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Joe Taylor | 8 Jun 16:30
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WSE Freq-select box

Having finished the building of a new 4 x 14 xpol EME antenna, I 
have now turned to completing the task of reconfiguring my 
station.

After 6 months of not using Linrad, my old brain seems 
befuddled.  The box that one clicks to increase/decrease 
frequency by 25 kHz steps -- it controls the crystal oscillators 
in the WSE converters -- has disappeared from my Linrad screen. 
  What have I mistakenly done, when re-connecting and restarting 
things, to make this box disappear?  How do I get it back?  Can 
anyone shed some light on this for me?

	-- 73, Joe, K1JT

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Leif Asbrink | 9 Jun 12:13

Re: WSE Freq-select box

Hello Joe,

Maybe your Linrad version is very old? The current version
is 02-34.

The freq control box was originaly intended for controlling
the frequency of the hardware. The standard package
supports the WSE units and the SDR-14 and users with other
hardwares were supposed to add their own users_hwaredriver
to set the frequency of other hardwares. With this intended
usage, the frequency control box was only displayed when
there was some hardware present (and properly set-up)

The frequency control box will not only affect the hardware, 
it will also change the frequency scales, and someone asked me
to allow it always. Therefore it should be present always
in recent versions.

If you use Linux you have to set the parallel port to whatever 
value your computer uses (PC COM1 is usually 888) and if you
do not, the freq control box would not appear in old Linrad
versions. 

In case the freq control box does not re-appear when you
make a test with Linrad-02.34 there is something unexpected
going on and if it happens, please pack all par* files and
send them to me. There might be something that I do no longer
remember.....

The box should always be there:-)
(Continue reading)

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Joe Taylor | 9 Jun 15:33
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Re: WSE Freq-select box

Hi Leif,

Thanks for the reply.  Yes, I am using a somewhat older Linrad 
version, 02.20.  It is the one I was using last November, and I 
thought to bring things up as they were working before, and then 
upgrade my Linrad version when all is well.

It appears that I may have lost communication between the 
parallel port and the WSE converters.  I will look further into 
that possibility ...

	-- Joe, K1JT

Leif Asbrink wrote:
> Hello Joe,
> 
> Maybe your Linrad version is very old? The current version
> is 02-34.
> 
> The freq control box was originaly intended for controlling
> the frequency of the hardware. The standard package
> supports the WSE units and the SDR-14 and users with other
> hardwares were supposed to add their own users_hwaredriver
> to set the frequency of other hardwares. With this intended
> usage, the frequency control box was only displayed when
> there was some hardware present (and properly set-up)
> 
> The frequency control box will not only affect the hardware, 
> it will also change the frequency scales, and someone asked me
> to allow it always. Therefore it should be present always
(Continue reading)

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Joe Taylor | 9 Jun 21:57
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Re: WSE Freq-select box

Leif, and all --

Cockpit error, as they say.  My old mind was indeed befuddled -- 
and I forgot that direct access to hardware -- in this case, the 
parallel port -- requires root privileges.  Once I became root, 
all was well.

	-- 73, Joe, K1JT

Joe Taylor wrote:
> Hi Leif,
> 
> Thanks for the reply.  Yes, I am using a somewhat older Linrad version, 
> 02.20.  It is the one I was using last November, and I thought to bring 
> things up as they were working before, and then upgrade my Linrad 
> version when all is well.
> 
> It appears that I may have lost communication between the parallel port 
> and the WSE converters.  I will look further into that possibility ...
> 
>     -- Joe, K1JT
> 
> Leif Asbrink wrote:
> 
>> Hello Joe,
>>
>> Maybe your Linrad version is very old? The current version
>> is 02-34.
>>
>> The freq control box was originaly intended for controlling
(Continue reading)

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Joe Taylor | 10 Jun 16:02
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Polarization question

Hi Leif (or anyone else who knows),

Ideally, I suppose, with an xpol antenna one would like to have 
phase-matched preamps for the two polarizations and equal 
electrical lengths for the two Rx feedlines.

Suppose they are not well matched.  In other words, suppose that 
the complex gains and signal delays in the two polarization 
channels are not equal.  Will Linrad's polarization-matching 
capability be compromised?  As far as I can see, it still works 
well even with poorly matched feedlines.  I suppose this must 
mean that Linrad solves for a differential complex gain, and 
that over a fairly narrow bandwidth a different delay can be 
treated as a phase shift.

Is this the correct way to look at it?  Can you enlighten me any 
further?

	-- 73, Joe, K1JT

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'Zaba' OH1ZAA | 10 Jun 17:48
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Re: Polarization question


Sir Joe!

As far as I have understood Linrad tries to combine the incoming 
spectrum of two
antennas in order to reach a signal vector maximum for each spectral component.
Thus it does not seem to matter (at least for that summation process) what the
absolute length of feed lines or relative signal amplitude in each 
channel is.

I have also the full WSE-set since 2005 or so, but I have never even 
attempted to
power it up (that will be one of this Summer's projects). So far I 
have run Linrad as
a home-brew single-channel I/Q direct conversion receiver, and man-made noise
suppression has already been quite impressive without calibration. I 
have plans
to expand to a multi-path take-off angle analyzer with the two 
channels activated.

It is probably already 7 years ago (at the 2000 VHF/UHF/SHF-meeting 
in Finland)
that the three of us: SM5BSZ/OZ1RH/OH1ZAA discussed all night (probably up to
4 - 5 AM) about the early Linrad and other properties of weak signal 
detection. It was
one of the most interesting discussions that I have ever experienced 
during my ham
career. Most probably we did not define everything very accurately at 
that time, as
at least one of the topics was "how deep we could go into the noise"
(Continue reading)

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Leif Asbrink | 10 Jun 18:54

Re: Polarization question

Hi Joe, Zaba and all,

> Ideally, I suppose, with an xpol antenna one would like to have 
> phase-matched preamps for the two polarizations and equal 
> electrical lengths for the two Rx feedlines.
Sure:-)

> Suppose they are not well matched.  In other words, suppose that 
> the complex gains and signal delays in the two polarization 
> channels are not equal.  Will Linrad's polarization-matching 
> capability be compromised?  As far as I can see, it still works 
> well even with poorly matched feedlines.  I suppose this must 
> mean that Linrad solves for a differential complex gain, and 
> that over a fairly narrow bandwidth a different delay can be 
> treated as a phase shift.
From a practical point of view the cables are well matched. I think
it is a safe assumption to guess that the length differences will 
be very small and of no concern.

Much more important would be the phase shift through very
narrow filters in case you have such at the output of
the preamplifier. A filter with 1 MHz bandwidth has a
delay of something like 1us and in case the other channel
has a filter with 1.5 MHz bandwidth, it would have much 
less delay and that could be a problem.

When the phase is not matched, the polarisation indicator
will not show the correct polarisation. That will not
cause any loss of sensitivity, only make it more difficult
to decide what tx polarisation to use.
(Continue reading)

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'Zaba' OH1ZAA | 10 Jun 23:52
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Re: Polarization question


Thanks Leif for all explications!

As such it is clear that in stable conditions (no polarization 
change) a signal
emanating from one source must be able to show a fixed polarization state
irrespective of its spectral content, but any offset from the real 
value is due
to feed line length differences or disparity in pre-amp phase curves or gain
differences (as a function of frequency). And there another source within the
same spectral range would probably result in an error signal, as one
cannot show two different polarization states with a single graphical line,
i.e. at each instant just one phase would be shown, but it is a transformed
(restless) plot of two independent signals?

Actually my plan is to measure the phase difference between two horizontal
antennas (with known radiation patterns) at different heights. With just one
take-off angle (incoming signal) Linrad would be able to show the phase
difference between these two antennas, and the if the amplitude is also
available, then from the math with the radiation pattern, the 
angle(s) of arrival
would be solved for up to dual-path openings. Of course the ever changing
ionosphere makes it a dynamic challenge, also due to phase reversals of
the skipping wave. However, it would make home-operating a much deeper
experience from the scientific point of view (compared to regular 
59-operating).

Recent experiments have involved the phase / out-of-phase combining of any
two given antennas on 50 MHz (still without Linrad). That adds a lot of extras
too in operating. With little more definition and Linrad this will
(Continue reading)

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Joe Taylor | 11 Jun 02:25
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Re: Polarization question

Leif, Zaba, and all,

Many thanks for the clear explanations!

	-- Joe, K1JT

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Robert McGwier | 12 Jun 15:50
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Congratulations Roger!!

Congratulations to Roger Rehr, W3SZ!  He came in first place single op 
low power in the ARRL January VHF Sweepstakes.  Drat, this was the first 
one I have missed in several years and now I have missed the June VHF 
contest as well.  I know Roger is looking forward to having all  sorts 
of SDR stuff at his remote site and our incipient remoting capabilities 
with the SDR's.

For those who do not know, Roger has been steadily, relentlessly 
pursuing the upgrade path to a first rate VHF+ station.  He puts out a 
really great signal on 6m through 24 GHz!

Again, my sincerest congratulations to our fellow SDR enthusiast.

Bob
N4HY

--

-- 
AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
"If you're going to be crazy, you have to get paid for it or
else you're going to be locked up." Hunter S. Thompson

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Gmane