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Description  |
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BACKGROUND OF THE INVENTION
The present invention generally relates to a scanning receiver, and
particularly relates to a scanning receiver having a large number of
channel memories.
Scanning receivers now available on the market have channel memories for
channels in a range of from about 10 channels to about 200 channels.
Reception frequencies corresponding to reception channels are stored in the
respective channel memories. In reception, the reception frequencies are
read in a predetermined order by means of a microcomputer so that radio
waves tuned to the reception frequencies are received.
In this case, the receiving methods are largely grouped into two, one being
a method in which reception is made successively with the reception
frequencies registered by a user in the respective channel memories, the
other being a method in which reception is made successively with the
reception frequencies registered as fixed frequencies by a manufacturer
when the receiver is forwarded from a factory.
Therefore, in order to receive both the frequencies registered by a user
and the frequencies registered by a manufacturer alternately, it is
necessary for the user to perform a change-over operation every time.
Further, there has been a defect that the fixed frequencies registered by
a manufacturer cannot be made invalid even if any of the fixed frequencies
is not necessary.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a scanning
receiver in which the foregoing defect in the conventional art can be
eliminated.
In order to attain the above object, according to the present invention,
the scanning receiver comprises: a memory for storing reception
frequencies corresponding to a plurality of reception channels; a
receiving section for receiving radio waves to be tuned to the reception
frequencies; a control means for controlling the memory and the receiving
section so as to read out the reception frequencies corresponding to the
reception channels successively in a predetermined order from the memory
in predetermined order to thereby cause the receiving section to operate,
the memory including a fixed storage portion in which parts of the
reception frequencies are fixedly written and an additional storage
portion in which parts of the reception frequencies are rewritable
written, the additional storage portion including a select/non-select
setting area in which select/non-select information is written, the
select/non-select information indicating that when the reception
frequencies corresponding to the reception channels are read out from the
fixed and additional storage portions, the reading out of each of the
reception frequencies is necessary or not.
Preferably, the fixed storage portion is constituted by read only memories
and the additional storage portion is constituted by random access
memories.
Desired reception frequencies are set by a user in the additional storage
portion. Further, the select/non-select information as to whether
reception of any of the reception frequencies is necessary or not is set
in the select/non-select setting area. As a result, of the reception
frequencies registered in the fixed and additional storage portions, only
those selected are successively read out to thereby carry out the
reception.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a block diagram schematically showing an embodiment of the
present invention;
FIG. 2 is a diagram typically showing a combination of ROM and RAM
belonging to each of groups;
FIG. 3 is a diagram for explaining a memory map of ROM;
FIG. 4 is a diagram for explaining a memory map of RAM; and
FIG. 5 is a flowchart of subroutine for explaining the operation for
reading out data from channel memories.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Next, an embodiment of the present invention will be described with
reference to the accompanying drawings. FIG. 1 is a block diagram
schematically showing the scanning receiver according to the present
invention. In this embodiment, the scanning receiver has a memory 1 in
which reception frequencies are stored, a receiving section 2 for
receiving radio waves respectively tuned to the reception frequencies, a
central processing unit (CPU) 3 functioning as a control means for
controlling the memory 1 and the receiving section 2, an operating
keyboard 4, and a display section 5 constituted by LEDs, LCDs, or the
like.
In this embodiment, the memory 1 is divided into groups G1 through G5 in
accordance with the use. For example, the groups G1, G2, G3, G4 and G5 are
assigned to police radio, fire fighting and emergency radio, aircraft
radio, weather forecast broadcasting, and marine craft radio,
respectively.
The group G1 has ROM (read only memory) 1 and RAM (random access memory) 1,
the group G2 has ROM 2 and RAM 2, the group G3 has ROM 3 and RAM 3, the
group G4 has ROM 4 and RAM 4, and the group G5 has a pair of ROM 5 and RAM
5.
Referring to FIG. 2, now, the combination of ROM 1 and RAM 1 constituting
the group G1 will be described by way of example.
In this embodiment, each of the groups G1 through G5 has 10 reception
channels. In the illustrated case, the channels CH1 through CH7 are
assigned to ROM 1 and the residual channels CH8 through CH10 are assigned
to the RAM 1.
Further, a select/non-select setting area S for allowing only the necessary
channels to be received is provided in the RAM 1. That is, 10 storage
domains respectively corresponding to the ten channels CH1 through CH10
are allotted in the select/non-select setting area S. In each of the ten
domains, "0" or "1" is written to control the reading of the reception
frequency of controlled.
In this embodiment, "0" represents necessity of reading while "1"
represents un-necessity of reading. Therefore, in the illustrated case of
FIG. 2, reading of reception is carried out successively in the order of
the channels CH1, CH3, CH4, CH7, CH8, and CH9, while the channels CH2,
CH5, CH6, and CH10 are not read.
Further, reception frequencies are registered in advance in the channels
CH1 through CH7 of the ROM 1 in the manufacture's side, for example, at
the time of forwarding from a factory, and, on the contrary, a user can
temporarily write desired reception frequencies into the respective
channels CH8 through CH10 in the RAM 1. Writing into the RAM 1 may be
performed from the keyboard 4 through the CPU 3.
The receiving section 2 includes an RF (radio frequency) section, an AF
(audio frequency) section, and a PLL (phase locked loop) circuit although
those members are not illustrated in detail, and receives radio waves
tuned to the reception frequencies to be read from the memory 1.
Next, referring to a memory map of FIG. 3, description will be made as to a
state where data are written into the ROM. Although reception frequency
data are constituted by 20 bits for every channel. The actual frequency
data are constituted by 16 bits and the residual 4 bits (MSB side) are
assigned for controlling the peripheral circuits.
In the illustrated embodiment, an 8-bit ROM is employed and 3 bites thereof
are allotted per channel because the reception frequency data are allotted
with 20 bits for every channel. Accordingly, 105 bites (address 0-address
104) are required for registration of 35 channels (7 channels for each of
5 groups, that is, from CH1 of the group G1 to CH7 of the group G5) and
the addresses 105 et seq are used other programs.
FIG. 4 shows the memory map of the RAM. In the illustrated embodiment,
since a 4-bit CPU is employed as the CPU 3, the RAM has a configuration in
which 4 bits are prepared per address.
First, the select/non-select setting area S is set in the RAM. In the
illustrated embodiment, since the total of the channels of the five groups
from G1 to G5 is 50, 50 bits or 12.5 (=50 .div.4) are required for the
registration of select/non-select setting for all the 50 channels. That
is, the LSB is allotted for the select/non-select setting of the channel
CH1 of ROM 1, the second bit is allotted to the channel CH2 of ROM 1, . .
. , and the MSB is allotted to the channel CH10 of ROM 5.
The reception frequency data of the channel CH8 of the RAM 1 are written in
the 13th address et seq. That is, 5 bites are required for the
registration of the channel CH8 of the RAM 1 because the reception
frequency data for each channel are constituted by 20 bits.
After writing of the channel CH8 of the RAM 1, the reception frequency data
for the channels CH9 and CH10 of the RAM 1 are written. Thereafter, the
reception frequency data of the channels CH8-CH10 of the RAM 2, . . . the
reception frequency data of the channels CH8-CH10 of the RAM 5 are
successively written. The thus written reception frequency data in the RAM
can be rewritten if necessary.
Next, description will be made as to the operation for reading out the
reception frequency data with respect to the groups G1 through G5 in
accordance with the subroutine of FIG. 5. It is assumed that scanning is
performed from the group G1 for the sake of convenience in explanation.
First, the first channel CH1 of the group G1 is designated as the channel
number 1 in the first step ST1. Then, judgment is made as to whether the
channel CH1 is selected or not in the next step ST2. That is, it is
detected which one of "0" and "1" has been written in the LSB of the RAM
corresponding to the channel CH1 of the group G1, and if "0" is detected,
it is judged that the channel CH1 of the group 1 is selected so that the
operation is shifted to the next step ST3.
Judgment is made in the step ST3 as to whether the channel CH1 of the group
1 is written in the ROM or the RAM. This is judged on the basis of
the-surplus obtained by dividing the channel number by 10, because each
group has 10 channels in which the first to seventh channels are
registered in the ROM and the eighth to tenth channels are registered in
the RAM in the illustrated embodiment. Accordingly, if the surplus is
ranged from 1 to 7, it is concluded that the channel is written in the
ROM, while if the surplus is 8, 9, or 10, it is concluded that the channel
is written in the RAM. This applies to the case where all the channels of
the groups G1 to G5 are serially numbered.
Since the channel number is now "1", the surplus is "1" and the ROM is
determined, and the address corresponding to the channel CH1 is designated
in the step ST4. Subsequently, in the step ST5, the reception frequency
data are read out on the base of the three addresses including the
designated address in the step ST5.
Then, in the step ST6 the read-out reception frequency data are supplied to
the PLL circuit of the receiving section 2, so that the receiving circuit
is tuned to the aimed frequency and the other circuits are changed over in
accordance with the reception frequency.
After the RF section and PLL circuit has been stabilized (for about 20 to
100 msec) in the step ST7, judgment is made as to whether a radio wave is
received or not at the tuned frequency in the step ST8. In this case, if
the tuned frequency is received, the contents of reception such as aural
information or the like are outputted from a speaker through the AF
section. The reception state is held until the radio wave input disappears
in the step ST9.
In the case where the radio wave input is interrupted for a predetermined
time in the step ST9 or in the case where the aimed radio wave cannot be
received in the step ST8, "1" is added in the step ST10 to the channel
number to make the channel be "2". Then, the new channel number is
compared with "11" in the step ST11, and the operation is returned to the
step ST2 because the channel number is smaller than "11" in this case.
Thus, the channel CH is successively incrementally designated, and if the
channel number reaches "8", the RAM is determined in the step ST3. As a
result, in the step ST4a, the address corresponding to the channel CH8 is
designated, the next reception frequency data are read on the basis of 5
addresses including the designated address. The steps ST6 et seq. are
executed in the same manner as in the foregoing case.
In the illustrated embodiment, "1" has been written as the
select/non-select information with respect to each of the channels CH2,
CH5, CH6, and CH10, and in the step ST2, it is concluded that the channels
CH2, CH5, CH6, and CH10 are not selected in the step ST2 in this case. The
operation is shifted to the step ST10 without reading the reception
frequency data thereof, that is, while making jump over the steps ST3
through 8.
Then, when "1" is added to the channel number so that the new channel
number becomes "11" in the step ST10, NO is selected in the step ST11 and
scanning is performed with respect to the next group G2. Thereafter, the
operation is repeated till the step operation is performed.
Although the memory is divided into 5 groups each of which is constituted
by 10 channels in the foregoing embodiment, the present invention is not
limited to this, and the number of the groups and the number of the
channels may be set desirably.
Further, although each of the ROM and RAM is divided into five groups in
FIG. 1, this division is merely for the sake of convenience in
explanation, and in practice, a one-chip microcomputer including the CPU 3
is used.
As described above, according to the present invention, the ROM and RAM are
formed so as to constitute a series of channel memory. Consequently,
reception frequency data fixed in the ROM and reception frequency data
additionally registered by a user in the RAM can be successively serially
read without requiring any manual operation by the user.
Further, by writing select/non-select information, it is possible to
perform temporary deletion of a frequency registered in the ROM and it is
possible to easily perform addition of a new frequency and to conveniently
carry out the scanning reception.
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