ITU-R BS.450-1
FM Stereo Coder
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 at 19 kHz and a 38-kHz carrier modulate with difference signal, according to ITU-R BS.450-1.
The algorithm provides proper band shaping; audio signal is limited to 15 kHz and rejection at 19 
kHz is in excess to all standard.
The double balance modulator has a carrier rejection impossible in analog modulators.

Features and Benefits

•	Lower cost than analog
•	Very efficient assembly-optimized language code
•	Absolute stability—no retuning or balance adjustment
•	Program is downloaded to internal RAM for fast execution
•	First class THD, noise level, and spurious response
•	Pilot tone and subcarrier phases and amplitudes can be changed at run time

Processor and System Requirements

•	Supported on 'C30 or `C31 @ 50 or 60 MHz
•	Audio input via serial port
•	Audio output via serial port or bus
•	Optional parameters are stored in external RAM
•	Input sampling rate: 32, 44.1, 48k samples @ 16 to 24 bits
•	Output sampling rate: 192, 176.4, or 220.5, 192k samples @ 16 to 24 bits

Usage Limitations or Performance Considerations

•	External program memory (ROM): 1k words
•	External optional parameters memory (RAM): 5 words
•	Internal data memory: 1k words
•	Internal program memory: 1k words
•	Processor loading: requires exclusive use of processor

Algorithm Verification

•	15 tone THD test signal supplied
•	Single-tone spurious test signal supplied
•	Pulse for frequency and group delay measurement supplied
•	Conforms to ITU-R BS.450-1

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