# Welcome to QUISK (December 2018)

This is Quisk, a Software Defined Radio (SDR). You supply an antenna and a complex (I/Q) mixer to convert the radio spectrum to a low IF. Then send that IF to your computer using the sound card, Ethernet or USB. The Quisk software will read the I/Q data, tune it, filter it, demodulate it, and send the audio to headphones or speakers. Quisk has a microphone input and a key input so it can operate as a complete transceiver. Quisk works with this hardware:

- SoftRock connected to the sound card
- Many other SDR's connected to the sound card
- SDR-IQ connected by USB
- N2ADR hardware connected by Ethernet and IP
- HiQSDR hardware connected by Ethernet and IP
- The Hermes-Lite project at hermeslite.com
- Quisk can be used as a pan adapter, and can control some radios

Quisk is small and simple, and has been designed so that it is easy to change Quisk to suit your own hardware. Quisk rhymes with "brisk", and is QSK plus a few letters to make it easier to pronounce. QSK is a Q signal meaning full breakin CW operation, and Quisk has been designed for low latency. Quisk includes an input keying signal that can mute the audio and substitute a sidetone.
Please read the file CHANGELOG.txt for changes.
When running Quisk for the first time, please press the "Help" button on the lower right.

## Credits

Quisk was originally written by James Ahlstrom, N2ADR.
Thanks to Leigh L. Klotz, Jr. WA5ZNU for configuration improvements, factoring out my eccentric hardware control, and adding panadapter and other hardware support.
Thanks to Franco Spinelli for a fix for the H101 hardware.
Thanks to Andrew Nilsson VK6JBL for adding support for SoftRock Rx and Tx.
Thanks to Terry Fox, WB4JFI, for code to support the Charleston hardware.
Thanks to Maitland Bottoms, AA4HS, for the sub-module linkage patches.
Thanks to Philip G. Lee for adding native support for PulseAudio.
Thanks to Eric Thornton, KM4DSJ, for adding async support for PulseAudio.
Many others contributed to Quisk, and are mentioned in comments in the source code.

## Installation

Quisk is free open source software. It is hosted on the PyPi repository https://pypi.org. It can be installed using the standard Python setup tools. See specific directions below. Python is available as a series 2.7 release or a series 3 release, and there are 32-bit and 64-bit versions of each. You can continue to use the Python you have. If you don't have Python, install the most recent 64-bit Python3. It is possible to have both Python 2.7 and Python3 installed, and then install Quisk on both. If you have both Python2 and Python3, you can start them with "py -2" or "py -3". See the Python documentation for the py launcher.

Note that the 32 and 64-bit versions of Quisk are for the 32 and 64-bit versions of Python. The machine archetecture (32 or 64 bit) does not matter. Quisk must agree with the Python version. But a machine with 32-bit archetecture will not run 64-bit software, so you will need 32-bit Python. If you have a 64-bit machine, you can use either 32 or 64-bit Python, but most software is changing to 64 bit. You don't have to worry about this, because when you run pip from Python, pip will choose the correct version of Quisk.

### Windows Initial Installation

If you have Python, you can continue to use the version you have if it is recent. If you don't have Python installed, visit http://www.python.org and download the Windows installer for the most recent Python3. Use 64-bit for a 64-bit computer. To get there from python.org, click on "Downloads", then "Windows", then "Latest Python 3 Release". Under "Files" click on "Windows installer". The x86 is the 32-bit version and x86-64 is the 64-bit version. When installing, write down your install directory so you know where Python is located. There is an option to "Add python.exe to Path". It is best to select this option so that you can start python by just typing "python" instead of the whole path from your install directory. But don't do this if you have multiple versions of Python.

Next open a Command Prompt. This is located under "Windows System" on Windows 10; or use the search bar. Enter "python --version" and then "pip --version" to make sure that these programs are installed, and what version you have. If "python" is not found, it might not be on your Path. Try your_install_directory\python --version. For pip, it is your_install_directory\Scripts\pip --version. If you can find Python but not pip, you can run pip with "python -m pip".

First upgrade some Python modules to the newest version, then install Quisk. Enter these commands. The upgrade of pip gave error messages on my machine, but it worked anyway.

pip install --upgrade pip
pip install --upgrade setuptools
pip install --upgrade wxPython
pip install --upgrade pyserial
pip install --upgrade quisk

You should then be able to start Quisk with the command "quisk" or "your_install_directory\Scripts\quisk". To create a Quisk shortcut on your desktop, right-click an empty space and select "New" and "Shortcut". Use "your_install_directory\Scripts\quisk.exe" as the command and "Quisk" as the name. Create another shortcut for quisk_vna if you plan to use it. To install a newer version of Quisk, just use "pip install --upgrade quisk". You could check for newer versions of the other modules twice a year if you want.

To get started you must tell Quisk what kind of radio hardware you have. Press the Config button and select Radios. Then set your sound devices for that radio; the device for the radio speakers, the microphone and so forth. All configuration is (mostly) from the Config button. Ignore old directions and don't bother with a config file.

### Windows Quisk Upgrade

To upgrade to a newer version of Quisk, use pip. Remember that if Python is not on your Path, you will need to type out the whole path.
pip install --upgrade quisk

### Windows Uninstall Quisk

pip uninstall quisk

### Linux Initial Installation

Most likely both Python2 and Python3 are already installed on your computer. Either the 32-bit or 64-bit version will work. On my Ubuntu machine, "python2" starts Python2 and "python3" starts Python3. Just "python" starts python2, but this will change as Python2 is phased out. Install these packages. Some of these can be installed from Python using "pip", but it is better to use your package manager because pip and the package manager do not coordinate. If newer versions of these packages become available, Linux will notify you.
sudo apt-get install python-wxgtk3.0 ## Use this for Python2
sudo apt-get install python3-wxgtk4.0 ## Use this for Python3
sudo apt-get install libfftw3-dev
sudo apt-get install libasound2-dev
sudo apt-get install portaudio19-dev
sudo apt-get install libpulse-dev
sudo apt-get install libpython2.7-dev
sudo apt-get install libpython3-dev
sudo apt-get install python-usb
sudo apt-get install python3-usb
sudo apt-get install python-setuptools
sudo apt-get install python3-setuptools
sudo apt-get install python-pip
sudo apt-get install python3-pip
Then install either or both versions of quisk. They will not interfere with each other.
sudo python2 -m pip install --upgrade quisk
sudo python3 -m pip install --upgrade quisk
This will install the Python files and all other files except for the C source. This is the easiest method if you do not want to work in C. If you have both Python2 and Python3 quisk, you can run either with these commands:
python2 -m quisk
python3 -m quisk
If you have only one quisk you can run it with the command "quisk". You can create a panel launcher on your desktop with the command to run Quisk.
To get started you must tell Quisk what kind of radio hardware you have. Press the Config button and select Radios. Then set your sound devices for that radio; the device for the radio speakers, the microphone and so forth. All configuration is (mostly) from the Config button. Ignore old directions and don't bother with a config file.
To edit the Quisk Python files you need to know where they are. To find out, import quisk and print it:

    jim@IntelNUC:~$ python
    Python 2.7.12 (default, Nov 12 2018, 14:36:49)
    [GCC 5.4.0 20160609] on linux2
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import quisk
    >>> quisk
     module 'quisk' from '/usr/local/lib/python2.7/dist-packages/quisk/__init__.pyc'
    >>>

### Linux Quisk Upgrade

To upgrade to a newer version of Quisk, use pip:
sudo python2 -m pip install --upgrade quisk
sudo python3 -m pip install --upgrade quisk

### Linux Uninstall Quisk

sudo python2 -m pip uninstall quisk
sudo python3 -m pip uninstall quisk

### Linux Quisk Source Files

The previous method using pip is simple, but will not install the C source files. If you want those proceed as follows. Go to https://pypi.org/project/quisk and under "Navigation" select "Download files". Download the quisk-x-x-xx.tar.gz file. This is the source file. The ".whl" files are for Windows. Change directory to where the file was downloaded, probably "Downloads", and uncompress and untar it.
cd ~/Downloads
tar zxf quisk-x.x.xx.tar.gz
Change directories to the Quisk directory:
cd quisk-x.x.xx
Now compile Quisk with the "make" command:
make quisk2 # for python2
make quisk3 # for python3
If "make" fails, you probably have missing packages or missing "-dev" packages. Try to figure out what is missing from the error messages. Now you can run quisk with the command:
python2 quisk.py
python3 quisk.py
At this point you have a choice of where to install Quisk. You could just rename the quisk-x.x.xx directory to a more convenient name, like "quisk" in your home directory, and run Quisk from there. This is convenient if you want to alter the Quisk code. Or you could install Quisk into the Python system.
python2 setup.py build
sudo python2 setup.py install

### Quisk Files

These are the Quisk files in the distribution:

- quisk.py is the main program and is written in the Python language. Python is a powerful but easy to learn language, and I hope you have fun changing Quisk to make it do what you want. Python is also useful for general electronics calculations such as complex arithmetic. See www.python.org. Quisk.py uses the wxPython Python package to make the screen interface.

- help.html is the help file for quisk. Press the "Help" button.

- _quisk.so is the _quisk extension module for Linux, and _quisk.pyd is the extension module DLL used by Windows.

- sdriq.so is the extension module needed for the SDR-IQ. It needs _quisk.so to be available when it starts.

- makefile is the makefile, and you must run "make" to create a new _quisk.so unless you use a Python installer that creates _quisk.so itself.

- setup.py is used by makefile and the Python installers.

- quisk_conf_defaults.py is the basic configuration file imported into all other configuration files. Read it (but don't change it) to see what you can change in your own quisk_conf.py.

- quisk_conf_*.py are various Quisk configuration files. Copy one of them to your own .quisk_conf.py and edit that file. I may publish new model files in the future, and you don't want your changes to be overwritten.

- quisk_hardware_*.py are various quisk hardware control programs. If you have custom hardware, import one of these files into your quisk_conf.py. Or copy one of them to your own quisk_hardware.py, edit that file, and import it in .quisk_conf.py.

- quisk.c, quisk.h are the files for the _quisk extension module used by quisk.py. The other C-language files are linked with these to make _quisk.so and _quisk.pyd.

- sound.c is the general purpose sound code for all sources.

- sound_portaudio.c is the sound card access code for PortAudio.

- sound_pulseaudio.c is the sound card access code for PulseAudio.

- sound_alsa.c is the sound card access code for the ALSA drivers.

- sound_directx.c is the sound card access code for DirectX.

- is_key_down.c is the hardware key checker for the PC. I use Ethernet to send the key status, but there is code for the parallel port and dummy code too.

- sdriq.c, sdriq.h are the files that make sdriq.so and support the SDR-IQ.

- microphone.c reads the microphone audio and sends it to your hardware using Ethernet. Change it for other sound access.

- docs.html is Quisk documentation. Look for other *.html and *.txt too.

- portaudio.py is a utility program. Run it to list your PortAudio devices. It is not used by the Quisk program.

## Configuration

The Quisk "Config" button brings up a number of status and configuration screens. When starting with Quisk, you need to create a named "radio" and then set the configuration for that radio. You can have multiple radios to support several hardwares, or different settings for the same hardware. Use the "Help with Radios" button for documentation. A special radio named "ConfigFileRadio" is always available. It doesn't use the settings screens and takes all its settings from the configuration file. When Quisk starts, it reads an initial configuration from the Quisk file quisk_conf_defaults.py. Then it reads your configuration file if you have one. Then it reads settings from the configuration screens, which are stored in the file quisk_settings.json. You can set almost everything with the screens, but you can have a configuration file if you want. For Linux, the default configuration file name is ".quisk_conf.py" in your home directory; that is, "~/.quisk_conf.py". For Windows, the default configuration file name is quisk_conf.py in your My Documents folder.

- Linux config file: ~/.quisk_conf.py
- Windows config file: My Documents/quisk_conf.py

To help you get started, there are several configuration files included, such as quisk_conf_model.py for sound card, quisk_conf_sdriq.py for SDR-IQ, and quisk_conf_fixed.py for fixed VFO such as SoftRock. Do not change any of the quisk_conf_*.py files. Instead copy one of these files (but NOT quisk_conf_defaults.py) to your own config file. Newer versions of Quisk will not overwrite your personal config file.
The file quisk_conf_defaults.py contains all Quisk's parameters, and you can read it to see what can be changed.
If you are controlling custom hardware, you will need to specify a hardware file in quisk_conf.py. The default is quisk_hardware_model.py. Look at the other quisk_hardware_*.py files. For example, quisk_hardware_fixed.py is for crystal controlled SoftRock. To use that hardware file, change your quisk_conf.py to include:
import quisk_hardware_fixed as quisk_hardware
There are comments in quisk_conf_model.py showing this change. If none of the hardware files do exactly what you want, copy one of them to your own quisk_hardware.py, edit that file, and include this line in quisk_conf.py:
import quisk_hardware
Newer versions of Quisk will not overwrite your quisk_hardware.py. Your hardware file enables you to customize Quisk without changing the Quisk program files.
Alternatively, you can define a class named "Hardware" in your config file, and that class will be used instead of a hardware file. This is recommended only for simple hardware needs. The class should start like this:

    from quisk_hardware_model import Hardware as BaseHardware
    class Hardware(BaseHardware):
        def __init__(self, app, conf):
            BaseHardware.__init__(self, app, conf)
            # Start your hardware control here.
            # For ideas, see one of the other hardware modules.

Both the config file and your hardware file are written in the Python language. Python is an easy to learn but powerful computer language. Quisk can be adapted to different hardware because of the power of Python.

## Sound Cards

If you use a sound card for input, the quality of your sound card is critical; but you can start with the sound card you have. Check the Graph screen with no input to see the noise floor. It should be as flat and as low as possible, with no bump near zero Hertz. The 0dB line at the top of the Graph screen is the maximum level, so if your noise floor is at -90 dB, you have that much dynamic range. The IF (sound) input to the sound card should raise the noise floor only slightly to avoid losing dynamic range.
The sample rate determines how much of the band you can see on the screen. My 96 kHz card shows a little over 80 kHz of bandwidth, from -40 kHz to + 40 kHz centered at the VFO frequency. Generally you would choose the highest rate available to get the most visible bandwidth. Be aware that a card claiming to work at (say) 192 kHz may in fact play at that rate, but only capture (record) audio at a lower rate. It is the capture rate that matters. Enter only the sample rate you know your raw hardware supports for capture.
If you use the SDR-IQ or other hardware for input, you still need a sound card for sound output. The quality of this card is not so important, so try the one you have. Be aware that most sound cards require the capture and playback rate to be the same when used for both. Here are some sample configurations:

- SoftRock Rx/Tx: Receive to card 1, Transmit to card 1 at the same rate, radio sound to card 2 at 48 kHz, microphone input from card 2 or 3 at 48 kHz.
- SoftRock Rx: Receive to card 1, radio sound to card1 at the same rate; OR radio sound to card 2 at 48 kHz.
- Other: Receive from SDR-IQ or other hardware, radio sound to card 1 at 48 kHz. Add a microphone to card1 at 48 kHz, or to card2 at 48 kHz.
- Panadapter: There is no radio sound. Enter a null name "" for the play device.

If you buy a new sound card, make sure you know the capture (recording) sample rates and the noise level. Sound cards are usually specified over the audio range up to 24 kHz or so. But we need low noise and distortion over the whole range.

### Linux Names

Quisk can use PulseAudio, PortAudio or ALSA to access your sound card. Names can be a fragment of text from the device description. It is better to use this text search rather than an index number, because the index number can change if you plug and unplug USB sound cards.
The ALSA drivers use different names for the same sound card to provide different access. The names "hw:0" and "hw:1" refer to the raw hardware devices of the first and second sound card. You should use the raw hardware if possible. If the raw devices don't work, use the "plughw" name. The ALSA name can also be a string name. Here are some ALSA names:

    "hw:0"		# First sound card
    "hw:1"		# Second sound card, etc.
    "plughw"	# plug device
    "default"	# alsa default device
    "alsa:NVidia"	# Search for the name in the alsa device description

Alsa names starting with "alsa:" are an extension to the normal alsa names. They search for the text after the colon in the alsa device name. The alsa device names are shown on the config screen. Or you can start a terminal window and enter "aplay -l" for a list of play devices, or "arecord -l" for a list of capture devices. See alsa_names for more information.
The PortAudio interface is newer, may be easier to get working, and may be used to connect Quisk to other programs (I have not tried this). But for CW, ALSA has lower latency. Run "python portaudio.py" in a terminal window to see a list of available names, or use a different PortAudio tool. Here are some PortAudio names:

    "portaudio:(hw:0,0)"    First sound card.
    "portaudio:(hw:1,0)"    Second sound card, etc.
    "portaudio:NVidia"      Search for the name in the portaudio device description.
    "portaudio#1"           Directly specified index.
    "portaudiodefault"      May give poor performance on capture.

### Linux Sound Servers

Newer Linux systems are now shipping with PulseAudio enabled. PulseAudio is a sound server, a program that takes control of your sound cards, and controls usage by applications. The idea is that your applications talk to PulseAudio, and PulseAudio talks to the sound cards. Another example of a sound server is JACK. You can control the sound routing with the pavucontrol program. Remarkably, this is not included with PulseAudio, and you will need to install the pavucontrol package first.
Thanks to Philip G. Lee and Eric Thornton, KM4DSJ, Quisk now has native support for PulseAudio. For PulseAudio devices, use the name "pulse:name" and connect the streams to your hardware devices using a PulseAudio control program like pavucontrol. The name "pulse" alone refers to the "default" device. The PulseAudio names are quite long; for example "alsa_output.pci-0000_00_1b.0.analog-stereo". Look on the screen Config/Sound to see the device names. There is a description, a PulseAudio name, and for ALSA devices, the ALSA name. Instead of the long PulseAudio name, you can enter a substring of any of these three strings. An example is:

    # As seen on the Config/Sound screen:
         CM106 Like Sound Device Analog Stereo
         alsa_output.usb-0d8c_USB_Sound_Device-00-Device.analog-stereo
         USB Sound Device USB Audio (hw:1,0)

    # Use the default pulse device for radio sound:
       "pulse"
    # Use a PulseAudio name for radio sound:
       "pulse:alsa_output.usb-0d8c_USB_Sound_Device-00-Device.analog-stereo"
    # Abbreviate the PulseAudio name:
       "pulse:alsa_output.usb"
    # Another abbreviation:
       "pulse:CM106"

The PulseAudio code should not cause problems, but I am not sure what happens if PulseAudio is not installed, or if you replace it with JACK. This config file option will turn off all but directly entered "pulse:" names:

    show_pulse_audio_devices = False

### Linux Problems

If Quisk appears to run but you get no sound input or output, you may be having trouble with your settings. Start Quisk and look at the graph. You should get a moving line display. Look at the Config screen. Interrupts should be increasing and latencies should fluctuate. If all this looks normal, but you get no sound output, or you get only white noise output, then you may need to change your settings with a mixer program.
If you capture data with the sound card (no SDR-IQ) then you need to set the "capture device" to the line-in jack, and set the volume of the line-in to 100%. To play sound, you need to increase the volume of the playback device. Since a typical sound card has ten or twenty controls for all its analog and digital inputs and outputs, it is a guessing game to figure out which control to adjust.
Basically you start the alsamixer program (use "man alsamixer" first) and adjust the volume controls and capture device until Quisk works. It is wise to reduce or mute unwanted inputs to avoid adding extra noise. Quisk does not do this for you. But once you have the controls set, they will stay the same and Quisk should keep working until you run another audio program that changes them.
To make Quisk adjust the mixer controls when it starts, you need to know the control id number. Run the command "amixer -c 0 contents" (for card zero) and look at the control ids, names and values of all your controls. Figure out the control you need to adjust. For a setable option (on/off) the control value is one or zero. For a volume it is a number from 0.0 to 1.0. Make a list of (device_name, numid, value) and add it to mixer_settings in your .quisk_conf.py file (see quisk_conf_defaults.py). I don't need to do this on my computer except for the microphone input on my second sound card.
If you really get stuck, try one of these commands (see the "man" page):

- alsamixer An ALSA mixer program with a curses interface.

- amixer A character ALSA mixer.

- aplay Play sound.

- arecord Capture sound.

- speaker-test Play sound to test your speakers.

And try to play an audio CD or run some other Linux audio program just to see that you have a working sound system. If you can't get ALSA to work, you could try the PortAudio or PulseAudio interface by just changing the sound card names.
For more information try these articles:
http://linuxplanet.com/linuxplanet/tutorials/6465/1/
http://linuxplanet.com/linuxplanet/tutorials/6466/1/

### Windows Names

To see what sound cards you have, use the Control Panel item Sound Devices. There is a separate list for capture (recording) and playback devices, and a specified default device for each. The name of the default device is "Primary". To specify your sound card name, use either "Primary" or a substring of the device name. The search is case sensitive.

## SDR-IQ as Input

Quisk can use an SDR-IQ from RfSpace instead of a sound card as input. Set up a radio of type SdrIQ. The SDR-IQ uses a serial port to connect to Quisk. When you plug it in, it will create a USB serial port and connect to it.

On Linux the serial port has a name like /dev/ttyUSB0. Look in /dev or use "dmesg | tail" to figure out what port it is using. Then enter that port as the "Serial port" on the Config/radio/Hardware screen. The serial ports are part of the "dialout" group. Add yourself to the "dialout" group so you have permission to use the serial port. You also need a serial port USB driver for the ft245 chip in the SDR-IQ, but Linux generally comes with a suitable driver.

On Windows the "Serial port" name is not used, and Quisk will search for the port in use. On Windows 10, you should see a device "SDR-IQ" in Device Manager in the "View/Devices by Container" tab. In earlier versions of Windows, port names are COM1, COM2 etc. and use the "USB Serial Converter" driver. Windows should find this driver by itself.

## Timing

There are several configuration parameters devoted to tuning; read the file quisk_conf_defaults.py for documentation. For most users, Quisk should run fine with the default settings. But if you use Quisk as part of a QSK CW transmitter, you should reduce latency_millisecs to as low a value as possible. This will reduce latency, but increase the likelihood of clicks and pops due to sound buffer underruns.

## USB Control

Many radio devices are now controlled through a USB interface. In many cases, the interface is actually a serial port, and an external or internal USB to serial converter is used. In other cases, the USB is native, but requires a custom device driver. In still other cases, the USB device announces itself as a standard device such as a sound device or human interface device, and uses a standard operating system built-in driver.

### Linux

Default USB permissions do not allow a non-root user to write to the bus. You may find that Quisk will complain about lack of permission to access the USB. You could test this by running Quisk as root and seeing if that works; but this is not acceptable except for testing. To change USB permissions, add a rule to /etc/udev/rules.d/local.rules (for SoftRock on Debian and Ubuntu) like this:
SUBSYSTEM=="usb", ATTR{idVendor}=="16c0" , ATTR{idProduct}=="05dc", MODE="0666", GROUP="dialout"
This changes the USB device permissions to read/write for all users, and changes the group to the "dialout" group. Default group permissions are read/write, so if you are in the "dialout" group, you don't need "MODE"; modify as appropriate. To load the new rule, you can either reboot or on Ubuntu use
sudo udevadm control --reload-rules

## Custom Hardware

Quisk receives RF using your sound card or your SDR-IQ out of the box. But if you have custom hardware such as a VFO or a transmitter, you need to describe your hardware to Quisk.

First, Quisk has a transmit (Tx) frequency and a receive (Rx) frequency. The transmit frequency is the one shown in the frequency display, and shown by the tuning line on the graph and the waterfall. The Rx frequency is always equal to the Tx frequency except when the RIT (receiver incremental tuning) button is down or the Split feature is in use. The primary frequency in Quisk is the Tx frequency, even when you are receiving.
Quisk has a "VFO" frequency. This is the RF frequency corresponding to zero Hertz audio frequency, and is the frequency shown at the center of the graph display. For a SoftRock or a direct conversion receiver (Tayloe detector, SDR1000-type hardware, etc.) this really is the VFO frequency. But consider an AOR AR8600 receiver with a 10.7 MHz IF output to a pan adapter. For that case, the VFO is always 10.7 MHz since that is the center point of the display, and signals at exactly 10.7 MHz are at zero Hertz audio. But to display the correct frequency within Quisk, the VFO would be the tuning frequency of the AR8600.
When Quisk starts, it uses the hardware description in quisk_hardware_model.py, but this file doesn't do much. It is mostly useful as a model or starting point. To use a different hardware file, first create a custom file such as my_hardware.py. Look at the various quisk_hardware_*.py for ideas. Then import your file in your config file:

     import my_hardware as quisk_hardware.

Suppose you have a crystal controlled SoftRock. A good model hardware file is quisk_hardware_fixed.py. Copy quisk_hardware_fixed.py to my_hardware.py, make any changes to my_hardware.py, and import it in your config file.
At my shack, I control an AT-200PC antenna tuner, my SDR-IQ, my filter boxes and my SSB transceiver (using Ethernet) all with Quisk. Take a look at my n2adr subdirectory.
The quisk_hardware_model.py file shows the basics of hardware control. There is an open() and close() function called once on startup and shutdown. The ChangeMode() and ChangeBand() functions are called when the user changes the mode or band with the corresponding buttons. The HeartBeat() function is called at about 10 Hz by Quisk. You can put code there to poll a serial port or to perform other housekeeping functions (try to be efficient). The two remaining functions deserve more documentation.

### ChangeFrequency(self, tune, vfo, source='', band='', event=None)

Quisk calls the ChangeFrequency() function when the user changes the Tx frequency with a mouse click on the graph or waterfall, with the entry box, with the band Up/Down buttons, etc. The "source" is a string giving the reason for the change:

BtnBand | A band button was pressed (the string band is in the band argument)
BtnUpDown | The band Up/Down buttons were pressed
FreqEntry | The user entered a frequency in the box
MouseBtn1 | Left mouse button was pressed (for the mouse, "event" is the handler event)
MouseBtn3 | Right mouse button was pressed
MouseMotion | The user is dragging with the left button
MouseWheel | The mouse wheel up/down was used

Most of the time you will not care about the "source". You just need to react to the user's action, perhaps by changing the hardware VFO frequency. It is not necessary to actually make the change requested. Just adjust your hardware as required, and return the actual (tune, vfo) that you want. Quisk will ignore its requested values and use your actual values instead.
For example, suppose you have a crystal controlled SoftRock. The VFO frequency is fixed at (say) 7.025 MHz. Then when ChangeFrequency() is called, return (tune, 7025000). This will fix your VFO frequency to the only one available.
Suppose Quisk calls ChangeFrequency() with vfo=7050000 and tune=7100000, so the tune is 50 kHz above the VFO. Suppose that is unacceptable because of (say) bandwidth limitations, so you want the VFO closer to the tune. Set your hardware VFO to 7090000 instead, and return (tune, 7090000).
Suppose Quisk is just controlling a receiver and the audio is demodulated by the receiver and not by Quisk. Then the center frequency is always the tuning frequency, and you would set the receiver frequency to tune, and return (tune, tune).

### ReturnFrequency(self)

When Quisk starts, it calls ReturnFrequency() to get the initial tune and VFO. To display an initial frequency, return (tune, vfo) on the first call.
Thereafter, Quisk calls ReturnFrequency() at a 10 Hz rate to poll for frequency changes. You should almost always return (None, None) to indicate that the frequencies have not changed since the last time ReturnFrequency() or ChangeFrequency() was called. Returning (None, None) is slightly more efficient than returning the actual frequencies, and thus forcing Quisk to see if its frequencies are out of date.
The only reason to return something other than (None, None) is if your hardware can change frequency by itself; that is, other than in response to ChangeFrequency(). For example, if your hardware is a receiver with a tuning knob, and the user turns the knob, you must return the new frequencies from ReturnFrequency() or else Quisk will be unaware of the change.

## Extension Packages

Quisk comes with two extension packages. The freedvpkg package supports FreeDV digital voice. The n2adr package supports the hardware in my shack. There are other extension packages available from third parties.
All extension packages are directories (folders) in the Quisk root; that is, in the directory where quisk.py is located. This enables Quisk to find extension modules, and extension modules to find each other. You can install in a different place, but you will need to know what you are doing.
Starting with Quisk 3.6 C-language extension modules are not linked with _quisk.so. Certain symbols from _quisk.so are exported using the Python CObject or Capsule interface. That simplifies linkage and eliminates problems with module search paths. See the documentation in import_quisk_api.c. This change was suggested by Maitland Bottoms, AA4HS, and he also provided patches.

### Shared Libraries

The main Python extension module for Quisk is _quisk.so or _quisk.pyd. It is a shared library. To import it, it must be on the Python path. There are other Python extension modules (shared libraries) for other hardware, for example, sdriq.so. Quisk works fine when all these modules are in package subdirectories. If you want to put them somewhere else, be sure that the Python import mechanism can find them.
If you link your sub-packages against _quisk so you can use _quisk functions, be aware that your sub-package must be able to find _quisk.so at both compile and run time. You need to follow the Linux rules for searching for shared libraries. Try using the "ldd sdriq.so" command to see your library dependencies. Also try readelf -d sdriq.so.
For Quisk version 3.6 and newer, you should use the Python CObject or Capsule mechanism instead of using the C linker to access _quisk functions and data. Quisk will prepare an array of function and data pointers and transfer them to your sub-module without using the C linker. Only minimal changes to your sub-module are required. The SDR-IQ module sdriq.so uses this method, and you can use it as a model. See the file import_quisk_api.c for documentation.

### New Packages

If you have more complex needs or want to distribute your code more widely, you need to create a new Quisk package. That is easily done by modeling your code after the existing packages. To create a new package you need a subdirectory of the Quisk root to hold it, perhaps "mypak". Then create these files in mypak:

- __init__.py This file just consists of the character "#". Its existence identifies mypak as a Python package.

- makefile Only needed if you have C-language extensions.

- MANIFEST.in A list of files you want to distribute in your package. This file often consists of just one line: include *.c *.h *.py *.txt *.html *.so makefile

- README.txt This file is expected to be present.

- setup.py This file describes your package. It contains the package name, author, C source files and compiler options, etc. See http://docs.python.org/distutils/setupscript.html and use other packages as examples.

To these files, you add all your Python files, C-language files and any other files you need. If you have a hardware or widget file, they should be named quisk_hardware.py and quisk_widgets.py. Longer names are not needed because you are within a package. You should include a sample quisk_conf.py too.
To compile C-language extensions (if you have any) enter "make". To import your hardware and widgets files from other modules, use:
from mypak import quisk_hardware
from mypak import quisk_widgets
from mypak import myext as EXT
The setup.py file describes how to build your package. But it is also used to distribute it. To create a mypak-1.0.tar.gz file in the "dist" subdirectory, use:
python setup.py sdist
You can then put the file on your web page (for example). To make your package available on PyPi.Python.org, first register with PyPi and then use:
python setup.py register sdist upload
Python supports quite complicated packages; see the distutils documentation.

### Installing Packages

Your package mypak will run on your machine as is. But when another user gets mypak-1.0.tar.gz they need to install it. Basically, they just put it in the Quisk root with the same name as on your machine. Here is an INSTALL.txt:
Unzip and untar this archive at the root of the Quisk directory; that is, where the file quisk.py is located. In this example, the archive is named "mypak" and the path to quisk.py is /home/jim/quisk/quisk.py.
mv mypak-1.0.tar.gz /home/jim/quisk
cd /home/jim/quisk
gunzip mypak-1.0.tar.gz
tar xf mypak-1.0.tar
# Make sure that directory mypak-1.0 exists before removing the archive.
rm mypak-1.0.tar # tar file is no longer needed
mv mypak-1.0 mypak # change to the correct name

## Digital Modes

Quisk has a number of modes "DGT-" to receive and transmit digital signals. The modes "DGT-U" and "DGT-L" decode the signal as upper or lower sideband, and send the monophonic audio to the digital sound device. The mode "DGT-IQ" does not decode the audio; the I/Q samples are sent directly to the (stereo) digital sound device. The bandwidth of the digital signals is set with the filter buttons as usual, and the filter center is 1500 Hertz.
Digital modes require an external program such as Fldigi or wsjtx to decode the received audio and to generate transmit audio. There are two aspects, rig control and audio transfer. Rig control is needed to synchronize the transmit frequency between Quisk and Fldigi (or other program) and to operate the PTT (push to talk). You can control Quisk using either XML-RPC or Hamlib. See Rig Control and Logging below.
Quisk has an additional audio input and output for digital programs. They are named digital_input_name and digital_output_name in the config file. They are Digital Input and Digital Output on your radio's Sound configuration screen. You need to set these names to a sound device, and then set the Fldigi (or other program) sound card to the same device. The sound device is not a real sound card; it is some sort of loopback device, and is only needed because there is no standard way of sending sound samples between two programs (yet). The method to use for Quisk is the same as for other programs, and is on the web. It works for any digital program, not just Fldigi.
If you use Windows, you need to purchase a Virtual Audio Cable (VAC). Connect Quisk to one side, and your digital program to the other. I haven't tried this, so I don't know the device names to use, but it is straight forward.
If you use Linux, you can use the ALSA loopback device, or use PortAudio, PulseAudio or Jack to route your audio. Using PulseAudio is the easiest method because Quisk can set up the loopback devices when it starts. Set Digital Input to pulse:QuiskDigitalInput.monitor, and set Digital Output to pulse:QuiskDigitalOutput. These names should be on the drop down list. If they are missing, make sure that you didn't set "show_pulse_audio_devices" to False in your config file. Then restart Quisk. In your digital program, connect the digital input to QuiskDigitalOutput.monitor and the digital output to QuiskDigitalInput. These names will be on the sound menu in wsjtx, and you should be receiving and transmitting digital data.
Fldigi only has a PulseAudio check box, and there is no way to set the proper device. In this case, first install the program pavucontrol to control PulseAudio. This is a useful program to control and understand PulseAudio even if you are not using digital. Set the Quisk devices as above. Now start both Quisk and Fldigi, and then pavucontrol. The Playback and Recording screens in pavucontrol will show the devices being used. Change the Fldigi playback to QuiskDigitalInput, and the Fldigi recording to Monitor of QuiskDigitalOutput. Then everything should work. You do not need to use pavucontrol again because PulseAudio will remember the settings.
If you don't have PulseAudio or don't want to use it, you can use the ALSA loopback device. The ALSA loopback device works the same way as the Windows VAC. First create the loopback device with the command "modprobe snd-aloop" (you will need to be root). You can create the loopback device when the system starts, but the way to do that depends on your version of Linux. I added snd-aloop to /etc/modules. You could put the modprobe command in /etc/rc.local instead. Restart Linux. Now you can enter "cat /proc/asound/cards" to print out your sound cards, and you should see a "Loopback" card listed. The cards are also shown on the Quisk config screen. The Loopback card has one side that connects to Quisk and another side that connects to your digital program. For the Quisk side connect both Digital Input and Digital Output to Loopback,0. Note that the Loopback card is full duplex, and handles both input and output. There are actually eight loopbacks created at once, but we are only using subdevice 0. For the digital program side, set the input and output to "Loopback,1". For Fldigi this is in the Audio / Devices / PortAudio menu. Your audio is now connected and you should be able to receive digital signals. Be sure to test your transmit signal off the air. You may need to reduce power to improve linearity.
The sample rate for Quisk Digital Input (transmit audio) is fixed at 48000 sps. The sample rate for Quisk Digital Output (received audio) is the same as the rate sent to your speakers. The Loopback device adopts the rate of the first program to use it. So starting Quisk first and your digital program next should work. Or you may need to set the appropriate rates. It is probably best to set all sample rates to 48000 sps because the digital signals are so narrow, and this make them easier to see.

## Rig Control and Logging

Digital mode and logging programs need to control Quisk to read and set the frequency and mode and to operate PTT. Quisk has three options for external control and they can all be used together to connect to multiple programs. See the Config/radio/Remote screen. See http://james.ahlstrom.name/hamlib.html for more information.
To connect an external program to Quisk using Hamlib, configure your program to use "Hamlib NET rigctl" (rig 2). Then go to the Quisk "Remote" config screen for your radio and set "IP port for Hamlib" to 4532. This assumes you are not using the rigctld daemon program. If you are, set the Quisk port to 4575 and tell rigctld to control quisk on port 4575. Now changing the frequency on one program will change the other. Keying Quisk to key down (however you do that with your hardware) will set the external program to Transmit. Pressing the PTT control in the external program will also press the PTT button in Quisk.
You can also control Quisk from another program by using the XML-RPC method if this is available in your program. Fldigi can use this method.
If your program only uses a serial port (N1MM+) then use Hamlib with the rig set to "Flex" and connect to the Quisk serial port set on the Remote screen. For Linux, Quisk can set up these ports itself, and they have names like "/tmp/QuiskTTY0". On Windows you need a "Virtual Serial Port" that is set up by an external program. This is like the "Virtual Audio Cable" needed for samples. An Internet search will turn up HDD Software, Eltima Software and many others. Set up a port pair, and enter one name on the Quisk Remote screen and the other name in the external program.

## Vector Network Analyzer

If you have my transceiver hardware from 2010 QEX, or the newer HiQSDR hardware, or the Hermes-Lite you can use it as a vector network analyzer by using a special program. You must be using FPGA firmware version 1.3 or newer. Run the VNA program with "python quisk_vna.py" or use a shortcut. The VNA program will not work with SoftRock or other hardware. The "Help" button explains how to use it, and should get you started. This VNA program enables you to analyze your antennas without additional expense.
A calibration run must be taken before any data can be obtained. The calibrations request a scan of data points every 15 killohertz from zero to 60 megahertz, or a little over 4000 points. These data are saved so that the scan frequencies can be changed without a new calibration. For any start and end scan frequency the user chooses, these saved calibrations are used with linear interpolation.

### HiQSDR Internals

When running in VNA mode the two control bytes [18:20] are the 16-bit non-zero VNA count "vna_count", the number of data points to send. This locks the transmit and receive frequency to the same value. The phases are also equal except for a fixed time delay, which causes a linear change of phase with frequency. The starting frequency is the receive frequency (actually phase) rx_phase. Subsequent points have the transmit phase tx_phase added to create a frequency scan. Specifically, after each data point, the tx_phase is added to create the RF output at the next frequency; then there is a pause of 65 microseconds to allow the external device under test to stabilize; then 4096 data points are added together to create the sample; then the sample is added to the block of data to send by UDP. A sample of zero is sent after the last data point, and the process repeats. The receiving software must look for the zero sample that marks the start of a new scan. The total number of points in the scan is vna_count, and blocks received with a different length should be rejected. Since the transmit and receive frequency are the same, the data points are I/Q values at DC; that is, a complex number representing a voltage and phase. If vna_count is zero, the firmware is operating normally, and not in VNA mode.