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+--- Thread: Why FM mode carrier on 107.3MHz from Mount Isa? (/thread-1445.html)
Why FM mode carrier on 107.3MHz from Mount Isa? - JR4ENY/1 - 17-08-2024
I am checking FMBC from Australia by MROFFT software these days.
And found from Mount Isa have the carrier-like signal on 107.3MHz.
It is very useful to check weak TEP path but only 107.3 have it for a long time.
(I could see it on 106.5 too but it did'nt continue long time)
107.3 carrier-like signal continues long time but sometimes stops.
I can't find go and stop pattern yet.
The attached file shows a good sample when the carrier-like signal was cut off halfway through.
Why 107.3 have carrier-like signal on FM mode.
And why no others?
I guess in Australia uses a different FM broadcast modulation method than JA.
FB DX!
de JR4ENY/1 Awa
RE: Why FM mode carrier on 107.3MHz from Mount Isa? - VK5TM - 17-08-2024
Not sure re the mode, but 107.3 is Australian Broadcasting Corporation's Radio National service.
Are you sure it's Mount Isa?
That frequency is used all round Australia for the RN service, you can check locations here https://www.transparency.gov.au/publications/communications-and-the-arts/australian-broadcasting-corporation/australian-broadcasting-corporation-annual-report-2018-19/appendices/appendix-12---radio-transmission-frequencies
RE: Why FM mode carrier on 107.3MHz from Mount Isa? - VK2AZ - 17-08-2024
Is that a narrow band signal or a wideband broadcast signal (200KHz)?
If I do a search on the ACMA register:
https://web.acma.gov.au/rrl/assignment_range.search
There are many wideband 200KHz Broadcast signals across Australia, but only one from Mount Isa that I can see.
RE: Why FM mode carrier on 107.3MHz from Mount Isa? - JR4ENY/1 - 17-08-2024
(17-08-2024, 01:22 PM)>Are you sure it's Mount Isa? Wrote: Yes.
I can hear FMBC stations from Mount Isa every night these days.
101.7 102.5 103.3 104.1 104.9 106.5 107.3
And around equinox we can hear high-power FMBC stations from Cairns
101.1 105.1 105.9 106.7 107.5
and from Townsville
101.5 104.7 105.5.
Attached files are 104.7 from Townsville and 105.1 from Cairns.
Both seems to have carrier-like as the same as 107.3 from Mount Isa.
(only 1 time I could see trace on those frequencies this August)
My antenna is 6el yagi for VOR.
So lower frequencies are no good because of gain.
Anyway it is curious for me to see carrier in FM modulation on 107.3MHz.
de JR4ENY/1 Awa in Kawasaki JAPAN PM95SN
RE: Why FM mode carrier on 107.3MHz from Mount Isa? - VK5TM - 18-08-2024
I wonder if it might be the RDS signal.
There was talk of it being turned on across the ABC network some years ago but the funding wasn't available then, maybe things have/are changing in that regard.
RE: Why FM mode carrier on 107.3MHz from Mount Isa? - JR4ENY/1 - 18-08-2024
(17-08-2024, 11:32 AM)Last night,TEP condx was better. Wrote: I hrd FMBC from Townsville,Mount Isa+ and Cairns peaking S=7 1853-2105LT.
Then I found stations with carrier were mainly 4ABCRN.
I don't really understand the principle of RDS,
but I'm sure it involves superimposing carrier.
Anyway.I am a 2m DX lover and seriously want to work VK on 2m.
We JA1s QRV 144.460 FT8 actively.
PSE try to check JA-VK path there.
I guess no problems with Mount Isa by FT8.
FB DX! JR4ENY/1 Awa
RE: Why FM mode carrier on 107.3MHz from Mount Isa? - VK5TM - 19-08-2024
The RDS signal is a 57kHz subcarrier imposed on the main signal - same as the 19kHz pilot tone in FM signals.
RE: Why FM mode carrier on 107.3MHz from Mount Isa? - JR4ENY/1 - 19-08-2024
(19-08-2024, 10:01 AM)VK5TM Wrote: The RDS signal is a 57kHz subcarrier imposed on the main signal - same as the 19kHz pilot tone in FM signals.
When RDS information is being sent,the carrier's trace disappears but when no RDS info,trace is visible.
In other words, 4ABCRN is RDS compatible,but it hardly transmits any RDS information.
Is it correct?