[Lowfer] 185.3 party tonight!

Wed, 23 Jan 2002 22:51:34 -0500

WOW, I leave you guys for an hour and now the mail screen is all filled up.

Hi Jay, glad you joined in. 

Nice analysis below. So how did you happen to read the WA signal ratio so
close to the correct value, earlier, if you are seeing a step error of ~2db?

Bill

-----Original Message-----
From: Jay Rusgrove [mailto:[email protected]]
Sent: Wednesday, January 23, 2002 9:34 PM
To: [email protected]
Subject: Re: [Lowfer] 185.3 party tonight!

Bill and all

Thanks for the invite. I sure hope this isn't a black tie affair! I prefer
come
as you are...

Well, until we have Lowfer slow-scan TV you're OK.

Per my earlier e mail I brought some test equipment home to measure the Argo
"signal strength meter". I used a trusty old L/C HP 652A "audio" generator
into
the RF-590 receiver through HP 355C and HP 355D attenuators. Both the signal
generator and the receiver had extra pads to stabilze any impedance
variations.
The output of the generator was 185.300 and after a good warmup the
frequency
was pretty stable. The output level is very stable. I centered the signal at
800
Hz and made output steps of 10 dB. Multiple 10 dB steps up and down were
made
running Argo in the 10 seconds per dot mode. My sound card (part of the
limitation in performance I'm sure) is a Sound Blaster Live 5.1.

Results were pretty good - if you are careful with your measuring technique.
I
have no idea how the program determines what it displays as a signal level,
but
dragging the cursor over a seemingly constant white line yields varying
signal
levels of  several dB. By dragging the cursor over an entire section of a
line
or character you can easily find a maximum level. When you compare one
segment
with others that are stepped up or down by 10 dB using the maximum level
method
you can probably be within  2 dB (or better) of the actual step without a
great
deal of difficulty. As the signal gets weaker and approaches the background
noise this figure gets worse. Errors of 3 dB or more are possible. I think
the
white specs of background noise add to the weak desired signal to give an
unexpectedly high reading  - which is to be expected.  All in all, as a
relative
indicator,  I would say it is quite useful. Measurements within at least a
few
dB should be possible.

More testing is in order.

Jay Rusgrove, W1VD

"Ashlock,William" wrote:

> All,
>
> This message is to invite you to all to another rip roaring 185.3 party!
> John A. will be home (not doing the bar scene like last night), watching
the
> e-mail for any glimmer of a TAG capture from a party goer. Bill will be
here
> at work finishing up the first build of a new PCB, due tomorrow morning,
> distracted only by reports of distant captures of his -20.0000db down
> signal. Dex will be working like crazy thinking up a new prank (since
Bills
> retaliation today for his prank last night) .  Mitch will be reconnecting
to
> that land line to Boston that allows him to fake the all-day sizzling
> captures of WA.  Jay will be madly clicking on our ARGO traces to see if
our
> ERPs are exceeding the UK 'guidelines'. ....And I know there are many more
> guys that were onboard last night that should be getting recognition, but
> I've got to go home for a tasty dinner!
>
> Please join in tonight!!
>
> Bill
>
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