JPS5922422B2 - Squelch method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a squelch method when a plurality of wireless stations communicate over a single wireless channel.

Allocate a single radio channel to multiple radio stations,
When communicating between desired wireless stations, a tone squelch method is used.

For example, when a base station and a certain wireless station A communicate with each other, only the wireless station A can receive a signal from the base station by transmitting a tone signal assigned to the wireless station A. Figure 1 shows an example of the time chart, Figure a shows the transmission of radio waves, and Figure 1 shows the tone signal of radio station A.
The tone signal TA is transmitted to the radio station B, and the tone signal TB is transmitted to the radio station B. Therefore, as shown in FIG. You will only be able to make calls. The tone signal is usually 1
00 to 200Hz, but since the carrier wave is modulated at the same time as the speech signal, even if the tone signal is removed by a filter on the receiving side, the S/N will deteriorate due to cross-modulation distortion of the speech signal. I will do it.

The present invention has been made to improve the conventional drawbacks as described above, and aims to improve VS/N with a simple configuration and also enable various types of control.

Examples will be described in detail below. FIG. 2 is a block diagram of an embodiment of the present invention, in which 1 is an antenna, 2 is a reception section including a demodulation section, 3 is an analog switch section, 4 is a noise squelch section, 5 is a tone signal detection section, and 6 is a A flip-flop, 7 is an AND circuit, and 8 is an audio output. The received and demodulated audio signal is output via the analog switch section 3, and the analog switch section 3 is controlled by the output of the AND circuit T. FIG. 3 shows an example of a time chart, in which the transmitting side sends out radio waves as shown in FIG.

The noise squelch unit 4 detects that the noise level when receiving radio waves is smaller than the noise level when not receiving radio waves, as shown in c in the same figure, and when the noise level is small, The output is set to ``1''. Also, the tone signal detection unit 5 identifies whether or not the short-time tone signal shown in the figure is the tone signal assigned to the own station. When it is detected that the output is "1", the flip-flop 6 is set. Therefore, if the set output of flip-flop 6 is ``1'', V,
Since the output of the AND circuit 7 becomes 617 as shown in d of the figure, the analog switch section 3 is turned on and the demodulated audio signal 8 is output. When the radio wave disappears due to the end of the call, the noise level rises and the output of the noise squelch section 4 becomes ``01'', and as this output changes from 61'' to 607, the flip-flop 6 is reset.

Therefore, a conversation will take place as shown in FIG. 3e, and since no tone signal is superimposed during the conversation, S
/N will be improved. Since the tone signal is only sent out for a short time, the receiving radio station stores it in a storage means such as the flip-flop 6 and uses the AND condition with the noise squelch output as the squelch output. This is done by noise squelch output. Furthermore, the tone signal can include information that not only specifies the receiving radio station but also indicates the operating state and the like. For example, in a wireless communication system where there are multiple groups of multiple wireless stations, tone signals may be determined so that the wireless stations within the same group can receive signals at the same time, and furthermore, communications may only be made between specific wireless stations within the same group. It is also possible to use a predetermined tone signal.

Alternatively, the tone signal may include information for notifying the mobile radio station number from the mobile radio station to the base station. As explained above, the present invention transmits a control and status signal from a transmitting radio station and a signal specifying a receiving radio station as a short-time tone signal, and the receiving radio station receives noise from the transmitting radio station as shown in FIG. It is equipped with a squelch section 4, a tone signal detection section 5, and a storage means such as a flip-flop 6, and the output of this storage means and the noise squelch output corresponding to the reduction in the noise level during radio wave transmission in the noise squelch section 4. The AND condition is used as a squelch output, and the received and demodulated audio signal is output. During a P1 call, a tone signal is not superimposed as in the conventional example, so the S/N ratio is improved, and the receiving radio station is specified prior to the call. Although the tone signal is sent out for a short time, it can also be used as various control or status signals to expand the scope of communication using a single wireless channel.

[Brief explanation of the drawing]

FIG. 1 is a time chart of an example of the tone squelch system of Jubei, FIG. 2 is a block diagram of a main part of an embodiment of the present invention, and FIG. 3 is a time chart of an example of an embodiment of the present invention. 1 is an antenna, 2 is a receiving section, 3 is an analog switch section,
4 is a noise squelch section, 5 is a tone signal detection section, 6 is a flip-flop, and 7 is an AND circuit.

Claims (1)

[Claims] 1 In the squelch method in a wireless communication system where multiple wireless stations communicate using a single wireless channel, the transmitting wireless station controls and sends a status signal and a signal specifying the receiving wireless station to a short tone signal. The receiving radio station includes a detection means for the tone signal, a storage means for storing the detection output of the detection means, and a noise squelch section, and the receiving radio station includes a tone signal detection means, a storage means for storing the detection output of the detection means, and a noise squelch section, and the output of the storage means and the noise squelch output of the noise squelch section. A squelch method characterized in that the received and demodulated audio signal is output as a squelch output based on the AND condition, and the storage means is cleared by a noise squelch output caused by stopping the transmission of radio waves.