JPH0133972B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a variable frequency generator used in a receiver or the like that selects a broadcast channel based on digital data, and more particularly to a variable frequency generator having a storage section containing information for changing the oscillation frequency. In recent years, with improvements in integrated circuit technology, integrated circuits for memory and microcomputers (hereinafter referred to as microcomputers) have become available at low cost and in large quantities, and digital receivers and the like using these digital elements have been developed. The most important features of digital receivers are that they have excellent reception stability, are easy to operate, and can be made smaller and lower in price. For example, broadcast bands (AM, FM, SW, etc.)
The so-called "preset channel memory" function allows you to receive preset stations by simply setting the channel code within the memory as channel selection information and turning on the switch corresponding to this memory. Compared to conventional analog receivers, the so-called "auto scan" function sequentially sweeps within the broadcast band and, if there is a station transmitting in the middle, tunes to that frequency and stops the sweep. It can be constructed inexpensively and compactly. Additionally, in conventional analog multi-band receivers, the tuning dial is common to all bands, so when switching from one band to another, the broadcast channel must be searched within the switched band. It was inconvenient. In a general analog AM/FM receiver, when receiving 531kHz of the AM band, after switching the band to FM and moving the tuning dial, the band changes to AM again.
If you switch to
It was not possible to automatically tune to 531kHz. Digital receivers have a last channel memory function to eliminate this drawback. This function stores the tuning information before switching bands in memory, and when the band is switched again, it automatically tunes based on the previously stored tuning information. It is a function that takes This last channel memory function is effective even when the radio is powered off, and when the radio is powered on again, it can tune based on the channel selection information from just before the power was cut off. However, in general digital receivers, the tuning information is stored as a binary code of the frequency or channel information within the receiving band.
In the case of medium wave broadcasting bands in Japan, it takes at least 7 bits to store one channel selection information, and
In the case of the FM band, 8-bit memory capacity was required. For this reason, if an AM/FM digital receiver is equipped with 10 common channel setting memories for AM/FM bands (hereinafter referred to as preset channel memories), and if this is to include a last channel memory function, As shown in FIG. 5, the memory area required to store channel selection information is
A total of 90 bits (9×10), 9 bits each for 1 to 120, and a total of 15 bits (7+8) are required for the FM and AM last channel memories 121 and 122. Preset channel memory 1
The reason why 9 bits of memory are required for each channel number 11 to 120 is that the preset channel memory is common to AM/FM bands, so in addition to the 8 bits of channel information within the band, the 1 bit of band information is This is because information is required. In this example, there are two bands, AM and FM, but as the number of bands to be received (shortwave broadcast SW) increases, the number of memory bits required for last channel memory increases linearly with the reception band. increase proportionately. Therefore, in order to receive multiple bands with a digital receiver, a considerable amount of memory capacity is required, and most of the memory in the integrated circuit is used just for selection, and other clock functions and It is no longer possible to have a timer function, etc.
This caused a decrease in the processing capacity of microcomputers. SUMMARY OF THE INVENTION An object of the present invention is to provide a variable frequency generator for use in a digital receiver, etc., which can significantly reduce the number of memory bits required for channel selection without degrading the characteristics of the digital system. The configuration of the present invention will be explained using FIG. 1. A predetermined address is assigned to each of the plurality of first storage units, and both broadcast band information and channel information are preset in each of the plurality of first storage units. The plurality of second storage units are allocated to each broadcast band. The key operating means is provided with a plurality of keys, and the key determining means determines which key has been operated. The key determination means outputs a first determination output when a key for reading the contents of one of the plurality of first storage sections is operated, and the key determination means outputs a first determination output when a key for reading the contents of one of the plurality of first storage sections is operated. A second judgment output is output when a key for switching from to another broadcast band is operated. In response to the first determination output, the first storage section content reading means as the first means accesses the first storage section corresponding to the operated key and reads the contents, and the address information writing means as the second means writes the address information of the first storage section into the second storage section allocated to the same broadcast band as the broadcast band information of the accessed first storage section. On the other hand, in response to the second determination output, the second storage section content reading means as a third means reads address information from the second storage section assigned to the broadcast band to be received;
The first storage section reading means as the fourth means accesses the first storage section based on the read address information and reads the contents thereof. A frequency division ratio data generating means as a fifth means generates predetermined frequency division ratio data based on the broadcast band and channel information in the first storage section read by the first or fourth means. The frequency dividing means divides the frequency of the oscillation signal from the controlled oscillator based on the frequency division ratio data, and the phase comparing means compares the phase of the frequency-divided signal with a reference signal to control the oscillation frequency of the controlled oscillator. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 is a block diagram in which the variable frequency generator of the present invention is used as a local oscillator in a digital receiver. Note that the key operation means, key determination means, and first to fifth means shown in FIG. 1 are represented as a controller 44 in FIG. VCO) 39, the frequency dividing means is a variable frequency divider 40
, the phase comparison means are shown as a phase comparator 41 and a low-pass filter 43, respectively, and the reference signal is supplied from a reference frequency oscillator (OSC) 42. In FIG. 2, a signal received by an antenna 32 is mixed with a local oscillation frequency signal from a VCO 39 by a mixer (MIX) 34 via a radio frequency amplifier (RFA) 33, and is mixed with a mixer (MIX) 34 by an intermediate frequency amplifier 3.
5. Detector 36, audio amplifier (AFA) 3
Audio is output from the speaker 38 via 7.
The oscillation signal from the VCO 39 is frequency-divided by a variable frequency divider 40 based on the frequency division ratio data from the controller 44, and the phase of the frequency-divided signal is compared with the reference signal from the OSC 42. The comparison result is filter 43
It is fed back to VCO39 via. Thus the VCO
The oscillation frequency of 39 is controlled to be a desired local oscillation frequency. Referring to FIG. 3, the memory 45 in FIG.
It has a plurality of preset channel memory sections 20 as a first storage section and a plurality of memory sections 31 as a second storage section. Each preset memory P has band information a and channel information b.
Furthermore, the first storage section 20 has n presets that can set channels for n stations.
It has a channel memory section and a last preset number memory assigned to m broadcast bands (AM, FM, SW, etc.) as a second storage section 31 (however, n and m are integers of 2 or more). ).
The preset channel memory section 20 includes n memories that can store selection information for one station (channel code b and broadcast band code a), and each memory has memory numbers P ₁ to Pn. An identification number is assigned as an address name. The memory 45 according to this embodiment further includes a current channel memory 21, which stores channel selection information (code data in the selected preset channel memory) that is selected and currently being received. Each preset
It has the same bit length as channel memories P ₁ to Pn. The last preset number memory section 31 is
It consists of m memories _L1 to Lm that correspond one-to-one with designated broadcast bands (AM, FM, SW, etc.) that can be selected in the receiver, and the contents of any memory in the preset channel memory section 20 can be read. When the channel is selected, the preset channel memories P ₁ to 1 are read out to predetermined memories L ₁ to Lm in the last preset number memory section 31 corresponding to the band specified in the area a. The identification number (address name) of Pn is stored. here,
Of the data setting areas of each memory _P1 to Pn of the preset channel memory section 20, area a is a place where bit information for identifying broadcast bands is set, and has the following relationship with the number of bands m. . However, in the following formula, [ ] is a symbol that means rounding up the decimal point. a=[log ₂ m] Also, last preset number memory section 31
The total area c of each memory (L ₁ to Lm) and the number n of preset channel memories have the following relationship. c=[log ₂ n] In other words, area c is the preset channel memory
It is determined according to the number of P ₁ to Pn; 2 bits are required for 4, 3 bits are required for 8, and 4 bits are required for 10. Next, the preset channel memory section 20
Assuming that each of the memories _P1 to Pn stores the channel selection information shown in Table 1, the channel selection operation based on the following operations will be described in detail with reference to the flowchart shown in FIG.

[Table] The controller 44 performs the following operations based on the switch ON. That is, the contents of the current channel memory 21 are first read out (401). Control is performed to receive broadcast waves of a designated band according to the band information a of the read contents (402). Further, predetermined frequency division ratio data is calculated according to the channel information b and set in the variable frequency divider 40 (403). In this way, the broadcast waves of the band and channel specified by the data stored in the current channel memory 21 are received. After this, the key operation means is in a state where the key operation is held. In the following, three operations using the key operation means, namely, a preset memory key operation, a sweep key operation, and a band switching key operation will be explained. The key determination means needs to determine whether or not a key operation has been performed, and if so, which information key was operated, and for this purpose, four determination processes (404 to 407) are performed as shown in FIG. ) and performs data processing according to the determination result. First, the channel selection operation based on the operation of the preset memory key will be explained. In this case, the key determination means outputs the first determination output, and the processing in response to this is based on the flow shown in "1" in FIG. That is,
For example, when a key operation corresponding to the preset channel memory _P1 is performed, the memory _P1 in the preset channel memory 20 is accessed and its contents, coded channel information b and band information a, are read out (408 ). The read contents are stored in the current channel memory 21 (409). Also, write 1 (00...001), which is the identification number (address name) of the accessed memory P ₁ , into the FM memory L ₁ of the preset number memory section 31 corresponding to the broadcast band information a (for example, FM) ( 410). After this, the operation moves to step 401, where the contents of the current channel memory 21 are read out.
As a result, channel broadcast waves within the band specified by the data in memory _P1 are received. Next, the operation based on the band switching key operation will be explained. Now, preset channel memory section 20
Suppose that we are receiving a channel in the band specified by memory _P3 . In this state, as described above, the contents of the current channel memory 21 are the same as the memory _P3 , and the memory _L3 of the preset number memory section 31 contains the identification number ₃ of the memory P3.
(address name 00...0011) is stored. now,
When there is an operation to switch the reception band from code 3 to code 1, the key determination means outputs a second determination output. In response to this, the memory of the preset number memory section 31 corresponding to the operated band key is
_L1 is accessed and its contents are read (411).
Since code ₁ specifying the address of preset channel memory _P1 is stored in memory L1, memory _P1 is accessed by the read address code and its contents are read out (412). The read contents of memory _P1 are stored in the current channel memory 21 (413), and the flow of operation returns to step 401. That is, when the broadcast band is switched, the channel that was last received in the band to which the broadcast band has been switched is received again in accordance with the band switch. Finally, the operation based on the sweep operation will be explained.
If the sweep up key is operated, the process moves to "3", reads the contents of the current channel memory 21, adds 1 to the channel information, and stores it again (414). If the sweep down key is operated, 1 is subtracted from the channel information in the current channel memory 21 and the channel information is stored again (415). Then, the process returns to step 401, and as a result, the broadcast wave of the next channel is received. It will be clear from FIG. 4 that this series of operations continues as long as the sweep key is operated. When the power switch is turned off and then turned on again, by backing up the memory section 45 with an auxiliary power source, the channel within the band specified by the current channel memory 21 is received. As a result, the channel selection state before the power was turned off can be immediately restored. In this way, in this embodiment, as a method of tuning to a certain station in the band that has been switched when switching bands, the last
Rather than storing all channel selection information in channel memory, preset channel
All you need to do is set the memory address name, so
Even if the number of broadcast bands increases, the last channel
The increase in memory storage capacity is extremely small compared to the past. For example, if the number of preset channels and memories is for 10 stations and the number of bands is two, AM and FM, as in the conventional example described above, the number of bits for each of L ₁ and L ₂ of the last preset number and memory is Since each bit requires 4 bits, the total number of bits is 7.
Bits of memory capacity is saved. Needless to say, this tendency becomes more pronounced as the number of bands increases. During the explanation of the operation of this embodiment, if 10 channels in the band specified by code 1 are received by operating the preset key and another channel in the same band is selected by operating the sweep key, that is, by the sweep operation, the band will be switched. In the subsequent band restoration operation,
The 10 channels of band 1 set in preset channel memory _P1 are received. Strictly speaking, this does not mean that the last channel has been received, but since the preset channel memory generally stores tuning information for frequently received stations, it does not cause any inconvenience in practice. As explained above, according to the present invention, a digital receiver with preset channel memory and last channel memory functions can be realized with extremely small memory capacity compared to conventional systems, resulting in savings. Clock and timer functions can also be provided using other memory areas, making it possible to make maximum use of the processing power of the microcomputer. It is also clear that low cost and miniaturization can be achieved. In the present invention, as long as the memory section is backed up with an auxiliary power source, the contents of the memory will not be erased even if the main power source is turned off. The number of preset channels can be set arbitrarily, and it can be set in any area in memory.
It can be any type of memory, including RAM. Note that the variable frequency oscillator according to the present invention is fully applicable not only to receivers but also to receivers and the like.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of the present invention, Figure 2 is a block diagram showing the configuration of the present invention.
3 is a block diagram showing the configuration of a digital receiver to which the present invention is applied, FIG. 3 is a block diagram of the memory shown in FIG. 2, and FIG. 4 is a flowchart showing the operation of the controller shown in FIG. 2. FIG. 5 is a block diagram of a memory in a conventional digital receiver. 20...Preset channel memory section, 2
1...Current channel memory, 31...
Last preset/number memory section, 32... antenna, 33... high frequency amplifier, 34... mixer, 35... intermediate frequency amplifier, 36... detector,
37...AF amplifier, 38...speaker, 39...
...Voltage controlled oscillator, 40... Variable frequency divider, 41...
...Phase comparator, 42...Reference frequency oscillator, 43
...Low pass filter, 44...Controller,
45...Memory.

Claims (1)

[Claims] 1 A plurality of first storage sections in which both broadcast band information and channel information are preset at each address, and a plurality of second storage sections assigned to each broadcast band.
a storage unit; a key operation unit; outputting a first determination output when a key for reading the contents of one address of the plurality of first storage units is operated on the key operation unit; and receiving a reception band; key determining means for outputting a second determination output when a key for switching from one broadcast band to another broadcast band is operated; and a first determination unit corresponding to the operated key in response to the first determination output; The first step is to access the storage section and read its contents.
and a second broadcast band assigned to the same broadcast band as the broadcast band information in the accessed first storage unit.
A second storage unit that writes the address information of the first storage unit into the storage unit.
means, third means for reading address information from a second storage section assigned to a broadcast band to be received in response to the second determination output, and a third means for reading address information from a second storage section assigned to a broadcast band to be received; fourth means for accessing and reading out the contents; and generating predetermined frequency division ratio data based on the broadcast band information and channel information in the first storage section read by the first means or the fourth means. a controlled oscillator; frequency dividing means for frequency dividing the oscillation signal from the oscillator based on the frequency division ratio data; and oscillation of the controlled oscillator by comparing the phase of the frequency-divided signal with a reference signal. A variable frequency generator comprising: phase comparison means for controlling frequency.