Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dd02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 68DB7380000BA; Sun, 7 Aug 2011 12:37:56 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Qq6LO-00076h-Ft for rs_out_1@blacksheep.org; Sun, 07 Aug 2011 17:36:54 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Qq6LN-00076Y-IH for rsgb_lf_group@blacksheep.org; Sun, 07 Aug 2011 17:36:53 +0100 Received: from relay2.uni-heidelberg.de ([129.206.210.211]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Qq6LM-0003j3-7N for rsgb_lf_group@blacksheep.org; Sun, 07 Aug 2011 17:36:53 +0100 Received: from ix.urz.uni-heidelberg.de (cyrus-portal.urz.uni-heidelberg.de [129.206.100.176]) by relay2.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id p77GapLQ008938 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Sun, 7 Aug 2011 18:36:51 +0200 Received: from extmail.urz.uni-heidelberg.de (extmail.urz.uni-heidelberg.de [129.206.100.140]) by ix.urz.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id p77GaoHm021272 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Sun, 7 Aug 2011 18:36:50 +0200 Received: from [129.206.205.195] (vpn205-195.rzuser.uni-heidelberg.de [129.206.205.195]) by extmail.urz.uni-heidelberg.de (8.13.4/8.13.1) with ESMTP id p77GanTt011543 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Sun, 7 Aug 2011 18:36:49 +0200 Message-ID: <4E3EBF3F.6090604@iup.uni-heidelberg.de> Date: Sun, 07 Aug 2011 18:37:19 +0200 From: =?UTF-8?B?U3RlZmFuIFNjaMOkZmVy?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.11) Gecko/20100711 Thunderbird/3.0.6 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <4E3B1BFD.5090807@iup.uni-heidelberg.de> <4E3B2EA3.90003@iup.uni-heidelberg.de> <26D9EBB1476B467E9E02C10B3FACC2C8@PcMinto> <4E3D54DE.1000202@iup.uni-heidelberg.de> <5D042DA2B0C04AA09C5416113128574C@PcMinto> <4E3E614D.3060409@iup.uni-heidelberg.de> In-Reply-To: X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Re: CW sked on 137 friday morning? Content-Type: multipart/alternative; boundary="------------040306090106030707050908" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:481418656:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d408e4e3ebf631b6d X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. --------------040306090106030707050908 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay2.uni-heidelberg.de id p77GapLQ008938 Hello Minto, Nice to read about your progress! Am 07.08.2011 18:06, schrieb Minto Witteveen: > Hi Stefan, > > I noticed I wrote ALC, but obviously this must be AGC=E2=80=A6. > I installed Speclab, and did some tests with the 879. With the ACG=20 > off I adjusted the gain just to the threshold of (audible) distortion=20 > of the DCF39 signal (500 Hz filter) and read-out the level in=20 > Speclab. Then I dialed to 137.700 and read out the (average) noise=20 > level. This turned out to be a 40 dB lower, however I could hear NO=20 > bandnoise at this setting of the manual AGC=E2=80=A6 only the receiver= noise. So DCF-39 would just be 40 dB above the noise? This is much to low. At=20 least 30 dB would be missed i estimate. But what was the FFT setting "width of one FFT bin" in the FFT register=20 card? >> From this I inferred two things: > A. DCF39 is more than 40 dB above the noise (but how much I cannot=20 > measure with this method) > B. The 879 is a really lousy receiver (But I already knew that) > > But: there is also good news! I did see (but not hear) your CQ at=20 > 17:40 HR CET, see attached screenshot. My first RX on 137! *Congrats to your first LF reception!* And it shows me that my calls are=20 not only for my pleasure :-) So here we may better estimate how many dBs=20 are missed. Looks like you choosed a relative broad BW for the FFT=20 settings. 488 (some use 366 mHz) mHz would be a better choice. And i=20 assume you don't use a noise blanker so far. This will improve thing too! > So at least the receiver + software works. > In the screenshot you can see your first CQ recorded with the FT897.=20 > At 17:32 I switched to the TS130. At first glance the signal looks=20 > better on the TS130. Also notice that this trace is a bit=20 > off-frequency and drifts visibly. The 130 has an analog VFO, and the=20 > frequency readout is in 100 Hz steps. The drift might also be=20 > attributable to the SA612 mixer I use (now with a 10 MHz xtal) > > This proves that at least QRSS3 QSO=E2=80=99s will be possible, so I ha= ve no=20 > excuse not finishing my PA and variometer. Yes! :-) How do you go on improving the RX system? Ah, i have an idea: Display=20 the whole band, as broad as the SSB filter permits. Use a slow scrolling=20 spectrogram and make your local noise visible. Normally local QRM=20 sources disappear and appear from time to time. And they could be band=20 limited. You should see the band noise ideally and its minimum just after the=20 local sunrise and a few hours later... If that all is on an equal level,=20 it must be covered by local noise! Try to run the PA0RDT on batteries and your TRX and PC as well=20 (netbook). Do not change the antenna position and see how and if the=20 noise is changing and so on... :-) 73, Stefan/DK7FC > > Regards, > Minto pa3bca > > > > > > > -----------------------------------------------------------------------= ---=20 > > Ceterum censeo Carthaginem delendam esse > -----Original Message----- From: Stefan Sch=C3=A4fer > Sent: Sunday, August 07, 2011 11:56 > To: rsgb_lf_group@blacksheep.org > Subject: Re: LF: Re: CW sked on 137 friday morning? > > Hello Minto, > > Am 07.08.2011 00:10, schrieb Minto Witteveen: >> Just a question: How do you use speclab to measure the signal level=20 >> of for instance DCF39 AND the noisefloor.. By measuring both and=20 >> comparing? > I don't use a commercial HF TRX for LF but a down-converter (LF-125 kHz= ) > so i am not limited to a SSB filter bandwidth. I can display 125...149 > kHz when running the soundcard at 48 kS/s. So a slight difference here. > But generally you must switch off the AGC and ALC and noise blanking an= d > all that affects the output AF level. Then you can measure the absolute > levels, e.g. -10 dB for DCF and -80 dB for the band noise and -90 dB fo= r > the RX noise. > Just read it out on the right side. > I did a audio recording during the QSOs. My loop was beaming N/S, so no= t > optimally for DCF-39. Anyway it was 85 dB S/N in 488 mHz (i use 488 mHz > for QRSS-3). So this is an example how to simply read out the SNR: > http://dl.dropbox.com/u/19882028/LF/DCF39%20in%20488%20mHz.png > Anyway there could be 10 dB more sensitivity on my RX to have best > reception in a quiet sunday morning in winther... > >> - but then I would have to disable the ALC of the FT817?. > Not sure but i would disable anything ;-) >> I can try /p sometime, go out in the fields far away from man-made=20 >> noise, with the miniwhip, a 12 meter fiberglass pole, a 7Ah SLA, the=20 >> transverter and the 817. > If you are outside in a flat field, you maybe do not need to lift the > antenna to 12m! 3m could be reasonable. Yes, beeing outside will at > least show you if its all caused by local QRM... > > 73, Stefan/DK7FC > > >> >> Regards, Minto pa3bca >> >> >> >> >> ----------------------------------------------------------------------= ----=20 >> >> Ceterum censeo Carthaginem delendam esse >> -----Original Message----- From: Stefan Sch=C3=A4fer >> Sent: Saturday, August 06, 2011 16:51 >> To: rsgb_lf_group@blacksheep.org >> Subject: Re: LF: Re: CW sked on 137 friday morning? >> >> Hello Minto, >> >> Am 05.08.2011 23:59, schrieb Minto Witteveen: >>> Stefan (et al), >>> I did listen this morning on 136.8 to see if I could copy you or any=20 >>> other station, but the results were disappointing: I heard nothing. >> Thanks for trying anyway. >> Well, i was in QSO mit PA0A who must be close to you, so something mus= t >> be wrong... >>> I have an FT817 and an FT879 as possible receivers. Both are not=20 >>> known for their superb receive quality but with a 5 pole filter +=20 >>> additional amplification I got them to work quite reasonable on 500=20 >>> KHz. >>> Both rigs are very bad on LF. Very insensitive and prone to heavy=20 >>> intermodulation, especially at night. >>> So this weekend I build a quick-and-dirty 4 MHz uptransverter with a=20 >>> SA612. The Yeasu=E2=80=99s are much more sensitive at these frequenci= es. To=20 >>> keep strong LF and MF stations from causing intermodulation had to=20 >>> add 7-pole Chebishev filter between a PA0RDT miniwhip and the=20 >>> transverter. For details see: >>> http://www.pa3bca.nl/index.php?option=3Dcom_content&view=3Darticle&id= =3D23&Itemid=3D17=20 >>> >> Looks good, that page. >>> This morning (when there was almost no man-made QRM form TV=E2=80=99s= etc)=20 >>> DCF39 was S9+30dB on the 897. On (4000+) 136.8 the noise was S 5=20 >>> with the 2.4 KHz SSB filter, and S1 with the 500 Hz filter. >>> Now I know that the FT=E2=80=99s S-meter is not very reliable, especi= ally=20 >>> from S1-S9. But between S9 and S9+40 it is =E2=80=9Creasonably=E2=80=9D= accurate. >> If you use SpecLab for receiving, you directly get the signal level in >> dB (i.e. dB below full scale of the ADC). Then you can measure the DCF= 39 >> level and the noise floor level. Meanwhile i am getting DCF39 at 80 dB >> above noise in 488 mHz with the RX loop. >>> As far as I could find out DCF39 generates 50 KW ERP. If Stefan=20 >>> generates 0.5 Watt ERP (My guestimate) >> Should be a few dB more ;-) >>> and the distance to my QTH is approximately the same, I would expect=20 >>> Stefan to be 50 dB weaker. But 50 dB below DCF39 would still be=20 >>> above the noise floor? So why didn=E2=80=99t I hear him (or for that = matter,=20 >>> PA0A who is closer and has 1 Watt ERP). >> Maybe the S meter is worse than you think, maybe. >>> Before I finish my 1 kW TX I first have to make sure that I will be=20 >>> able to copy any other station.... :-) >> I had the same problems. But i immediately received DF6NM audible. So = if >> you don't even receive PA0A, there seems to be lack of sensitivity. >> What happens with the noise floor if you disconnect the PA0RDT? How ma= ny >> dB does the noise floor decrease? >> Can you do /p tests? >> >> Don't expect to much activity on LF. But there are new stations coming >> on the band and you could be one of them and help making the band alie >> again. >> >> CU there :-) >> >> 73, Stefan/DK7FC=20 --------------040306090106030707050908 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay2.uni-heidelberg.de id p77GapLQ008938 Hello Minto,

Nice to read about your progress!

Am 07.08.2011 18:06, schrieb Minto Witteveen:
Hi Stefan,

I noticed I wrote ALC, but obviously this must be AGC=E2=80=A6.
I=C2=A0 installed Speclab, and did some tests with the 879. With the ACG = off I adjusted the gain just to the threshold of (audible) distortion of the DCF39 signal (500 Hz filter) and read-out the level=C2=A0 in Speclab. Then I dialed to 137.700 and read out the (average) noise level. This turned out to be a 40 dB lower, however I could hear NO bandnoise at this setting of the manual AGC=E2=80=A6=C2=A0 only the receiver noise.
So DCF-39 would just be 40 dB above the noise? This is much to low. At least 30 dB would be missed i estimate.
But what was the FFT setting "width of one FFT bin" in the FFT register card?
From this I inferred two things:
A. DCF39 is more than 40 dB above the noise (but how much I cannot measure with this method)
B. The 879 is a really lousy receiver (But I already knew that)

But: there is also good news! I did see (but not hear) your CQ at 17:40 HR CET, see attached screenshot. My first RX on 137!

Congrats to your first LF reception! And it shows me that my calls are not only for my pleasure :-) So here we may better estimate how many dBs are missed. Looks like you choosed a relative broad BW for the FFT settings. 488 (some use 366 mHz) mHz would be a better choice. And i assume you don't use a noise blanker so far. This will improve thing too!

So at least the receiver + software works.
In the screenshot you can see your first CQ recorded with the FT897. At 17:32 I switched to the TS130. At first glance the signal looks better on the TS130. Also notice that this trace is a bit off-frequency and drifts visibly. The 130 has an analog VFO, and the frequency readout is in 100 Hz steps. The drift might also be attributable to the SA612 mixer I use (now with a 10 MHz xtal)

This proves that at least QRSS3 QSO=E2=80=99s will be possible, so I have= no excuse not finishing my PA and variometer.
Yes! :-)
How do you go on improving the RX system? Ah, i have an idea: Display the whole band, as broad as the SSB filter permits. Use a slow scrolling spectrogram and make your local noise visible. Normally local QRM sources disappear and appear from time to time. And they could be band limited.
You should see the band noise ideally and its minimum just after the local sunrise and a few hours later... If that all is on an equal level, it must be covered by local noise!
Try to run the PA0RDT on batteries and your TRX and PC as well (netbook). Do not change the antenna position and see how and if the noise is changing and so on... :-)

73, Stefan/DK7FC


Regards,
Minto pa3bca






-------------------------------------------------------------------------= -
Ceterum censeo Carthaginem delendam esse
-----Original Message----- From: Stefan Sch=C3=A4fer
Sent: Sunday, August 07, 2011 11:56
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Re: CW sked on 137 friday morning?

Hello Minto,

Am 07.08.2011 00:10, schrieb Minto Witteveen:
Just a question: How do you use speclab to measure the signal level of for instance DCF39 AND the noisefloor.. By measuring both and comparing?
I don't use a commercial HF TRX for LF but a down-converter (LF-125 kHz)
so i am not limited to a SSB filter bandwidth. I can display 125...149
kHz when running the soundcard at 48 kS/s. So a slight difference here.
But generally you must switch off the AGC and ALC and noise blanking and
all that affects the output AF level. Then you can measure the absolute
levels, e.g. -10 dB for DCF and -80 dB for the band noise and -90 dB for
the RX noise.
Just read it out on the right side.
I did a audio recording during the QSOs. My loop was beaming N/S, so not
optimally for DCF-39. Anyway it was 85 dB S/N in 488 mHz (i use 488 mHz
for QRSS-3). So this is an example how to simply read out the SNR:
http://dl.dropbox.com/u/19882028/LF/DCF= 39%20in%20488%20mHz.png
Anyway there could be 10 dB more sensitivity on my RX to have best
reception in a quiet sunday morning in winther...

- but then I would have to disable the ALC of the FT817?.
Not sure but i would disable anything ;-)
I can try /p sometime, go out in the fields far away from man-made noise, with the miniwhip, a 12 meter fiberglass pole, a 7Ah SLA, the transverter and the 817.
If you are outside in a flat field, you maybe do not need to lift the
antenna to 12m! 3m could be reasonable. Yes, beeing outside will at
least show you if its all caused by local QRM...

73, Stefan/DK7FC



Regards, Minto pa3bca




-------------------------------------------------------------------------= -
Ceterum censeo Carthaginem delendam esse
-----Original Message----- From: Stefan Sch=C3=A4fer
Sent: Saturday, August 06, 2011 16:51
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Re: CW sked on 137 friday morning?

Hello Minto,

Am 05.08.2011 23:59, schrieb Minto Witteveen:
Stefan (et al),
I did listen this morning on 136.8 to see if I could copy you or any other station, but the results were disappointing: I heard nothing.
Thanks for trying anyway.
Well, i was in QSO mit PA0A who must be close to you, so something must
be wrong...
I have an FT817 and an FT879 as possible receivers. Both are not known for their superb receive quality but with a 5 pole filter + additional amplification I got them to work quite reasonable on 500 KHz.
Both rigs are very bad on LF. Very insensitive and prone to heavy intermodulation, especially at night.
So this weekend I build a quick-and-dirty 4 MHz uptransverter with a SA612. The Yeasu=E2=80=99s are much more sensitive at these frequencies. = To keep strong LF and MF stations from causing intermodulation had to add 7-pole Chebishev filter between a PA0RDT miniwhip and the transverter. For details see:
htt= p://www.pa3bca.nl/index.php?option=3Dcom_content&view=3Darticle&i= d=3D23&Itemid=3D17
Looks good, that page.
This morning (when there was almost no man-made QRM form TV=E2=80=99s etc) DCF39 was S9+30dB on the 897. On (400= 0+) 136.8 the noise was S 5 with the 2.4 KHz SSB filter, and S1 with the 500 Hz filter.
Now I know that the FT=E2=80=99s S-meter is not very reliable, especially= from S1-S9. But between S9 and S9+40 it is =E2=80=9Creasonably=E2=80=9D accura= te.
If you use SpecLab for receiving, you directly get the signal level in
dB (i.e. dB below full scale of the ADC). Then you can measure the DCF39
level and the noise floor level. Meanwhile i am getting DCF39 at 80 dB
above noise in 488 mHz with the RX loop.
As far as I could find out DCF39 generates 50 KW ERP. If Stefan generates 0.5 Watt ERP (My guestimate)
Should be a few dB more ;-)
and the distance to my QTH is approximately the same, I would expect Stefan to be 50 dB weaker. But 50 dB below DCF39 would still be above the noise floor? So why didn=E2=80=99t I hear = him (or for that matter, PA0A who is closer and has 1 Watt ERP).
Maybe the S meter is worse than you think, maybe.
Before I finish my 1 kW TX I first have to make sure that I will be able to copy any other station.... :-)
I had the same problems. But i immediately received DF6NM audible. So if
you don't even receive PA0A, there seems to be lack of sensitivity.
What happens with the noise floor if you disconnect the PA0RDT? How many
dB does the noise floor decrease?
Can you do /p tests?

Don't expect to much activity on LF. But there are new stations coming
on the band and you could be one of them and help making the band alie
again.

CU there :-)

73, Stefan/DK7FC
--------------040306090106030707050908--