Commercial Broadcasting Service, All India Radio, Thiruvananthapuram was commissioned on 1.5.1975 on an 1 KW AM transmitter. Though the reach of the station was confined to the Thiruvananthapuram city at that time, it became immensely popular because it was an entertainment channel offering very good music programmes. Programmes from Vividh Bharati, Mumbai were also being relayed.
Commercials were introduced in all the stations of All India Radio in 1985, and from then onwards, CBS, AIR, Thiruvananthapuram has been in charge of canvassing and broadcasting commercial advertisements over all the stations located in Kerala. The thrust of CBS from then on has been to market airtime and thus earn commercial revenue for All India Radio.
On 15.8.1999 the new 2 x 5 KW FM transmitter was commissioned for CBS, AIR, Thiruvananthapuram and this brought about a vast change in the listnership of programmes. With the commissioning of the new 2 x 5 KW FM transmitter, the programmes of CBS, AIR, Thiruvananthapuram have acquired tremendous popularity because of its crystal-clear reception. The expansion in the area of coverage coupled with the quality of reception has resulted in an immense growth as far as the number of listeners are concerned. With the growth in popularity and area of coverage, the transmission hours were also increased. Now, the transmission which starts at 5.55 AM extends up to 11.00 PM without any break. The broadcast of Malayalam programmes have been increased by two hours daily and this has been appreciated by the public very well and the listeners response now is tremendous.
Very popular programmes like Phone-in film songs requests, Old film songs and Listeners requests are well received both by the listeners and advertisers. Film Sound Tracks and Film Songs presented by well-known Film personalities have attracted the listeners very much. Due to the betterment of the technical qualities, the programmes relayed from Vividh Bharathi, Mumbai have become technically very clear and this also was a blessing to the listeners. Even though Kerala has a number of very strong private TV channels, the popularity of the music programmes on Radio has been going up day by day. With the starting of the FM transmission, the number of users of car radios has shown a steep increase. The introduction of public utility announcements like train timings, traffic diversions, disruption in water supply etc have become beneficial to the listeners.
The programmes of CBS, AIR, Thiruvananthapuram are received by the listeners owning FM radio sets in the entire Thiruvananthapuram district and major parts of Kollam and Pathanamthitta districts. The programmes are received also in parts of Alappuzha and Kottayam districts. Kanyakumari district, which is in Tamil Nadu also is able to receive these programmes.
The area covered is around 3660 sq.kms and the population, which is able to receive the programmes, is 4526766.