Q&A: FM 92.4MHz in Ipoh, Perak from Gunung Kledang. Suitable or non-compliance?

2.5 years ago, my blog Philip DXing Log received a comment from Syafiq on "Kool FM Perak frequency (PART 1 suggestion)".

First of all, thanks for everyone's feedback on my blog post. Can FM 92.4MHz be used in Gunung Kledang Ipoh?

This was an interesting question, but the answer is NO! I will share about the reasons.

The reason why isn't FM 92.4MHz suitable to be used for Ipoh radio transmission from Gunung Kledang is there are already having two radio stations which transmitted from Gunung Kledang and their frequencies allocations are nearby FM 92.4MHz, namely Ai FM 92.1MHz Gunung Kledang and Hitz FM 92.7MHz Gunung Kledang.

If a radio station assigns its Ipoh frequency on FM 92.4MHz, it will definitely interfered to Ai FM 92.1MHz and Hitz FM 92.7MHz, or FM 92.4MHz is badly interfered by Ai FM 92.1MHz and Hitz FM 92.7MHz. Just like a burger is centered by two breads, when you eat a hamburger, two breads will "press" the burger because it located between two breads. 

The maximum frequency deviation of a radio station is 75kHz +/-. For this study, even if install with band pass filter (4 or more poles), this does not guarantee FM 92.4MHz avoids interference each other.

92.1MHz: Ai FM Gunung Kledang

92.4MHz: Gunung Kledang

92.7MHz: Hitz FM Gunung Kledang

<300kHz, NOT GOOD>

Technically, the minimum frequency separation for radio station within same sites and coverage is 400kHz. It is impossible to have a band pass filter to be installed for these 3 stations in Gunung Kledang.

Another different case is One FM 87.6MHz and Fly FM 87.9MHz, both are from Gunung Kledang, and having 300kHz separation. For this case, it is still ok because "no sandwich" allocation within same sites. In addition, both of them are using high pass filter.

In addition, FM 92.4MHz is not suitable to be used in Gunung Kledang due to interference with Nasional FM 92.3MHz Bukit Ladang Teh, minimum separation must be at least 200kHz. 

If FM 92.4MHz is used in Perak's gap filler transmission site such as FELDA Terolak, or Ulu Slim (like Perak FM), it is ok because those gap filler areas are not Gunung Kledang coverage. Currently, FM 93.3MHz is the only available frequency in Gunung Kledang, Ipoh, Perak.

MCMC is performing FM frequency re-planning study, and all broadcasters frequency applications are suspended until frequency re-planning study is done. Therefore, frequency proposal is not suitable to be done at the moment.