I finally remembered to bring some of the radio test gear home from work, & had time to do some test comparisons between 2HD 90.5 MHz Belmont North translator, Hit 106.9 & NEWFM 105.3, this afternoon. These tests were done with the test antenna inside my garage at Floraville NSW, I disconnected the GPS, so my exact home location wasn’t plastered all over the internet.
2HD was on network programming out of the Newcastle (2HD) studios.
2HD 90.5 Belmont is definitely a mono program with a Stereo pilot. I can’t say where the true stereo starts & ends, or if it even starts anywhere at all, but I can say without a doubt, the FM translator output is stereo with no channel separation (mono).
If you look at the Stereo Quality graph on 2HD, that’s mono audio (no stereo separation), whereas NEW & Hit have stereo separation.
I also noticed that the Stereo Pilot on 2HD doesn’t vary with the program, it’s fixed at 7.1kHz.
Being a percentage of the overall modulation level, it should vary in it’s frequency as the program changes, but it doesn’t, & that has me a bit perplexed as to where & how it’s being generated & injected, as it’s obviously not being related to the rest of the modulated signal, the RDS frequency does change as normal.
Normal Stereo Pilot is recommended to be 9% of the 75kHz deviation, RDS levels are recommended to be 5% of the 75kHz deviation & should vary in size relating to the deviation. In 2HD’s case, the fixed pilot will sometimes be a higher percentage & sometimes a lower percentage of the overall deviation, as it seems to be a fixed (not variable) level.
The first 2HD graph set is playing Goanna - Solid Rock, the second 2HD graph set is playing Richard Harris - MacArthur Park, Hit was playing Pink, & NEWFM was playing Nickelback.
