[OZAPRS] 80m on thursday night

[G T & C A Beagley]

OK. I have no problem with that.

BUT If Scott VK7HSE is using the same tones then why does he think he 
will be out of band? I can't see any problem with him using LSB and it 
will get him away from the interference problem! The point I raised has 
nothing to do with what tones I am using but was to do with Scott's 
statement that he can't use LSB. Of course he can.
You still haven't said what 2 frequencies are being used in VK7 and that 
is the main info required. As long as the highest freq is at least 150hz 
(according to your info) inside there should be no problem.

Graham

ZL1GTB

Hamish Moffatt wrote:

> 
> 
> Agreed. But that does not change anything.
> 
> You have 2100 Hz and 2300 Hz tones from your modem, but they are not 
> single point frequencies (of infinitely small width). When you switch
> between them at 300 bps to convey information, there are sidebands
> created around each tone, proportional to the switching frequency.
> 
> You can expect the sidebands to be at least the baud rate around each
> tone, ie 300 Hz. That means +/- 150 Hz from the tone frequency. Thus
> the 2300 Hz tone extends up to 2450 Hz. 
> 
> For an upper limit of 3.625 MHz, you can afford your dial frequency to
be 
> no higher than 3.62745 MHz (3625 + 2.45 kHz). If higher, you are out of
band.
> 
> Hamish


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