They look like they might be REGdracastdrplled 1000 dvgled 1000 plusseriesdaylight . html LEDs to me . I could be wrong though . <| sep |> I am a broadcast engineer in the united states . Most of the answers here are on the right track . You have to have a basic understanding of the FM transmission system first to gain a better working knowledge from start to finish of RDSRDBS . I ' m trying to explain this in a simple way With ANALOG FM transmission in the US a baseband or multiplexed signal is generated , to then transmitted using frequency modulation . So when you tune your car radio to 104 . 9 MHZ the station is actually covering a little bit more bandwidth to left and right of 104 . 9 FM , that is one reason why stations are spaced apart . you won ' t see or be able to tune 105 . 0 FM , , try it ! Back to the baseband that is being generated . It actually has several parts to it . A portion of it is for LEFTRIGHT or mono audio . Another portion is for LEFTRIGHT audio . If you sum together the LR and LR you receive STEREO . There is also a tone at 19 KHZ in the baseband . This is how your car radio knows to look for the LR portion , to give you that stereo image . If the 19 KHZ tone is too weak to receive the radio understands that it should only latch onto the LR or mono portion . The LR is injected at a stronger level than the LR . This is done on purpose , so when you are far away from the radio station transmitting antenna you can still get the MONO audio , with less noise than if you were trying to get stereo reception at that distance . There is more space left in the baseband for auxiliary services . Most notably the RDS RDBS standard for US stations portion , this is where the data bits are inserted . The radio station will extract their own metadata from whichever computer system they use to playout their audio known as automation systems , and they can configure how they want this data to be formatted when it appears on the radio display . Some stations have a static text that doesn ' t change , like just showing the call letters and maybe a call in number . Most are dynamic and update the text for different songs or programs or sports scores if they wish . There is still more space in the baseband to insert a few more narrow band mono audio programs . You would need a special FM tuner that can switch over to these SCA Subsidiary Communications Authorization channels embedded into the baseband . Back in the day , radio station owners would lease these SCA channels to companies like Muzak . Muzak would then use the SCA channel to broadcast their own music meant for malls , hotels , elevators , ETC . Muzak would sell the rights to carry their music format to the malls to use . $$$ Reading for the blind services would also use and still use these hidden mono program channels that can be received with the correct tuner . Back to RDS or RDBS . The original RDS can also direct your FM radio to do things like change frequencies . This is mostly used for European other non US broadcast stations that consist of many low power FM transmitters across multiple frequencies . So if you are driving across the country and Capital FM is your station of choice , it will automatically retune to the next strongest repeater station making it appear as one large high powered FM station . In the US , the FM band is configured a little bit different so we don ' t use the alternate frequency flag . We also don ' t use the traffic flag where if 98 . 5 MHZ has relevant traffic info you could tell the radio to goto 98 . 5 MHZ when they go to read a traffic report . The radio would jump to 98 . 5 MHZ and then go back to your other selection when the traffic read was over . So RDBS is a very stripped down version of the European RDS system and featuresNow HD radio is a totally different set of standards . All you need to understand is that in the US you will have the analog FM station , and on left and right sidebands you will have the digital HD carriers as well . If you have the HD compatible radio it will see the digital signals and lock onto those instead of the analog . The digital bit streams of HD radio contain the HD 1 , and HD 2 to 4 audio sub streams if valid , as well as all the PAD data like artist and title , and even album art is being transmitted over the air . Unfortunately in the US HD radio adoption is not large . Different counties use different systems so don ' t confuse HD radio with DAB as its totally different . Even though a lot of stations have purchased the equipment to transmit HD radio , the general consumers are not aware that it exists .