Well I am glad I was persuaded to keep trying by Pete! On 136kHz WSPR 4 
different stations have been received in the last day despite my totally 
useless setup. Thank you to everyone for the encouragement.

73s
Roger G3XBM

On 22 Jan 2018, at 23:55, "Alan Melia" <[email protected]> wrote:

> Hi Martin I think Andy has answered the question for me so I wont confuse 
> your with further facts :-))
> 
> In the days when I used to pontificate daily on propagation I tried hard to 
> ensure the sensitivity of the rx system was reasonably constant and I did not 
> have too much external noise. We had problems but Brian CT1DRP had a line on 
> his waterfall we never located but was external and very constant. It 
> provided a very good confidence boost and I believe did show Brian when his 
> earth connection corroded and fell off. The general opinion for the source of 
> the signal was a harmonic from a digital comms line (I think it was a 
> harmonic of 8kHz) I came across a couple of ceramic 'bookends' the other day 
> which I never used :-))
> 
> Happy LFing
> Alan
> G3NYK
> 
> 
> ----- Original Message ----- From: "Martin Evans" <[email protected]>
> To: <[email protected]>
> Sent: Monday, January 22, 2018 8:06 PM
> Subject: Re: LF: 136kHz - this is how badmy system is!
> 
> 
>> 
>> Alan - thanks for this.
>> Being a bear of very little brain ( I wouldn't recognise a Newton if I 
>> tripped over one!) much of your explanation goes over my head, but I 
>> understand well enough your conclusion that "that is not bad".
>> 
>> One thing that I don't understand is the relevance of bandwidth to an SDR 
>> receiver.
>> 
>> If I short my receiver input, my baseline stands at -140dB ( that's the 
>> lowest that the spectrum display goes); connect my antenna and my background 
>> noise level around 137kHz is around -120dB; DCF30 is around -70dB at the 
>> moment, and if I increase my scan width, R4 on 198kHz is -40dB. All these 
>> measurements are taken from the spectrum display in the Elad software.
>> 
>> I don't see where bandwidth comes into the picture(!!)
>> 
>> No doubt one of these days some of this will begin to make sense....
>> 
>> Thanks again,
>> 
>> Martin GW3UCJ.
>> 
>> ********************
>>> Hi Martin, I would estimate the field strength from DCF39 in your area is 
>>> about 0.5mV/m (from measurements done by PA0SE in the UK) and from your 
>>> data that gives about 1.5uV at the RX input as the level of the noise. If 
>>> that is in an SSB bandwidth that is not bad. I remember the noise plotted 
>>> on my CFH measurements in around 2002 was in this area but in a 300Hz bw, 
>>> on the AOR7030 (Remembering WSPR s/n is related to a 2.3kHz bw if I 
>>> remember right)
>>> My minimum signal detection using a waterfall on the audio was 5nV (rx bw 
>>> not relevant) but 0.3Hz bin size using a good sig-gen. I guess this was 
>>> little more than 1 to 1.5dB above the noise. I think it was probably 
>>> quieter here in East Anglia 15 years ago than it i now.
>>> 
>>> I hope that helps (saves you ripping your station apart :-)) )
>>> Alan
>>> G3NYK
>>> 
>>> ----- Original Message ----- From: "Martin Evans" <[email protected]>
>>> To: <[email protected]>
>>> Sent: Monday, January 22, 2018 4:51 PM
>>> Subject: Re: LF: 136kHz - this is how badmy system is!
>>> 
>>> 
>>>> 
>>>> Watching Roger's adventures on 136kHz, I thought I'd go take a look and I 
>>>> wondered -
>>>> 
>>>> DCF39 is about 50dB above the noise at 16:44UTC.
>>>> 
>>>> I'm using a 150ft inverted L, untuned, stuffed directly into an Elad 
>>>> FDM-S2 SDR.
>>>> 
>>>> Decoded G3XIZ, G4FTC, G8HUH & G4GIR between 16:12 and 16:44.
>>>> 
>>>> What does this say about my setup?
>>>> 
>>>> Is it deaf/average/ok?
>>>> 
>>>> How far above the noise is DCF39 in an optimised "good" setup?
>>>> 
>>>> Anyone tell me?
>>>> 
>>>> Martin GW3UCJ Swansea.
> 
>