# Welcome to QUISK (December 2023)

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
- Perseus 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.

## News

The newest versions of Linux and Raspberry Pi OS do not allow installing Quisk in the system Python package directory. Use the Linux Source Installation below instead.

Python 2 is no longer supported. Python 2 was obsolete as of January 1, 2020. And the new code by Ben, AC2YD, needs Python 3. It is troublesome to write code that runs on both Python 2 and Python 3. So it is time to stop supporting Python 2 in Quisk. Please upgrade to Python 3. If you have both versions, use Python 3 for Quisk.

## 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 written in Python and C. It is hosted on the PyPi repository https://pypi.org and it is available on github.

If you have Python 3 installed on your computer, just continue to use that version. On Windows Quisk requires Python 3.8 or 3.9 or 3.10 or 3.11. If you want to install a more recent version of Python, uninstall the old version first. Running multiple versions of Python is possible but can be confusing and is not necessary. A Quisk installation is needed for each version of Python you have.

### Windows Initial Installation

Windows does not include Python, so you must first install a recent version of 64-bit Python 3. If you already have 64-bit Python 3 installed, just keep using it. On Windows Quisk requires Python 3.8 or 3.9 or 3.10 or 3.11. There may be newer versions of Python, but until support is added, use the versions listed above. Python is available from http://www.python.org. There is an option to Add Python to PATH. You MUST select this option so that you can start python by just typing "python" instead of the whole path to your install directory. My install directory is:
C:\users\jim\AppData\Local\Programs\Python\Python39
And "AppData" is invisible. To avoid problems, check Add Python to PATH. If you forget, it is worth it to uninstall and reinstall Python. Quisk is really designed for curious people who want to play with the code, but Windows tries to shield users from program details.

Next open Windows PowerShell (not PowerShell ISE). This is on the Start button menu on Windows 10; or use the search bar. Enter "python --version" to make sure that Python is installed and what version you have. If "python" is not found, it might not be on your Path. You will need to keep typing your_install_directory\python instead of "python".

Next upgrade some Python modules to the newest version, then install Quisk. Enter these commands:
python -m pip install --upgrade pip
python -m pip install --upgrade setuptools
python -m pip install --upgrade wxPython
python -m pip install --upgrade pyserial
python -m pip install --upgrade quisk
You should then be able to start Quisk with the command "quisk". You can also start Quisk with "python -m quisk". To create a Quisk shortcut on your desktop, right-click an empty space and select "New" and "Shortcut". Use "quisk.exe" as the command and "Quisk" as the name. The "quisk.exe" program is in your_install_directory\Scripts. If you are curious, Quisk and its Python source files are installed in "your_install_directory\Lib\site-packages\quisk". If you change to that directory you can run Quisk with "python quisk.py".

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. You should check for newer versions of the other modules twice a year.
python -m pip install --upgrade quisk
You can also install an older version of Quisk. You may need to do that if the most recent version fails for some reason. Use:
python -m pip install quisk==4.1.51

### Windows Uninstall Quisk

python -m pip uninstall quisk

### Linux Initial Installation

Linux runs on a wide variety of computers with different processors and versions of Linux. Therefore Quisk is compiled for each one. To do this, Python and a number of other packages are required. Most likely both Python2 and Python3 are already installed on your computer. On my Ubuntu machine, "python2" starts Python2 and "python3" starts Python3. Just "python" starts Python2, but this will change as Python2 is phased out. Python2 is obsolete, so you should only install Quisk to Python3, and use "python3" to start it. Install these packages by using your package manager, not Python pip. If newer versions of these packages become available, Linux will notify you. Use the most recent version of python3-wxgtk available for your Python version.

These are part of your operating system. You only install them once unless it changes.

    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 python3-dev
    sudo apt-get install libpython3-dev

These are part of Python. You only install them once unless the Python started by "python3" changes.

    sudo apt-get install python3-wxgtk4.0
    sudo apt-get install python3-usb
    sudo apt-get install python3-serial
    sudo apt-get install python3-setuptools

If you want to use the SoapySDR module make sure that SoapySDR is installed from its Pothosware site before you build Quisk. Otherwise Quisk will not have the files it needs. You can install SoapySDR later, but then you will need to run "make" again. This is also true of any other external packages that have their own C source.

### Linux Pip Installation

Installation of Quisk using Python tools like pip is deprecated.

Installation to the system Python is no longer allowed, and you may get the message "error: externally-managed-environment". If you used pip to install Quisk you can continue to upgrade with "sudo python3 -m pip install --upgrade quisk" until you get this error message. But it is best to uninstall the pip Quisk. If you installed with pipx, uninstall that too.

    sudo python3 -m pip uninstall quisk
    pipx uninstall quisk

Then use the Linux Source Installation.

### Linux Source Installation

On Linux, Quisk is installed from github, and it is contained in a "quisk" directory. First you need to decide where to put the quisk directory. Anywhere will do, but it is best to use a directory where you have write permission so you don't need to use "sudo". The examples below assume you used your home directory indicated by "~". Just replace "~" by your desired location.

To install a fresh copy of Quisk, change to your desired directory, clone the github site, change to the quisk directory and run "make". Then run the python program quisk.py.

    cd ~
    git clone https://github.com/jimahlstrom/quisk
    cd quisk
    make
    python3 quisk.py

If "make" fails, you probably have missing packages or missing "-dev" packages. Try to figure out what is missing from the error messages. You only clone github for the initial installation. To update Quisk, use pull:

    cd ~/quisk
    git pull

You run Quisk by running the file quisk.py with python3. For example, "python3 /home/jim/quisk/quisk.py". You can create a desktop icon to do that, but the method depends on your version of Linux. Never run Quisk with root privelege by using sudo. Fix the permission problem instead. 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 uninstall Quisk, just delete the quisk directory.

### 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. PortAudio is optional.

- 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. Quisk supports multiple types of radio hardware and each type has different parameters. Each block of parameters is called a "radio". It is a named block of settings Quisk uses to control a specific kind of hardware. So a single Quisk can have parameters for a SoftRock and an HL2. You specfy the radio you want when starting Quisk.
When you first install Quisk, you will not have any settings for your radio. Press the Config button and go to the Radios screen. Then create a radio by specifying the general hardware type and give it a name of your choosing. For a Hermes-Lite, specify "Hermes" as the hardware type and call it "HL2" (or some other name). Press "Add" and a new tab for your radio will appear. Look through the various settings on the HL2 tab. The parameters for the radios are stored in the file quisk_settings.json.
A special radio called "ConfigFileRadio" is always available. It takes its parameters from a configuration file. You can set almost everything with the screens, but you can have a configuration file if you want. Most users will not need a configuration file. 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.

## 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 now optional. Many users are changing to PulseAudio. You can run "python portaudio.py" in a terminal window to see a list of available PortAudio names. 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.

### 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.

## SoftRock

SoftRock radios use an analog mixer to change the RF signal to stereo audio, and then use a sound card to digitize it. A high quality sound card is advisable. The analog mixer is not perfect, and it will be necessary to adjust the I and Q signals to equal amplitude and 90 degrees phase difference. Use the Config/Config screen buttons to bring up an adjustment screen. Adjustments must be made for each band, and separately for transmit and receive. The adjustment depends on both the VFO frequency and the tuning offset from the VFO. See my paper http://james.ahlstrom.name/phase_corr.html for more information. A good strategy is to pick a VFO near the band center, and record corrections at an Rx frequency of -15000, -1000, 1000 and 15000 Hertz. If the corrections are sensitive to VFO, record the corrections for these same Rx frequencies at VFOs equal to or slightly outside the upper and lower band edges. To effectively adjust for multiple VFO frequencies, the VFOs must have the same table of Rx frequencies. You can add as many correction points as desired. The corrections are saved in the file quisk_init.json. This file can be edited by hand if you are a Python expert. Otherwise you can just read the values.
To create a Receive correction point for a given VFO and frequency, attach a signal generator to the SoftRock through an attenuator, and look at the image on the graph screen. If the signal is 3500 Hertz above the VFO, the image is 3500 Hertz below it. Choose "Measure" to measure the corrections and then "Add Cell". If you don't have a signal generator, find a strong station on the band and look at its image. Choose "Manual adjustment". Minimize the image by adjusting the amplitude and phase sliders on the adjustment screen, and then press "Add cell".
To create a Transmit correction point for a given VFO and frequency, attach the SoftRock RF output to a spectrum analyzer through an attenuator, and look at the image. If you don't have a spectrum analyzer use a second receiver tuned to the image. Minimize the image by adjusting the amplitude and phase sliders on the adjustment screen, and then press "Add cell".

## 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.

## Perseus as Input

Quisk can use an Perseus HF receiver from Microtelecom instead of a sound card as input. Set up a radio of type Perseus. The Perseus uses a native USB interface to connect to Quisk. The Quisk perseuspkg extension relies on libperseus-sdr open source library to manage Perseus hardware and receive the I/Q samples stream.

Follow the instruction into GitHub repository to compile and install the library. On Suse distribution the library is available as binary package. Next compile the perseuspkg using the command:

    make perseus3

The several sample rates can be selected opening Config panel: in the Config tab there is the Samples rates dropdown. The input analog filter can be switched in using the button Wideband.
The input attenuator is operate via the button RF, that allows to select the four attenuator steps.
The ADC commands for dithering and preamplifier are found on left bottom corner as ADC Dither and ADC Preamp.

## 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 comes with hardware files for many types of radio. See the various quisk_hardware_*.py files. But if you have a radio that Quisk does not support, or if you want to customize an included hardware file, you can write your own hardware file and enter the name on the Config/radio/Hardware screen. A model hardware file is included as quisk_hardware_model.py. It is useful as a starting point and as documentation. Hardware files use Python class inheritance. That is, all hardware files inherit methods from a parent file and then add their custom methods. Hardware files can control other hardware too. 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.

Here is the start of the SDR-IQ hardware file:

    from quisk_hardware_model import Hardware as BaseHardware

    class Hardware(BaseHardware):
      def __init__(self, app, conf):
        BaseHardware.__init__(self, app, conf)
        # etc.
      def ChangeBand(self, band):
        # etc.

The file imports the Hardware from quisk_hardware_model and uses it as the basis of the SDR-IQ Hardware class. It calls the base init function and then adds its own methods for ChangeBand() and other methods. If it does not define a method, the method from quisk_hardware_model is used. Please refer to Python documentation if you are not familiar with inheritance.

If you want to write a hardware file from scratch, your file would start the same way. But if you have a radio like the SDR-IQ but want to customize it, your hardware file would look like this:

    from quisk_hardware_sdriq import Hardware as BaseHardware

    class Hardware(BaseHardware):
      def __init__(self, app, conf):
        BaseHardware.__init__(self, app, conf)
        # etc.
      def ChangeBand(self, band):
        # etc.

This file uses all the methods from the SDR-IQ file except ones that are defined here. The HL2 hardware file is in the hermes subdirectory, so to create a custom file you would use:

    from hermes.quisk_hardware import Hardware as BaseHardware

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.

### 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.

### Adding Custom Hardware to the Config/Radios Screen

If you have unique hardware and want to add it to the list of available radio types and add its configuration options to its Config/radios/Hardware screen, create a subdirectory of the Quisk directory with a name ending in "pkg"; for example, "myradiopkg". Then put your hardware file in this subdirectory with the name "quisk_hardware.py". You will need at least one configuration option to specify the hardware file name. Add this code (all comments) near the top of quisk_hardware.py:

    # Define the name of the hardware and the items on the hardware screen (see quisk_conf_defaults.py):
    ################ Receivers MyRadio, The special radio that I own
    ## hardware_file_name		Hardware file path, rfile
    # This is the file that contains the control logic for each radio.
    #hardware_file_name = 'myradiopkg/quisk_hardware.py'

Of course, change the names of the radio and subdirectory as appropriate. Your radio of general type "MyRadio" will now appear in the list of radios on the Config/Radios screen, and its configuration items will appear on the Config/radio/Hardware screen. You can add additional items. See quisk_conf_defaults.py and the *pkg subdirectories for examples.

## 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 stereo audio to the digital sound device. The left and right channel are the same. The bandwidth is set with the filter buttons as usual, and the filter center is 1500 Hertz. The mode "DGT-IQ" does not decode the audio; the I/Q samples are sent directly to the stereo digital sound device.
Digital modes require an external digital program such as Fldigi or WSJT-X 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 WSJT-X and to operate the PTT (push to talk). You can control Quisk using XML-RPC, Hamlib or a serial port. See Rig Control and Logging below.
Quisk has additional audio inputs and outputs for digital programs. On the radio Sound screen "Digital Tx0 Input" is the Quisk input for transmitted audio. The "Digital Rx0 Output" is the Quisk output of the received digital signals. You need to set these names to a sound 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 digital 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.
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. The name of the sound device depends on which VAC you use.
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 Tx0 Input" to "pulse: Use name QuiskDigitalInput". Set "Digital Rx0 Output" to "pulse: Use name QuiskDigitalOutput.monitor". These names are on the drop down list for the sound device. 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 of the digital program, and you should be receiving and transmitting digital data. Remember to select one of the DGT-* modes.
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 your digital program only uses Alsa devices or you don't want to use PulseAudio, you can use the ALSA loopback device. It works the same way as the Windows VAC. First create the loopback device with this command:

    sudo modprobe snd-aloop index=19

The "index" is the card number, and it is best to use a number higher than your regular cards. The loopback device will be gone on the next restart. You can create the loopback device every time the system starts, but the way to do that depends on your version of Linux. You could add this line to /etc/modprobe.d/alsa-base.conf:

    options snd-aloop index=19

Or you could add snd-aloop to /etc/modules or 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 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 the Loopback at hw:19,0. 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 the Loopback at hw:19,1. 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.

## 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 address for Hamlib Rig 2" to "localhost", 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.

## WSJT-X

Quisk has special support for the digital program WSJT-X. There is a button to start WSJT-X on the Config/Config screen. Look for "Start WSJT-X" and select "Main Rx0 now". This starts WSJT-X with radio "quisk" and you will see "WSJT-X - quisk" in the title bar. Then under WSJT-X File/Settings set up the Radio and Audio as described above. For Linux, use the pulseaudio devices:

Quisk Name | Quisk Value | WSJT-X Name | WSJT-X Value
--- | --- | --- | ---
IP address for Hamlib Rig 2 | localhost | Radio Rig | Hamlib NET rigctl
IP port for Hamlib | 4532 | Network Server | localhost:4532
Digital Tx0 Input | Use name QuiskDigitalInput | Audio Soundcard Output | QuiskDigitalInput
Digital Rx0 Output | Use name QuiskDigitalOutput.monitor | Audio Soundcard Input | QuiskDigitalOutput.monitor

## Vector Network Analyzer

If you have my transceiver hardware from 2010 QEX, or the newer HiQSDR hardware you can use it as a vector network analyzer by using a special program. As of 2021 the HL2 no longer works as a VNA. This may change in the future. Run the VNA program with "python quisk_vna.py" or use a shortcut. The VNA program will not work with SoftRock or other hardware. 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.

## Remote Operation

Ben, AC2YD, contributed a feature that enables you to run a radio at a remote location from a control head. The remote radio could be on your local area network or somewhere on the Internet. The remote radio is connected to a computer running Quisk, the computer could run Linux or Windows, and it could be a single-board computer such as Raspberry Pi. The two computers communicate using the TCP and UDP protocols. You can use either a wired connection or WiFi. The feature uses TCP port 4585 and two UDP ports 4586 and 4587. These must be open at the remote radio. It should not be necessary to open ports at the control head as it initiates all communication. A paper describing the original design is here.
Nigel, G4ZAL wrote a quick guide here.

The version of Quisk running on the control head must exactly match the version at the remote radio. Also, each type of radio has its own remote hardware file and control head hardware file. The supported radios are softrock, hermes and hiqsdr.

If you have dropouts in the sound, try increasing the "Play latency msec" on the Config/Timing screen. Quisk buffers sound, and the buffer size can be adjusted.

Create a radio of type "Control Head", and on the Radio/Remote screen enter the IP address or host name of the remote radio and a password. Change the hardware file to ac2yd/control_softrock.py or ac2yd/control_hermes.py or ac2yd/control_hiqsdr.py. Enter the usual widget file for that radio if any. Create sound devices for radio sound and microphone sound. Do not create devices for samples or digital modes.

Create a radio of the correct type at the remote site. This must be softrock, hermes or hiqsdr. Configure the radio to correctly control the hardware. You should be able to operate successfully at the remote. Then change the hardware file to ac2yd/remote_softrock.py or ac2yd/remote_hermes.py or ac2yd/remote_hiqsdr.py. Enter the usual widget file if any. The radio will still operate normally unless the control head is connected. Enter the same password on the Radio/Remote screen. The password only needs to be entered once at each end. It is a "shared secret". Use a somewhat lengthy pass phrase of random words, at least 20 characters long.

You can use Windows, Mac or Linux at either end. But for Windows, the Windows Firewall will interfere. Do not turn the firewall off. Change the network profile type from the default Public to Private if you are on a private home network. The setting is under Settings, Network, WiFi or Ethernet, Network Profile. If you are on a public network, you should use a VPN for security.

For security, Quisk will not accept remote operation unless the special hardware files are used. And the password or pass phrase must match. But you must (as usual) make sure both computers are secure and can not be broken into. You must (as usual) have a good router password and secure settings to protect your home network.

The AC2YD remote feature was designed to send back demodulated audio, not samples, in order to reduce the bandwidth to a minimum. Running digital modes on the control head would require more data streams for digital in/out. Also, note that recording samples to a file fails for the same reason. And most hardware config settings are inoperative on the control head. I can add some more interaction like a clip indicator, but complete control, such as adding recording samples, is a never-ending list.

Because of the low bandwidth and the time stamps on the CW keying, the AC2YD feature achieves fast classic ham radio over a network. For digital modes, it seems workable to run everything on the remote and control it with remote terminal software because fast response is not required.