Process for storing of data of a received carrier frequency of a broadcast transmitter

A method for storing the data of a received carrier frequency of a radio transmitter, and/or of the evaluation of its reception, in a data memory of a radio receiver. In the method, the regional identifier is detached from the particular PI code received with the carrier frequency; and the remaining main portion of the PI code, the detached regional identifier, and lastly the received carrier frequency are respectively written into empty locations, existing or to be created, between the stored data, arranged in ascending order, of other carrier frequencies, if the data are not already stored.

FIELD OF THE INVENTION 
The present invention relates to a method for storing the data of a 
received carrier frequency of a radio transmitter. 
BACKGROUND INFORMATION 
There are on the market radio receivers having a data memory in which the 
transmitters being received are stored, with their PI codes and their 
alternative frequencies, in the sequence of their reception. 
Also known, from German Pat. No. DE 39 17 263 A1, are data memories in 
which there is associated with each memory cell for an alternative 
frequency an evaluation memory which registers how often it is received. 
In the known radio receivers, when a change occurs in the program being 
received, a check is first made as to whether the PI code associated with 
the program just selected, and the carrier frequency being received, are 
already stored. When, for example, the result is only that the number in 
the evaluation memory is incremented because the carrier frequency is 
already stored.

DETAILED DESCRIPTION 
The radio receiver as shown in FIG. 1 is set, by means of an operating 
element 1, to a specific carrier frequency of a radio transmitter which 
lies in the frequency spectrum received via the attached antenna 2. In 
mixer stage 3, the selected carrier frequency is separated from the other 
carrier frequencies in the frequency spectrum being received. The 
modulation of the selected carrier frequency is converted to an 
intermediate frequency and amplified in IF stage 4, and then separated 
from the intermediate frequency in demodulator 5. The modulation then 
passes through a frequency splitter 6. The low-frequency program signal in 
the modulation is amplified in a LF stage 7, and made audible via a 
connected loudspeaker 8. 
In a decoder 9 which is located downstream from a second output of 
frequency splitter 6, the 57-kHz auxiliary carrier for the RDS signals are 
demodulated in the modulation of a received RDS transmitter, and the 
recovered RDS signals are decoded. 
The sequence of process steps in decoder 9 necessary for decoding and for 
storage of the received RDS signals in the circuit stages described below 
is controlled, in known fashion, by the program of a microprocessor .mu.P 
(not depicted in further detail). 
In FIG. 1, the functional stages described below are depicted, for the sake 
of clarity, as physically separated circuit stages. Their functions can, 
however, also be implemented by means of functional steps succeeding one 
another in time in a program-controlled circuit stage. 
After decoding, the data of the recovered PI code of the received RDS 
transmitter can be tapped at an output 10 of decoder 9, and the data of 
the selected carrier frequency can be tapped at an output 11 of decoder 9. 
These data are compared with the data stored in a main memory 12, and 
stored again if applicable. 
In FIG. 1, the memory cells for the data to be stored are depicted, for the 
sake of clarity, as being physically separated in terms of their various 
significances and pertinences, and those memory cells with the same 
significance are interconnected by means of a bus line. In practice, this 
association of the data with one another is achieved, in known fashion, by 
appropriate addressing of the data when they are stored. 
In contrast to the existing art, the program of the microprocessor is 
additionally designed, when new data are being stored, so that first the 
regional identifier is detached from the full PI code in a regional stage 
13 which is downstream from output 10 of decoder 9. When a PC code is 
received for the first time, this regional identifier is stored separately 
from the main portion of the PI code. 
The remaining main portion of the received PI code is then compared, in a 
first comparison stage 14 or in a first comparison step, with the main 
portions, arranged in ascending order and called up in succession from 
associated memory cells 15 of main memory 12, of previously received PI 
codes. As soon as the comparison yields a match, a second comparison stage 
16 or a second comparison step is enabled, in which the detached regional 
identifier in the received PI code is compared with the regional 
identifiers, arranged in ascending order and stored in associated memory 
cells 17 behind the main portion of the PI code, of transmitters received 
earlier. If a match results here as well, a third comparison stage 18, 
located in output 11 of the demodulator, is then enabled; from this, as 
already mentioned, the data of the selected carrier frequency can be 
tapped. 
In third comparison stage 18 or in a third comparison step, this frequency 
is compared with the successively called-up frequencies which are stored 
in memory cell 19 of one of the frequency blocks arranged after the 
detected region, and which had already been deposited there earlier, 
arranged in ascending order. In the event of a match, the output of third 
comparison stage 18 controls checking of the number which is stored in an 
evaluation memory 20 which is associated with memory cells 19 interrogated 
for the comparison. 
The significance of this number depends on the program of microprocessor 
.mu.P; it can, for example, contain an evaluation of the receivability of 
the carrier frequency on the last occasion it was received, e.g. the field 
strength. If this new field strength is greater than the stored value, 
this new value is then written into the evaluation memory. 
If no matching frequency indication is located in memory cells 19, the 
carrier frequency just selected is written into an empty memory cell at 
the point appropriate for it based on its magnitude. The regional 
identifier and the main portion of the PI code of the carrier frequency 
just selected are also written into a memory cell at the point appropriate 
for them, if one of the two comparison steps mentioned earlier yields no 
match. 
If no empty memory cell is located at the point appropriate for the data 
based on their magnitude, then either 
the data which are greater than the received data and which are located in 
front of the next empty memory cell or cells are shifted toward the end of 
the memory, so that one or more empty memory cells are created at the 
desired point; or 
the data which are less than the received data and are located behind the 
next empty memory cell are shifted toward the beginning of the memory, so 
that one or more empty memory cells are created at the desired point. 
If however, main memory 12 has no empty memory cell available, the program 
of microprocessor .mu.P then simultaneously decrements all the numbers 
written into evaluation memories 20 by one unit, or if applicable by 
several units, until at least one of evaluation memories 20 contains a 
zero, as a result of which the pertinent frequency is deleted and at least 
one empty memory cell 19' is created, into which the remaining data can be 
shifted in the manner mentioned. 
If the frequency to be deleted is the only frequency in the frequency block 
associated with a regional identifier, then the regional identifier itself 
and if applicable even the main portion of the PI code, is also deleted 
along with said frequency. 
The decrease in value of the contents of the evaluation memory can also be 
inserted at regular intervals, as a process step, into the program of 
microprocessor .mu.P, so that a frequency which was previously received 
properly and is thereafter not selected again, is automatically deleted 
after a certain time, and an empty memory cell is thus generated. 
Once all the necessary entries and deletions have been performed, the 
information stored in main memory 12 is transferred via a switch 23 into 
an identically configured nonvolatile memory 21. Only when this transfer 
is complete can power supply 22 be effectively disconnected from the radio 
receiver if necessary, by opening tracking switch 23'. 
Preferably a RAM can be utilized for main memory 12, and preferably an 
EEPROM can be utilized for nonvolatile memory 21.