[Lowfer] WSPR overload

jrusgrove at comcast.net jrusgrove at comcast.net
Wed Feb 6 14:56:12 EST 2013 

Pat

Said I was going to change the subject line last time ... doh!

I have been using Delta 44s exclusively for quite a few years now and have tried others but keep 
coming back. BTW, all the machines here are older Dell 4600s ... 2.8 GHz, 1-2 g Ram running XP SP2. 
Newer machines don't have PCI slots? Shows how out of touch I am.

You've probably already looked into this ... but just in case ... make sure that the audio going 
into your sound card isn't overdriving it. If you find that you're just barely cracking the computer 
volume slider and have romping stomping volume into the application try reducing the receiver audio 
output. One of the best parts of the Delta 44 is the M audio utility. Being able to see input and 
output levels on the bar graphs in relation to clipping levels, ability to select input levels and 
select/see the sampling rates requested by the application, etc is all useful information. Cheap on 
board audio cards don't tell you much of anything ;~(

Jay





----- Original Message ----- 
From: "pat bunn" <pbunn at patbunn.com>
To: "Discussion of the Lowfer (US, European, &amp;UK) and MedFer bands" <lowfer at mailman.qth.net>
Sent: Wednesday, February 06, 2013 2:00 PM
Subject: Re: [Lowfer] WSPR-15 tonite


> Jay,
>
> You mentioned one item that makes be very suspicious, the sound card. It is a Dell that came with 
> the new computer. It calibrates very well with respect to frequency but it is a "junk" type card. 
> I used to use a Delta 44, but they don't fit in the new machines so mine is laying in a pile of 
> parts somewhere around here. I bought a $125 external Soundblaster USB card last year but I think 
> I read that USB cards don't work all that well either. Anyone got a solution for a quality 
> soundcard that fits in the latest Windows machines. After I bought the computer, I went to the 
> Flex Radio site and to my dismay, they were recommending the Delta 44 card for their products and 
> really didn't recommend much else. I haven't looked lately.
>
> I had no noise blanker etc turned on.
>
>
>
>
> Pat
> N4LTA
>
>
>
>
>
> On 2/6/2013 1:46 PM, jrusgrove at comcast.net wrote:
>> I've been watching this thread for a while now ... here's my 2 cents. BTW, I've changed the 
>> subject line to one more in line with the discussion.
>>
>> No, Pat, I don't think you have a screw loose ;~) ... don't forget I'm in the 'near field' of 
>> this signal and see 'crushing' levels as well ... even with directional antennas pointed the 
>> other direction!
>>
>> First a comment about receiving setups. It really shouldn't make any difference whether one uses 
>> the R-75 for direct reception or a setup using the converter ahead of the receiver ... at least 
>> as far as WSPR overload is concerned. The 200 Hz WSPR bandwidth is contained within the 
>> boundaries of both the R-75 roofing and i-f filters. The overload is occuring within this area. 
>> In terms of the likelyhood of what's causing the problem I'd guess ... E probe (not likely), 
>> converter (not likely, but not completely ruled out), R75 (not likely especially since the K3 
>> produced similar results), A/D (possible depending on wherther it is a quality external sound 
>> card or 'onboard' audio junk) and software (probably the most likely). This assumes that no noise 
>> blanking, noise reduction, clipping, compression etc is in use - these are known bad things that 
>> cause overload.
>>
>> If there are visible 'phantom' products in the waterfall (as I sometimes see here) this overload 
>> is probably some sort of IM or 'image', and it should be possible to make two tone measurements 
>> to determine the offending component by inserting attenuation between each of the major system 
>> component and observing the overload level.
>>
>> Jay W1VD  WD2XNS  WE2XGR/2
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> ----- Original Message ----- From: "pbunn" <pbunn at matrixei.com>
>> To: "Discussion of the Lowfer (US, European, &amp; UK) and MedFer bands" <lowfer at mailman.qth.net>
>> Sent: Wednesday, February 06, 2013 9:57 AM
>> Subject: Re: [Lowfer] WSPR-15 tonite
>>
>>
>>> John,
>>>
>>> There seems to be a problem with strong signals and WSPR.  Eric has emailed me and seems to 
>>> think that the problem is with my R75 but I don't think so. I realize that an R75 has poor 
>>> strong signal performance but I have a very strong receive converter ahead of my R75. I use a 
>>> mini circuits +17 DBM with a 7 pole filter in front and a GPS disciplined LO followed by a good 
>>> diplexer and a Norton lossless FB post amp. Last night I could clearly hear a weak XSH/6 QRS3 in 
>>> the background when Bob was transmitting. I made an audio recording of it. Bobs signal was not 
>>> blocking.
>>>
>>> My WSPR panel gain had to be set  to where I had no green bar at all in order to decode Jay and 
>>> Eric. The background was jet black.
>>>
>>> I have a K3 that I could use as a receiver but in tests I see little difference. Jay asked me 
>>> this weekend why I was transmitting WSPR -15 at 468 KHz and I responded to "get away from the 
>>> strong signals"
>>>
>>> I think he thinks that I have a loose screw, but from my experience, if you have powerful 
>>> signals in the band pass or nearby, WSPR does not perform well.
>>>
>>> Thanks for the comment. This sure is fun. More fun than I have had in a long time with radio.
>>>
>>> Pat
>>> N4LTA
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: lowfer-bounces at mailman.qth.net [mailto:lowfer-bounces at mailman.qth.net] On Behalf Of John 
>>> Andrews
>>> Sent: Wednesday, February 06, 2013 9:45 AM
>>> To: Discussion of the Lowfer (US, European, &amp; UK) and MedFer bands
>>> Subject: Re: [Lowfer] WSPR-15 tonite
>>>
>>> Pat,
>>>
>>> I had something similar with Jay last evening. Very strong signal, and several missed decodes. 
>>> At least one was in a period where XGR/6 was off. Was running AGC on the R75, so it certainly 
>>> wasn't a receiver overload issue.
>>>
>>> John, W1TAG
>>>
>>>
>>>
>>> On Feb 5, 2013, at 10:58 PM, <pbunn at patbunn.com> wrote:
>>>
>>>> I have been running WSPR-15 since last night. When Gary noted that
>>>> someone was in the middle with a drifting signal, I went out to the
>>>> shop to see if I could see the signa
>>>>
>>>> What I saw was a surprise. I have not touched any gain setting since
>>>> last night and have been getting good decodes until recently.
>>>>
>>>> The screen shot shows what I found and shows where I reduced gain to
>>>> the point that very little noise is showing ( and very likely no weak
>>>> signal would be seen)
>>>>
>>>>
>>>> The screen can be seen at
>>>> http://i620.photobucket.com/albums/tt286/n4lta/wsprscrn_zps392e4d37.gi
>>>> f
>>>>
>>>> The screen is split between when I first found it first smeared in
>>>> red, my first gain reduction and then a further adjustment.
>>>>
>>>> The far left is Bobs WSPR 2 signal
>>>>
>>>> There is no noise here tonite to speak of. The S meter on the R75 is
>>>> below
>>>> S1 (no bars on the S meter) and goes to S4 when Bobs signal comes on.
>>>>
>>>> The gain setting was initially set last night and worked fine all
>>>> night with numerous decodes.
>>>>
>>>>
>>>> Something is unusual with WSPR and strong signals, and I am pretty
>>>> certain it is not my receiving equipment. I can hear the WD2XSG/6
>>>> beacon in the background at the same time Bob is transmitting. He is
>>>> not blocking the radio front end.
>>>>
>>>> Pat
>>>> N4LTA
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>
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