Many thanks to SWLing Post contributor, Dan Greenall, who writes:
This is a follow up to the SWLing Post article from last May informing about a frequency change at the Voice of Indonesia from 4750 to 4755 kHz.
My long time friend Ken (VE3HLS) has been retired and living in northern Thailand for several years now. He continues to enjoy his radio hobby from that location, and recently sent me a recording he made of the Voice of Indonesia on 4755 kHz:
He states:
“It’s not a vintage recording from back in the 70s. It’s from last night! I was tuning around and found the Voice of Indonesia booming in on 4755 kHz in English, no less!”
It reminded me of the good old days so I thought I would pass it along to share with the group.
73
Dan Greenall VE3HLC
Thank you Dan and Ken for sharing this recording!
Indonesia has some Digital Radio Mondiale in the FM band already. They are particularly wanting the Emergency Warning Functionality. If they were to add a DRM content server and modulator to the HF transmitter it would sound like FM complete with stereo sound and EWF.
https://radioinfo.asia/conference/drm-demonstrates-multi-standard-receiver-solution-at-indonesian-event/
Some background on RRI.
https://youtu.be/ZkkasCan4Yg
No, DRM on HF would not sound like FM, because the sound transmitted via DRM on the HF bands is highly compressed, the bitrates are ca. 30 kbps (even less than what dial-up could deliver in the late 90s) which results in considerably distorted quality with lots of digital artifacts. FM radio is not digitally compressed, which means absolutely no distortion of the transmitted signal. According to the results of independent tests conducted by HydrogenAudio forum members (google: “Personal Listening Test of AAC-LC and xHE-AAC at 96kbps and 128kbps”), even the newest xHE-AAC codec delivers only “perceptible, but not annoying” sound with 96 kbps. DRM on HF cannot deliver such high transmission speed. It would have need to be increased at least 5 times for the delivered sound to be indistinguishable from the one transmitted via FM radio. DRM was not able to enhance the transmission speed during the last 2 decades, so it’s highly unlikely they’ll be able to do it now.
As for the DRM implementation in Indonesia, do you have some info about the stations that transmit DRM signals on the FM band? How many of them are on the air? What types of DRM receivers are available in Indonesia? Which models of DRM receivers have implemented the Emergency Warning Functionality?