equivalent input voltage noise density of 400 nVeff/SQRT (Hz). Please your opinion about this concept? 73s de Bernd, DF9RB |
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| To: | [email protected] |
|---|---|
| Subject: | AW: Re: VLF: E-field receivers in Todmorden |
| From: | "Bernhard Wiesgickl (Asamnet)" <[email protected]> |
| Date: | Sun, 03 Sep 2017 09:35:48 +0200 |
| Importance: | normal |
| Reply-to: | [email protected] |
| Sender: | [email protected] |
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Hello Paul, I followed your reports about your disappointing results with a new low noise amplifier. I plan to build this amplifier: This LNA is built with 4 parallel FETs in front of a low noise OP-Amp and has an
Von Samsung-Tablet gesendet -------- Ursprüngliche Nachricht -------- Von: Paul Nicholson <[email protected]> Datum: 02.09.2017 8:43 (GMT+01:00) An: [email protected] Betreff: Re: VLF: E-field receivers in Todmorden Markus wrote: > maybe in the received signal level from the Alphas? > ... a bit of directivity due to environmental conditions I wonder. One curious fact supporting this is the noise blanker drop factor. This is the proportion of time the blanker is active. The drop factor is always a bit higher on the new rx than the old when I run the two signals through independent sferic blankers. The blanking threshold is set relative to the noise floor, which is tracked by an asymmetric moving average. The new rx must have a lower threshold to have a higher blanking factor, therefore vtblank is finding a lower floor (relative to the sferics) on the new rx compared with the old. So, the E-field probes are not quite omni-directional perhaps? I need to look at more signals, from different directions, to build a picture. -- Paul Nicholson -- |
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