FI70100B - AUTOMATIC SELECTIVE MOTTAGARE - Google Patents

Description

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Potent r. e ICelit 1. °. CO 1030 (51) Kv.lk.4 / lnt.CI. * H 03 J 7/18 gUQ | ^ | __p || ^ | ^ yy | ^ Q (21) Patent application - Patentansökning 78 1 030 (22) Application date - Ansökningsdag 04.04.78 (F ') (23) Start date - Giltighetsdag 0 * 4.04.78 (41) Become public - Blivit offentlig 1 ^ jq jc>

National Board of Patents and Registration of Finland Date of inspection and publication—

Patent and registration authorities in the United States and other Member States, 31, 01 .86 (32) (33) (31) Privilege requested — Begärd priority 14.04.77 Japan-Japan (JP) 43270/77 (71) Mitsubishi Denki Kabushiki Kaisha, 2-3, Marunouchi 2-chome,

Chiyoda-ku, Tokyo, Japan-Japan (JP) (72) Minori Kawano, Amagasaki-shi, Masumi Kosaka, Amagasaki-shi, Japan-Japan (JP) (74) Oy Koister Ab (54) Automatic selective receiver -Automatisk selective This invention relates to an automatic selective receiver used to selectively call targets of mobile local stations using radio links.

The following multi-radio paging systems have been proposed.

The selective call control signal is transmitted from the call center station for a certain period of time using the one that is free from several radio connections.

On the other hand, signals are usually received during a scan by multiple mobile stations over multiple radio links (hereafter referred to as scan reception), and when the radio link transmitting the control signal is found, the scan is stopped waiting to receive a selective radio call selective call.

Several mobile local stations operating at the scan 2 70100 reception are set up for a radio link that transmits a control signal at this rate. After the mobile local stations have established a special radio connection, the calling central station transmits a selective signal. A particular local station detects a selective signal, allowing a completely selective call to be made. In other mobile local stations, the scan stop mode is triggered by stopping the transmission of the call center station control signal and releasing the scan reception to wait for the next call.

There are two types of sweep reception systems. One is a system in which radio connections are connected to a receiver by converting the local oscillation signal of the receiver to numeric using a digital synthesizer. The other is a system in which a particular radio connection is scanned while constantly changing the frequency of the reception signal by scanning the local oscillation signal analogously.

Because radio connections travel in such wide frequency bands, an analog scanning system is advantageous because it is simple in structure.

The automatic selective receiver according to the present invention as defined in the appended claim represents an improvement over a conventional analog type device.

Referring to Figure 1, there is shown a conventional analog-scan type device.

In Fig. 1, reference numeral 1 denotes an input signal input point, 2 denotes a high-frequency amplifier, 3 denotes a mixer for mixing the signal amplified by the high-frequency amplifier 2 and a local oscillation signal to form an intermediate frequency signal, 4 denotes an intermediate frequency frequency range (e.g. -30 KHz) and a specified increase in signal strength, 5 denotes a detector that selectively detects the output signal of the intermediate frequency amplifier to regenerate the modulation signal transmitted with the receive signal, 6 denotes an output point, 7 denotes a control signal detector circuit,

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3 70100 to send the control signal. In one embodiment, the control signal is a low frequency signal (1KH) and the low frequency signal + z is filtered by a bandpass filter (1KHz to 0.5Hz). If the filtered level is higher than a predetermined value, it is expressed to supply a logic voltage "H" to the output side. Randomly, a logic voltage "H" is applied on the output side when a low frequency signal (1KH) is continuously applied to the input side of the low frequency bandpass filter for longer than t> t of the bandpass filter rise time t ~ 1 / B.

Reference numeral 8 denotes a sweep signal generator which generates a sweep signal. The height level of the sweep signal usually changes at a constant rate of change. When a stop signal is given to stop the change, the altitude prevailing at the time of signaling is maintained. In a conventional device, the output signal of the control signal detector is used as a stop signal. Reference 11 denotes a frequency discriminator whose input-output characteristics are of the S-type and whose center frequency is the same as that of the intermediate frequency amplifier 4, 12 describes an adder combining a sweep signal and a frequency discriminator output signal 9 means a local oscillator to the mixer 3.

The device works as follows.

The signal ratios of the different parts are shown in Figure 2.

The sweep signal changes at a constant rate of change, as shown in Fig. 2 (A), and the signal of the local oscillator is changed at a constant rate of change close to the time tQ ^. If a signal with frequency f1 is received near time t ^ and near the frequency oscillator f ^ of the local oscillator, there is an S-type signal at the output of the frequency discriminator near time t ^ in Fig. 2 (B) corresponding to the reception signal, and this signal is combined with the sweep signal. the resultant signal is subjected to oscillation near the time t ^ in Fig. 2 (C), which is transferred to the local oscillator 9, whereby the frequency of the local oscillator signal is changed in the same manner and the rate of change of the local oscillator frequency decreases at that moment. As a result, the frequency of the signal remains close to the value 4 70100 for a long time, and the signal detection signal is the output of the detector 5. If the control signal is not included in the reception signal having a frequency f ^, the time-dependent frequency of the local oscillation signal differs from the value f ^. Similarly, the frequency of the reception signal is maintained for a long time if the reception signal containing the control signal is detected at a frequency fo2 »near time t 2 · During this time, the control signal detector 7 detects the control signal and the detection signal

As a result, the sweep signal, the adder output signal and the local oscillation signal remain constant near the time t 2 'in Fig. 2, so that a reception signal having a frequency of f2 can be continuously received. Thus, a control signal can be received automatically and selectively by the transmitter.

As is clear from the above description, the duration of the reception signal frequency in the scan reception depends on the height level of the output of the frequency discriminator 11, which is not constant due to the change in the reception signal intensity and the receiver characteristics. If the output level of the frequency discriminator is steadily raised to detect the control signal even when the receiver has significantly deteriorated or the level of the reception signal has significantly decreased, the output level of the frequency discriminator is too high for a reception signal whose level is normal or exceeds it. As a result, the interference of the resultant signal near the time tg-j in Fig. 2 (C) becomes wide, whereby the scanning of the local oscillation signal remains close to the frequency f ^ for a long time, and the scanning speed decreases.

In order to perform a frequency sweep in a wide frequency band, an unnecessary reduction of the sweep rate during the sweep causes difficulties for a fast selective call.

SUMMARY OF THE INVENTION: It is an object of the present invention to obviate the disadvantages caused by unnecessarily reducing the sweep speed during sweeping, which prevents rapid selective calling. Another object of the present invention is to provide an automatic receiver which selectively takes over a short time by scanning a radio connection transmitting a special control signal at a constant scan rate without the side effects of receiver degradation.

Brief description of the drawings:

Figure 1 is a block diagram of a conventional device.

Figure 2 shows signals in different parts of a conventional device.

Figure 3 is a block diagram of one embodiment of a device according to the present invention.

Fig. 4 is a table illustrating a sweep operation in an embodiment of the present invention.

Figure 5 is a switch diagram of a timing signal generator.

Figure 6 shows signals in different parts of the timing signal generator.

Detailed description of the preferred embodiments:

With reference to Figure 3, one embodiment of a receiver according to the present invention will be described below.

In Fig. 3, the same reference numerals denote those parts whose function is the same as in Fig. 1.

Reference numeral 13 denotes a timing signal generator.

When the frequency of the intermediate frequency signal produced by the scanning of the local oscillation signal is consistent with the center frequency of the intermediate frequency, the timing signal generator detects it and generates a timing signal having a logic state of "H" and continuing for a certain time, such as 1 second. Details of the timing signal generator are shown in Figure 5.

Reference numeral 14 describes a stop signal generator, which may be an OR circuit which generates an output signal, either a control signal indicator signal or a timing signal is received, and the output signal is used as a stop signal to stop the sweep of the sweep signal generator 8.

The operation of an embodiment of the present invention is illustrated below.

Figure 4 shows the relationship between the sweep waveform and the signal frequency over time.

When the signal whose frequency is received during the signal frequency sweep 6,70000 is detected, the timing signal generator 13 currently detects a timing signal of a specified time At ^ 2. The signal is passed through a stop signal generator 14 and is used as a stop signal of a sweep signal generator 8. As a result, the sweep signal remains unchanged for the time, At 1, which is affected by the stop signal, whereby the frequency of the signal remains at a value fi for a certain time. If the reception signal having the frequency f ^ does not contain a control signal, the sweep will start again after a certain time, At1. If the frequency of the reception signal is and a control signal is transmitted, the reception signal, which frequency is f2, is detected at time t ^ 4, at which time a timing signal is generated which stops scanning.

When the time At2 (operation time of the control signal) has elapsed, starting from the stop of the sweep, the output signal of the control signal detector 7 given by the control signal detection is generated, which is controlled through the stop signal generator 14 and is used as the stop signal of the sweep signal generator 8.

When the time At ^ has elapsed since the time t ^ 4, the timing signal disappears, but the output signal of the control signal detector keeps the sweep in the stop state, so that a reception signal with a frequency f2> can be continuously received.

Figure 5 illustrates in detail an embodiment of the structure of the timing signal generator 13.

Reference numeral 13-1 denotes an intermediate frequency signal detector circuit in which a part of the output signal of the intermediate frequency amplifier 4 is detected, 13-2 describes a first level detector circuit in which the output signal of the intermediate frequency signal detector circuit 13-1 is cut at a specified level, and if it is higher than the level, it is detected and input. out logic state "H", 13-3 illustrates a derivation circuit which outputs the output signal of the intermediate frequency signal detector 13-1 as a derivative, 13-4 shows a full-wave rectifier circuit which rectifies the output signal of the derivative circuit 13-3, cut at a certain level and if it is higher than the level, express this and output a logic voltage "H" 13-6 means a gate circuit in which the second level detection circuit 13-5 7 70100 keeps the output signal of the first level detection circuit 13-2 blocked, 13-7 means a monostable multivibrator , used by the ascending Signa a sub that currently generates an output signal of the gate circuit 13-6 so that a timing signal is generated for a specified time.

The operation of the timing signal is described below.

Fig. 6 shows signals in different parts of the timing signal generator 13, in which the reception signal whose frequency is changed to the intermediate frequency changes f-1 -> f-2 -> f-3 -> f

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center frequency of the frequency) -> f + 3 -> f + 2 -> f + 1, depending on the change in the local oscillation signal.

The signal shown in Fig. 6 (A) comes from the intermediate frequency air circuit 13-1. The waveform of the signal depends mainly on the selective characteristics of the intermediate frequency amplifier 4. The first level detector 13-2 cuts the signal at a certain level E1 to provide the output signal shown in Fig. 6 (B).

On the other hand, the derivation circuit 13 to 3 derives the signal shown in Fig. 6 (A) to generate the output signal shown in Fig. 6 (C). Thereafter, the output signal is rectified by a double-sided rectification circuit 13-4 to form the output signal shown in Fig. 6 (D).

The signal has two peaks and drops to zero near the center frequency f. The second level detection circuit 13-5 cuts the signal at a certain level E2 to generate the signal shown in Fig. 6 (E). As a result, the output of the gate circuit 13-6 is output as shown in Fig. 6 (F). Similarly, when the transmitted hair signal is close to f due to the sweeping of the local oscillation signal, the output of the gate circuit 13-6 is provided, whereby the monostable multivibrator 13-7 starts to generate a timing signal which continues for a certain time.

As described according to the embodiment, a monostable multivibrator is controlled if the frequency of the signal converted to an intermediate frequency signal is close to the center frequency, whereby the sweep of the sweep signal generator stops for a while to keep the frequency as the frequency of the reception signal. During that time, it is determined whether or not there is a control signal. If a control signal is transmitted, the sweep in stop mode is still held by the signal 8 70100 given when the control signal was detected. Similarly, the sweep stop time during sweeping can be kept constant, whereby the sweep stop time can be minimized to achieve a stable and fast sweep.

The timing signal generator 13 need not be limited to the embodiment shown in Fig. 5 and is caused to generate a timing signal to continue for a period of time by considering the fact that the frequency of the signal converted to the intermediate frequency is close to the center of the intermediate frequency.

As described, the automatic selective receiver of the present invention has the feature that the local oscillation signal is scanned to receive the reception signal, and when the reception signal is detected, the scan is stopped for a while, and if the scan signal is stopped, the control signal is detected, the stop is continued. specified signal for a short time.

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Claims (1)

An automatic selective receiver comprising a sweep signal generator (8) which generates a sweep signal whose altitude level changes at a predetermined rate of change and stops at the level of the moment when the stop signal is given when the stop signal is given; a local oscillator (9) generating a local oscillation signal having a frequency corresponding to the level of the sweep signal; a timer signal generator (13) for mixing the signal received from the outside and the local oscillation signal to form an intermediate frequency signal, indicating that the frequency of the intermediate frequency signal corresponding to the frequency change of the local oscillation signal is adjusted according to a stop signal generator (14) which generates for a period of time a stop signal corresponding to the timing signal of the timing signal generator and which maintains the stop signal at the time the control signal for controlling the automatic selective receiver is transmitted, the signal being transmitted with the received signal, the signal , received automatically and selectively, characterized in that the timing signal generator (13) comprises an intermediate frequency signal detecting circuit (13-1) for detecting the intermediate frequency signal, first a level detector (13-2) which provides a special logic signal if the output of the intermediate frequency signal detection circuit (13-1) is higher than a certain level; a derivation circuit (13-3) which provides a derivative signal from the output signal of the intermediate frequency signal detection circuit to rectify the output signal of the derivation circuit of the rectification circuit (13-4), a second height level detector (13-5) which provides a special logic signal if the rectification circuit 13-4 ) the output is higher than a certain level, to prevent the output of the first elevation detector of the gate circuit (13-6) by the output of the second elevation detector and a monostable multivibrator (13-7) to which the output signal of the gate circuit (13-6) is input.