Telecommunications – Receiver or analog modulated signal frequency converter – Signal selection based on frequency
Reexamination Certificate
2000-01-05
2002-06-25
Le, Thanh Cong (Department: 2684)
Telecommunications
Receiver or analog modulated signal frequency converter
Signal selection based on frequency
C455S045000, C455S154100
Reexamination Certificate
active
06411800
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a communication system for transmitting and receiving enhanced text messages with commercial FM radio broadcasts; and more particularly, to a radio communication system wherein the enhanced text messages are displayed on the face of a radio receiver.
2. Description of the Prior Art
The Radio Data Systems (RDS) was developed in Germany in the 1980s as an outgrowth of a traffic alerting system. It is widespread throughout Europe, and was introduced into the US in 1993 where it is known as Radio Broadcast Data System (RBDS). In 1997, numerous automakers introduced RDS radios in the US. RDS uses a low data rate digital subcarrier at 57 kHz to transmit data such as a station's call letters or program type (Jazz, etc.) along with the main radio signal. The data rate is 1187.5 bits per second, equivalent to a 1200 baud modem, although after overhead and mandatory protocol elements are accounted for the remaining data rate available to applications is about 300 bits per second. There is also a provision for sending 32 or 64 character text messages, referred to as “Radio Text”. The data is typically displayed on a small monochrome text screen mounted on the radio's face. Most commonly, this screen is 8 characters long, and Radio Text messages are scrolled across the screen to present the entire message.
The RBDS standard is created and published by the National Radio Systems Committee (NRSC), formed jointly by the National Association of Broadcasters (NAB) and the Consumer Electronics Manufacturers Association (CEMA), a division of the Electronics Industry Association (EIA). The RBDS standard is a derivative of the RDS standard published by the European Broadcasting Union, headquartered in Geneva, Switzerland, as CENELEC EN50067.
The RDS data stream consists of 16-bit blocks called A, B, C, and D, which are transmitted sequentially in endless repetition. Each block carries a specific data type, which is defined by the RDS protocol. The A block always carries the radio station ID, B-blocks contain control information, the C block carries either station ID or data, and the D-blocks contain data. Each specific arrangement of A, B, C, and D blocks is called a group, of which there are 32 types, divided into 16 type A groups, and 16 type B groups. The RDS and RBDS standards define specific meanings or applications for several of these groups, while several groups remain unused and undefined. The first four bits of the B block defines to the group number of the possible 16 groups within a group type, and the next bit defines if it is a group type A (bit 5=0) or a group of type B (bit 5=1). Group types are referred to with the notation
0
A,
0
B through
15
A,
15
B. The distinguishing character of group type B is that the station ID from the A-Block is duplicated in the C-block of the group, making this slot unavailable for data. In the US, the station ID serves no purpose.
The Group Type determines the application, and thereby the definition of all the variable bits in the B-Block. The Group Types and applications of primary interest to broadcasters in the US include:
0
A, Alternate Frequency and Program Service Name (Slogan);
2
A &
2
B, Radio Text;
10
A, Program Type Name (PTYN); and
0
B &
15
A, Program Service Name (Slogan).
Only one or two applications can be defined by an individual Group Type, that matter being determined by whether the C- and D-Blocks will be used for the same application, or whether the C-Block will carry one application while the D-Block will carry another. As an example, the Group
0
A has two applications, one in which the C-Block carries Alternate Frequency information, and one in which the D-block carries Program Service information (also called Slogan).
Two individual bits in the B block are used for highway traffic announcement related indicators (the TP bit, and the TA bit). The TP bit assignment is common to all group types, while the TA bit assignment is only defined in three of the group types. In the prior art, the B block was configured as described in FIG.
2
.
One deficiency of the present arrangement is that radio stations can identify themselves as one, but only one, of the 32 categories of Program Types using the PTY bits as listed in TABLE I below. Thus a radio station could define itself as a Rock station, and a listener using an RDS receiver designed to scan for stations by format would be able to find this station. If during a News, Weather, or Sports announcement the station wished to be found by scanning, they could change their PTY to one of News, Weather, or Sports. If the station had selected News, and a listener were scanning at that moment for News, the station would be found. However, once the station changes its PTY from Rock to News, other receivers searching for Rock stations will not discover it until it changes back. Thus, a station can use RDS to identify itself by any one of the available Program Types, specifying a music format (Rock, Classical, Jazz, etc.), or a non-musical program format (News, Weather, or Sports), but only one at a time; and if the station is classified by anything other than what a listener is scanning for, it won't be found.
TABLE I
RBDS LISTING OF PROGRAM TYPES (PTY)
Binary
8-char
Number
Value
Display
Meaning
0
00000
* * * *
No Program Type
1
00001
NEWS
News
2
00010
INFORM
Information
3
00011
SPORTS
Sports
4
00100
TALK
Talk
5
00101
ROCK
Rock
6
00110
CLS ROCK
Classic Rock
7
00111
ADLT HIT
Adult Hits
8
01000
SOFT ROCK
Soft Rock
9
01001
TOP 40
Top 40
10
01010
COUNTRY
Country
11
01011
OLDIES
Oldies
12
01100
SOFT
Soft
13
01101
NOSTALGA
Nostalgia
14
01110
JAZZ
Jazz
15
01111
CLASSICL
Classical
16
10000
R & B
Rhythm & Blues
17
10001
SOFT R&B
Soft Rhythm & Blues
18
10010
LANGUAGE
Language
19
10011
REL MUS
Religious Music
20
10100
REL TALK
Religious Talk
21
10101
PERSNLTY
Personality
22
10110
PUBLIC
Public
23-29
10111-
Unused
11100
30
11101
TEST
Emergency Test
31
11111
ALERT!
Emergency
A similar deficiency relates to the Traffic Program (TP) identifier bit. According to the standards, a radio station may turn on the TP bit to indicate that the station does provide traffic announcements sometime during the day. Obviously, this fact by itself is not very meaningful to listeners interested in hearing a traffic report. The TP bit is associated with a Traffic Announcement (TA) bit (bit
4
) for group types
0
A,
0
B, and
15
B. The meanings of TP/TA bit combinations according to the RBDS standard are described in TABLE II.
TABLE II
MEANINGS OF RBDS TP/TA BIT COMBINATIONS
TP (bit 10)
TA (bit 4)
Applications (in groups 0A, 0B, 15B)
0
0
No traffic announcement either on this station
or on a network affiliate station
0
1
This station carries information about a
network affiliate station that may broadcast
traffic announcements
1
0
This station carries traffic announcements, and
may carry information about a network affiliate
that may carry traffic announcements, but no
announcements are currently being broadcast
1
1
A traffic announcement is currently being
broadcast on this station
In groups such as
1
A &
1
B where bit
4
is not defined as TA, an explanation of how to interpret the TP bit is not provided in the standard. The way the TP/TA scheme is designed, the broadcaster must send a group
0
A,
0
B, or
15
B with both TP and TA set to one to set a flag in a receiver indicating that the station is now transmitting a traffic report, and send a similar message with TP/TA set to 0 to turn off the flag.
In order for a receiver to scan the band to find a station broadcasting a traffic report, the data indicating a traffic report would need to be available in every B-Block being transmitted. Otherwise, if the moment a receiver tuned to a specific station and did not find the desired data, it would have to interpret the absence of that data as an indication that no traffic report is present, and go on to the next station. Otherwise,
Buff Ernest D.
Cong Le Thanh
Ernest D. Buff & Associates LLC
Fish Gordon E.
Le Lana
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