RDS vs RDS-2 | Difference between RDS and RDS-2

This page compares RDS vs RDS-2 and mentions difference between RDS and RDS-2.

Introduction : RDS (Radio Data System) signal is transmitted by FM radio station along with other signals such as mono audio, stereo audio, tone and direct band. The European standard specifications are published under document CENELEC EN 50067. Most of the FM stations use RDS mostly in car radio receivers in Europe.

RDS carries informations such as station identification, time, program information along with audio. RDS occupies about 4 KHz bandwidth and it is transmitted on 57 KHz center frequency using BPSK modulation. BPSK modulated RDS information is frequency shifted to 57 KHz and mixed with other components of the FM signal before FM transmission. BPSK symbols are transmitted at the rate of about 1187.5 symbols/sec. Hence RDS raw data rate is about 1.2 Kbps including overhead information. RDS uses CRC (Cyclic Redundancy Check) for error detection.

RDS has been in use since 1984 and standardized in 1990. In 2016, RDS forum has proposed modifications to existing RDS. The RDS-2 specifications are published in Oct. 2018 under IEC 62106:2018 document. RDS forum has developed new protocol known as RDS2 file transfer which can be used to transfer all kinds of file types up to the size of 163 KB. RDS-2 is backward compatible with RDS version. RDS is used with FM and digital radio where as RDS-2 is used by FM/digital radio and internet radio. Following table summarizes difference between RDS and RDS2 versions.

Specifications/Features RDS RDS-2
AFs (Alternative Frequencies) 87.5 to 108 MHz 64 to 108 MHz
PS (Programme Service) 8 characters (Max.) Upto 32 bytes, UTF-8 coded
Programme Logo Not available Various formats up to 12 Kbyte size can be used
Enhanced radio text Up to 64 characters (Latin/UTF-8 coded) Up to 128 byte (UTF-8 coded)
Traffic Message Channel Carries few messages viz. 50 messages/minute (max.) Carries many more messages viz. 250 messages/minute using second subcarrier
Number of subcarriers (SCs) 1 Up to 4
Number of parallel active open data applications 20 (8 in Type-A, 12 in Type-B) As supported in RDS plus additional 64 (Type-C)
Cost of implementation Low High


• https://www.radioworld.com/
• https://www.rds.org.uk/

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