8
3.3
Power Supply
The RDS encoder can be supplied from any power supply, which delivers a stabilized DC 12 V voltage and a current of at least 500 mA and no
more than 2 A. Commonly available switching wall adapters are usually suitable for that purpose. The RDS encoder includes polarity and short-
circuit protection. The central conductor of the power supply connector is positive (+).
Note: After first power-up, there is no need to configure anything to turn on the RDS subcarrier. The RDS encoder will immediately start to
generate the RDS signal with factory default values (PS: * RDS *, PI: FFFF, RDS level: 4000 mV p-p).
3.4
Connecting the RDS Encoder to a Local PC
For the purpose of initial configuration and local control requirements the RDS encoder is equipped with standard USB interface provided on
the rear panel of the RDS encoder. This connector allows direct connection to a PC using USB cable type A-B.
USB driver must be installed prior to start communicating. Virtual COM port feature provides seamless compatibility with broadcast automation
software. After successful installation a new COM port will appear in Windows Control Panels / Device Manager.
3.5
RDS Level Adjustment
Important note:
There is no universal setting for the RDS level. Due to different input sensitivity of different FM broadcast equipment it's
necessary to check and adjust the RDS level!
The correct level should be between 2 and 11 % of the audio multiplex signal, measured by oscilloscope in peak-to-peak values on the
modulator input. Recommended value is such that results in 3.4 kHz deviation of the FM carrier. Don’t forget that the maximum total FM carrier
deviation with RDS and MPX signal is 75 kHz. It is much easier to use any FM broadcast analyzer for setting the RDS level precisely.
The RDS level can be adjusted after establishing a connection to the encoder, using one of these two methods:
In the Windows software
Go to
Options – Preferences – Control
and check the item ‘Enable RDS level control’. Now the control is available on the System sheet in the
main window.
The software allows adjusting the RDS level in range 0.4 to 100 %. In the P132 RDS encoder, that range is proportional to the output level
range of 15.6 to 4000 mV p-p. Confirm the setting by Store button.
In the embedded website
Click on menu item Setup – Signal Control and enter the RDS level directly in mV p-p unit.
In terminal, using ASCII command
LEVEL=
The P132 RDS encoder allows direct adjusting of the RDS level in 256 steps, in range 0 to 255, by assigning a corresponding value to the
LEVEL parameter. Each step represents approx. 15.6 mV increase.
Desired step count can be calculated as
1
4000
256
level
RDS
Output
LEVEL
Actual output RDS level (in
mV p-p
) can be calculated as
4000
256
1
LEVEL
level
RDS
Output
The deviation range of the FM carrier caused by RDS/RBDS is
1.0 to 7.5 kHz
.
The deviation range of the FM carrier caused by stereo pilot tone is
6.0 to 7.5 kHz
.
The overall peak frequency deviation shall not exceed
75 kHz
.