PSKmeter.py

[See CentOS/Fedora notes from David Ranch, below - 11/2009.]

PSKmeter.py is a display and analysis program for the PSKmeter station accessory. It is written in Python under Linux, but it should be portable to Windows or MacOS systems. It uses the Tkinter package for window management and display. If you wish to use PSKmeter.py, you will have to obtain the pyserial package for serial port I/O.

View or download pskmeter.py. [Rename the file, if necessary.] This is new and improved Version 0.25. This version is more tolerant of disconnecting and reconnecting the serial port or the power supply.

PSKmeter.py is copyrighted software. You may copy or adapt it freely for non-commercial applications. It may not be republished without permission.

Release Notes

Features

• Full-cycle IMD analysis using "derectified" data.
• Improved zero detection capability
• ADC data are now linearized against a measured calibration function.
• Controls soundcard PCM level - manual, not automatic
• Provides optional raw data dump
• Overload indicator

Known issues and areas for development

• There is still some jitter in the waveform sync. This is mainly an esthetic problem. A complete cure would mean going to a 128 or 256 point interpolated data array.
• Some improvements to the IMD / modulation quality index are possible, by choosing other statistics, by averaging over cycles, etc.
• The PSKmeter is a great tuning aid, but it has limited dynamic range and it's not very linear. As such, I don't advise relying on its "IMD" numbers too much.
• The calibration curve, overload limit, etc. are based on my particular unit. Your mileage may vary.
• This program was developed using Python 2.2.3 under Fedora Linux FC1.
• Because Python 2.2.3 does not have direct support for audio mixer control, PSKmeter.py 0.20 uses a piped process running 'aumix'. With Python 2.3, direct OSS audio support is available.
• The audio mixer interface is Linux-specific, but should be adaptable to other platforms.

Your comments and suggestions are welcome -- to aa6e ...at... arrl.net.

Updated: 3/14/2004, 11/18/2009

PSK meter for Centos5 / Fedora9:

(David Ranch, Nov., 2009)

Download the ported pskmeter.py app and the currently stable versionof
pyserial module at http://aa6e.net/software/psk/

As root,

- download and install the pyserial module (for version 2.4):
python setup.py install

- install Tkinter
yum install tkinter

- install aumix (no Yum package available)
download from http://freshmeat.net/projects/aumix/
#This is a nice mixer that gives you NUMBERS for levels instead of
just the usual arbitrary ticks:

tar xivf aumix-2.8.tar.bz2
cd aumix-2.8
./configure
make
sudo make install
ln -s /usr/local/bin/aumix /usr/bin/aumix

Note: I re-used the USB to serial interface I had connected to my Yaesu
FT-950's CAT interface. To make sure that fldigi wasn't going to
conflict, I disabled the HAMLIB interface.

Configuring pskmeter.py:

- the pskmeter.py program defaults to looking for it's controlling
serial interface at /dev/ham.pskmtr. To make it work for my setup, I
did the following as root:

ln -s /dev/ttyUSB0 /dev/ham.pskmtr

- Make sure you run "chmod 666 /dev/ttyUSB0" so that the pskmeter.py
program can access the serial port

- The pskmeter.py program defaults to an alternative mixer. Edit the
pskmeter.py program file and change the MIXER setting to:

MIXER="/dev/mixer"

- Follow the PSKmeter instructions in testing the PSKmeter's serial
port but if you run minicom at 19200-8N1 and turn it on, you should see
a plain english initialization string

Now, fire up fldigi (or whatever app your using to do PSK31):

- find a clear, open frequency
- set your rig to low power
- tune up to a low SWR
- now insert the pskmeter between the rig and the antenna tuner to protect
it from reflected power
- Start up the meter with:
python pskmeter025.py

- In Fldigi, there is the TUNE button in the upper right but that
transmits SINGLE tone. Not what you want. You want to run a PSK Tx by
typing in control-t

Note on changing your soundcard's volume settings:
- setting the PCM output too low only looses resolution but
doesn't distort the signal. Setting it too high creates distortion and
the tops of the pskmeter lobes start to drop in. That's bad.

> On Mon, Nov 16, 2009 at 12:47 AM, David Ranch wrote:
>>
>> Anyway, I appreciate your work on the port. I'm working on this with Centos 5.4 (I can send you the instructions if you'd like to post it) and it's responding but it's not graphing anything within the double lobes. If I view the RAW mode, the digits from 00 to 62 do increase though they are all the same number as I increase power. Running pskmeter on windows does graph things though all bars are the same height which seems to agree with why pskmeter.py shows though without any green bars.
>>
>> Thoughts?
>>
>> --Davi
>>
>

11/18/09
Hello Martin,

It turns out that the test signal I was sending was CW and not PSK.
Upon reflection, that makes perfect sense of why all the values would be the same!

To me, adding a FAQ entries to the original PSKmeter (and #3 on your
page) would be helpful:

1. If there isn't any signal waveform but under the text view, all
fields are equal and increase as you add more Tx power, you're probably
sending a CW test signal and NOT a PSK signal

2. PSKmeter for linux won't display any signal graphics until the
expected PSK waveform is detected. For example, PSKmeter for Linux
won't display a flat CW waveform

Btw, here are my notes on how to get PSKmeter for LInux installed and
working. Discovering and fixing some of the dependances might be
overwhelming for newbies. They are easy to do and the more we can do to get/keep HAMs on Linux, the better!

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