[Lowfer] ARGO

Mon Dec 31 16:28:36 EST 2012

Anyone have the exact transmit frequency for XNS at the moment?

On Mon, Dec 31, 2012 at 4:20 PM, Douglas D. Williams <kb4oer at gmail.com>wrote:

> Nope, gonna have to eat some crow. That's not MP I'm seeing, so I may be
> off more than I think. :-)
>
> Still looking for MP.
>
> 73, Doug KB4OER
>
>
>
>
> On Mon, Dec 31, 2012 at 4:13 PM, Douglas D. Williams <kb4oer at gmail.com>wrote:
>
>> John,
>>
>> I'm sure you are absolutely correct. The method I described is just a
>> quick and dirty method, not needing a frequency counter, known calibrated
>> audio tone source, or any other equipment whatsoever. It has worked well
>> enough for me for several years now that I know when (after I allow my
>> receiver to warm up) I tune to a certain frequency from 10-500 kHz to
>> receive a QRSS or WSPR signal I'm never more than half a Hz off. Looking at
>> MP scrolling across now.... it looks like, now that my receiver has warmed
>> up (and assuming MP is right on frequency), that I am one tenth of one Hz
>> off in my calibration. I can't remember when I last did an Argo calibration
>> on this receiver+upconverter....probably early October, when the listening
>> season started.
>>
>> I rarely tune above 500 kHz, so I don't give much thought to frequency
>> calibration errors at HF or above.
>>
>> 73, Doug KB4OER
>>
>>
>>
>> On Mon, Dec 31, 2012 at 3:50 PM, John Andrews <w1tag at charter.net> wrote:
>>
>>> Doug,
>>>
>>> Just to split a couple of hairs:
>>>
>>> You need a known audio frequency to calibrate the sound card sampling
>>> rate. An audio tone from a receiver that depends on a converter L.O., and
>>> one or more conversion oscillators (and maybe the BFO) doesn't qualify.
>>>
>>> The combination of the converter and receiver likely has a frequency
>>> offset that varies with receiver tuning. Calibration of that offset at 60
>>> kHz may be in error at other frequencies.
>>>
>>> The above applies to fussy situations like WOLF and slow PSK modes,
>>> where sampling rate must be nailed to keep framing consistent, and receiver
>>> offsets nulled out.  For QRSS use, you'll likely see cal errors between
>>> bands, and they MAY be small enough to ignore.
>>>
>>> John, W1TAG
>>>
>>>
>>>
>>> On Dec 31, 2012, at 2:43 PM, "Douglas D. Williams" <kb4oer at gmail.com>
>>> wrote:
>>>
>>> > Hi Mike. My method for calibrating ARGO is very simple, and does not
>>> > require any extra equipment. As someone else pointed out, first you
>>> have to
>>> > know the BFO sidetone of your receiver. Most modern receivers allow
>>> you to
>>> > vary this sidetone through some sort of menu. I happen to like to hear
>>> a
>>> > 700Hz tone when listening to CW, so that's what I keep mine at. I tune
>>> to
>>> > 60 kHz WWBV with the receiver set to CW mode (reverse CW for Icom
>>> > receivers), and allow the receiver to warm up for an hour. If you are
>>> using
>>> > an upconverter, then simply tune to the converter's LO frequency + 60
>>> kHz,
>>> > so in my case that would be 3.060 MHz. At this point I would set Argo
>>> to
>>> > some relatively fast QRSS speed such as QRSS10, and center 700Hz on the
>>> > right side scale. You may have to reduce the receiver's audio gain and
>>> > lower Argo's sensitivity slider quite a bit because WWVB is very
>>> strong in
>>> > the lower 48. If your total system calibration is within 20Hz or so of
>>> > being correct, you should see a bold, thick line start scrolling
>>> across the
>>> > screen, with thinner lines (sidebands, I guess) above and below it.
>>> What
>>> > you want to do is go into Argo's setup menu and choose Calibration. If
>>> you
>>> > see the bold line at, say 705Hz then you would enter 700 (if that's the
>>> > sidetone you are using) in the Measured frequency box and 705 in the
>>> > Displayed frequency box. That should get you within one Hz of being
>>> dead
>>> > on. You can dial it in even more at the slower QRSS speeds by using
>>> decimal
>>> > places in the numbers you put in the Displayed frequency box.
>>> >
>>> > What you are doing is calibrating the total receive system (receiver,
>>> > upconverter, computer sound card) to be correct on the Argo screen. Of
>>> > course, the job is easier if the oscillators in your receiver and
>>> > upconverter are close to the frequency they should be. If you are
>>> using an
>>> > upconverter with one of those little 4 MHz crystals about the size of a
>>> > child's fingernail, good luck. ;-)
>>> >
>>> > At this point, many people go a step further because they like to have
>>> > Argo's frequency scale (the one on the right) display the actual
>>> frequency
>>> > (in Hz) that they have the receiver tuned to. This can be accomplished
>>> by
>>> > using the Offset box in the Calibration window and typing in the
>>> frequency
>>> > you have the receiver tuned to, minus your BFO frequency, if I remember
>>> > correctly. I'm usually too lazy to do this, so my screen captures tend
>>> to
>>> > just have the BFO sidetone frequency.
>>> >
>>> > Well, that was a lot of typing to describe something that generally
>>> only
>>> > takes about five minutes to do, once the receiver is warmed up. ;-)
>>> >
>>> > 73, Doug KB4OER
>>> >
>>> > On Mon, Dec 31, 2012 at 1:58 PM, Mike Sanders <k0az at centurytel.net>
>>> wrote:
>>> >
>>> >> Stan, Charlie and Mark, Thanks very much for all your input.
>>> >> I am going to continue to follow through with this until I get it.
>>> >> Your help may make the difference.
>>> >> I am also using a converter and it is introducing minus 302 hz
>>> >> of aggravation from the LO. My first lowfer target is WMS only
>>> >> about 170 miles South of me.
>>> >> I have not looked through all your email info yet but will as well
>>> >> as checking out John's write up on ARGO set up.
>>> >> Thanks again and you will know when I get a good capture.  73
>>> >>
>>> >> Happy New Year
>>> >> Mike Sanders
>>> >>      K0AZ
>>> >>
>>> >>
>>> >>
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>>
>>
>