Introduction to PSK31 - Receiving


Uploaded by K7AGE on 11.08.2007

Transcript:
Hi, Randy K7AGE. Today we are going to do an introduction to PSK-31
my goal to get to you receiving PSK-31
in a very few minutes
this is not difficult it's easy to do
we're not going to build any interfaces today we are going to do
it's simple things and you should be able to receive PSK-31 in
about the length of time of this this video.
PSK-31 was developed by Peter Martinez G3PLX
in 1998
his idea was to use a single sideband transciever
which has audio in and out microphone in, speaker out
and use the DSP
processing of
today's PCs and sound cards
and cross connect
the microphone
from the computer to the speaker of the radio and vice versa
audio in and out back in forth
PSK-31 was designed to support keyboard to keyboard communications
people on the air
chatting typing away to each other
the data rate basically supports people typing the maximum speed of fifty words per minute
now that is faster I can't type
we really don't need a lot of
bandwidth
or a lot of speed
speed and bandwidth go hand in hand
the higher the data rate the more bandwidth we need
32 bits per second is
the data rate and bandwidth required
for PSK-31
so where does this 32 and 31 come about?
31.5 was easily
derived from
clocks in sound cards
this case PSK-31.25 or we just call it
PSK-31
Anyway, that is more theory that we need to know for now
there's a couple of good web sites out there
take some time and go look, the notes are off to the side
of the video here with the web links
one is
www.psk31.com
they have articles on here
the described his PSK theory interfacing and such
there's an area that deals with hooks ups
we are not going to hook anything up today we're going to do it
really simple
we are going to use a micrphone
this is a computer
headset style microphone
you probably just use the microphone with in your laptop maybe
they also have on that website a list of software
we are going to use Digipan today
it's one of the first ones that came out
it's free
it's easy to use easy to set up
another website to look at is Wikipedia
do a PSK31 search
you'll get some of the history technical details links to other things
so we're going to hear now is
I feel like Mr Wizzard
go to the Digipan website
we'll download the software
we'll install it on the computer
we will
do some simple set-up
simple configuration
and
then be able to receive PSK-31
www.digipan.net
go to the site
Digipan download page
and a scroll down here a little bit
and we come to
downloaded Digipanl 2.0
700K
Just click on that
I'm going to save the file
and we have downloaded
the program here
at this point I get rid of the web site
I can click on open
and I get the Digipan setup window It say this will install Digipan on your computer
as recommended
close everything else
it says to quit any version of Digipan we are installing this for the first time just hit next
we want to put the file in, same as before, go ahead
Let's create a desktop icon
and install
it says to you want to launch Digipan click yes
it then opens Digipan and it pops up this window for personal data
and here you can put in your call sign
put your call in here, not mine. K7AGE
tab
I'm going to put my name in here
QTH
so now it knows a little bit about me
and here's the
the window at the default opens here
one of things that
that Digipan will do its simultaneous
receive multiple PSK signals I am going to turn that off
because it just gets kind of confusing
so up here is the top right is a Multi button just click on it
turns off
the multiple receives
next thing we want to do
is going to change the window sizes
bring that line up
and I bring up
down here the waterfall so
this area here is the receive data
this is where I transmit
this is where
the waterfall this is where I see the spectrum
what I need to do now it
hook up my audio interface
for the system
so what I have here
it's all tangled up
doesn't matter
but it's just a very simple
some sound card headset with a microphone
so plug it into the microphone input here
you'll see
some various
lines and
information
on the waterfall here
so if we are lucky
the microphone is picking things up see as I
for up to my mouth here
it's a
picking me up
so, but, you may have to set this up
so the way to do this
if you go to configure
click on that
and go to
first sound card
you basically want to use your default
soundcard that is in the computer. It says computer soundcard
that's where defaults here for preferred
it seems to work for me
I'm happy with that I'll just click OK
we have
selected were is coming from the soundcard coming from now we have to configure
the audio level
so go to waterfall drive
and it brings up
the recording
computer panel
and we're going to use the microphone we have microphone selected
clicked selected down here
many computers have this advanced button
and what this gives you
which you may or may not need is the microphone boost. I have it on it seems to work
so get your microphone set
now I need some audio
and the audio is
my FT-817
let's go ahead and
turn it on
turn the volume up
what can we hear?
and we want to tune the radio to 14.070 MHz
USB, upper sideband
that's where the PSK the activity
will be
here we go we are getting close
USB 14.070
perfect day, listen to all that activity
hope you can here this since it is not mixed in
turn the volume up
no single tone
but a lot of tones
Now, zoom out
we're going to make
the soundcard interface to the radio
I watch this this is very high tech
we take the microphone
and I am just going to
put it on the speaker
no cables plugged in
no attenuators, no transformers
this will get you receiving in
just a few minutes everything's working you should have signals in the bottom down here
that's to let the microphone control open here
you see if I even turn this all the way down
actually I have a lot of level here
still getting signals
If I turn it up too much
I see I get too much
background so
we basically want to turn this down I am going to turn off
the microphone boost
this appears to be a real hot like there you can see now
of almost lost the signals there
let me just turn this up
I am getting lots of traces here
I am going to
turn the boost back on
you have to play with this to get something that seems to work
Try that, I think it will fine
so lets go ahead and close this
and
so what's going on here?
righ now just a bunch of garbage on the screen
but to make it easier to read I'm going to go to configure
fonts
and lets
take it up to maybe about a size 16 here we go
a little easier for you to see
anyway, just a bunch of garbage
the radio is set at 14.070
that's the very left part of the screen
one killocycle is 1000 so this is all the audio
between almost DC- that 1 kilohertz
to tune PSK-31 we don't tune the radio would just leave it set at 14.070
but since we have this audio spectrum here and see 1 2 3 4 0:10:26.450,0:10:27.559 5
looks like a 6th signal there is weak
so to tune on this one over here which apparently is
looks to be fairly strong, I just click in the red
click the center of the lines
and
the little red box appears here
and if everything's working
we should see real text appearing in the screen
so it was pretty easy
got a wider shot here
lets see what this signal here is doing
W4GPL
he looks like he just stop transmitting
next station came on
and he looks to be
looks to be calling CQ DX here
6H1
6H1MW
a Mexico station
and he dropped off
ah so is he getting someone coming back to him? yes
also PSK-31 supports upper and lower case
so there we are we got you
to find the software
showed you how to download it
how to
configure the audio
pick your sound board
select your microphone
get the radio get the microphone near the radio
how to set the level so you see
hum
see the vertical lines all the signals in the spectrum and such
then just click on the line then you should be receiving
again, set your radio to 14.070
USB and you should be hearing a lot of signals
and I've also uploaded
a video file of PSK-31
what I did was just
record about 20 minutes
off of 20 meters
and that's a video
up on youtube
so what you can do even if you don't have a radio
I mean you may be watching this in your hotel room you want to give this a try
go ahead and download everything
and I'll show you how to
change where your audio comes from
so that you can play the youtube file
and run digipan at the same time and be able to play the
the signal that I recorded for you
let me just show to do that
it's pretty simple
On my youtube page you will find
a PSK-31 sample video
go ahead and play that
we hear
lots of PSK pretty busy time
and the picture will change
and we will see the waterfront. Okay here section of about twenty minutes here
they have a lot to deal with
this is your information file don't be clicking on here trying to receive that's not
going to work
I'm going to pause this for a minute
we're back here to Digipan the audio is now is not coming from the microphone is coming from
the internal file in the computer
so if I go to
waterfall drive this is where we set our
audio input
we get to get the recorder mixer panel
and what I need to get to
is the stereo mix
so go to options
properties
I will see various
sources of audio my computer
I want to turn on the stereo mix
press okay, you can see now
have another column here
so I want to select on
stereo mixer
okay let's bring up my
my video, I am going to move that over here a little screen arranging
here's my file I am going to start playing that
bring up to Digipan
the front here
and let's bring my mixer controls back up
move things around
here we go
now here's the signals I can control the level
I can see various signals on the waterfall
and when I click here
so I have Digipan running
I can click on that various signals here. I am going to clear the screen
I can receive these, a bit off tuning
there is VE3NFU
calling CQ
I can go to this other signal here
you will notice two straight lines
it means they
are probably not typing
if you see more squizley lines, they are actually typing
even if you don't have a receiver or not near one
go to youtube and play the file
see who is on the air in about 19:00 UTC Aug 11
if I stop the video
you see everything stops
start the video
back to Digipan and a strong signal here VA7GEM
so there you go
I showed how to do it, now to download it
how to configure it
you have a sample file, play away
the next couple videos that
go along with this
will be one just to talk about interfaces in general
anything from
you saw what we did today was just a microphone
simple cables - commercial boxes
the next thing we need to do was to get those interfaces running that will allow us to transmit
so right now
have fun receiving
see how much DX there are a few DX stations in that
youtube file
see how many can find
See you later, bye