JPH11251937A - Receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To switch and control a reception sensitivity characteristic from the outside at the time of using a moving station and at the time of using a fixed station by providing an attenuator switching attenuation quantity by a control signal from the outside and attenuating a reception carrier level for an operation block. SOLUTION: When a moving/fixed stations switch terminal is set to a moving station (low level)-side in the case of using a radio equipment as a moving station radio equipment, an outer control voltage generation part 16 to which a low level signal is inputted generates analog DC voltage and it is inputted to a variable attenuator 2. The variable attenuator 2 changes the resistance value of resistance being the attenuator with DC voltage and changes attenuation quantity. Attenuation quantity is set to be zero with DV voltage. When the moving/fixed stations switch terminal is set to a fixed station (high level)- side for using the radio machine as the fixed station radio machine, the outer control voltage generation part 16 to which the high level signal is inputted generates analog DC voltage (+voltage other than 0V) and the variable attenuator 2 becomes attenuation quantity ndB with DC voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a receiver commonly used for mobile stations and fixed stations.

[0002]

2. Description of the Related Art Mobile station radios generally have a low antenna height and also move a reception position, so that a change in the reception level is large and a function with good reception sensitivity performance is required. Is high, the receiving position is fixed, and the line condition is set to a good place. If the receiving sensitivity characteristic is too good, an unnecessary wave may be received. Therefore, there are many cases where the reception sensitivity performance required for the mobile station may be worse. Conventionally, when a mobile station radio is used as a fixed station radio, an attenuator is installed between the radio and the antenna in order to avoid overreach of radio waves between radio stations and reception of interfering waves, as described above. By adding
In some cases, the receiving sensitivity characteristics were degraded.

[0003]

In the above prior art,
When a mobile station radio is used as a fixed station radio and there is a need to degrade reception sensitivity characteristics, there is a disadvantage that a new attenuator must be provided outside the radio. Further, the reception determination level using the noise squelch circuit changes due to the deterioration of the reception sensitivity, so that there is a problem that the reception determination level is readjusted. A first object of the present invention is to eliminate these disadvantages, externally control the switching of the receiving sensitivity characteristic between the use of a mobile station and the use of a fixed station, and provide a radio apparatus that can be commonly used for mobile stations and fixed stations. Is to provide.
According to a second object of the present invention, when the reception sensitivity characteristic is switched according to the first object, the determination level of the presence / absence of the reception of the received signal using the noise squelch circuit changes. Another object of the present invention is to provide a function of switching according to the condition.

[0004]

According to the present invention, there is provided a receiver for performing band limitation, amplification, frequency conversion, and demodulation on a reception signal input to an antenna in order to achieve the first object. An arbitrary block of each operation block for performing band limiting, amplification, frequency conversion, and demodulation is provided with an attenuator for attenuating a received carrier wave level, which can switch an attenuation amount by a control signal supplied from the outside. Further, in order to achieve the second object, in a receiver for performing band limitation, amplification, frequency conversion, and demodulation on a reception signal input to an antenna for receiving the reception signal, the band limitation, amplification, and frequency An arbitrary block of each operation block for performing conversion and demodulation is provided with an attenuator for attenuating a received carrier wave level which can switch an attenuation amount by a control signal supplied from the outside, and a noise component extracted from a demodulated output is provided as a DC voltage. The detected and detected DC voltage is connected to a first input of a voltage comparator, and a DC voltage that is switched according to the amount of attenuation of the attenuator is applied to a second input of the comparator.
A result of comparing the magnitude of the first input and the second input level is output to the comparator output as a binary logic level, and the output is connected to a control unit for determining whether or not there is an incoming call. It is what constituted.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an antenna input terminal, 2 is a variable attenuator, 3 is a bandpass filter, 4 is an amplifier,
5 is a bandpass filter, 6 is a first local oscillation signal input terminal, 7 is a first
A mixer, 8 is a first intermediate frequency signal processing unit, 9 is a second local oscillation signal input terminal, 10 is a second mixer, 11 is a second intermediate frequency signal processing unit, 12 is a demodulation output terminal, and 13 is a band filter. 14 is a DC detector, 15 is a voltage comparator, 16 is an external control voltage generator, 17 is a CPU, and 18 is a mobile / fixed station switching terminal.

Next, this operation will be described. In FIG. 1, when this radio is used as a mobile station radio, when the mobile / fixed station switching terminal is set to the mobile station (LOW level) side, this LOW level signal is input to the external control voltage generator 16. You. The external control voltage generator 16 receives the signal and generates an analog DC voltage, which is input to the variable attenuator 2. The variable attenuator 2 can change the amount of attenuation by changing the resistance value of the resistor constituting the attenuator according to the input DC voltage, and the amount of attenuation is 0 (no attenuation) at the DC voltage. . When the wireless device is used as a fixed station wireless device, when the mobile / fixed station switching terminal is set to the fixed station (HIGH level) side, the HIGH level signal is input to the external control voltage generator 16. The external control voltage generator 16 receives the signal, generates an analog DC voltage (+ V voltage other than 0 V), and inputs it to the variable attenuator 2. By the above operation, the variable attenuator 2 becomes the attenuation amount ndB by the DC voltage.

As described above, the reception sensitivity level is attenuated by the variable attenuator 2 by an amount controlled by the mobile station or the fixed station, band-limited by the band-pass filter 3, amplified by the amplifier 4, and amplified by the band-pass filter 5. , Is mixed with the first local oscillation signal input from the first local oscillation signal input terminal 6 by the first mixer 7, converted into a first intermediate frequency signal, and input to the first intermediate frequency signal processing unit 8. Is done. The received signal output from the first intermediate frequency signal processing unit 8 is mixed with the second local oscillation signal input from the second local oscillation signal input terminal 9 by the second mixer 10,
The signal is converted into a second intermediate frequency signal, passes through the second intermediate frequency signal processing unit 11, and is output to the demodulation output terminal 12. A part of the demodulated output signal is supplied to the bandpass filter 1.
3, the noise component is extracted from the demodulated output signal, the noise component is DC detected by the DC detector 14, and this voltage is connected to the first input of the voltage comparator 15 as the incoming call determination comparison voltage. Here, when this radio is used as a mobile station radio, the mobile / fixed station switching terminal is connected to the mobile station (LOW).
On the other hand, the LOW level signal is input to the external control voltage generator 16. External control voltage generator 16
Receives the control signal and generates an analog DC voltage,
This DC voltage is used as the incoming call determination reference voltage, and the voltage comparator 1
5 is connected to the second input.

When the present radio is used as a fixed station radio, if the mobile / fixed station switching terminal is set to the fixed station (HIGH level) side, this HIGH level signal is input to the external control voltage generator 16. . External control voltage generator 16
Receives the control signal and generates an analog DC voltage,
This DC voltage is used as the incoming call determination reference voltage, and the voltage comparator 1
5 is connected to the second input. The result of the comparison between the incoming call determination reference voltage and the incoming call determination comparison voltage by the voltage comparator 15 is input to the CPU 17 as a binary logical level, and outputs a control signal for controlling MUTE / UNMUTE of audio output. Next, when this radio is used as a mobile station radio (the attenuation of the variable attenuator 2 is 0), the demodulation output level becomes SI
The reception sensitivity level (the level of the input terminal 1) which becomes 12 dB in the NAD level is obtained below.

Reception sensitivity level (at 12 dB BSINAD) = K · T · B · NF (C / N) (1) where K = Boltzmann constant (1.38 × 10 to ²³ J /
K) T = Temperature (290 ° K) B = Reception bandwidth (16 kHz) NF = Receiver circuit total noise figure after input terminal 1 C / N = 12 dB Relative value of carrier level and noise level when obtaining SINAD (4 .5 dB).

At this time, when the variable attenuator 2 is omitted, the NF is expressed by equation (3). NF = ｛(L ₁ -1 + 1) (1 / L ₁ ) G ₁ (1 / L ₂ ) + (NF ₁ -1) G ₁ (1 / L ₂ ) + (L ₂ -1) (1 / L ₂ ) + (NF _T -1)} / (1 / L ₁ ) G ₁ (1 / L ₂ ) (2) = L ₁ NF ₁ + ｛(L ₂ N F _T -1) / (G ₁ / L ₁ )｝ (3) Here, as an example, each value is as follows. L ₁ = loss of band-limited filter 3 (L ₂ = 3 dB) L ₂ = loss of band-limited filter 5 (L ₂ = 3 dB) G ₁ = gain of amplifier 4 (G ₁ = 8 dB) NF ₁ = Noise figure of the amplifier 4 (NF ₁ = 2 dB) NF _T = total noise figure of the receiving circuit after the first mixer 7 (N
F _T = 2 dB) at this time, NF becomes NF = 9.24dB. here,
Substituting the values of K, T, B, NF, and C / N into equation (1), the reception sensitivity level (at 12 dBBSINAD) =-11
It becomes 8.26 dBm.

On the other hand, when this wireless device is used as a fixed-station wireless device (for example, the attenuation of the variable attenuator 2 is 5 dB), the reception sensitivity level (input terminal 1) at which the demodulation output level is 12 dB at the SINAD level. Is determined below.

First, a total noise figure NF of the receiving circuit after the input terminal 1 is obtained. At this time, NF is represented by equation (5). _{NF = [{(L 1 +} L X) -1 + 1} (1 / L 1 + L X) G 1 (1 / L 2) + (NF 1 -1) G 1 (1 / L 2) + (L 2 -1 ) (1 / L ₂ ) + (NF _T −1)] / (1 / L ₁ ) G ₁ (1 / L ₂ ) (4) = (L ₁ + L _X ) NF ₁ + [(L ₂ N F _T −1) / {G ₁ / (L ₁ + L _X )}] (5) Here, L ₁ , L ₂ , G ₁ , NF ₁ , and NF are taken as examples.
_T is the same as above, and L _X = attenuation amount of the variable attenuator 2 (5
dB). At this time, NF is NF = 14.24 dB.
Becomes Next, a reception sensitivity level is obtained. At this time, the reception sensitivity level is expressed by equation (1), and K, T, B, N
By substituting the values of F and C / N, the receiving sensitivity level becomes −113.26 dBm, which is smaller than when the attenuation of the variable attenuator 2 is not used.
It can be seen that the signal is attenuated by the attenuation (5 dB). As described above, the attenuation amount of the variable attenuator 2 can be changed by the analog DC voltage output from the external control voltage generator 16 and the reception sensitivity level can be switched.
This is a wireless device that can be commonly used by mobile stations and fixed stations.

On the other hand, an embodiment will be described below in which the reception sensitivity characteristic is changed by switching the attenuation amount of the variable attenuator 2 and it is necessary to switch the incoming call judgment level by noise squelch. First, when this wireless device is used as a mobile station wireless device (there is no attenuation of the variable attenuator 2),
When the mobile / fixed station switching terminal is set to the mobile station (LOW level) side in FIG. 1, the LOW level signal is input to the external control voltage generator 16. The external control voltage generator 16 receives the control signal and generates an analog DC voltage.
Is connected to the second input of. In FIG. 3, a part of the demodulated output signal is band-limited by the bandpass filter 13, a noise component is extracted from the demodulated output signal, the DC component of the noise component is detected by the DC detector 14, and this voltage is compared with the incoming call determination comparison voltage. Connected to the first input of the voltage comparator 15. The result of the comparison between the incoming call determination reference voltage and the incoming call determination comparison voltage by the voltage comparator 15 is input to the CPU 17 as a binary logical level, a control signal is output from the CPU 17, and ON / OFF control of the noise squelch (specifically, Typically, the audio output M
UTE / UNMUTE control).

Next, when this radio is used as a fixed station radio (the attenuation of the variable attenuator 2 is assumed to be ndB), in FIG. 1, the mobile / fixed station switching terminal is connected to the fixed station (HIGH).
On the other hand, the HIGH level signal is input to the external control voltage generator 16 when the signal is on the level side. External control voltage generator 1
6 receives the control signal and generates an analog DC voltage, and this DC voltage is connected to a second input of the voltage comparator 15 as an incoming call determination reference voltage. The DC voltage of the fixed station is higher than that of the mobile station because the attenuation of the variable attenuator 2 is larger, so that the reception sensitivity is deteriorated. For squelch to work, the DC voltage must be reduced. Therefore, the mobile / fixed station switching terminal is set to the fixed station (high level).
, The DC voltage is output lower than the mobile station. A part of the demodulated output signal is band-limited by the bandpass filter 13 similarly to the mobile station, a noise component is extracted from the demodulated output signal, and the noise component is DC-detected by the DC detector 14. Is connected to the first input of the voltage comparator 15. The result of the comparison between the incoming call determination reference voltage and the incoming call determination comparison voltage by the voltage comparator 15 is input to the CPU 17 as a binary logic level,
A control signal is output from U17, and noise squelch is turned on.
/ OFF control (specifically, MUTE / U of audio output)
NMUTE control). Therefore, when the mobile / fixed station switching terminal is switched, the analog DC voltage generated by the external control voltage generator 16 changes, so that the incoming call determination reference voltage changes and the ON / OF of noise squelch changes.
The level of the F control can be switched.

Conventionally, when a mobile station radio is used as a fixed station radio, an attenuator is added between the radio and an antenna in order to avoid overreach of radio waves between radio stations and reception of interference waves. In some cases, the received signal level was degraded. However, as in the above embodiment, the movement and
When the fixed station switching terminal is set to the fixed station (high level) side, this high level signal is output to the external control voltage generator 16.
And receives the signal to generate an analog DC voltage (+ V voltage other than 0 V), which is input to the variable attenuator 2. The variable attenuator 2 becomes the attenuation amount ndB by the DC voltage by the above operation, and the receiving sensitivity characteristic is attenuated. Therefore, it is not necessary to add an attenuator between the wireless device and the antenna, and external control is possible. Become. Conventionally, when a mobile station radio is used as a fixed station radio, the reception sensitivity characteristic may change and the determination level of the presence / absence of a reception signal using noise squelch may change. Conventionally, it has not been possible to switch the determination level of the presence / absence of the reception of a reception signal even if the reception sensitivity characteristic changes. However, when the mobile / fixed station switching terminal of the wireless device according to the present invention is set to the fixed station (HIGH level) side as in the present embodiment, the external control voltage generator 16 is controlled similarly to the control of the variable attenuator 2 described above. The analog DC voltage switched for the fixed station radio is input to the voltage comparator 15 as the incoming call determination reference voltage. Therefore, even if the reception sensitivity characteristic changes, it is possible to switch the incoming call determination reference level by switching the mobile / fixed station switching terminal.

[0016]

As described above, when the radio according to the present invention is used as a fixed station radio, the variable attenuator 2 is switched by switching the mobile / fixed station switching terminal to the fixed station side.
Can be switched and controlled. This allows
Conventionally, the mobile station radio could not be used as a fixed station radio as it was due to problems such as overreach and interference wave reception. However, by performing the above switching control, the attenuation of the variable attenuator 2 was switched. In addition, since the reception sensitivity characteristic can be degraded, the above-described problem can be solved, and the mobile station and the fixed station radio can be shared. Conventionally, when used as a fixed station radio as described above, the reception sensitivity level may be degraded, and the determination level of the presence / absence of a reception signal using noise squelch may change.

However, by switching the mobile / fixed station switching terminal to the fixed station side as in the above-described embodiment, it is possible to switch the determination level of the presence or absence of an incoming call. Therefore, conventionally, when a mobile station radio was used as a fixed station radio, it was necessary to readjust the noise squelch. However, by switching the mobile / fixed station switching terminal, the incoming call determination level was switched, and the noise squelch was changed. Readjustment is no longer necessary.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

[Explanation of symbols]

1: antenna input terminal, 2: variable attenuator,
3: bandpass filter, 4: amplifier, 5:
6: first local oscillator signal input terminal, 7: first mixer, 8: first intermediate frequency signal processing unit, 9: second local oscillator signal input terminal,
10: second mixer, 11: second intermediate frequency signal processing unit, 12: demodulation output terminal, 13: bandpass filter,
14: DC detector, 15: voltage comparator,
16: external control voltage generator, 17: CP
U, 18: Mobile / fixed station switching terminal.

Claims (2)

[Claims] 1. A receiver for performing band limitation, amplification, frequency conversion, and demodulation on a received signal input to an antenna. A receiver comprising an attenuator for attenuating a received carrier level, the amount of attenuation of which can be switched by an externally supplied control signal. 2. A receiver for performing band limiting, amplification, frequency conversion, and demodulation on a received signal input to an antenna, wherein the receiver performs any of the operation blocks for performing band limitation, amplification, frequency conversion, and demodulation. An attenuator for attenuating the received carrier level, which can switch the amount of attenuation by a control signal supplied from the outside, detects a DC component of a noise component extracted from a demodulated output, and converts the detected DC voltage to a voltage comparator. A DC voltage that is connected to a first input and that switches in accordance with the amount of attenuation of the attenuator is applied to a second input of the comparator, and the first input is compared with a second input level. The receiver outputs the result of the comparison at a binary logical level to the comparator output, and connects the output to a control unit that determines whether or not there is an incoming call.