| |
EB2DVY > PSK31 19.09.99 15:06l 349 Lines 13704 Bytes #-9813 (0) @ WW.SYD.NSW
BID : 419-EB2DVY
Read: OE1HLW OE1RRB GUEST
Subj: PSK31 Digest V1 #176
Path: OE1XAB<OE3XSR<OK0PPR<OK0PKL<DB0MAK<DB0SON<DB0SIF<DB0SRS<DB0ZDF<DB0HOM<
F6KDL<F8KOX<F6KNP<F8KLY<F5KPO<F5KAT<EA3D<EA3B<EA3ARR<EA2C<EA2K<EA1URR<
EA1URM<EA2RCF<EA2G<EA2URV
Sent: 990917/2333Z @:EA2URV.EABI.ESP.EU #:10216 [URV-ABRA Bilbao] $:419-EB2DVY
From: EB2DVY@EA2URV.EABI.ESP.EU
To : PSK31@WW.SYD.NSW.AUS.OC
De: Psk31 Digest <owner-psk31@aintel.bi.ehu.es>
Para: <psk31-digest@aintel.bi.ehu.es>
Asunto: Psk31 Digest V1 #176
Fecha: miércoles 15 de septiembre de 1999 4:44
Psk31 Digest Wednesday, September 15 1999 Volume 01 : Number 176
In this issue:
[psk31] dB indicate of PSK31SBW1.08
Re: [psk31] dB indicate of PSK31SBW1.08
[psk31] Notebook problem
Re: [psk31] dB indicate of PSK31SBW1.08
Re: [psk31] dB indicate of PSK31SBW1.08
See the end of the digest for information about psk31-digest
----------------------------------------------------------------------
Date: Tue, 14 Sep 1999 13:59:02 +0900
From: TOSHIAKI_KUROSAKI@m1.shinko.co.jp
Subject: [psk31] dB indicate of PSK31SBW1.08
To all,
Could anyone let me know the usage, utility, or effects of
dB indicattion added to Ver1.08 in a simple description.
I am beginner for PSK31 mode.
Thank you.
JA0KSB T.Kurosaki
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
to unsuscribe from the list send to majordomo@aintel.bi.ehu.es a message
with a text line as follow: unsubscribe psk31 or unsubscribe psk31-digest
More instructions on PSK31 Webpage: http://aintel.bi.ehu.es/psk31.html
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
------------------------------
Date: Tue, 14 Sep 1999 08:58:19 -0400
From: "Robert Lay" <w9dmk@crosslink.net>
Subject: Re: [psk31] dB indicate of PSK31SBW1.08
Dear JA0KSB T.Kurosaki and others,
Historically, it has been an objective of the PSK31 Mode to produce the minimum
bandwidth signal, consistent with the fundamental characteristics of the mode.
Operators have no trouble seeing on the waterfall that a signal is emitting
excessive sidebands. Usually, this problem occurs with improper adjustments of
the sound card Mixer Levels or with improper adjustment of the drive level and
power output of the transceiver.
These mis-adjustments are typically the result of bad assumptions.
Inexperienced operators may make the assumption that the sound card does not
produce distortion at its higher output levels, and also that the transceiver
can
operate at full SSB power levels without distortion. Neither of those
assumptions are always valid.
In fact, most operators have learned that the sound card should not be set for
output levels higher than 50 to 75% of maximum. Also, many transceivers are not
clean
above 30 to 60 watts. The power levels mentioned here are the power levels at
"idle" - i.e., you are "on the air", but not typing.
So, even though most operators could give you a report on how many sidebands
they see in the waterfall, it was very subjective and no two operators would
agree on whether the signal was "clean enough" or not. Various schemes for
measurement of the distortion were proposed. One method
was to use a graphics program to measure the different brightness levels of
unwanted sidebands relative to the main signal.
Peter Martinez, the designer/developer of the PSK31 mode, recently developed a
modification to his software that provides for an automatic display of the
distortion levels whenever the received signal is in "idle" mode. The display is
in dB relative to main signal and represents the amount of unwanted signal
products
relative to the main signal.
I have extracted a fragment from one of Peter's messages that relate to Quality
of Signal. This provides some guidance for "how much distortion" is considered
acceptable and how much is not acceptable.
Directly after that quote I am also reproducing that section of the Help file
that is relevant. So, in case anyone has been unable to find the relevant
section of Peter's Help file, it will be found at the end of this message, and
is required reading for all users of PSK31 - Hi!
_______Quote from Peter Martinez_____________
.................. in order to come up with
some estimates as to what consitutes a "bad" PSK31 signal that should
be dealt with. I am giving myself the impression that worse than 20dB
means "I tell him it's bad even if he didn't ask", 20-25dB means "if
he asks me, I tell him it could be better", 25-30dB means "if he asks
me, I tell him it's fine", and more tha 30dB means "I tell him how
good his signal is even if he didn't ask".
_________________End of Quote___________
_______Extract from the Help File_____________
To transmit PSK31 correctly, the transmitter must be operated with good
linearity, just like an SSB transmission. In the past with RTTY it has not been
necessary for the transmitter to be linear. This has meant than some newcomers
to PSK31 have not found it easy to set up the transmitter. This program has a
feature which shows the linearity of the received signal, so it is easy to
report the quality of the signal to the distant operator.
The quality readout appears in the middle of the phase scope circle when the
signal is idling. It is a measure, in dB, of the level of the first pair of
unwanted sidebands (at +/-46Hz from the centre-frequency) compared to the main
pair of wanted sidebands (at +/-15Hz). The readout appears only when the signal
is idling, that is, when the emission is actually the same two-tone signal that
is used for checking the quality of SSB transmitters. In fact the dB figure in
the quality readout is the same as the third-order intermodulation performance
figure given for SSB transmitters.
To give a PSK31 signal quality report, wait until the signal is idling, or ask
the distant station to leave a pause so that you can get a reading, then tell
him the dB figure on your next transmission. Of course, if he is also using
PSK31SBW (version 1.08 or later), you can leave a pause in your transmission and
ask the distant operator to give you a report.
Warnings
There are some times when this readout will give a false reading:
1. If there is another signal very close in frequency, it may be close enough to
affect the readout even if it does not affect the wanted signal itself.
2. A very weak signal may give a low quality reading if the unwanted sidebands
are below the band noise.
3. Remember that a bad quality reading could also be caused by distortion in
your own receiver. For example, fast AGC can sometimes cause distortion of the
received signal, and sometimes the speaker output may be poor quality but the
aux. output is better. A poor quality readout on all signals might be a clue
that there is a problem in the receiver which could make strong signals on the
band look like they are splattering.
Quality guide
The higher the dB figure the better the quality. Higher dB figures mean less
interference. A normal SSB transmitter can give better than 25dB. If you get a
report worse than this, there is probably something wrong. Some not-so-good
transmitters may only give 20dB at full power and so it may be necessary to run
lower power to get a better signal. A figure worse than 20dB usually means that
the transmitter is overdriven from the soundcard. 10dB is the readout you would
get by feeding square-waves to the transmitter instead of sinewaves. If it's
worse than 10dB then the transmitter is being pulse-modulated.
______End of the Help File extract___________
73 de Bob Lay, w9dmk@arrl.net, King George, VA
http://www.qsl.net/w9dmk
http://www.fortunecity.com/meltingpot/albania/784
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
to unsuscribe from the list send to majordomo@aintel.bi.ehu.es a message
with a text line as follow: unsubscribe psk31 or unsubscribe psk31-digest
More instructions on PSK31 Webpage: http://aintel.bi.ehu.es/psk31.html
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
------------------------------
Date: Tue, 14 Sep 1999 11:39:34 -0700 (PDT)
From: Carl Hyde <cshyde@yahoo.com>
Subject: [psk31] Notebook problem
I am using a Toshiba Sattelite Pro 462? laptop running
Win 95 for PSK-31. When I transmit anything there is
no sound from the sound card. I'm using the standard
drivers that came with it. Also the microphone seems
to be on all the time. If I touch the little grill
over the mic I can hear it from the speakers. If I
close the top the audio feedback from the speakers to
the mic is loud. I also have tried the line in to
the notebook for receiving and this works but I can't
transmit. What the heck is going on with this
thing???
===
Carl S.HYDE
W2CSH
Eagles May Soar, But Weasles Never Get Sucked Into Jet Engines!
Politics: From the Greek word Poli, meaning many and
the word tics, meaning blood sucking parasites.
__________________________________________________
Do You Yahoo!?
Bid and sell for free at http://auctions.yahoo.com
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
to unsuscribe from the list send to majordomo@aintel.bi.ehu.es a message
with a text line as follow: unsubscribe psk31 or unsubscribe psk31-digest
More instructions on PSK31 Webpage: http://aintel.bi.ehu.es/psk31.html
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
------------------------------
Date: Tue, 14 Sep 1999 15:47:46 -0500
From: "hasan schiers" <schiers@netins.net>
Subject: Re: [psk31] dB indicate of PSK31SBW1.08
The dB indication is the IMD (intermodulation distortion) of the signal you
are copying. This number is a reflection of the "cleanliness" of the signal
you are receiving. Be sure to set your agc to slow for an accurate
measurement. It is a function of the purity of the source signal, how much
they are overdriving their audio input stages and how hard they are hitting
their finals. My experience shows me so far that when setting your audio
input levels to the transmitter, for MOST radios, you want NO ALC action
whatsoever.
Now...what do the numbers really mean? These are my "assessments". They have
no technical basis whatsoever, but are based on what I've seen on the band
and comparing the signal levels in -dB (how many dB the undesired distortion
is suppressed) to a really good looking waterfall display.
Theoretical Maximum Suppression = 56 dB (from Peter as I recall)
Best signal I've seen = 44 dB
Range of Good Signals = 30 dB or better
Signals That Need Improvement = 25 to 29 dB
Signals That Need a LOT of Improvment = 22 db or worse
Signals That Shouldn't Be Transmitting = 20 dB or worse.
I've yet to see a -25 dB signal that couldn't be improved in real time
chatting with the person on the air to better than -30 dB.
These are nothing but my own opinions and observations. Suffice it say, any
signal showing no more than 20 dB of suppression produces pretty remarkable
"banding" in the waterfall display indicating an unnecessarily broad signal.
If I were going to guess at the distribution of signals I see on the air
according to IMD, it would look something like this:
- - 40 dB or better 5 % (Excellent quality)
- -30 dB to -39 dB 15 % (Good Quality)
- -25 dB to -29 dB 35 % (Average Quality, needs improvement)
- -20 dB to - 25 dB 30 % (Below Average Quality)
- - 19 dB and below 15% (Terrible Quality)
So, about 20% of all signals are good to excellent, 35% need some
improvement and about 45% of the signals need quite a bit of work.
If someone else has developed a different scale, please share it. (In terms
of what level of suppression corresponds to Excellent, Good, Average, Below
Average and Terrible).
Hope this helps ya. 73
hasan schiers, N0AN
schiers@netins.net
- ----- Original Message -----
From: <TOSHIAKI_KUROSAKI@m1.shinko.co.jp>
To: <psk31@bipt106.bi.ehu.es>
Sent: Monday, September 13, 1999 11:59 PM
Subject: [psk31] dB indicate of PSK31SBW1.08
>
> To all,
>
> Could anyone let me know the usage, utility, or effects of
> dB indicattion added to Ver1.08 in a simple description.
> I am beginner for PSK31 mode.
>
>
> Thank you.
>
>
> JA0KSB T.Kurosaki
>
>
>
>
>
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> to unsuscribe from the list send to majordomo@aintel.bi.ehu.es a message
> with a text line as follow: unsubscribe psk31 or unsubscribe psk31-digest
>
> More instructions on PSK31 Webpage: http://aintel.bi.ehu.es/psk31.html
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
to unsuscribe from the list send to majordomo@aintel.bi.ehu.es a message
with a text line as follow: unsubscribe psk31 or unsubscribe psk31-digest
More instructions on PSK31 Webpage: http://aintel.bi.ehu.es/psk31.html
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
------------------------------
Date: Tue, 14 Sep 1999 17:01:49 -0600
From: "Gary McDuffie, Sr." <mcduffie@scottsbluff.net>
Subject: Re: [psk31] dB indicate of PSK31SBW1.08
On Tue, 14 Sep 1999 08:58:19 -0400, Robert Lay wrote:
> If it's
> worse than 10dB then the transmitter is being pulse-modulated.
Hi Bob. I thought it was interesting last week when I observed a
European (don't remember who or where) that was showing 8db. That
signal was so bad you could hear it up and down the band for a
considerable spread. I called him but he didn't come back.
Gary
- --
Please notify your ISP if you don't receive this.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
to unsuscribe from the list send to majordomo@aintel.bi.ehu.es a message
with a text line as follow: unsubscribe psk31 or unsubscribe psk31-digest
More instructions on PSK31 Webpage: http://aintel.bi.ehu.es/psk31.html
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
------------------------------
End of Psk31 Digest V1 #176
***************************
Read previous mail | Read next mail
| |
