1. Career Episode 2
RDS Encoder
1
RDS Encoder
Introduction
CE2.1
Designing and Construction of RDS modulator was one of my valuable experiences in TAKTA
Company that I did it in 2011 and it was developed in 2012. New version with more features
and new options ended in 2011 and now it’s ready for industrial productions after prototyping
production, debugging in software and hardware. I have tried to give a good overview about
RDS system in broadcasting with related software and hardware and my experience about this
part of FM Transmitter.
Background
The nature of overall engineering project:
CE 2.2
RDS (Radio Data System) is a protocol for transferring digital information in conventional FM (or
VHF) broadcast over regular audio programs. This information include date and time,
advertising and other text messages, and perform additional ID, control and housekeeping
functions. On the other hand RDS offers the possibility for data service provider to introduce
new data services to many users. Thus RDS can accommodate a wide range of possible
implementation options.
Physical layer of RDS system
Method of modulation
CE 2.3
The subcarrier is amplitude modulated by the shaped and bi-phase coded signal. The subcarrier
is suppressed. This method of modulation may alternatively be thought of as a form of two-
phase shift keying (PSK) with a phase deviation of ± 90 degrees.

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RDS Encoder
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The source data at the transmitter are differentially encoded using below table:
Where 𝑡𝑡𝑖𝑖 is some arbitrary time and 𝑡𝑡𝑖𝑖−1 is the time one message-data clock period earlier, and
where the message-data-clock rate is equal to 1187.5 Hz.
Thus when the input level is 0, the output remains unchanged from the previous output bit, and
when an input 1 occurs, the new output bit is the complement of the previous output bit.
Baseband coding
CE 2.4
Figure below shows the structure of the baseband coding. The largest element in the structure
is called a “group” of 104 bits. Each group comprises 4 blocks of 26 bits. Each block comprises
an information word and a check word. Each information word comprises 16 bits and each
check word comprises 10 bits.

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RDS Encoder
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Objectives to be achieved with RDS
Features
CE 2.5
The following fields are some features in RDS system:
- AF (Alternative Frequency)
This option allows a receiver to retune to a different frequency providing the same station
when the first signal becomes too weak. That is, RDS receivers (e.g. car radio receivers) search
for the best signal that carries the same program with no audible interruption.
- CT (Clock Time)
RDS is capable of setting the date and time on RDS receivers equipped with a clock. Using of
this option is arbitrary.
- PS (Program Service)
This is the station’s name that might typically appear on the receiver faceplate display. PS can
be up to eight characters in length and can be as simple as the station’s call letters. For long
message transferring, RDS use dynamic PS, that is, it sends long message in a succession of
eight character frames.
- PTY (Program Type)
This data flag identifies the station format from a list of pre-assigned categories. Many RDS
receivers are able to seek the listener’s preferred listening preference automatically. This helps
a broadcaster catch a certain transient audience share …
- RT (Radio Text)
This is a 64-character block of plain text that the listener is able to select for visual display, but
on only those radios that have an INFO or TEXT button. The RT is not typically available on
automobile receivers for legacy safety considerations.
- TMC (Traffic Message Channel)
Traffic information can be send by RDS. It is often available for automotive navigation systems.
In many countries only encrypted traffic data is broadcast, and so an appropriate decoder,
possibly tied to a subscription service, is required to use the traffic data.

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RDS Encoder
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The nature of my particular work area:
CE 2.6
The RDS project was done in TAKTA Company and was divided into different parts: Designing
the overall block diagram, Designing the schematics and circuits, analyzing different parts of the
circuits, Assembly, Connecting different parts together, constructing, programming and finally
testing and optimizing it.
Designing the circuits, programming and analyzing it, was my particular work in this project as
an electronic-communication engineer. I was also regularly controlling the progress of the
project and was responsible for different stages of construction.
It was a golden opportunity for me to increase my project management abilities and skills to
professionally utilize the resources of the project.
A chart of the organizational structure highlighting my position:
CE 2.7
TAKTA Electronic Research and Production Company have three main divisions: Business
Department, Technical Department and Financial Department. The Research and Development
(R&D) Section is a Technical division.

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RDS Encoder
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TAKTA
Electronic Research and
Production Company
Financial SectionTechnical SectionCommercial Section
Research and
Develeopment
(R&D)
Production Section
Technical Support
Suppervisor
Technical Engineer
Technician
(Mountaging)
Quality Control
I have been working as an Electronic and Microwave Engineer in the Research and
Development Department (R&D).
My job includes designing, simulation, optimization and test of different electronic and
communication circuits. I have designed the main passive parts of digital UHF Transmitters and
High Power FM Transmitter(for example: combiner, splitter, sampler, directional coupler,
different types of adaptors and connectors, impedance matching circuits and etc.) and some
electronic and active parts of UHF Digital transmitters and FM Transmitter (for example: High
power amplifier, AGC, Drive Amplifier, RDS Encoder and etc). At the first stage I design and
simulate circuits with related software (for example: ADS, CST Microwave office, HFSS, DXP and
etc). After an optimization and simulation, I draw its PCB with Alitium2004 software. Then these
Circuits Boards files are sent to print. After the print, I usually assemble different elements on
the PCB and test it with different advanced Electronic Measurement instruments.
At the end of the process, I usually write a complete report and documentation about my work
to be able to have a useful background from my jobs in the future.

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RDS Encoder
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A statement of my duties:
CE 2.8
I was responsible to:
- Design the Block diagram of different parts of the project.
- Design, Simulation and programming of the circuit of the project (with related software).
- Assembling, test and Correction of the PCB.
- Supervise on each step of my tasks and finalize the construction.
- Manage the team and control the project progress steps.
Personal Workplace Activity
CE 2.9
Leading features of my board include:
. All of groups in RDS (EN50067 standard) supported.
. UECP protocol supported (it use for RDS parameter control in network)
. Offers RS232, RS485 serial and TCP/IP connectivity
. The front-panel LCD screen and keyboard for local data entry without computer using
. A build-in scheduler can automatically transmit RDS commands based on date & time
. Embedded web server (HTTP)
.Convenient loop-through or side-chain operation with any exciter/stereo coder combination
. Software adjustable amplitude and phase of output signal
. High security and conditional access for network data entry
. Huge memory for data bank saving
. Software development by customer ordering

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RDS Encoder
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Strategies devised by me including any original or creative design work
CE 2.10
I designed and assembled the below circuit according to the purposes of the project and my
electronic engineering studies.
Technical Specifications:
My project technical parameters are summarized in below table:
RDS Signal
Differential & BiphaseCoding
DSSCModulation
57 KHz±6HzCenter Frequency
±2.4 KHzBand Width
0-2500mv p-p (5mv Step)Level
0-360 (6˚ Step)Phase
Internal or External(Automatic Switching)Synchronization
Un balancedOutput Type
Interface
RS232 , RS485 (DB9)Serial
Full duplen 10/100 M Base-T (RJ45)TCP/IP
2 opto – isolation & 1 relay (DB9)I/O
MPX or 19KHz in (BNC)Connector In
RDS Out (BNC)Connector Out
RDS Features
PS-PI-TP-TA-PTY-PTYN-MS-DI-RT-CT-AF-EON-EWS-IH-TMC-TDC-PIN-SLC-LINK-FFG-ODA

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RDS Encoder
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Block diagram
CE 2.11
Below figure is a simplified block diagram of my board. As a brief description, output signal is
produced in CPU2 after D/A (Digital to Analog conversion) and filtering with gain control
process. It may be added to MPX input signal if you need or send to output connector directly.
Synchronization signal (114 KHz clock) can be constructed in TIMEBASE unit internally or may
be extracted from input signal by filtering and other process in PLL unit.
CPU2 acts as a communicator with other devices via serial port and LAN port. It processes all of
the information and then it sends the results to CPU1.
Input signal will be send to output connector without any change via bypass relay when there is
any problem in the board or if encoder power is lost.
On the other hand, there is a RTC chip (Real Time Clock) with battery backup in my board for
date and clock synchronization.
CPU2
CPU1
3bit
D/A
Gain
Control
57 KHz
BPF
D/A
Rectifier
12 bit
∑
Rectifier
+5 V
Bypass Relay RDS/MPX
Output
Side/Loop
SwitchPilot/MPX
Input
19 KHz
BPF
PLL
LOCK
114 KHz Clock
Time Base
114 KHz Clock
SPI
LAN
Processor
3 bit
SPI
Interupt
Clock
RJ45 LCD
Key Pad
LED
I/O
DB9
EEPROMRTC
BAT
RS232
DB9
RS485
DB9
Block Diagram

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RDS Encoder
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Circuit Description:
CE 2.12
Circuit descriptions refer to the next two pages schematic diagram.
Stereo pilot recovery- a sample of MPX signal is filtered by the band pass configuration of op-
amp U8 (TL072 from TI) to recover the 19 KHz stereo pilot. Tone decoder U14 (LM567 from
national) lends further filtering action and squares up the 19 KHz waveform. PLL unit consists of
U10 (CD4046) and U11 (CD4018), the output of PLL unit is a 114 KHz square wave six times
multiplication of the stereo pilot. This is a clocking that is used by digital processing stages to
generate the RDS subcarrier.
RDS waveform synthesis- U7(DSPIC33FJ128GP804 from Microchip) is a high speed
microprocessor with onboard memory and other useful subsystems. The function of this unit is
to synthesize the RDS waveform. This chip has an on-board crystal oscillator to establish an
internal master clock for RDS waveform generation if the stereo pilot is not obtained. Digital
subcarrier waveform are sent to D/A chip U6 (DAC902 from TI) for digital to analog conversion.
Band-pass filter and combining stage- the segmented RDS waveform from the D/A chip is
passed through dual band pass filter stages, U4 (TL072 from TI). This 57 KHz filter removes
higher order distortion components. U3 (AD817 from AD) is a unity gain output driver stage for
combining. with switching K1 in side chain mode , only the RDS subcarrier will be passed at
combining stage to the output connector. With switch K1 in loop through operation, MPX signal
applied to MPX input connector will be added to RDS subcarrier and combining signal will
appear at output connector.
Encoder data formatting- U20(DSPIC33FJ256GP710 from microchip) is a second microprocessor
that is responsible for receiving and formatting all incoming RDS data. This chip is able to
interface directly with the LAN port, U23 (ENC424J600 from microchip), and RS-232 serial
interface, U16 (MAX232 from maxim), and RS485 interface, U18 & U19 (MAX 485 from maxim).
U20 also addresses the LCD display and receive menu commands from the keypad.

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RDS Encoder
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11. Career Episode 2
RDS Encoder
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12. Career Episode 2
RDS Encoder
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My engineering knowledge and skills in this project
CE 2.13
Software consideration
Proteus- I have used this software for some hardware parts such as filters, buffers and amplifier
simulation after first designing.
Protel DXP- I used this one for PCB (Printed Circuit Board) preparation. The last and final PCB
was provided after three times by prototype debugging and board development. Next picture is
a sample layer of my board. This board was constructed on 2-layer FR4 board.
Microsoft office Front page- by notice that my board acts as web server, I need to design some
web page for all RDS parameter setting and monitoring. This software is like as other HTML
programming software. For example, you can see code and final related web page below.

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RDS Encoder
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My project programming code:
~inc:header.inc~
<div class="result fail" style="display:~status_fail~">Error: ~err_cont~</div>
<form method=post action=dpsrt.htm name=dpsrt>
<input type=hidden id=kka name=kka>
<table class="one">
<caption><h1>Dynamic PS & RT</h1></caption>
<thead><tr><th><br/>DPS buffer:&nbsp;&nbsp;
<input type=radio name=dps value=1 checked>Cyclic&nbsp;
<input type=radio name=dps value=3>del&nbsp;
<input type=radio name=dps value=4>del All&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<input type=button name=set value=update onclick=subcheck(1)>
</th></tr>
</thead>
<tbody><tr><td><div class=scrollarea style="height: 100px; width:99%;">
<table width=96% id=test onclick="ROW()">
<thead><tr><th width=10%>DPS No.</th><th width=85%>Content</th></tr></thead>
<tbody>
<tr><td>01</td><td>~da(0)~</td></tr>
<tr><td>02</td><td>~da(1)~</td></tr>
<tr><td>03</td><td>~da(2)~</td></tr>
<tr><td>04</td><td>~da(3)~</td></tr>
<tr><td>05</td><td>~da(4)~</td></tr>
</tbody></table></div></td></tr>
<tr><td>No.:<select id=dpn name=dpn></select>&nbsp;<input type=text name=ddd style=width:85%></td>
<tr><td>Repetition(1-5):<input type=text name=psr value=~db~ size=1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Scrolling speed:<select name=dss>
<option value=30 ~dc(0)~>Low</option>
<option value=20 ~dc(1)~>Normal</option>
<option value=10 ~dc(2)~>Fast</option>
</select>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Scrolling char(1-8):<input type=text name=psc value=~dd~ size=2 maxlength=1>
</td></tr>
<thead>
<tr><th>&nbsp;RT buffer:&nbsp;&nbsp;&nbsp;
<input type=radio name=rts value=1 checked>Cyclic&nbsp;
<input type=radio name=rts value=3>del&nbsp;
<input type=radio name=rts value=4>del All&nbsp;&nbsp;nbsp;
<input type=button name=set value=update onclick=subcheck(2)>
</th></tr></thead>
<tr><td><div class=scrollarea style="height: 100px; width:99%;"><table width=96%>
<thead><tr><th width=9%>RT No.</th><th width=80%>Content</th></tr></thead>
<tbody>
<tr><td>01</td><td>~de(0)~</td></tr>
<tr><td>02</td><td>~de(1)~</td></tr>
<tr><td>03</td><td>~de(2)~</td></tr>
<tr><td>04</td><td>~de(3)~</td></tr>
<tr><td>05</td><td>~de(4)~</td></tr>
</tbody></table></div></td></tr>
<tr><td>No.:<select id=rtn name=rtn></select><input type=text id=rt1 name=rt1 onkeydown=RTBoxes()></td></tr>
<tr><td>Repetition(1-5):<input type=text name=rtr value=~df~ size=1 maxlength=1>&nbsp;&nbsp;&nbsp;&nbsp;
Group version:<select name=rtg>
<option value=0 ~dg(0)~>A type</option>
<option value=1 ~dg(1)~>B type</option>
</select>&nbsp;&nbsp;RT A/B flag:<select name=rtf>

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RDS Encoder
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<option value=0 ~dh(0)~>ON</option>
<option value=1 ~dh(1)~>OFF</option>
</select>
</td></tr> </tbody>
</table><br/></form></div>
<script language="javascript">
<!--
function subcheck(kk) {
if(kk===undefined)return;
document.getElementById('kka').value=kk;
document.dpsrt.submit();
}
subcheck();
function ROW(){
var tab=document.getElementById('test');
var row=document.dpsrt.test.rows.item ;
document.dpsrt.dpn.selectedIndex=row;
document.dpsrt.rtr.value='3';
}
ROW();
function RTBoxes() {
e = document.forms.dpsrt;
st = document.dpsrt.rtg.selectedIndex;
if(st) document.getElementById('rt1').maxLength=32;
else document.getElementById('rt1').maxLength=64;
}
RTBoxes();
-->
</script>
~inc:footer.inc~

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RDS Encoder
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Web Page
Mplab- this is a C compiler from Microchip Co. main part of program in relation with CPU1 and
CPU2 was written in this environment. All of programs were implemented on their Flash
memory.
Any particular difficulties /problems I encountered and how I solved them
CE 2.14
Hardware consideration
All of main parts of hardware were installed and tested separately. By this step by step
procedure, I could debug and solve some problem like these:
Regulator temperature- at the first design, I used only one regulator to supply 3,3v to CPU1 and
CPU2 and some other components. It became hot after 15 minutes working. So I decided to use
two regulators for CPUs separately. Then they work in better conditions and I got good noise
reduction additionally.
LAN fail- when we connect to board via Ethernet port, some packet will be lost. I reduced the
data transfer speed but I could not solve the problem, so I understood that there is no software

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RDS Encoder
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problem. I checked the hardware, by try and error and changing the capacitance of related
crystal oscillator, I could solve this problem (by using of 10pF capacitor instead of 20pF).
RTC fail- CPU1 had not good performance and worked slowly in final board checking. When I
checked it , I saw that RTC chip (PCF8593) interrupt the CPU1 in one second interval except one
minute. That is, CPU was very busy for RTC chip interruption. I changed this chip by new and
original one, so it worked properly.
How I worked with other team members
CE 2.15
Team working was important factor in my achievement to the progress. Apart from exclusive
design related activities done by me, I was responsible for all stages of the project procedure. I
had very friendly relationship with all team members. I prepared project schedule and
determined each member task. I carefully followed and updated schedule based on the reports
given by project team members. I collected very useful information from other experienced
engineers and different books and web sites to increase my technical knowledge and share all
information with other team members. There was not any conflict between team members
because I tried to clearly define all tasks of project. In a word it was very successful team
working and I earned many practical and valuable experiences during the project progress.
Summary
My view of the overall project
CE 2.16
RDS project was one of the best and high tech projects of TAKTA Company which I did it with
the help of other team members. I considered many different factors in this project. For
example I selected my necessary Electronic and Mechanic elements according to their quality,
prices and their accessibility. Many costumers before this project and our RDS Encoder product,
were complaining about the minor quality and high price of other similar RDS Encoder systems
which had been produced.
After finishing the project, customer feedback showed a significant rise in the customer
satisfaction. To sum up, it was very successful project both in technically and financially view.

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RDS Encoder
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How my personal role contributed to the project
CE 2.17
Before the starting the project I spent a considerable time on gaining more information about
different types of RDS Encoders. I studied different related books, surfed the web and talked to
expert engineers about this subject. Finally according to collected information and other
important factors (financial, accessibility, quality, features and etc) I designed the best block
diagram for this project.
In addition my knowledge about the designing and analyzing electronic circuits and equipment
specifications helped the project to be successful considerably.