JPS6232660B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for monitoring a phase modulator in a wireless transmitter.

In general, base station radio transmitting devices used for public mobile communications etc. are operated while constantly monitoring the operations of modulators, power amplifiers, etc. in some way to ensure high system reliability. The invention relates therein to a monitoring device for a phase modulator.

To outline such a conventional phase modulator monitoring device with reference to FIG. 1, the phase modulator monitoring device 1 includes a local oscillator 3, a mixer 4, and a discriminator 5.
, an integrator 6 , an amplifier 7 , and a comparator 8 . This monitoring device 1 mixes the phase modulated signal of a phase modulator 11 that phase modulates the output signal of the original oscillator 10 and the output signal of the local oscillator 3 using the mixer 4, and converts the frequency into an intermediate frequency. Then, it is sent to the discriminator 5. This discriminator 5 demodulates the frequency of the frequency-converted signal and sends it to the integrator 6. The integrator 6 equivalently demodulates the phase of the demodulated signal, amplifies it with the amplifier 7, and supplies it to the comparator 8 as a demodulated wave.

On the other hand, a modulation input signal from the modulation input terminal 12 is applied to the comparator 8 and the phase modulator 1
1 is operating normally by checking whether the output signals of the phase modulated signal output terminal 13 and the phase modulator monitoring output terminal 14 connected to the output of the comparator 8 match.

That is, in the conventional phase modulator monitoring device, a wireless receiver such as a mobile device is used as it is to monitor the phase modulator, so the structure of this monitoring device is complicated and the cost is high.

The present invention is characterized in that the mixer utilizes the characteristic of operating as a phase detector to add the phase modulated signal and the original oscillation signal to the mixer to obtain a direct demodulated output.

That is, an object of the present invention is to provide an economical phase modulator monitoring device that does not require the local oscillator 3, the discriminator 5, and the integrator 6, has a simple configuration, and is economical.

The present invention provides a mixer that mixes a phase modulated signal of a phase modulator and an original oscillation signal of a carrier wave, an amplifier that amplifies the output of this mixer as a demodulated output, and the amplified demodulated output and the phase modulated signal. It is characterized by comprising a comparator for comparing the phase modulated input signal applied to the device.

Next, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a circuit diagram of a device according to an embodiment of the present invention. In FIG. 2, each symbol corresponds to each symbol in FIG. 1, respectively. The characteristic configuration of this embodiment is as follows:
The phase modulator monitoring device 1 is composed of a mixer 4, an amplifier 7, a comparator 8, and a low-pass wave generator 9.

With this configuration, a phase modulated signal obtained by phase modulating the output of the original oscillator 10 by the phase modulator 11 and the output of the original oscillator 10 are added to the mixer 4, and the output of the mixer 4 is phase-detected. The low-frequency signal obtained is waved by a low-pass transducer 9, this signal is amplified by the amplifier 7, and is applied to a comparator 8 together with the phase modulation input signal sent from the modulation input terminal 12, where it is compared and monitored.

At the output of the mixer 4, a signal having a frequency that is the difference between the modulated signal and the carrier wave is obtained. The signal at this difference frequency contains many spectral components, but
Its low frequency component corresponds to the modulated input signal. Although this correspondence is not completely one-to-one, it is practically sufficient for monitoring the presence or absence of modulation.

Also, when the output of the phase modulator 2 is multiplied to increase the modulation degree to obtain a transmission wave, the multiplied phase modulated signal and the original oscillation signal are directly applied to the mixer 4 using the same configuration. It can be monitored by In this case, the phase of the multiplied phase modulated signal is detected in the mixer 4 using harmonics of the original oscillation signal. Therefore, the demodulation sensitivity decreases, but this can be easily compensated for by increasing the amplification degree of the low frequency amplifier 7 in the subsequent stage.

As described above, according to the present invention, by utilizing the phase detection characteristics of the mixer, the conventional local oscillator,
It is possible to obtain an excellent phase modulator monitoring device that can economically monitor a phase modulated signal of a phase modulator with a simple configuration without requiring a discriminator or an integrator. When the device of the above embodiment was tested, very good results were obtained, and it was confirmed that sufficient monitoring could be performed using this device.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional device. FIG. 2 is a circuit diagram of a device according to an embodiment of the present invention. 1... Phase modulator monitoring device, 3... Local oscillator, 4... Mixer, 5... Discriminator, 6
... Integrator, 7 ... Amplifier, 8 ... Comparator, 9 ... Low-pass wave generator, 10 ... Original oscillator,
11... Phase modulator, 12... Modulation input terminal, 1
3... Phase modulated signal output terminal, 14... Phase modulator monitoring output terminal.

Claims (1)

[Claims] 1. A mixer that mixes the phase modulated signal of the phase modulator and the original oscillation signal of the carrier wave, an amplifier that amplifies the output of this mixer as a demodulated output, and provides the amplified demodulated output to the phase modulator. A phase modulator monitoring device comprising a comparator for comparing a phase modulated input signal.