JPH022333B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radio receiver equipped with a band frequency shift device, and relates to a shift adjustment method and a method for displaying shift results. [Prior art] Band frequency shifting in radio receivers usually involves shifting the intermediate frequency (IF) passband frequency of the receiver slightly above and below the center frequency to avoid sideband interference from adjacent radio waves. In particular, when adjacent interference occurs only in the reception of the own station in the transmitter/receiver, it is convenient to be able to perform interference-free communication by simply shifting the IF frequency without changing the communication frequency. Therefore, an adjustment knob called "IF shift" is sometimes provided. Initially, this technical method was
This is done by changing the L or C constant of the transformer, but since it is not possible to adjust the frequency externally with the crystal filters and ceramic filters that are commonly used today, it is necessary to shift the IF frequency of the received wave instead. This changes the relative position of the received wave with respect to the passband of the IF filter. As a means of achieving this, in the AM receiving circuit shown in Figure 4A, the IF frequency is shifted by finely adjusting the local oscillation frequency, so the operation of tuning to the tuning position with the least interference during tuning is essentially an IF shift. It means it's on. However, when receiving SSB or CW, if only the local oscillation frequency is changed, the relative frequency with BFO changes in the demodulator, resulting in BFO
There is the inconvenience of having to readjust the IF frequency, so practical IF shifting methods include changing the local oscillation and BFO frequencies by mechanically or electrically interlocking them, and changing the BFO frequency at a constant value as shown in Figure 4B. As,
There is a method in which a main IF filter is placed between the front-stage mixer and the rear-stage mixer, the local oscillation frequencies of the front-stage mixer and the rear-stage mixer are supplied from the same oscillator, and the oscillation frequency is finely adjusted. In both cases, a frequency fine adjuster is added to the local oscillator, which originally has a fixed frequency, and an IF shift display, as well as a shift direction and shift amount display, are used as a guide for use. However, recent mobile communication devices have become significantly smaller, and although this can be achieved in terms of circuitry by making components smaller and using ICs, the number of operation knobs is limited due to the smaller panel surface, making it difficult to operate devices such as IF shift. The reality is that the auxiliary operation knob has no choice but to be omitted. [Problems to be Solved by the Invention] In this invention, the IF shift operation is switched by mechanically or electrically pushing in or pulling out the adjustment knob of the main tuning frequency adjuster, which also serves as a rotating part. The purpose is to omit the adjustment knob. In addition, at that time
This configuration also provides a method for displaying the direction and amount of IF shift. [Means for Solving the Problems] In this invention, the IF (band frequency) shift adjustment is also performed by switching the operation of the main tuning frequency adjuster (tuning knob), and the IF shift adjustment knob is omitted. The step-type light display S indicates the direction and amount of shift that cannot be performed.
This is done using a meter. First, a method of using the main tuning frequency adjuster for IF shift adjustment will be described. In the receiver circuit block diagram of FIG. 1, 1 is the first mixer, 2 is the second mixer
3 is a third mixer, 4 is a main IF filter at an intermediate stage between the second mixer 2 and third mixer 3, 5 is a demodulator, 6 is a BFO, and the output of the demodulator 5 is SSB
Or one that can provide CW audio frequency output. The first local oscillator 7 is also called a VFO, and selectively tunes the reception frequency by changing the oscillation frequency. Adjustment operations for this purpose are performed by the tuning knob 10 via the coupling portion 9A of the operation switching mechanism 9 .
Further, the second local oscillator 8 is common to the second mixer 2 and the third mixer 3, and the IF shift is performed by finely adjusting its oscillation frequency. This is done with the tuning knob 10 through the
When 0 is pressed, the connecting part 9A is connected, and the connecting part 9B is disconnected (or vice versa), and the tuning knob 10 is released.
tunes the received wave, and when the tuning knob 10 is pulled, the coupling portion 9B is coupled, 9A is removed, and the tuning knob 10 adjusts the IF shift . Therefore, by providing the operation switch 9, the IF shift adjustment operation can be performed. The tuning knob 10 can be used for both purposes.
In addition to this mechanical switching method, there is also a switching method using an electric circuit, which will be described in detail in the embodiments. There are two types of IF shift: a shift to the + side of the band frequency and a shift to the - side, and the amount of shift is usually about several kHz within the band. Therefore, in order to know the current shift status, conventionally
The IF shift knob is equipped with a ± shift amount display, but as in the present invention, when the tuning knob is set to 10,
If it is also used as an IF shift, the position of the knob is indeterminate, so it is inconvenient that a shift display cannot be attached. Therefore, in the present invention, a shift display is performed using an S meter with a step type optical display. The S meter in the receiver is a display that displays the strength of the received wave in decibels or S value, and previously a highly sensitive ammeter of 1 mA or less was used.
Due to their precision structure, they are susceptible to vibrations, so step-type light display types are becoming more common these days. This display uses five light emitting diodes or liquid crystal elements.
One to ten of them are lined up in a row, and they emit light or color sequentially from one end depending on the input intensity to display a step display. Because they have the advantages of being mechanically strong and occupying a small space, their use is expanding, especially for mobile devices. How to use it is shown in Figure 1.
This can be done by applying the AGC voltage 20 to the drive circuit 11 formed into an IC. An example of a circuit using this step type light emitting display 12 for IF shift display is as shown in Fig. 2, which uses a VCO system in which fine adjustment of the frequency of the second local oscillator 8 for IF shift is performed electrically by voltage changes. A potentiometer 15 for adjusting the voltage 81 is made variable by a tuning knob 10 via a connecting portion 9B of the operation switching mechanism 9 . The control voltage 81 sends out an output at the operating level from the level comparator 13, and the drive circuit 11 uses the AGC voltage 20.
This is done by selecting and selecting the output from the electronic switch 14 and supplying it to the optical display 12. The electronic switch 14 is switched in conjunction with the operation of the operation switching mechanism 9 , and the optical indicator 12 operates as an S meter in the tuned state and as a shift indicator in the IF shift state. The state of the shift display is such that when there is no shift, the display element in the center of the display 12 emits light (or develops color), and when there is a shift, for example, +
This is obtained by setting the control voltage 81 and the operating point of the level comparator 13 so that the elements on the right side of the center in a side shift and the elements on the left side of the center in a - side shift sequentially move outward according to the shift amount. [Example] In the previous section, an example of the basic configuration of the present invention was described, but in practice, it is possible to configure it using a microcomputer (referred to as MPU or CPU, hereinafter described as CPU, which is often used in Japan). Since it is convenient, an example will be described below. In FIG. 3, a first mixer 1, a second mixer 2, a third mixer 3, a main IF filter 4, a demodulator 5,
The configuration for performing IF shift by finely adjusting the frequencies of the BFO 6 and the local oscillators 8 of the second and third mixers is the same as that shown in FIGS. 1 and 2. The first local oscillator is used in most modern communication equipment.
PLL (Phase Locked Loop) controlled oscillator 55
, and its oscillation frequency is determined by the CPU (Central
Processing Unit) 50 is a frequency encoder 58
It is set by data 51 obtained by integrating pulses 54 generated by . At that time, the tuning/IF shift signal 59
is on the tuning side, but when it is set on the IF shift side (by operating the tuning knob back and forth, or by switching the switch), IF shift data 52 of the encoder output pulse is output, and this is controlled by the D/A converter 56. The IF shift is performed by converting it into a voltage 57 and slightly changing the frequency of the second local oscillator. At the same time, when the signal 59 is in the tuned state, the CPU 50 determines the level of the AGC voltage 20 and outputs the output 53 to the step type optical display 12, but when the signal 59 is in the IF shift state, the current value of the data 52 is set to the reference value (not shifted). A designation output 53 of the light emitting (coloring) position is outputted to the step type optical display 12 by comparing it with the state value). By fully utilizing the functions of the CPU 50 as described above, the configuration of the present invention can be simplified and productivity can be improved. [Effects of the Invention] IF shifting in receivers is a technology that has been applied for a long time, but in many cases, it cannot be used due to the space occupied by adjustment knobs on the panel surface, especially in devices that are significantly miniaturized such as mobile devices. It's summery. The present invention has the advantage that the IF shift adjustment can be performed regardless of the panel space by using the tuning knob that is used for a single purpose also for the IF shift. In this case, it is not possible to display the shift status depending on the position of the adjustment knob, so in the present invention, the shift status can be displayed using the step type optical indicator S meter used in most mobile communication devices. This eliminates this inconvenience, and has the effect of not requiring an additional mechanism on the panel surface while completely retaining the functions necessary for IF shift.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a partial diagram of a display circuit, FIG. 3 is a diagram showing an implementation circuit, and FIG. 4 is a block diagram of an example of an IF shift circuit. 1, 2, 3... mixer, 4... IF filter,
5...Demodulator, 6...BFO, 7, 8, 55...
Local oscillator, 9 ... Operation switching mechanism, 10... Tuning knob, 11... Drive circuit, 12... Step type optical indicator, 13... Level comparator, 14... Electronic switch, 15... Potentiometer , 50...
CPU, 56...D/A converter, 58...encoder.

Claims (1)

[Claims] 1 Equipped with a band frequency shift device in the intermediate frequency stage,
Further, in a wireless communication device having an S meter of a step type optical display, when one of the regulators with a switch function is selected, it becomes a main tuning regulator, and when the other is selected, it serves as a selection adjustment means for executing the band frequency shift. The S-meter of the step-type optical display is linked to the selection adjustment means, and when one is selected, it becomes an S-meter for signal strength, and when the other is selected, it becomes an indication of the band shift amount, and the intermediate frequency is set to the normal bandpass. Then, the center part emits light, and when the band is shifted to the higher frequency side or to the lower frequency side, the step type light indicator emits light to the right or left of the center part and at a distance corresponding to the amount of shift. A band frequency shifting method characterized by: