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BE
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Re
REP
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CIRCUIT DESCRIPTIONS
RDS (Radio Data System)
@® RDS is
anew FM-broadcasting system, which is promoted by European Broadcasting Union (EBU) in Europe and by National
Radio System Committee (NRSC) in U.S.A.. Inaudible control signals are transmitted with the subcarrior to automatize FM
reception and maximize operating ease. With RDS, the tuner can display the call name of the currently received station or
search automatically for the strongest transmitter signal with the same or any specified program. These features are highly
useful also for receiving traffic information or ensuring optimum reception in a car.
@ Main specifications of RDS
Data rate
1,187.5 bps
Signal format
~
(26,16) modified shortened cyclic code
Baseband signal format
Differential phase shift keying (DPSK)
Subcarrier frequency
57 kHz
Subcarrier frequency modulation
Doubie Side Band Suppressed Carrier Amplitude Modulation
Maincarrier frequency deviation
+2 kHz
@ Data channel
Data channel employs 57 kHz band to minimize interference to programme band. RDS signal is a signal with bit rate of
1,187.5 bps. modulated by differential phase shift keying (DPSK). This signal comprises the composite signal and an
additional! signal with subcarries of 57kHz modulated in amplitude by double side band suppressed carriers.
Pilot signai
"en
Main signal
3)
=
.
.
"
es
Stereo sub-signai
ARI (Signal for traffic information
5
'
system of German originality )
D
LR
L-R
2
2
2
&
wo
jam
15
19
23
38
53
57
Frequency (kHz)
@ Data Format
Ail data are transmitted in a group unit which comprises 104 bit. The 104 bit unit comprises 4 block, which format 26 bit block
respectively. Each block comprises 16 bit information words and 10 bit check words. Data in each block are specified
depending on the situation: The first 16 bit of the first block is always the program identification (Pl) code, the first 5 bit of the
second block is a group-type to clarify the group application, the next 1 bit is Traffic Program Identification (TP) code, and
the following 5 bit is Program Type (PTY) code. Each contents of data is specified for remainder of the second block, the third
and fourth block data respectively. Group type comprises 32 types of OA~15B, which transmit different contents in each group
respectively. Group OA has a role of basic tuning function, and therefore is transmitted most often. "
1 Group = 4 blocks = 104 bit
oa
Block 4
Block 2
Block 3
Block4
a
-
-
-
ale
$$$
nformation
Check
Information
Check
Information
Check
as Information
aoe
| |
pry code (5 bit)
,
TP code (1 bit)
Pl code
(16 bit)
Group type codf
(5 bit)
Pl: Program Identification Code (Country identification, Area coverage, Programme reference number)
TP: Traffic Program Identification Code.
;
PTY: Program Type Code (News, Sports, Classical, Rock)
30
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