[hpsdr] MDS

[john_eckert at agilent.com]

Hi Folks,

I haven't been following this too closely, but I would add another angle.

The atmospheric noise level numbers suggest that sensitivities greater 
than these are a waste. I.E., you can't hear below the atmospheric noise.

There are two cases I can think of where I would want all the sensitivity 
I can get:

i. When we are at the bottom of a sunspot cycle as we are now. On forty meters during the day I'm limited by my receiver MDS.

ii. On 160 meters I use a beverage and it normally reduces signals by
greater than 30db and noise by 40db.  So I get 10db better S/N but lose
30db sensitivity.  I can hear signals Q5 on the beverage that I can't 
detect on my dipole.  This is another case where I'm limited by NF(MDS)
rather than atmospheric noise.

Great job guys!  As always I want more.  More sensitivity and more 
dynamic range.

73,
John
k2ox


Message: 1
Date: Fri, 11 Aug 2006 13:23:14 +0100
From: "Grant Hodgson" <grant at ghengineering.co.uk>
Subject: Re: [hpsdr] MDS
To: hpsdr at hpsdr.org
Message-ID: <20060811122314.M27343 at ghengineering.co.uk>
Content-Type: text/plain; charset=iso-8859-1

John

Many thanks for posting this - I've never seen it before.  Please could you
post the data for 160m and 6m as well if you have it, to complete the list?

regards

Grant G8UBN

>Minimum atmospheric noise levels (above thermal noise) for the HF bands in
the quietest locations at the quietest time of the year are:
 
>80 m  38 dB
>40 m  33 dB
>20 m  28 dB
>15 m  23 dB
>10 m  18 dB
 
>This is according to CCIR surveys. The receiver NF should be 6-10 dB lower.


 1155406719.0