ITU-R BS.450-1 
FM Stereo Coder With ITU-R BS.643-1 RDS, ARI, and SCA
by M.B. International S.r.l.

Software Overview

The FM Stereo coder takes two audio signals, left and right channel, binary coded in accordance to 
AES/EBU standard and returns a complete stereo multiplex signal, composed of a sum signal, a pilot 
tone signal at 19 kHz, a 38-kHz carrier modulated with difference signal, a 57-kHz carrier 
modulated with RDS signal according to CENELEC EN 50067, a 57-kHz carrier modulated with ARI signal 
and two subcarriers modulated with a SCA signal.
The algorithm is compliant with recommendations ITU-R BS.450-1 and ITU-R BS.643-1
The algorithm provides proper band shaping; the audio signal is limited to 15 kHz and rejection at 
19 kHz is in excess to all standard.
The double-balance modulators have a carrier rejection impossible in analog modulators giving 
superior quality auxiliary services.

Features and Benefits

•	Lower cost than analogue
•	Pilot tone and subcarrier phases and amplitudes can be changed at run time
•	Absolute stability - no re-tuning or balance adjustment
•	Ready for every existing standard or service like German ARI or US SCA
•	First class THD, noise level, and spurious response
•	Scaleable to suit customer requirements
•	Very efficient assembly-optimized language code
•	Includes precision pre-emphasis with correct group delay
•	Program is downloaded to internal RAM for fast execution

Processor and System Requirements

•	Requires two processors: one `C30 or `C31 @ 50 or 60 MHz and a second `C3x @ 50 or 60 MHz 
including the `C32
•	Audio input via serial port
•	Interprocessor communication via serial port
•	Audio output via serial port or bus
•	Optional parameters are stored in external RAM
•	Input sampling rate: 32, 44.1, 48 k samples @ 16 to 24 bits
•	SCA and ARI: input from external bus
•	Output sampling rate: 192, 176.4, or 220.5, 192 k samples @ 16 to 24 bits

Usage Limitations or Performance Considerations

•	External program memory (ROM): 1k words each processor
•	External optional parameters memory (RAM): 1 words on first processor, 0 to 14 words on second
•	Internal data memory: 1k words first processor, 256 second
•	Internal program memory: 1k  words first processor, 256 words second;
•	Optional external RDS data memory (ROM): up to 3.5 Mwords on second processor bus
•	Processor loading: both algorithms require exclusive use of processors

Algorithm Verification

•	15-tone THD test signal supplied
•	Single-tone spurious test signal supplied
•	Dummy RDS message supplied
•	Pulse for frequency and group delay measurement supplied
•	Conforms to ITU-R BS.4501, ITU-R BS.643-1, and CENELEC EN 50067

Availability

Available now

Company Background and Contact Information

M.B. International is a research and design company serving mainly broadcasting equipment 
manufacturers. Our lab has 20 years of experience and has contributed to the big development of the 
Italian broadcasting industry. We are now an international company, serving customers worldwide. 
Several patents certify our involvement in new technologies.
Contact:	Mike Bargauan
		M.B. International srl
		Via Beolchi 1
		20151, Milano
		Italy
		+39 2 4091 0570
		Fax: +39 2 4091 0582
		e-mail: 
		  100522.2272@compuserve.com