JPH04132437A - Communication system - Google Patents

Abstract

PURPOSE:To easily send a transmission signal of an original transmission carrier frequency even when a reception signal is intermittently obtained by adding a reception offset frequency to a transmission information frequency, integrating the sum as a complex sinusoidal wave signal of a transmission information phase, applying orthogonal modulation to it with a transmission reference carrier signal and sending the result. CONSTITUTION:In the communication in which a transmission signal and a reception signal having an information frequency component changing with information are employed, a reception offset frequency of a reception signal including the reception information frequency component changing with information with respect to a reception carrier frequency of a current reception carrier frequency is detected, the reception offset frequency is added to a transmission information frequency component changing with information and the sum is integrated as complex sinusoidal wave signal of transmission information phase and it is subject to orthogonal modulation by the transmission reference carrier signal and the modulated signal is sent. Thus, even when the reception signal is intermittently obtained, the transmission signal of the original transmission carrier frequency having the transmission offset frequency following to the reception offset frequency is sent with excellent response.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a communication system using transmission signals and reception signals having information frequency components that change according to information.

[Summary of the invention]

The present invention detects a reception offset frequency (or a reception offset phase corresponding to it) of a reception reference reception carrier frequency of a current reception carrier frequency of a reception signal including a reception information frequency component that changes according to information, and Obtaining a complex sine wave signal of a transmission information phase obtained by adding and integrating a reception offset frequency (or reception offset phase) to a changing transmission information frequency (or transmission information phase) (or obtained by simply adding it), By orthogonally modulating the complex sine wave signal with the transmission reference carrier signal and transmitting it, even if the reception signal is obtained intermittently, the original transmission carrier having the transmission offset frequency that follows the reception offset frequency can be used. The frequency transmission signal can be easily transmitted with good responsiveness.

[Conventional technology]

Time division multiple access is a communication method that connects base stations (fixed stations) and mobile stations (car phones) using radio waves. For each channel, a plurality of reception slots are provided, and the reception signal of one of the slots is received for a predetermined time at predetermined time intervals, and similarly for each channel,
A plurality of transmission slots are provided, and the transmission signal of one of the slots is transmitted.

By the way, when the mobile station is moving, an offset frequency occurs in the current received carrier frequency due to the Doppler effect, and if the oscillation frequency of the base station's reference oscillator using a crystal etc. goes out of order, this may cause An off-cent frequency occurs.

Below, with reference to FIG. 2, a conventional example of a communication system using a transmission signal and a reception signal of the FSK (Frequency Shift Keying) system will be described.

The FSK system reception signal received by the reception antenna ANT-R is supplied to the receiver (25). (26) is PL
L, the angular frequency from the voltage controlled oscillator (27) is ωX
The oscillation signal of the receiver (25) is supplied to the receiver (25).
), the oscillation signal with an angular frequency of ωX and the received carrier signal with an angular frequency of ωC are multiplied or divided to make them the same frequency and the phases are compared, and the comparison output is passed through a loop filter to a voltage-controlled oscillator (27 ) to control its frequency.

An oscillation signal with an angular frequency of ωX from the voltage controlled oscillator (27) is supplied to the PLL synthesizer (29) to obtain a reference carrier signal with an angular frequency of ωC, which is then sent to the phase shifter (30).
) to output reference carrier signals with phases Oo and 90°, respectively.

Data (information) from input terminal (12) d (t)=
±1 is supplied to the coefficient multiplier (13) to provide the coefficient A-2
Multiplying by πmRb yields the instantaneous angular frequency ωm (t). Here, t is time, m is modulation index, Rh is bit rate (Hz), and FS when m = 0.5.
X is called MSK (minimum shift keying). This angular frequency ωm (t) is determined by the integrating circuit (16
) and integrated, the phase θm (
t) is obtained, which is connected in parallel to a cosine circuit (3
1) and a sine circuit (3). In addition, a numerically controlled oscillator (NG
O) (15) is constructed.

Then, cosine circuits (3
1) and the outputs x and y of the sine circuit (32) are supplied to multipliers (35) and (36) constituting the orthogonal transformer (19). It is multiplied by a 90° reference carrier signal, and each multiplication output is sent to an adder (3
7), the FSK method transmission signal rx(t) is output, and this is sent to the transmission antenna ANT.
- transmitted by T. Note that the transmission signal TX(t) is expressed as follows. Also, a phase shifter (30) and a multiplier (35),
At (36), a real part extraction circuit is configured.

[Problem to be solved by the invention]

In such conventional communication systems, when received signals are obtained intermittently, it is difficult to transmit with good responsiveness a transmission signal of an original transmission carrier frequency having a transmission offset frequency that follows the reception offset frequency. There are drawbacks.

In view of this, the present invention provides a method for easily transmitting a transmission signal of an original transmission carrier frequency having a transmission offset frequency that follows a reception offset frequency with good responsiveness even when a reception signal is obtained intermittently. This is an attempt to devise a communication method that can transmit data.

[Means and effects for solving the problem] The communication system according to the present invention is characterized in that the current reception carrier frequency of a reception signal containing a reception information frequency component that changes according to information is adjusted to a reception offset frequency (or Detect the corresponding reception offset phase), add the reception offset frequency (or reception offset phase) to the transmission information frequency (or transmission information phase) that changes depending on the information, and then integrate it (or simply add it). A complex sine wave signal of the transmission information phase (obtained) is obtained, and the complex sine wave signal is orthogonally modulated with a transmission reference carrier signal and then transmitted.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to FIG. (1) is a fixed oscillator (crystal oscillator) that generates a reference carrier signal cos (ωat).

(2) and (3) are PLL synthesizers, respectively, and the reference carrier signal cos (ωot) from the fixed oscillator (1)
The reception reference carrier signal exp (jω1 t
) and a transmission reference carrier signal exp (jω2 t). The accuracy of the received reference carrier signal is, for example, 2
Approximately ppn+ is possible. In addition, ω4 and ω2 are respectively,
ω1 = αω. , ω2 = βω0, where α and β are each arbitrary coefficients, and of course may be α−β.

First, the receiving system RX will be explained. Receiving antenna AN
FSK received signal RX(t) received from T-R
is supplied to the multiplier (4). This received signal RX(t
) is expressed as RX (t) = cos (ωrt + θ(t)), where ωr is the current received carrier angular frequency, θ(
t) is a phase representing received data (information), and t is time.

In the multiplier (4), the received signal Rχ(t) is converted into the received reference carrier signal exp (j
After being multiplied by ω, 1>, it is supplied to an A/D converter (5) and digitized. Output e of A/D converter (5)
xp Cj (ωr−ωI)t+θ(t)] is the multiplier (
6) and a numerically controlled oscillator (10), which will be described later.
is multiplied by the oscillation signal exp (jΔωt) from the received data, and a complex sine wave signal exp Cj θ(t)] of the phase θ (t) of the received data is output to the output terminal (7).

This complex sine wave signal exp [j θ (t)] is
It is supplied to a phase detector (8), and its phase detection output is passed through a loop filter (9) to a numerically controlled oscillator (10).
and its oscillation angular frequency is controlled. Note that Δω of the oscillation signal of this numerically controlled oscillator (10) is Δω
=-ωr+ω. Also, numerically controlled oscillator (10)
Like the numerically controlled oscillator (15) described later, the oscillator is composed of an integrating circuit and a complex sine wave generating circuit connected in cascade to the output side of the integrating circuit.

Therefore, P
L L (22) is constructed.

Next, the transmission system TX will be explained. Input terminal (12)
The data d(t) from is fed to a coefficient multiplier (13). Here, the data d(t) is the original binary data “
The amplitude changes from +1 to -1 in response to 1"0". The coefficient A in the coefficient multiplier (13) is A=2πmRb,
m is the modulation index, and Rb is the bit rate (Hz). From the coefficient multiplier (13), the instantaneous angular frequency ω5(t)=2
πmRbd (t) is output and supplied to the adder (14). The angular frequency Δω=ωr+ω1, which is the output of the loop filter (9) of the receiving system RX, is supplied to the adder (14) and multiplied by the coefficient! The angular frequency ωl which is the output of (10)
It is subtracted from l1(t).

The output of the adder (14), ωl1(t)−Δω, is supplied to the integrating circuit (16) that constitutes the numerically controlled oscillator (NGO) (15) and is converted into a component, thereby changing the phase θ.
m(t) is output, which is also a numerically controlled oscillator (
15) (composed of a parallel circuit of a sine circuit and a cosine circuit, each consisting of a ROM table) (17), the complex sine wave signal exp (6m(J,'')' Generate J.

The complex sinusoidal signal exp(j f) m(t) is the D/A
After being supplied to a converter (18) and digitized, it is supplied to a multiplier (20) constituting a quadrature modulator (19), where it is combined with the transmission reference carrier signal exp (jω2t) from the PLL synthesizer (3). The signal is multiplied and its output is supplied to the real part extraction circuit (21) which also constitutes the orthogonal modulator (19), and the transmission signal TX(t) is outputted from the output side and transmitted from the transmission antenna ANT-T. Ru.

This transmission signal TX(t) is expressed as follows.

TX(t) = cos ((ω2−xΔω)t+2
5゛ω d t] = cos ((βω. - Indicates the frequency.In addition, ω
t has an accuracy of about 0.1 ppo+ with respect to ωr.

In the embodiment described above, the adder (14) is replaced by an integrating circuit (1
6) and the complex sine wave generating circuit (17), and an integrating circuit may also be provided on the output side of the coefficient multiplier (11).

Note that the present invention can also be applied to a communication system in which FM modulated signals of information signals are used as transmission signals and reception signals, respectively.

〔Effect of the invention〕

According to the present invention described above, the reception offset frequency (or the reception offset phase corresponding thereto) of the current reception carrier frequency of the reception signal containing the reception information frequency component that changes depending on the information with respect to the reception reference carrier frequency is detected. Then, the complex of the transmitted information phase obtained by adding the received offset frequency (or received offset phase) to the transmitted information frequency (or transmitted information phase) that changes depending on the information and then integrating (or simply adding it) Since a sine wave signal is obtained and the complex sine wave signal is orthogonally modulated with a transmission reference carrier signal and then transmitted, even if the reception signal is obtained intermittently, the transmission offset frequency that follows the reception offset frequency can be maintained. A transmission signal having an original transmission carrier frequency can be easily transmitted with good responsiveness.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional example. (2) is a PLL synthesizer that generates a reception reference carrier signal, and (3) is a PL synthesizer that generates a transmission reference carrier signal.
L synthesizer, (4) is a multiplier, (5) is an A/D converter, (6) is a multiplier, (8) is a phase detector, (9) is a loop filter, (1o) is a numerically controlled oscillator. , (11)
is a coefficient multiplier, (13) is a coefficient multiplier, (15) is a coefficient controlled oscillator, (16) is an integration circuit, (17) is a complex sine wave generation circuit, (18) is a D/A converter, ( 19) is a quadrature modulator, (20) is a multiplier, and (21) is a real part extraction circuit.

Claims (1)

[Claims] 1. Detecting the reception offset frequency of the current reception carrier frequency of the reception signal including the reception information frequency component that changes depending on the information with respect to the reception reference carrier frequency, and detecting the reception offset frequency with respect to the reception reference carrier frequency, A communication system characterized by: obtaining a complex sine wave signal of a transmission information phase obtained by adding and integrating the reception offset frequency, and transmitting the complex sine wave signal after quadrature modulation with a transmission reference carrier signal. 2. Detect the reception facet phase corresponding to the reception offset frequency of the current reception carrier frequency of the reception signal containing the reception information frequency component that changes depending on the information with respect to the reception reference carrier frequency, and adjust the reception phase to the transmission information phase that changes according to the information. A communication system characterized by: obtaining a complex sine wave signal with a transmission information phase obtained by adding the reception offset phases, and transmitting the complex sine wave signal after quadrature modulation with a transmission reference carrier signal.