RDS Decoder¶
- Table of contents
- RDS Decoder
https://sites.google.com/site/tekmanoid/rds
RDS Decoder Chips¶
To make RDS decoding fit on a project board, you need some help with the most difficult part, namely: the actual filtering of the RDS data stream from the radio. Thanks to Philips and SGS-Thompson, there are two chips that do the job!
SAA6579 - Philips
TDA7330 - SGS-Thompson
The two chips above are the most common. Personally I use the one from Philips. I will admit that the chips can be hard to get hold of. They cost roughly 5 euros each. But beware that depending on were you call, you will be "forced" to buy 1000 or more units or nothing at all. If you dont have any friend in the electronics business, you may try opening an old, broken?, RDS receiver locate the chip, and use that instead.
These chips are basically the same in the sense that they receive a multiplexed signal as an input, process the RDS stream, and give the RDS DATA and RDS CLOCK as outputs on two pins. This is raw data. It still needs a lot of manipulation / processing to make any use of it. From a techies point of view this is were the actual decoding will take place. The RDS protocol will have to be studied, and from there write a program (easier) or build hardware (harder) that decodes the information from this raw data stream into an understandable form. The decoder chip just needs a few external components to work. I decided to use SMD components on a small PCB (see below) and have a small RDS decoder unit which is easily transferable between projects.
PC based Decoder¶
If you want to make RDS decoding as simple as it gets, this is the approach for you, and it should satisfy most techies =)
There is a windows based RDS decoding program out there provided by Esslinger. They recently released a second version of their program which is very good. If you read the documentation of the program you will see that all you need to do, is connect the RDS DATA and RDS CLOCK pins through a simple interface to the PC’s COM port. This is described in detail in the software documentation.
Instead of the classic MAX232 voltage converter they advise you to use a cheaper TTL IC, the 74LS14.
{{Image("rdshookup.jpg")}}
