RDS audio receiver having interrupt mode

A Radio Data Systems (RDS) receiver has a decoder circuit to read RDS data from a broadcast transmission signal. From the RDS data, a control circuit determines a program of the received signal, a program category of the received signal, lists of programs and program categories of other stations, and a regional digit. The receiver has a controller to store a desired program category. The RDS data is used to control the receiver to perform several different functions. The receiver will interrupt reception of a signal, the category of which is different from a desired category and receive a signal that matches the desired category. The receiver will revert to a previous program when the category of the signal to which it switched no longer matches the desired category. The receiver will revert to the strongest signal having one of a specified set of regional digits. The receiver also permits the storage of a desired category using only an RDS key and at least one other key.

BACKGROUND OF THE INVENTION 
The present invention relates to radio receivers and specifically to radio 
receivers for receiving Radio Data System (RDS) broadcasts. 
Radio Data System (RDS) broadcasts are special types of radio broadcasts 
that are widely implemented in Europe. RDS broadcast transmissions 
incorporate several types of information in addition to the audio content 
of the program that is broadcast. 
Included in the incorporated information is a PTY (program type display) 
code. The PTY code is used to inform the listener of the general category 
of the program of the particular station to which an RDS receiver is 
tuned. For example, the category might be news, music, drama, educational, 
scientific, etc. 
Another type of information incorporated in RDS signals represents the 
identity of the specific program being received. The program is identified 
by program identification codes (PI codes). At a given time, in a given 
receiving region, a number of broadcasters may be transmitting the same 
program at different receivable frequencies, each having the same PI code. 
At a given time different programs with different PI codes, each in the 
same category and thus having the same PTY code, could be airing 
simultaneously. RDS broadcasters may also transmit a list, called an AF 
list, which correlates the freqencies of RDS broadcasters and PI codes of 
the broadcasts at each frequency. 
One feature that can be implemented in an RDS receiver is the PTY function. 
The PTY function shows, on a display, the category of the program being 
received. The display permits the user to select a station based on the 
general program content. 
The additional equipment in RDS receivers for performing the PTY function 
serves no special purpose at times when no program in the selected 
category is broadcasting. For example, such recievers require a key switch 
for the PTY function. This requirement increases the number of keys and 
thereby the difficulty of operation. 
OBJECTS AND SUMMARY OF THE INVENTION 
An object of the present invention is to provide a Radio Data System (RDS) 
receiver that overcomes the drawbacks of the prior art. 
Another object of the present invention is to provide an RDS receiver that 
makes additional active use of equipment for the Program Type Display 
(PTY) function to enhance the functionality of the receiver. 
Still another object of the present invention is to provide an RDS receiver 
that can automatically tune to a station broadcasting a desired program. 
Still another object of the present invention is to provide an RDS receiver 
that can automatically tune to a station broadcasting a desired general 
category of program. 
Still another object of the present invention is to provide an RDS receiver 
that can automatically tune to a station transmitting the strongest 
signal. 
Still another object of the present invention is to provide an RDS receiver 
with high operability, functionality and convenience. 
Briefly stated, there is disclosed, a Radio Data Systems (RDS) receiver has 
a decoder circuit to read RDS data from a broadcast transmission signal. 
From the RDS data, a control circuit determines a program of the received 
signal, a program category of the received signal, lists of programs and 
program categories of other stations, and a regional digit. The receiver 
has a controller to store a desired program category. The RDS data is used 
to control the receiver to perform several different functions. The 
receiver will interrupt reception of a signal, the category of which is 
different from a desired category and receive a signal that matches the 
desired category. The receiver will revert to a previous program when the 
category of the signal to which it switched no longer matches the desired 
category. The receiver will revert to the strongest signal having one of a 
specified set of regional digits. The receiver also permits the storage of 
a desired category using only an RDS key and at least one other key. 
According to an embodiment of the present invention, there is disclosed, an 
RDS receiver, comprising: means for receiving a broadcast transmission 
signal, the means for receiving including means for deriving a first audio 
signal from the broadcast transmission signal, means for determining a 
broadcast category of the broadcast transmission signal, controller means 
for storing a desired category, the controller means including means for 
activating an interrupt mode of the controller means, means for generating 
a second audio signal, the controller means including means for outputting 
the second audio signal and the controller means including means for 
outputting the first audio signal when the interrupt mode is activated and 
a desired category, stored in the controller means, matches the broadcast 
category of the broadcast transmission signal. 
According to another embodiment of the present invention, there is 
disclosed, an RDS receiver, comprising: tuner means for receiving a 
broadcast transmission signal, the tuner means including means for 
deriving a first audio signal from the broadcast transmission signal, 
means for extracting a data signal from the broadcast transmission signal, 
the data signal including data indicating a broadcast program of the 
broadcast transmission signal, controller means for storing a desired 
program in a memory of the controller means, the controller means 
including input means for activating an interrupt mode of the controller 
means, means for generating a second audio signal, the controller means 
including means for outputting the first audio signal when the interrupt 
mode is activated and a desired program, stored in the memory, matches the 
broadcast program of the broadcast transmission signal. 
According to still another embodiment of the present invention, there is 
disclosed, an RDS receiver, comprising: means for receiving broadcast 
transmission signals, means for monitoring a category of a first one of 
the broadcast transmission signals, controller means for storing a desired 
category, controller means including means for activating an interrupt 
mode of the controller means, the controller means including means for 
tuning the means for receiving to receive a first one of the broadcast 
transmission signals, the controller means including means for tuning the 
means for receiving to receive the second one of the broadcast 
transmission signals when the interrupt mode is activated and a stored 
desired category matches the first one category. 
According to still another embodiment of the present invention, there is 
disclosed, an RDS receiver, comprising: means for receiving broadcast 
transmission signals, each having a category, controller means for tuning 
the means for receiving to receive a first one of the broadcast 
transmission signals, the controller means including means for storing a 
desired category, means for determining a category of at least another of 
the broadcast transmission signals by scanning a list of data derived from 
the first one, the controller means including means for activating an 
interrupt mode of the controller means, the controller means including 
means for tuning the means for receiving to receive the at least another 
when the interrupt mode is activated and a stored desired category matches 
the at least another category. 
According to still another embodiment of the present invention, there is 
disclosed, an RDS receiver, comprising: means for receiving broadcast 
transmission signals, each of the broadcast transmission signal having a 
category, means for storing a desired category, controller means for 
monitoring a first broadcast transmission signal category and the 
controller means including means for scanning others of the broadcast 
transmission signal categories and the controller means including means 
for tuning the means for receiving to receive one of the others when the 
one category matches a stored desired category. 
According to still another embodiment of the present invention, there is 
disclosed, an RDS receiver, comprising: means for storing a desired 
category, means for receiving broadcast transmission signals each having a 
program and a category, controller means for tuning the means for 
receiving to receive a first one of the broadcast transmission signals 
after receiving a second one of the broadcast transmission signals when 
the second one matching a stored desired category, the controller means 
including means for activating an interrupt mode of the controller means, 
means for deactivating the interrupt mode when the first one category 
changes, the controller means including means for confirming a 
receivability of the second one after the first one category changes and 
the controller means including means for subsequently tuning the means for 
receiving to receive the second one when the receivability is confirmed. 
According to still another embodiment of the present invention, there is 
disclosed, a method for controlling a receiver, comprising the steps of: 
storing a desired category, generating a first audio signal from a first 
audio source, outputting the first audio signal, monitoring a category of 
a broadcast transmission signal, receiving the broadcast transmission 
signal and outputting a second audio signal derived from the broadcast 
transmission signal when the broadcast transmission signal category 
matches a stored desired category, continuing the outputting of the first 
audio signal when the broadcast transmission signal category is different 
from the desired category. 
According to still another embodiment of the present invention, there is 
disclosed, a method for controlling a receiver comprising the steps of: 
storing a desired category, receiving a first broadcast transmission 
signal having a category, storing a frequency of the first broadcast 
transmission signal, monitoring a category of the broadcast transmission 
signal, determining categories of other broadcast transmission signals 
when the first broadcast transmission signal category is different from a 
stored desired category, receiving one of the other broadcast transmission 
signals and storing a frequency of the one of when the one of category 
matches the stored desired category, receiving the first broadcast 
transmission signal when all of the other broadcast transmission signal 
categories are different from the desired category. 
According to still another embodiment of the present invention, there is 
disclosed, a method for controlling a receiver comprising the steps of: 
storing a desired category, receiving a first broadcast transmission 
signal containing encoded data indicating categories of other broadcast 
transmission signals, monitoring a category of the first broadcast 
transmission signal, continuing the receiving of the first broadcast 
transmission signal while the first broadcast transmission signal category 
matches a stored desired category, scanning the encoded data to determine 
if one of the other broadcast transmission signal categories matches the 
stored desired category and receiving the one of when the first broadcast 
transmission signal category is different from the desired category, 
displaying the stored desired category. 
According to still another embodiment of the present invention, there is 
disclosed, a method for controlling a receiver comprising the steps of: 
storing a desired category, receiving a first broadcast transmission 
signal, monitoring a category of the first broadcast transmission signal, 
continuing to receive the first broadcast transmission signal while the 
first broadcast transmission signal category matches a stored desired 
category, consecutively receiving and checking categories of other 
broadcast transmission signals to determine if one of the other broadcast 
transmission signal categories matches the stored desired category when 
the first broadcast transmission signal category is different from the 
stored desired category, receiving one of the other broadcast transmission 
signals when the one of category matches the stored desired category and 
the first broadcast transmission signal category is different from the 
stored desired category; and displaying the stored desired category. 
According to still another embodiment of the present invention, there is 
disclosed, a method for controlling a receiver, comprising the steps of: 
storing a desired category, receiving a first broadcast transmission 
signal, the first broadcast transmission signal having a program, storing 
the first broadcast transmission signal program, receiving a second 
broadcast transmission signal having a category matching a stored desired 
category, monitoring the second broadcast transmission signal category, 
continuing the receiving while the first broadcast transmission signal 
category matches the stored desired category, confirming a receivability 
of the first broadcast transmission signal when the first broadcast 
transmission signal category is different from the desired category, 
receiving the first broadcast transmission signal when the receivability 
is confirmed and receiving an alternative broadcast transmission signal 
when the first broadcast transmission signal when the receivability is 
unconfirmed. 
The above, and other objects, features and advantages of the present 
invention will become apparent from the following description read in 
conjunction with the accompanying drawings, in which like reference 
numerals designate the same elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, a Radio Data System (RDS) receiver 100 includes an FM 
tuner 1, with an antenna la, which receives an RDS broadcast transmission 
signal. An encoded RDS signal is derived from the RDS broadcast 
transmission signal by an RDS decoder 2. RDS decoder 2 outputs the RDS 
signal to a CPU 3. Command signals are sent to CPU 3 through a connected 
keyboard 4. Keyboard 4 includes an RDS key 10, a tune up/down key 11 and a 
preset key 12. CPU 3 outputs a variety of messages to a connected display 
5. 
An audio signal from FM tuner 1 is sent to a connected source selection 
switch 6. RDS receiver 100 contains a tape player 7 that sends an audio 
signal to source selection switch 6. Source selection switch 6 selects one 
of the audio signals from tape player 7 and FM tuner 1 for application to 
an input of an audio playing system 8. Audio playing system 8 demodulates 
and amplifies the selected audio signal to generate an output signal. The 
output signal of audio playing system 8 drives a speaker 9 to produce an 
audible signal. CPU 3 sends control signals to source selection switch 6 
through a control line to control it. CPU 3 also sends control signals to 
tuner 1 through a control line to tune it to desired frequencies. 
CPU 3 can support a function called program type display (PTY) which 
permits a user to select a desired category of program for listening. For 
example, the user may select one of news, music, drama, and educational 
categories. The RDS signal is a stream of RDS data derived from the RDS 
broadcast transmission signals by RDS decoder 2. These data are included 
in the RDS signal sent to CPU 3 by RDS decoder 2. Among the RDS data are 
PTY codes, which identify the program category of the RDS broadcast 
transmission being received by tuner 1. 
To cause RDS receiver 100 to tune to a broadcast with a desired program 
content, the user makes a PTY item, which represents the desired program 
category, using display 5 and keyboard 4. A PTY standby mode is selected 
through keyboard 4, which causes CPU 3 to search for an RDS broadcast 
transmission signal bearing a PTY code corresponding to the PTY item 
selected. If CPU 3 finds a transmission bearing the correct PTY code, it 
will adjust tuner 1 to receive the transmission. 
Referring to FIG. 2, if news is selected, for example, while tape player 7 
is playing in step 20, CPU 3 first determines if a news standby operation 
was selected through keyboard 4 in step 21. If news standby operation was 
selected, the RDS data received by FM tuner 1 is checked in step 22. If 
the content of the broadcast being received is news, source selection 
circuit 6 is switched from tape player 7 to FM tuner 1 in step 23. 
In some embodiments of the present invention CPU 3 automatically switches 
from the received RDS broadcast to a different broadcast based on a 
selected operating mode and certain criteria. These embodiments rely on 
Enhanced Other Network (EON) data to receive information regarding other 
networks. The EON data, which may be transmitted by RDS stations, provides 
information about the program content of other network stations besides 
the particular one being received. This data includes a list stations 
currently broadcasting, each correlated with a corresponding PTY code for 
the program being broadcast. 
Referring to FIG. 3, in step 30 a broadcast from a station providing EON 
data is received by tuner 1. Control then proceeds to step 31. If news 
standby mode is selected in step 31, control branches to step 32. If news 
standby mode is not selected, control returns to step 30. Step 32 branches 
to step 33 if the category of the broadcast being received is the same as 
the selected news category. In step 33, "NEWS" is shown on display 5, and 
the current station continues to be received. If the broadcast being 
received is not the same as the selected news category, control branches 
to step 34 where the EON data is scanned for another network with a 
matching program category. If a match is found, the corresponding station 
is tuned-in in step 35. In step 36, an identifier for the new station is 
stored in a memory. By permitting the selection of the PTY standby mode 
described above, this embodiment puts RDS key 10 to a use additional to 
its use in prior art RDS receivers, which is merely to activate the RDS 
display function. 
Referring now to FIG. 4, an RDS broadcast is being received in step 40. 
Control proceeds to step 41. Step 41 branches to step 42 if RDS key 10 is 
pressed for at least a specified interval (two seconds in the present 
embodiment). If RDS key 10 has not been pressed for at least two seconds 
in step 41, control returns to step 40. In step 42, a PTY selection mode 
is activated and the PTY item displayed on display 5. Control proceeds to 
step 43 which branches to step 44 if tune up/tune down key 11 has been 
pressed or to step 45 if it has not. Step 45 returns to step 42 if 5 
seconds have elapsed since the PTY selection mode was activated. Thus, 
control loops through 42, 43 and 45 until either 5 seconds pass, or tune 
up/tune down key 10 is pressed. If 5 seconds pass without the user 
pressing tune up/tune down key 10, control proceeds to step 46 where the 
PTY interrupt standby mode is activated and display 5 reverts to the 
original display. 
In Step 44, a consecutive PTY item from a stored list of PTY items is 
called and displayed. Control proceeds back to step 42. If the desired PTY 
item was the last one to be displayed, it is selected when the five second 
period in step 45 runs out. If tune up/tune down key 10 is pressed, 
another PTY item is called up from the list and displayed. This process 
continues until a desired PTY item is selected by permitting the 5 second 
timer to run out. Note that this selection process requires no keys 
additional to those for setting the PTY standby mode. 
Referring to FIG. 5, an RDS broadcast containing EON data is received in 
step 50. Control proceeds to step 51 where a PTY item is selected and PTY 
standby mode initiated. Control then proceeds to step 52, which branches 
to step 55 if the current station matches the PTY selected, or to step 53 
if the current station's PTY code and the selected PTY item do not match. 
In step 55 the selected PTY item is displayed and reception continued. 
Step 53 returns to step 51 if there is no other station in the EON link, 
i.e., there is no station in the list of stations whose PTY code matches 
the PTY item selected. If a matching station is found, tuner 1 is adjusted 
to receive the station in step 54. Control proceeds from step 54 to step 
55 where the current PTY item is displayed and the current station is 
received. 
Referring to FIG. 6, PTY standby mode is active in step 90. Control 
proceeds to step 91 which branches to step 92 if the PTY code of the 
current station has changed. If the PTY code of the current station has 
not changed, control returns to step 90. In step 92, a search over the 
entire broadcast band is executed to find a station broadcasting a signal 
with a PTY code that matches the selected PTY code. After step 92, control 
proceeds to step 93 which branches to step 95 if no matching PTY code is 
found, or to step 94 if a match is found. In step 94, the station with the 
matching PTY code is received. In step 95, the original station is 
received and standby operation resumed. 
Referring to FIG. 7, when PTY standby mode is activated in step 60, control 
proceeds to step 61. In step 61 it is determined if the PTY code of the 
program currently being received has changed. If the PTY code of the 
current station has changed, the PTY interrupt mode is disabled in step 
62. If the PTY code of the current station has not changed, control 
returns to step 60. In step 62, the station that was current prior to the 
activation of the PTY interrupt mode is tuned in, and the PTY interrupt 
mode disabled, at step 62. The PI code of this station is checked in step 
63 and, if the PI code can be read (confirmed), normal reception is 
activated. Failure to confirm the PI code indicates the signal quality is 
poor. When the PI code cannot be confirmed in step 63, control proceeds to 
either the embodiment shown in FIG. 8 or the embodiment shown in FIG. 9. 
With the above control sequence, if during PTY interrupt mode reception, 
the original station's field strength changes due to travel or other 
causes, the tuner reverts to the station that was received prior to 
interrupt only when a PI code can be confirmed. Confirmation of the PI 
code is possible only when a good signal is being received. Thus, this 
control sequence assures that good reception is maintained by not 
reverting to the previous station when the PI code cannot be confirmed. 
Referring to FIG. 8, if there is an AF list, the AF list is searched in 
step 70. An AF list is an encoded list of stations indicating the programs 
being broadcast by each station. The AF list may be included in the RDS 
data. If a signal is found in step 71, which has a PI code identical to 
that of that of the station received prior to activation of the PTY 
interrupt mode, control proceeds to step 76 where that signal is received. 
If no match is found, a scan for an identical PI code is performed in 
steps 72, 73 and 74. 
In step 72, the FM frequency band is scanned to find the frequency of the 
next receivable signal. In step 73, the PI code of that next receivable 
signal is compared to the PI code of the station selected prior to 
activation of the PTY interrupt mode. If a match is found, control 
branches to step 76 where the station with the matching PI code is tuned 
in. If no match is found control proceeds to step 74 which loops back to 
step 72 until the entire frequency band has been scanned and the 
corresponding PI codes of each signal checked. If no match is found after 
the scan of the entire band, the last frequency before the interrupt is 
and tuned in at step 75. 
Referring to FIG. 9, if there is an AF list memory, the AF list memory is 
searched in step 80. If a signal is found in step 81, which has a PI code 
identical to that of the station received prior to activation of the PTY 
interrupt mode, control proceeds to step 89 where the matching signal is 
received. If no match is found, control proceeds to step 82. 
At step 82, the FM band is scanned for an RDS station. Control proceeds to 
step 83 where the PI code of the new station is compared to that of that 
of the station received prior to activation of the PTY interrupt mode. If 
a match is found, control branches to step 89 where the matching station 
is tuned in. If no match is found in step 83, control proceeds to step 84 
where it is determined if a regional digit of the signal is one of 1, 2 
and 3. The regional digit is embedded in the RDS data of the signal being 
received. If the regional digit is the same, the signal strength at the 
previous frequency B is compared to that at the new frequency A in step 
85. If the regional digit is different, control advances to step 87. At 
step 85, if the strength of the signal at frequency A is higher, control 
proceeds to step 86 where the new frequency data are stored in memory 
location B. If the strength of the new frequency signal is lower than that 
of the signal stored at B, control proceeds to step 87. Step 87 returns to 
step 82 and the previous steps between 82 and 87 are repeated. These steps 
continue to be repeated for each new station until, either a matching PI 
code is found at step 83, or a scanning of the entire FM band is found to 
be completed in step 87. If the scanning of the FM band is completed 
without finding a matching PI code in step 83, control proceeds from step 
87 to step 88. In step 88, the frequency stored in memory location B, is 
tuned in. The frequency stored in memory location B is either the 
frequency being received when the PTY interrupt mode was activated or a 
new frequency. The frequency stored in memory location B is a new 
frequency if, while cycling through steps 84 through 86, a frequency was 
found which had the regional digits of 1, 2 or 3 and which had a greater 
field strength than the original frequency. The frequency at B would then 
be the frequency of the signal which had the greatest field strength of 
all such signals. At step 89, normal reception continues. 
According to the embodiment of FIG. 9, after the PTY interrupt mode is 
activated, it is possible to return to the same program being received at 
the time the PTY interrupt mode is invoked. If that program is not 
available, the receiver will tune in to the international, national or 
regional station having the strongest signal. 
Having described preferred embodiments of the invention with reference to 
the accompanying drawings, it is to be understood that the invention is 
not limited to those precise embodiments, and that various changes and 
modifications may be effected therein by one skilled in the art without 
departing from the scope or spirit of the invention as defined in the 
appended claims.