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AW: VLF: EbNaut transmission on 8270.1 Hz again and again

To: Paul Nicholson <[email protected]>, "[email protected]" <[email protected]>
Subject: AW: VLF: EbNaut transmission on 8270.1 Hz again and again
From: Markus Vester <[email protected]>
Date: Sat, 30 Apr 2016 15:59:51 +0200
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Stefan wrote:

> For slower modes (taking more then 12 hours), could it be

> useful to insert non-keyed sections to make a phase check

> each 2 hours or so?


Paul wrote:

> Maybe, but it would spoil the Eb/N0 capability of the mode.


Our way of generating the PSK signal already generates a very weak carrier component: At each bit transition, the phase takes a couple of seconds to swing around from -90 through 0 to +90 degrees (or vice versa). This creates short blips on the 0° real axis, on average a one second pulse every 80 seconds, equivalent to a -38 dB carrier. These blips are also causing the other spectral lines at clockrate multiples which are visible in the „6000“ window from the tree.


If you want you could create a stronger carrier component by slightly unbalancing the PSK phases. For example, switching from -80 to +80 degrees would create a sin(10°)=-15.3 dB in-phase carrier, while weakening the modulated quadrature component by only cos(10°)=-0.133 dB.


All the best,


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