JPS62216535A - Auxiliary signal transmission circuit - Google Patents

Abstract

PURPOSE:To reduce test/adjustment man-hours by adding a pilot oscillator generating a pilot signal to the transmission side and a Q controller controlling the Q of a low-pass filter corresponding to the level of the said pilot signal taken out by an output of an amplitude equalizer to the reception side. CONSTITUTION:A pilot signal having a frequency slightly higher the highest frequency of an auxiliary signal, e.g., 10kHz is always transmitted to the reception side from a pilot oscillator 5 at the transmission side regardless of the presence of the auxiliary signal. When the level of the pilot signal extracted by the Q controller 7 via a reception/demodulation section 2 and an amplitude equalizer 3 is at the outside of permissible range at the reception side, the Q of the LPF 6 is changed automatically to a predetermined value corresponding to its level to bring the amplitude characteristic of the auxiliary signal passing through the LPF 6 into the permissible range. In selecting properly the value Q, the amplitude characteristic of the auxiliary signal passing through the LPF 6 is brought into the permissible range.

Description

[Detailed Description of the Invention] [4 Already Required] In the auxiliary signal transmission circuit, the transmitting side modulates the frequency of a carrier wave with the auxiliary signal and the pilot signal and sends it to the receiving side, and the receiving side modulates the frequency of the carrier wave with the auxiliary signal and the pilot signal and sends it to the receiving side. The Q of the low-pass filter is controlled in accordance with the level of the pilot signal extracted through the converter to improve the amplitude characteristics of the auxiliary signal passing through the low-pass filter.

[Industrial application field]

The present invention relates to improvements in auxiliary signal transmission circuits for digital radio equipment.

In digital transmission systems using microwaves, meeting signals, monitoring signals, control signals, etc.
In order to transmit the 8KIIz signal (hereinafter referred to as the auxiliary signal), the carrier wave is shallowly frequency modulated with the auxiliary signal and sent to the receiving side. Although the auxiliary signal is extracted through the auxiliary signal, there is a desire to reduce the number of man-hours required for testing and adjusting the auxiliary signal transmission circuit that transmits this auxiliary signal.

[Conventional technology]

FIG. 5 is a block diagram of a conventional example, and FIG. 6 is an amplitude characteristic diagram of FIG. 5. 1 in FIG. 5 is a modulation/transmission section.

2 indicates a receiving/demodulating section.

The operation shown in FIG. 5 will be explained below with reference to FIG.

On the transmitting side of FIG. 5, the output of the oscillator 11, which has been shallowly frequency modulated with the auxiliary signal, is further PSK (phase shift keying) modulated with the main signal by the modulator 12 to ps. This modulated wave is converted into a predetermined transmission frequency and power by the transmitting section 13 and sent to the receiving side.

On the receiving side, a receiving section 21 converts the received wave to a predetermined frequency and level, and a PSK detector 22 extracts the main signal using the output of a voltage controlled oscillator (hereinafter abbreviated as VCO) 24. It is added to a carrier wave regeneration circuit (hereinafter abbreviated as CR circuit) 23.

Therefore, the CR circuit detects the phase difference between the outputs of the oscillator 11 on the transmitting side and the VCO 24, and controls the oscillation frequency of the VCO with a control signal so that this becomes O (VCO 24°PSK
Detector 22. The loop composed of the Cr1 circuit 23 is called a phase-locked loop), and since this control signal includes the above-mentioned auxiliary signal, the amplitude equalizer 3. An auxiliary signal is extracted through a low-pass active filter (hereinafter abbreviated as PF) 4.

Here, testing and adjustment of the part that transmits the auxiliary signal, that is, the auxiliary signal transmission circuit, is performed, for example, in the following procedure.

■ Standard modulation/transmission section 1 and adjusted reception/demodulation section 2.
The amplitude equalizer 3 is adjusted so that the amplitude characteristics of the auxiliary signal fall within the permissible range by combining the 4Ji width equalizer 3 and the LPF 4 which has been individually adjusted in advance and has a predetermined frequency characteristic.

For example, when panels that have been adjusted individually are combined, they may have amplitude characteristics as shown by the solid line in Figure 6 due to the characteristics of the phase-locked loop described above. Change the primary slope so that it falls within the tolerance range between the two diagonal lines.

■ If the test is performed by combining the modulation/transmission section to be tested instead of the standard modulation/transmission section and each panel on the receiving side adjusted in item 0, but the amplitude characteristics of the auxiliary signal do not fall within the allowable range. The amplitude characteristics of the modulation/transmission section are 0.3 to 8 K I
Assuming that Iz is flat, the already adjusted LPF 4 must be readjusted.

[Problem that the invention seeks to solve]

In other words, even if the amplitude equalizer is adjusted so that the amplitude characteristics of the auxiliary signal are within the permissible range when combined with a standard modulation/transmission section, the amplitude characteristics may still be within the permissible range when combined with a different modulation/transmission section. If not, the already adjusted LI"F4 must be readjusted, which poses a problem in that the number of man-hours for testing and adjustment increases.

[Means for solving problems]

As shown in FIG. 1, the present invention includes a pilot oscillator 5 that generates a pilot signal on the transmitting side, and a low-pass signal on the receiving side corresponding to the level of the pilot signal extracted from the output of the amplitude equalizer. This problem can be solved by the auxiliary signal transmission circuit of the present invention which includes a Q controller 7 for controlling the Q of the type filter 6.

[Effect]

In the present invention, a pilot signal having a frequency slightly higher than the highest frequency of the auxiliary signal is always sent to the receiving side from the biloft oscillator 5 on the transmitting side. On the receiving side, a receiving/demodulating section 2. When the level of the pilot signal extracted by the Qtlal'a unit 7 via the amplitude equalizer 3 is outside the predetermined tolerance range, the Q of the LPP 6 is adjusted to a predetermined value corresponding to the level. This value is automatically changed so that the amplitude characteristics of the auxiliary signal passing through this point are within a predetermined tolerance range.

This eliminates the need to readjust the LI'F 6, reducing the number of testing and adjustment steps.

[Embodiment] FIG. 2 is a block diagram of an embodiment of the present invention, FIG. 3 is a block diagram of the LPF and Q controller of FIG. 2, and FIG. 4 is a diagram of FIG. 8 of FIG. 3.

Hereinafter, the operation of the portion of the present invention will be explained with reference to FIGS. 2 to 4.

In FIG. 2, a frequency slightly higher than the highest frequency of the auxiliary signal, for example 1OK, is transmitted from the pilot oscillator 5 on the transmitting side.
A Hz pilot signal is always sent to the receiving side regardless of the presence or absence of an auxiliary signal.

On the receiving side, a receiving/demodulating section 2. Q via amplitude equalizer 3
When the level of the pilot signal extracted by the controller 7 is out of the permissible range, the Q of the LPF 6 is automatically changed to a predetermined value corresponding to the level, and this LP
Make sure that the amplitude characteristics of the auxiliary signal passing through F6 are within the permissible range.

In FIG. 3, a pilot signal passed through an amplitude equalizer 3 and extracted by a band-pass filter 71 is detected by a detector 72 to obtain a detected voltage Vd. ) added to 73.

Here, when the input voltage is between the thresholds V1 and V2, the W-COMP 731 is between the thresholds V2 and V3 (
7) At the time, W-COMP 732 is the threshold value v3~v4
When the input voltage is Vd, the W-COMP 733 operates, but for example, when the input voltage is Vd, the W-COMP 732 operates. Then, relay RL-2 is driven, contact rl-2 in LPF 66 is turned on, and capacitor C2 is connected to resistor R.

The LPF 6 is an active filter using a capacitor C and a resistor R, and its Q is given by 1/(2CωR). Therefore, when the value of C is changed, Q changes, and its frequency characteristics can be changed from the solid line to the dotted line in Figure 4 (a), or from the solid line to the dotted line in Figure 4 (bl). Therefore, by setting Q to an appropriate value, Lr'F 6
The amplitude characteristic of the auxiliary signal passing through can be kept within the permissible range (the shaded area in FIG. 4).

Now, in order to test and adjust this auxiliary signal transmission circuit, we need to: ■ Set the viroft signal level when the frequency characteristics of LPF 6 are within the allowable range, and the magnitude of the change in level when combined with the receiving/demodulating section. do.

(2) Set the Q of the LPF so that the amplitude characteristics of the auxiliary signal fall within the allowable range when there is a level change in the 0 term.

■ From sections ■ and ■, CI, C2, C3 and -CO of LPF
Set MP thresholds v1 to v4. At this time, when the amplitude characteristics are within the allowable range, -COMP 722 operates and C
Make sure that 2 is selected.

■ Standard modulation/transmission section T, AM-prepared reception/demodulation section 2
and LPF 6 and amplitude equalizer 3. In combination with the Q controller 7, the amplitude equalizer 3 is adjusted so that the amplitude characteristics fall within an allowable range.

■ When combined with the modulation/transmission unit to be tested instead of the standard modulation/transmission unit, if the level of the pilot signal changes from a predetermined value, the LPF 6 will be adjusted according to the magnitude of the change as described above. Since Q automatically becomes a predetermined value, the amplitude characteristics of the auxiliary signal fall within the permissible range.

In other words, terms 0 to 0 are design issues and become irrelevant during testing and adjustment once the design conditions are determined, and terms ■ and ■ become issues during testing and adjustment, but readjustment of term 0 is a problem in the present invention. Since this is done automatically, testing and adjustment man-hours can be reduced.

〔Effect of the invention〕

As described in detail above, the present invention has the effect of reducing the number of man-hours required for testing and adjusting the auxiliary signal transmission circuit.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is a block diagram of the low-pass filter shown in FIG. 2 and Q 1bll ? FIG. 5 shows a block diagram of a conventional example, and FIG. 6 shows an amplitude characteristic diagram of FIG. 5. In the figure, 1 is a modulation/transmission section, 2 is a reception/demodulation section, 3 is an amplitude equalizer, 4.6 is a low-pass filter, 5 is a pilot oscillator,

Claims (1)

[Claims] A modulation/transmission unit (1) that modulates a carrier wave with an auxiliary signal and converts it to a predetermined power and frequency on the transmitting side, and a modulation/transmission unit (1) that converts the received signal to a predetermined level and frequency on the receiving side, A receiver/demodulator (2) that extracts a signal including an auxiliary signal, and an amplitude equalizer (3) that equalizes the amplitude of the output of the receiver/demodulator.
) and a low-pass filter (6) that removes high-frequency components of the output of the amplitude equalizer to extract the auxiliary signal, the auxiliary signal transmission circuit includes a pilot oscillator that generates a pilot signal on the transmitting side. (
5), a Q controller (7) is added to the receiving side to control the Q of the low-pass filter in accordance with the level of the pilot signal extracted from the output of the amplitude equalizer. Characteristic auxiliary signal transmission circuit.