I have that also, running the last two official psdr versions on two
different computers.
Its built into the software it seems.
I was working some guys Sunday, a flex 1000, a 3000 and my 5000.
We were talking about the carrier level adjustment in the AM mode.
On my 5000, 100 equals 25 watts carrier, 100 watts pep like a normal AM
signal is, as I reduce the carrier setting, the 100 watts pep stays the
same, but the carrier level drops like I would expect it to.
I was running mine at 85% to get more audio on the carrier, you cant go to
far or boat anchor receivers distort badly.
The guy with the 3000 was running his at 35, the 1000 at 50.
When the guy running the 1000 turned it down the modulation went up, but he
runs it at 50 and gets just 100% modulation. He said, when you exceed the
normal setting, the modulation wraps around and goes positive introducing
lots of distortion.
I don't hear it but others can, and he said you can see it clearly with a
sine wave on a scope.
His 50% setting seems to equal normal 100% modulation.
I suspect we were all running different psdr versions, the 1000 something
old, the 3000 the PB version, I am running 1.18.3.
Is the difference the radios, or the software, and the 3000 seems out in
left field at 35, which should almost be double sideband if it acts like my
radio?
The manual for the 5000 says my radio is acting normal, and that it is ok to
adjust the carrier level down to get more modulation.
I THOUGHT it was doing it without excessive distortion, but people can hear
distortion (they say).
Anyone know how the flex actually does this, does it wrap the excessive
negative modulation around and make it positive?
Brett
----- Original Message -----
From: "Jordan" <outposte...@shaw.ca>
To: <flexe...@flex-radio.biz>
Cc: "FLEX USERS" <flexradio@flex-radio.biz>
Sent: Sunday, January 03, 2010 6:52 PM
Subject: Re: [Flexradio] [FlexEdge] AM/SAM receive problems
Hello Flexers...
I am replying en-masse so that perhaps others can re-create this
problem...
I've spent the last 2hrs scanning for weak AM SWBC stations, and find that
the problems occurs on almost any weak AM signal using either Slow or Long
AGC settings as long as there are a few random pulses or sharp noises such
as a lightswitch might make.
In my experience this occurs in almost any typical SW DX session. It does
not occur while listening to your local AM outlet.
The DSP settings do not matter, and the Display and S-metering do not show
any change when this occurs.
It appears that the AGC decay in these 2 modes is somehow getting
disabled, as I've had recovery times of 20 seconds+ ....
To quickly recover the gain I've been re-selecting MED AGC, and it
recovers in ~ 200ms usually.
I can't say if I've noticed this on 80m Amateur AM signals, but I've
noticed it on the 2.3Mhz Australians and right through to the 19m SWBC
band.
I'm going to try to put together some more info, but time isn't in surplus
for me right now, so perhaps others could try and reproduce and document
their findings as well.... 73...Jordan VE6ZT
----- Original Message -----
From: "Bob McGwier" <rwmcgw...@gmail.com>
To: <flexe...@flex-radio.biz>
Cc: "FLEX USERS" <flexradio@flex-radio.biz>
Sent: Sunday, January 03, 2010 12:23 PM
Subject: [FlexEdge] AM/SAM receive problems
I am really having trouble getting a copy of an IQ file upon which I can
demonstrate any kind of AGC problem. I want to fix this but if I cannot
hear, see, etc. it in action, I am unable to perform a diagnosis.
I need "before and after" IQ files.
1) Find an AM station exhibiting the problem.
2) Recording your AGC settings in an email to me along with the names of
the files and a description of what you are seeing. Recording which
version of code your are running. Save your database.xml file for me to
be transmitted as below.
Please use the wave recorder.
3) Make a PRE DETECTION (pre-processing) IQ recording of a station
exhibiting the problem.
4) Repeat this with a POST DETECTION of the same station (ideally) so I
can hear what you are hearing.
5) Zip all of these files, including the database.xml into a single zip
file.
Run a google search for a large free file sharing service.
http://www.google.com/search?rlz=1C1GGLS_enUS359US359&aq=f&sourceid=chrome&ie=UTF-8&q=free+large+file+sharing
Pick one that is acceptable to you and put the file there if you do not
have a personal service we can use. I will download the file, and
complete my analysis on the actual signal files and look for the problem
and fix it.
I do not believe than any AGC problem is unique to AM. I believe that if
it REALLY IS an AGC problem, it will exhibit artifacts on other modes,
including transmit, if it really is AGC. It might be some inadvertent
changes to AM/SAM. I do not believe this. I have had files sent to me
by Tim and they exhibit no problems whatsoever so far as I can tell.
When I listen to local strong AM stations, all seems well here. I am
motivated to find and fix this. But I cannot do it without your aide.
HNY!
Bob
N4HY
--
(Co)Author: DttSP, Quiktrak, PowerSDR, GnuRadio
Member: ARRL, AMSAT, AMSAT-DL, TAPR, Packrats,
NJQRP, QRP ARCI, QCWA, FRC.
"the only people for me are the mad ones,
the ones who are mad to live, mad to talk,
mad to be saved, desirous of everything at
the same time, the ones who never yawn or
say a commonplace thing, but burn, burn, burn
like fabulous yellow roman candles" Kerouac
Twitter:rwmcgwier
Active: Facebook,Myspace,LinkedIn
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