JPH02143704A - Image cancel type frequency converter - Google Patents

Abstract

PURPOSE:To reduce a setting man-hour to extract an output signal in a prescribed frequency by switching a switch means automatically when a local frequency is changed. CONSTITUTION:A local oscillator 18 is provided with a control signal transmission section 3 sending a control signal representing it that a prescribed frequency comes to upper or a lower side of the frequency of the local oscillation signal according a predetermined frequency arrange when the frequency of the local oscillation signal is changed. When the local oscillation frequency is changed, a switch means 4 is switched automatically corresponding to the state of the control signal sent from the section 3 to extract an output signal in a prescribed frequency from mixers 15,16. Thus, the setting man-hour to extract the output signal in a prescribed frequency is decreased.

Description

[Detailed Description of the Invention] [Summary] For example, regarding an image canceling frequency converter used in a transmitting section of a microwave multiplexing radio device, when changing the local oscillation frequency, the setting man-hours required to extract an output signal of a predetermined frequency. For the purpose of reducing the phase difference, the input signal whose phase differs by 90 degrees from each other and the local oscillator signal sent from the local oscillator whose phase differs by 90 degrees from each other are connected to the first . In addition to the second mixer, an image canceling type frequency converter performs frequency conversion and then synthesizes to extract an output signal of a predetermined frequency. a switch means for mutually switching the phase of the local oscillation signal applied to the second mixer, and when the frequency of the local oscillation signal is specified, the predetermined frequency is placed above the local oscillation signal according to a predetermined frequency arrangement; It is configured to include a control signal sending part that sends out a control signal indicating whether it is on the upper or lower side.

[Industrial application field]

The present invention relates to an image canceling frequency converter used, for example, in a transmitting section of a microwave multiplexing radio device.

FIG. 4 shows an example of a frequency map.

In the figure, the frequency band used is from frequency F0 to Fl, and the transmission frequency is fl+r2...fl. If so.

The frequency fL of the local oscillation signal is determined, for example, as follows.

First, the frequency band used is divided by the dashed-dotted line, and the frequency fL of the local signal on the left side (the dotted line in the figure) is the transmission frequency (
The arrangement is determined in advance so that the part on the right side is on the upper side (solid line in the figure) and the part on the right side is on the lower side.

This means that if all local signal frequencies are placed above the transmission frequency, they will be F or higher when the highest transmission frequency is r1°, and if they are set lower, they will be below F0 when the lowest transmission frequency is f1, which is outside the frequency band used. This is to avoid this possibility.

Therefore, when changing the local oscillator frequency, it is determined from the above whether the upper or lower side of this frequency is to be used as the transmission frequency. (omitted)), you must configure the switch connections.

At this time, it is necessary to try to reduce the number of setting steps.

[Conventional technology]

FIG. 5 is a block diagram of a conventional example, and FIG. 6 is an explanatory diagram of the operation of an image-cancelling frequency converter.

The operation shown in FIG. 5 will be explained below with reference to FIG. still,
Let the angular frequency of the intermediate frequency band signal be ωlF+the angular frequency of the local oscillation signal be ωLO.

First, sinωlFt of the input intermediate frequency band signal (hereinafter, IF multiplied signal will be omitted) is divided into signals −cosωIFt and si with a phase difference of 90° by the 90° hybrid 14.
nωlFt and added to mixer 15.16.

On the other hand, the local oscillator signal from the local oscillator 11 is a 90-degree hybrid I2, and the local oscillator signal CO3ω has a phase difference of 90 degrees from each other.
1. o(sin ω, −ot) 9 For example, a−s,
The signal is added to the mixer 16.15 through the switch 13 which is switched from a' to c' (solid line in the figure). Therefore, after the two signals are mixed, they are combined in the same phase by the hybrid 17, and a -cos (azFt +ωtot) USB signal and a local oscillation signal are sent out.

Also, when the switch is switched to a-c, a'-b' (dotted line in the figure), the L of +5 in (ω,,t +ω,.t)
An SB signal and a local oscillator signal are transmitted.

Here, although the image canceling frequency converter theoretically does not send out image frequency components.

In reality, as shown in Figure 6, r++ or f, □ of the image frequency component attenuated by the image cancellation amount is L.
Attenuated from the SB signal or tlsB signal level'
appears.

[Problem to be solved by the invention]

Now, for example, if there is one standby local oscillator for N working local oscillators, and one working local oscillator fails and is replaced with a standby local oscillator, the oscillation frequency of the standby oscillator must be replaced. must be changed to the transmit frequency of the working oscillator.

At this time, the transmission frequency is either LSB or USB depending on the oscillation frequency of the local oscillator.

You have to find out which one to use and switch the switch accordingly, but this switching is done by soldering.

That is, when changing the local oscillation frequency, there is a problem in that the number of setting steps increases in order to extract an output signal of a predetermined frequency.

[Means to solve problems]

FIG. 1 shows a block diagram of the principle of the present invention.

In the figure, 4 corresponds to the state of the input control signal.

Part 1. 3 is a switch means for mutually switching the phase of the local oscillation signal applied to the second mixer, and when changing the frequency of the local oscillation signal, the predetermined frequency is placed above the local oscillation signal according to a predetermined frequency arrangement. This is a control signal sending part that sends out a control signal indicating whether the value will be 1 or below.

[Effect]

The present invention provides a control signal sending section 3 in the local oscillation section 18,
By automatically switching the switch means 4 in accordance with the state of the control signal sent from this part, the mixer 1
5.16 to extract an output signal of a predetermined frequency.

That is, due to the frequency arrangement of the local frequency f, as described above,
Whether the upper USB or lower LSB of the local oscillation frequency fL is used as the output frequency is determined in advance, so when changing the local oscillation frequency, the control signal sending section 3
A control signal indicating USB or LSB is sent to the switch means 4 from.

Therefore, the switch means 4 a in response to the state of the control signal.
-b, a'-b' or a-b', a'
-b is automatically switched to maintain the phase relationship of the local oscillator output as it is or to reverse the mixer 15.16.
By adding it to , an output signal of a predetermined frequency can be obtained.

As a result, when changing the local oscillation frequency, the number of setting steps for extracting an output signal of a predetermined frequency is reduced.

〔Example〕

FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is an example of a circuit diagram of the switch in FIG.

Here, the local oscillator 11 and the hybrid 12 are components of the local oscillator 18, and resistors R1 to R11 + capacitor C
1~CB+ Diode D1~D3+ Comparator 41.4
2 shows the constituent parts of the switch means. Note that the same reference numerals indicate the same objects throughout the figures. The operation of FIG. 2 will be described below with reference to FIGS. 3 and 5.

First, as shown in Figure 6, f, , (LSB), f, □(
USB) is the transmission frequency + fLI + fL2 is the respective local frequency. Also, from the control signal sending section 3 added to the local oscillator 11, for example, when fLl, ov, rL
2, it is assumed that a 5V control signal is sent out.

Now, when the transmission frequency is f□, the local frequency is "Ll,
Ov control signal causes the switch means 4 to switch 4. as will be described later.
, a141, and a local oscillation signal that is 90 degrees ahead of the mixer 16 is added to the mixer 15 and mixed, and then synthesized by the hybrid 17 to obtain a transmission signal of frequency rs+.

On the other hand, when the transmission frequency is f3□, when the local frequency is changed to rLz, the switch means 4 is set to 4+ by the 5V control signal.
, a14, a local oscillator signal delayed by 90 degrees with respect to the mixer 16 is added to the mixer 15 and mixed, and then synthesized by the hybrid 17 to obtain a transmission signal of frequency f, 2.

Next, the control signal sending section 3 includes 1, for example, a transistor/transistor/logic TTL circuit (not shown).
When the local oscillator sends out an output of frequency fLl as shown in FIG. 6, it sends out a control signal of Ov, and when it sends out an output of 1 frequency fLz, it sends out a control signal of 5V. This can be done, for example, by preparing local oscillators for one day and one for rtz, and when the latter is activated, send the corresponding signal to the control signal sending section so that 5V is output from the TTL circuit above. .

Further, the switch means 4 is constituted by a diode switch as shown in FIG. 3, and the threshold voltage of the comparators 41 and 42 is set to 3, for example, +2.5V.

Now, when the Ov control signal is input, the comparator 41 outputs 2.5
Since +2.5V is output from the comparator 42, the diode D3+04 is turned on, and the diodes D+ and Dz are turned off, so the local oscillator signal with a phase difference of 90 degrees that has passed through the hybrid 12 is directly sent to the mixer 16. Added to .15. However, when a 5V control signal is input, the comparator 41
+2.5v is output from the comparator 42, and -2.5v is output from the comparator 42, so the diode D3+ Da is turned off and the diodes D, D, are turned on, and the local oscillation signal with the reversed phase difference is sent to the mixer 16.15. added to.

That is, since the switching means 4 is automatically switched when changing the local oscillation frequency, the number of setting steps for extracting an output signal of a desired frequency is reduced.

〔Effect of the invention〕

As described above in detail, according to the present invention, when changing the oscillation frequency of one station, the number of setting steps for extracting an output signal of a desired frequency is reduced.

[Brief explanation of the drawing]

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, FIG. 3 is an example of a circuit diagram of the switch in FIG. 2, FIG. 4 is an example of frequency arrangement, The figure shows a block diagram of a conventional example, and FIG. 6 shows an operation explanatory diagram of an image cancellation type frequency converter. In the figure, 3 is a control signal sending portion, 4 is a switch means, 11 is a local oscillator, and 15 and 16 are mixers. Kihatsu Sun Moon's Oshio Tsuku 5 Ig 1's Pro-Tsuku Diagram Z Diagram The Door of the Invention

Claims (1)

[Claims] An input signal and a local oscillation unit (18
) is added to the first and second mixers (15, 16) to frequency convert the local oscillator signals sent out from the oscillators (15, 16), and then combine them to obtain an output signal of a predetermined frequency. In the frequency converter, switch means (4) for mutually switching the phase of the local oscillation signal applied to the first and second mixers in accordance with the state of the input control signal; When changing, whether the predetermined frequency is above the local signal according to the predetermined frequency arrangement,
An image canceling type frequency converter characterized in that it is provided with a control 1 signal sending part (3) that sends a control signal indicating whether the position is on the lower side.