JPH0620186B2 - Portable radio - Google Patents

Description

The present invention relates to a portable radio device to which a diversity reception technique is applied and which is applied to mobile use.

[Conventional technology]

In conventional portable radios, rod antennas are generally used except for medium- and short-waves, and 1 is used for VHF and UHF bands.
Since it works efficiently with a short antenna of less than a meter,
Portable communication devices exclusively use the VHF band / UHF band rather than the SW band, and the FM broadcast uses the VHF band, and the TV broadcast uses the VHF band and the UHF band.

Similarly to light, radio waves have the property of traveling straight and the property of reflecting, and this property becomes more remarkable as the frequency increases, and the direct wave and the reflected wave interfere with each other, resulting in a difference in strength. It has been attempted to obtain a good reception condition by moving the position of or moving the direction of the rod antenna, but strong reception fading is an unavoidable phenomenon. As a countermeasure for this, a directional antenna is used for fixed reception to eliminate the influence of reflected waves, and as disclosed in Japanese Patent Laid-Open No. 58-182927, two receivers are used in the diversity reception system. In order to correct the variation in envelope detection characteristics in the signal comparison according to (3), the envelope detector output is used in a time-division manner for determination and the receiver system is switched. For mobile radio, Japanese Patent Laid-Open No. 58-184837 uses one receiver and two antennas, the main antenna is connected to the receiving section through the combining section, and the sub-antenna is controlled by the control section at a constant cycle. For example, there is one that compensates the fluctuation margin of the received electric field supplied to the combining section through the varying modulator.

[Problems to be Solved by the Invention]

The present invention relates to a VHF band / UHF band portable radio device which is apt to cause radio wave interference due to reflected waves from the surroundings when the mobile device is moved, without the need for a special diversity antenna or two sets of receiving circuits. The purpose is to obtain an effect.

[Means for Solving the Problems]

Matching the squelch signal of the clock generator, the output of the clock generator, and the antenna means by the microphone cord that is connected from the microphone code to the transmission unit via the high frequency coil and to the diversity switcher via the coupling capacitor AND circuit, and a diversity switching signal generating means comprising a circuit for outputting the output of a flip-flop for dividing the output of the AND circuit to the diversity switching device, wherein the diversity switching signal generating means attenuates the reception input. During squelch operation, the diversity air exchanger is driven at the output cycle of the flip-flop to alternately switch the main antenna and the second antenna to detect the reception state of both antennas, and the squelch operation is stopped due to the reception input. The diversity switch is configured to hold the antenna state when it is turned on.

〔Example〕

To explain the portable radio apparatus of the present invention with reference to the drawings, and the normal reception time of transmission in the first figure, the radio device main body 1
When the received electric field strength decreases due to the interference with the reflected wave, the main antenna 2 is used to automatically change to the antenna for diversity reception. In the present invention, the microphone cord 3 or the earphone is used for this main antenna. Code 4 (hereinafter,
If necessary, these are referred to as a second antenna) are used as the second antenna.

There are frequency diversity methods and space diversity methods as diversity reception methods.Since frequency diversity methods simultaneously transmit the same communication content by radio waves of different frequencies, important commercial lines and some broadcasts. Except for waves and the like, this is not necessary for the portable radio device and the like of the present invention. Therefore, the present invention employs a space diversity system in which a plurality of antennas are switched and used.

Next, in FIG. 2 shows an exemplary configuration example of applying the present invention to a radio device body 1, and when receiving, the wireless device main body 1
A radio wave is induced in the main antenna 2 of, and this radio wave is connected to the input circuit of the receiving unit 14 through the TR changeover switch 11 and the diversity changeover device 12. The TR switch 11 and the diversity switch 12 may be mechanical relays or electronic switches such as diodes. When the intensity of the received radio wave drops below the downlink squelch output squelch set level, the diversity switch 12 operates the diversity switch 12 by the diversity switch signal 15 generated from the receiving section 14, and the main antenna 2 outputs the microphone code. The input of the receiving unit 14 is connected to the microphone cord 3 via the coupling capacitor 16 so as to switch to the second antenna, and operates as a receiving antenna.

Further, the microphone circuit and the transmitter 13 are connected to each other through the high-frequency choke coil 17 so as to maintain a high-frequency potential and prevent sneak of radio waves during transmission.

For handy transceivers and radio receivers that do not use microphone cords as diversity switching antennas,
The same effect can be obtained by using the earphone cord 4.

Next, FIG. 3 shows a circuit for obtaining the diversity switching signal 15, in which the squelch control voltage 51 output from the detector 5 is at L level during normal reception, and the squelch gate 6 is opened. However, when the input of the detector 5 drops below a predetermined value, the squelch control voltage 51 becomes H level and the squelch gate 6 is closed so that reception is not possible. Therefore, the main antenna 2 can be switched to the second antenna at that time. is there. Therefore, the squelch control output 51
The output CLK of the clock oscillator 7 is applied to the AND gate 8, and its output is added to the CLK input 15 of the flip-flop (FF) 9 which directly connects the output and the D input, and the diversity switching signal 15 is obtained from the Q output. As shown in FIG. 4, the timing chart of the operation is such that if the intensity of the received radio wave is normal and the squelch control output (SQ) 51 is at the L level, the flip-flop FF9 maintains the same state. However, when the intensity of the received radio wave is lowered and the squelch gate is closed and the SQ51 becomes H level, the Q output of the flip-flop FF9 (that is, the diversity switching signal 15) is inverted and the main antenna is switched to the second antenna. Further, if the input of the second antenna is sufficient, the SQ51 becomes L level and the Q output of the flip-flop FF9 is held as it is. However, the input intensity of the second antenna is also low and SQ51 is at H level. The flip-flop FF9 repeats inversion according to CLK (cycle of about 1 ms to 10 ms), and the main antenna 2 and the second
Alternate between antenna and. Then, if there is an input feeling exceeding the squelch setting level, the flip-flop FF9 is held with the antenna connected, and the space diversity operation by the two antennas is automated. Although the squelch gate 6 is provided with an RC holding time constant circuit in order to eliminate unstable operation near the threshold operating point, this operation requires a holding time constant smaller than that of the conventional circuit. Thus, the stop time of the audio output 61 is shortened.

〔The invention's effect〕

The present invention adopts a diversity receiving system by one receiving section by the main antenna and the second antenna by the microphone code, and the switching of the diversity is alternately switched at a cycle of twice the clock pulse by the signal at the time of squelch operation to check the receiving state. However, since it is configured to hold the antenna side when the squelch is in the open state, it has the effect of being able to automatically respond quickly to radio wave interference during mobile operation.

[Brief description of drawings]

1 is an external view showing an embodiment of the present invention, FIG. 2 is an internal configuration diagram of the present invention, FIG. 3 is a circuit diagram for generating a diversity switching signal in a receiving section, and FIG. 4 is FIG. 3 is an operation timing chart of FIG. 1 ... Radio device main body, 2 ... Main antenna, 3 ... Microphone code, 4 ... Earphone code, 5 ... Detector, 51 ...
Squelch control output, 6 ... Squelch gate, 61 ... Voice output, 7 ... Clock oscillator, 8 ... AND gate,
9 ... Flip-flop, 11 ... TR switch,
12 ... Diversity switch, 13 ... Transmitter, 14 ...
... Reception unit, 15 ... Diversity switching signal, 16 ... Coupling capacitor, 17 ... High frequency choke coil.

Claims (1)

[Claims] 1. A second antenna means by a microphone cord for connecting a microphone cord to a transmitter via a high frequency coil and a diversity switch via a coupling capacitor, a clock generator, and output and reception of the clock generator. An AND circuit for detecting the coincidence of the squelch signal of the circuit, a flip-flop for dividing the output of the AND circuit, and a diversity switching signal generating means for supplying and switching the output of the flip-flop to the diversity switching device,
When the reception input is weak and the squelch operating state, a coincidence detection signal is output from the flip-flop to intermittently drive the diversity switch to alternately switch the main antenna and the second antenna to detect the reception state of both antennas. However, when there is a received signal and the squelch operation is stopped, the diversity switching device holds the antenna state at that time, the portable radio device.