Terry,
Alas, we've lost the Loran calibration method over here. My current
approach is to use a 1 kHz signal divided from a 10 MHz GPS-disciplined
source. That signal is used for two things:
1. It makes an old-fashioned "crystal calibrator" to nail down the
receiver frequency calibration at the nearest 1 kHz point. Since that
error varies with frequency, I wind up using different corrections for
137 kHz and the U.S. Lowfer allocation.
2. It allows easy calibration of the sound card sampling rate by feeding
the tone (rectangular or not) into the sound card input and using the
routines in WOLF or SpecLab to come up with the actual sampling rate.
The accuracy of the receiver output is important only to be sure that
the signal is within the nominal 1 Hz passband. It makes no difference
in the quality of copy if the frequency error is reported as 0.01 or
0.498 Hz. Of course, with the transmitted and received frequencies
closely established, you do get a feeling for when the decoder may be
locking onto something real.
The sampling rate determination is essential to the build-up of copy in
WOLF. With a strong signal, you'll probably be OK with a default value.
But in copying a weak signal, if you notice that the framing "jm:"
values are creeping, then the sampling rate is suspect.
In your case, where everything is more tightly integrated, I'm not sure.
The best test would be to have a weak WOLF signal to work with...you may
have already nailed things down with your Loran calibration. Armed with
the results of a successful capture, any faults should be obvious.
John, W1TAG
On 1/29/2012 9:15 AM, Terry GW0EZY wrote:
Hi Alan
I thought I should open a new subject thread.
Thanks. Yes you're right about the need for calibration of the soundcard S/R
and DL4YHF's site (for the Wolf GUI) provides a link to the site of John,
W1TAG for detailed descriptions of methods using Loran lines. I have had a
preliminary try using Loran for this and the error displayed was very small
but I have a feeling that it was too easy! I do not use any sound card in
the decoding chain but using a VAC might still cause a problem. I assume the
VAC uses the internal CPU clock for S/R timing.
73 Terry GW0EZY
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Alan Melia
Sent: 29 January 2012 13:57
To: [email protected]
Subject: Re: LF: WD2XES WOLF Saturday Night
Hi Terry I cant remember now when I last used this with John but I seen to
remember it was very finicky about the Soundcard calibration, and you have
to trim it to pretty close of it wont copy. John is the obvious guide on
that.
Alan
G3NYK
----- Original Message -----
From: "Terry GW0EZY"<[email protected]>
To:<[email protected]>
Sent: Sunday, January 29, 2012 1:41 PM
Subject: RE: LF: WD2XES WOLF Saturday Night
John& Chris
Thanks for the info on your settings.
I use an SDR-IQ with output to Virtual Audio Cable VAC. The SDR-IQ is set
to
produce an 2 kHz audio output from 136-138 kHz so that 136 kHz = 0 Hz
audio.
SL, Opera WSPR and now Wolf are connected via the VAC. With these settings
a
Wolf signal Tx = 137.249 kHz should produce an audio signal of 1249 kHz
and
I have set the Wolf centre frequency to this. I wait to see if I get any
decodes!
However, there may be other issues such as sample rate for the VAC. What
happens when different programs using different sample rates connect to a
single VAC? I have just been experimenting with the dual receive facility
of
the SDR-IQ and stereo processing mode of SL to feed the 19580.0 kHz signal
(GBZ, MSK200) into the left channel and 136-138 KHz into the right. The SL
sampling rate detector shows a "lock" and measures the SR error of the
VAC.
But whether this is actually of benefit I'm not sure!!
73 Terry GW0EZY
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Chris 4X1RF
Sent: 29 January 2012 00:21
To: [email protected]
Subject: Re: LF: WD2XES WOLF Saturday Night
Terry, John,
In my case I've chosen 1500Hz for no particular reason, the receiver
is a direct conversion front-end feeding an M-Audio board run at
48ks/s and SpectrumLab as the mixer-filter-demodulator stage. Audio is
routed to Wolf with VAC.
QRV now on 137294 for the night... time to get some sleep....
73s
Chris 4X1RF
On 1/29/12, John Andrews<[email protected]> wrote:
Terry,
In receiving, I use the default center frequency of 800 Hz, and put the
receiver into CW mode. I have the receiver BFO set for an 800 Hz pitch,
and the dial frequency set to the transmit carrier frequency of 137.294
kHz. In my case, this allows use of a 250 Hz IF filter in the receiver,
which can be an advantage if other stations fire up a bit higher in the
band.
Chris's settings are fine, but I've had better luck at this QTH with the
receiver run in a narrower BW.
John, W1TAG
On 1/28/2012 6:51 PM, Terry GW0EZY wrote:
Chris/John
Please could you provide more information on your Wolf configuration
settings? There are a few variables and it would increase the chance of
decoding if these were known. Sorry if I missed this an earlier email.
The default Centre frequency in the Wolf GUI is 800 Hz but in your
decodes you (seem to) have f=1500. How does this relate to a Tx
frequency of 137.294 kHz? I'm assuming the operating frequency for Rx
is
USB dial + Wolf Rx centre frequency?
73s Terry GW0EZY
------------------------------------------------------------------------
*From:*[email protected]
[mailto:[email protected]] *On Behalf Of *Chris 4X1RF
*Sent:* 28 January 2012 23:18
*To:* [email protected]
*Subject:* Re: LF: WD2XES WOLF Saturday Night
John,
Following the successful receive of Markus's Wolf10 transmission this
evening, I'm now QRV on 137.294kHz. Will report tomorrow.
73s
Chris 4X1RF
On Sat, Jan 28, 2012 at 11:03 PM, John Andrews<[email protected]
<mailto:[email protected]>> wrote:
WD2XES will be running WOLF(10) on 137.294 kHz tonight starting around
00 UTC. If CFH comes back on in the interim, I may have to QSY, but
they
appear to have been off all day.
Reports are welcome.
John, W1TAG/WD2XES
FN42ch
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.455 / Virus Database: 271.1.1/4171 - Release Date:
01/27/12
19:34:00
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.455 / Virus Database: 271.1.1/4173 - Release Date: 01/28/12
19:33:00
|
