'-1- shown in FIG. 5, the movement (i) of the example shown in FIG. 4 is read +jll.

Nubeku 1-ram amnesty I v1 SOS sent from the sending side
(v) is PSK demodulation same 1 1 2, 2, L times 1 Raku 5
and added to Michili-8, 5° this subek l
is 1.1 of the waveform ε155 ((1)), and this signal S(shi) is the carrier wave component cos wCt shown in FIG. (1 Rini/J Squirrel 1? N - υ+) (t) tr % 5 Figure (e)
VC information: N f -tl <L)l)”jM
r> It was sent out.

Squared 11: I] When the other −υ・S (L) or 2 m is added for each tl of 5, ++ (1,) −+1, p(t)
”+1, so the output is (+++180)(+1・
)2=Yu (1+co, 52ωC also). Then, only the circumference/Bi and convergence components of 2ωC are extracted by the Huff 1-Vanu filter 6, and then counted down by the binary counter 7 to calculate C.
O80) (・1° obtained (see Figure 5(f)).This 1
, 1'zryo sending (+-i" 1 Illl's 卦 1 n sending i no zu is the same as 75-. Therefore, mixer 8 sends signal 5 (
t) and the signal cosωC, the output 1i''H
As shown in Figure 5 (gl), this word becomes one word from which the carrier component has been removed. When this one word is further passed through the low-pass filter 9 and binarized by the binarization circuit 10, it becomes the fifth word. As shown in Figure (1), the PSK demodulated signal d(t)・p
(t+ is obtained. And this signal d(t)・P(t)
is applied to the D1 input terminal of the correlation circuit 6.

On the other hand, the COSωCt signal of the two-step counter 7 is further frequency-divided by the advance counter 11 to generate a P N code clock.
This is added to the PNI signal generation circuit 12, and P s' on the transmitting side is
Receiving side PN code p(t+(fifth) same as J code p(t+)
Generates a figure ('1! light). The PNN code (t) from the PN code + j - generation amount circuit 12 is (・interval circuit 3
is added to the D2 input terminal of.

+11 function circuit 6 is applied to D1 input terminal d t −p
(t) PNN code (t
Find the + correlation and output the result (Figure 5 (, 1)
reference).

In the waveform example shown in Fig. 5, both signal waveforms are the same between Jυ and t2, so the output is +1.
゛, but between t2 and t6 between )lj'3, both degrees are 1
Since the speech waveforms do not match, the output c(t) is -1
becomes.

The output c (t) of the fourth I-heater 6 is converted to 2 by the binarization circuit 14.
11 is chastised and added to flip-flop 15 D human power disease.

Also, the decoder circuit 13 emits the PN I゛! 1 mi times b16
12, the PNN code (t) (7
) 11Fj, H (lJ Output the sample timing signal (tic 5 (see 11G) in Figure 10) to Hj4 and add it to 1 width 1 child of flip-flop 15. Flip-flop 15!d Sample timing signal 11 is applied Sample No. 18 from the binarization circuit 1 every time and obtain the information data d
(see t+ (in FIG. 5)). As described above, the demodulation of the 'itQ report data is completed.

Note that the receiving circuit of the present invention *)i+=+Partially, it appears that the error rate of data due to demodulation increases slightly because the wideband signal is first demodulated using PSK, but the error rate of data due to demodulation seems to increase slightly. Since the ratio is improved by the correlation 1iJJ path, the effective ratio is greatly improved.

This point will be explained more specifically.

Now, the OH rate after PSK recovery is P e , ,
If the bit discrepancy of the 1ull correlation circuit is L, then the rate of 1 bit matching in the correlation circuit is distributed around 2. Therefore, the actual bitonic error rate Pe of the 1d information data dt is
For example, if L = 15, then even if pQ = (li, Pe = 0.000033)
The rate of adjustment becomes very small.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a receiving circuit for conventional spread spectrum communication, and Figures 2 (a) and (b) are frequency distribution band characteristics when the communication signal includes and does not include a PN code. FIG. 6 is a block diagram showing the configuration of a receiving circuit for spread spectrum communication according to the present invention, FIG. 4 is a block diagram of a receiving circuit for spread spectrum communication showing an embodiment of the present invention, and FIG. This is a signal waveform timing chart for explaining the operation of the fruitful side circuit shown in FIG. Sample circuit. 5: Square circuit, 6: Band bus filter. 7: 2 quasi-count, 8: Migiza, 9: l-go bus filter, 10・1/I: 2 (direction circuit. 11: Decimal counter, 12: PI dimension light life path, 13: decoder circuit, 15: flip-flop.

Claims (1)

[Claims] (1) A PSK demodulation circuit that receives a spread spectrum signal, mixes the spread spectrum signal with a carrier component, and demodulates a mixed signal of information and a PN code. a PN code generator that generates a PN code for the receiving side; Mixed fH number and 1jiJ from the p S K deco aa circuit
A spread spectrum receiver circuit comprising a correlation circuit for determining the correlation between the PN code generation circuit and the PN code, and a sample circuit for sampling the output of the correlation circuit at a specific timing of the PN code.