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RE: LF: RE: Japan on 475 kHz.

To: <[email protected]>
Subject: RE: LF: RE: Japan on 475 kHz.
From: "Hideho YAMAMURA" <[email protected]>
Date: Tue, 23 Dec 2014 12:25:21 +0900
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Hello Dimitris-san,

> 1) 43 db + 10*log(PEP)
> 2) 50 dB
we have the same regulation (with grace period now),
but, it seems that the ministry was afraid of the actual interference,
hence, on site test.

In my quick calculation, I assumed 0.3uV/m harmonic at AM BC receiver point,
which is about -60dBc from AM BC carrier 250uV/m in weak areas,
assuming S/N of about 40dB for audio output,
and, for distance of 30m, 1pW EIRP was the limit,
and for 10m distance 1fW EIRP was the limit,
that are -120dBc to -150dBc relative to 1W EIRP transmit.
I hope my calculation is wrong.

Do people have measured data of the noise level at around 950kHz?
I am to try to measure it quantitatively, hopefully during the new year holiday.

 73,

  Hideho YAMAMUA, JF1DMQ


> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Dimitrios
> Tsifakis
> Sent: Tuesday, December 23, 2014 10:58 AM
> To: [email protected]
> Subject: Re: LF: RE: Japan on 475 kHz.
> 
> Hi Hideho san,
> 
> >> I use a low pass filter which ensures that the harmonics are -50 dBc
> >> or lower. I think the tuned antenna also helps with not radiating too
> >> much
> > My quick calculation resulted in -120dBc necessary, to reduce QRM to
> > adjacent houses,  (I may be wrong)., and I am thinking how to make it.
> 
> In Australia, for frequencies below 30 MHz we need to reduce our harmonics
> by the lesser of:
> 1) 43 db + 10*log(PEP)
> 2) 50 dB
> 
> where PEP is peak power to the antenna. When I was allocated an experimental
> license for 500 kHz, I was asked to demonstrate that my harmonics are reduced
> by 60 dB (from memory).
> 
> 73, Dimitris Vk1SV



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