The current CHANGELOG.txt is here.

The documentation is here.

This is the Help file for Quisk, a Software Defined Radio (SDR). Quisk was written and is maintained by Jim Ahlstrom, N2ADR, www.james.ahlstrom.name. Mail to jahlstr at gmail.com. Quisk has been greatly improved and extended by Leigh L. Klotz Jr. WA5ZNU, and by Andrew Nilsson VK6JBL. Thanks to Terry Fox WB4JFI for code improvements, and for adding support for the Charleston hardware. Thanks to Sid Boyce, G3VBV, for sending me SoftRock hardware to work with. Thanks to Christof, DJ4CM, for many improvements to the GUI and for the Dx cluster display. Thanks to Philip G. Lee for adding native support for PulseAudio, and to Eric Thornton for adding PulseAudio async low-latency support. There are many other contributors who are mentioned in the source code.

Quisk supports several radios, such as HiQSDR, SDR-IQ, Hermes-Lite, SoftRock, etc. The Quisk software will read the samples from UDP or your sound card data, tune it, filter it, demodulate it, and send the audio to headphones or speakers. Quisk can also be used as a panadapter, by sending the radio IF output to Quisk.

Quisk rhymes with "brisk", and is QSK plus a few letters to make it easier to pronounce. QSK is a Q signal meaning full break in CW operation, and Quisk has been designed for low latency. Quisk includes an input keying signal that can mute the audio and substitute a side tone. To install and configure Quisk, please see the docs.html file in the Quisk directory.

Quisk is written in Python, an easy to learn but powerful language; see www.python.org. Source is provided because your own hardware is probably different from mine, and you will need to change something. Changing Python is easy.


Quisk is highly configurable. Many aspects of Quisk such as which buttons are displayed can be changed. You can even add additional buttons of your own. Quisk was originally designed to be a general purpose component in anyone's homebrew software defined radio. Besides the usual configuration settings, Quisk uses a hardware control file and an optional widgets file. Quisk comes with a variety of hardware control files for different radios, but you can also write your own custom hardware file. You can create a custom quisk_widgets.py file to add custom controls to the Quisk screen. I use custom files for both. See the n2adr directory for a rather complicated example. See docs.html for details.

There are three sources of configuration settings. When Quisk starts, it first imports default configuration information from the file quisk_conf_defaults.py. Then it reads your configuration file from either the standard location, or a custom location given by the command line "-c" option. Your configuration file should not be a copy of quisk_conf_defaults.py. It should be a small file with only the items that are different. The use of a configuration file is optional.

Quisk then reads the settings you have made on the configuration screens. Most settings are available here, so a configuration file will not be necessary for most users. To reach the configuration screens, press the Config button; or for the small screen layout, the screen selection master button followed by the Config button. The configuration screens are on the right side and are called "radios" because you can save different settings for different radios. There is a separate help screen describing the radio screens.

QUISK Screens

Quisk can run with either the "Large screen" or "Small screen" layout. The large screen layout is meant for PC screens, and all buttons are shown in four rows. The small screen layout is meant for small touch screen devices, for those with sight impairment, or for those who run Quisk at a small screen size. Most buttons are shown, but the band selection buttons, the mode buttons and the screen selection buttons are hidden behind three master buttons on the left. Pressing one of the master buttons pops up a row of choices.

The screen area can show a frequency graph, a waterfall display, an oscilloscope, the configuration screens, a graph of the receive filter in use or this Help screen. The screen selection buttons are shown when you use the large screen layout. Remember to press the master button the see the screen choices if you use the small screen layout.

The Graph screen shows a frequency graph of received signals. Use the scale "Ys" and zero "Yz" controls to adjust the graph scale. You should see a noise trace that changes randomly. Then press "Test 1". This generates a test signal at 10 kHz, and you should see the spike on the graph. To tune to that signal, click the mouse on the graph near the spike. Hold the mouse button down and drag the red tuning line back and forth across the test signal. You should head a pure audio tone in your speakers. Use the "Vol" (Volume) slider on the left to change the volume.

If you press Graph again, you will activate the peak hold functions labeled "GraphP1" and "GraphP2". These will cause the graph to follow the peak signal, and decay back down at a slow rate. You can configure the time constants. Some buttons, like the Graph button, can be pressed repeatedly to select different settings. These buttons have a circular arrow on the right.

The Waterfall shows a time history of the amplitude of received signals. You will need to adjust "Ys" (Y scale) and "Yz" (Y zero) to get a colored display. Press "Test 1" to turn the test signal on and off. Watch it appear and disappear from the waterfall. The top of the waterfall shows a small graph screen. You can grab the bar between the screens with your mouse and move it up and down to adjust the relative sizes. To adjust the scale and zero of this graph, hold down the Shift key while using the "Ys" and "Yz" sliders.

The oscilloscope and RX Filter screens are mostly used for debugging. The Config screen shows a number of sub-screens that display status, and provide for control of Quisk parameters. See below.

QUISK Controls

Below the screen area there are one or two slider controls to the left that control the radio sound volume, and optionally the CW sidetone volume. Side tone only appears if you configure Quisk to operate as a CW transceiver, and you provide a key signal. The four sliders to the right control RIT, the graph and waterfall scale and zero points, and the zoom feature. The Rit slider controls receiver incremental tuning, and is active when the RIT button is down. It adds a small offset to the receive frequency. Leave RIT off for SSB unless a station is off frequency a bit; then use RIT to tune him in while leaving your transmit frequency unchanged. When you select CW, the RIT must be turned on to provide an audio output, so Quisk automatically turns on RIT and sets it to plus or minus the configured CW tone frequency. The audio side tone (if a hardware key line is used) is set to the same. Just click CWL or CWU, tune the frequency by clicking exactly on the signal, and everything will work. The Ys and Yz sliders control the scale and zero of the screen in view. For the Graph screen and the Rx Filter screen they control the scale and zero of the Y axis. For the Waterfall screen they control the Waterfall color scale; and if the Shift key is down, they control the upper graph Y axis. For the Scope screen the Ys slider controls the Y axis scale, and the Yz slider does nothing. The sliders have no effect on other screens. The Zo (zoom) slider expands the frequency scale (X axis) of the Graph and Waterfall screens so that narrow signals can be examined. Quisk operates normally when this slider is all the way down. As it is raised, the frequency is expanded around the tuning frequency. That is, the tuning frequency is moved to the center, and the frequency scale is expanded. It is still possible to tune Quisk as usual while this control is in use.

The frequency display always displays the transmit frequency. This is the frequency shown by the red tuning line on the Graph and Waterfall screens. This equals the receive frequency unless Split is used (see below). You can change the transmit frequency by clicking the top or bottom of the digits, or by rolling the mouse wheel over the digit. The frequency display window will turn red to indicate sample capture overrun (ADC clipping). The large screen layout has a frequency entry window. Enter a frequency in Hertz without a decimal point, or megahertz with one. The up and down pointing arrows move the frequency up and down the band without changing the tuning. You can right or left click them, or hold them down with the mouse to keep moving.

The S-meter displays the signal strength in S units and in dB. Zero dB is clipping, the same as on the graph screen. The S-meter uses the specified filter bandwidth to choose the exact number of FFT bins to square and average. That is, it displays true RMS based on the FFT bins, not on the post-filter audio. Note that for a noise floor on the graph of -110 dB the S-meter will read -93 dB (depending on some details). That is because the bandwidth specified is much greater than the FFT bin width, and more noise is getting through. Find a flat noise frequency, change the filter bandwidth, and watch your S-meter measure the noise. The conversion from S-units to dB depends on your hardware. There are 6 dB per S-unit, and you can adjust to 50 microvolts for S9. If the correction depends on the band, you can make a band-dependent correction in your hardware file. The S-meter window has a button to the right to select what is shown; the S-meter, the frequency measurement or the RMS audio voltage. Quisk can measure and display the frequency of a continuous tone RF signal. To use this feature, press the S-meter button, and select one of the Frequency items. The numbers are the averaging times in seconds. Then find a signal of interest and put the tuning line exactly on it. Quisk will search 500 Hertz up and down from the tuning line and will display the frequency of the largest signal. This feature works on AM signals and continuous signals from oscillators, etc. It does not work for SSB as there is no continuous signal. To calibrate your hardware, measure the carrier from WWV or other frequency standard, and change your clock rate until the indicated frequency is correct. Quisk can display the RMS audio voltage. This is used for noise measurements.

QUISK Control Buttons

The Quisk buttons are the usual buttons you see on any radio. Some buttons have a cycle symbol or a cycle button marked ↷ that means the button can cycle through a list of values. Some buttons have a secondary button that can pop up a menu or a slider to make adjustments.

Mode: The mode buttons select CW, USB, AM, FM etc. This is a master button in the small screen layout. The special mode IMD generates a two-tone test signal for transmitter testing. The "DGT" modes are for external digital mode programs such as fldigi. See below.

Band: The band buttons select the band 40 meters, 20 meters etc. The bands shown can be configured. This is a master button in the small screen layout.

Screen: The screen button selects the screen that is shown. See above. This is a master button in the small screen layout.

Filters: The filter buttons select the bandwidth of the receive filters, 2700 Hertz, 6000 Hertz etc. The last filter button has an adjustable bandwidth.

Band Up/Down: The up and down arrow buttons move up and down the band without changing the tuning frequency.

Mute: Mute (zero) the receive audio volume.

AGC: Automatic gain control is active when this button is either up or down, but the settings are different. Adjust the AGC for both the up and down positions to control how much gain variation is allowed. When the slider is at maximum (all the way up), all signals, even band noise, will have the same maximum amplitude. For lower settings, loud signals will have the maximum amplitude, but weaker signals will have less amplitude. A medium setting allows you to hear the relative amplitude of signals and any QSB while still protecting your ears. I set the AGC On setting to a high value, and the AGC Off setting to a lower value that allows band noise to be faintly heard.

Squelch: This turns off the audio when there are no signals in the pass band. For FM, adjust the level on an empty channel. For SSB the adjustment for band noise is automatic, so start with a setting of 0.200.

NB: The noise blanker has several levels.

Notch: An automatic notch feature that can null out one or two continuous signals, such as AM carriers that interfere with SSB reception.

RfGain: The Rf gain control if your hardware supports this.

Antenna: Antenna selection if your hardware supports this.

Spot: This transmits a constant CW signal for tuning. The level is adjustable. You might also need to press PTT or assert your key line depending on your hardware.

Split: This splits the receive and transmit frequencies so they can be different. Two tuning lines will appear; red for the transmit frequency and green for the receive frequency. This is useful for working a DX station split. When you tune with the mouse, the closest tuning line is moved. You can lock the transmit frequency. You can reverse the receive and transmit frequencies. You can decode audio from both frequencies and play them on the left and right speakers.

FDX: Full duplex allows you to transmit and receive at the same time if your hardware allows this.

PTT: Push to talk; start transmitting.

VOX: Voice operated relay; turn on PTT when you speak into the microphone.

Test 1: Generate a test signal 10 kHz above the screen center frequency.

Memory buttons: Quisk can remember and return to stations. When you have tuned in a signal of interest, press the "Save" button Ⓜ↑ to save the frequency, band and mode. Repeat for more signals. Now press "Next" Ⓜ ➲, to switch to the next saved signal, and press "Next" repeatedly to cycle through the list. To delete a saved signal, first tune to it with "Next" and then press "Delete" Ⓜ ☓ . If you save a large number of signals, right click the "Next" button Ⓜ ➲, and you will get a popup menu so you can jump directly to a station. The saved stations will appear in the station window below the frequency X axis. The saved stations can be on different bands.

Favorites button: Quisk can save a list of favorite stations. Press Config/Favorites to access the screen, and right-click the left label to insert and delete stations, and to tune to them. The two favorites buttons provide direct access to this screen. The ★ ↑ button enters the current station into the screen; just provide a name. The ★ ↓ button jumps to the screen; right click the left label and choose "Tune to". Favorite stations will appear in the station window with a Star symbol ★ .

Recording Sound and Samples

There are Record and Playback buttons to save and recall radio sound from a temporary buffer. Push Record to start recording radio sound. The maximum time to record can be configured, and after this limit older sound is discarded. That is, the most recent sound is retained up to some maximum time. Push Playback to play the sound. If you are transmitting, the recorded sound is transmitted in place of mic input. This sound is not speech processed, so it can be used to give another station an accurate indication of how they sound. To write this sound to a file, right-click the Playback button.

Quisk can also record the speaker audio, mic audio and the digital I/Q samples to WAV files. Set the file names in the Config/Config screen. Enable the recording by checking the box. Then Press the "FileRecord" button to begin recording, and release it to stop. If you press it again, it starts a new recording with a sequence number 001, 002, 003 etc. Choose a directory (folder) to save these files because you will need to delete the ones you no longer need. The speaker and mic audio are stored as 16-bit monophonic samples at the audio play rate. Both the audio play and mic rates should be 48 ksps. The digital I/Q samples are stored as two IEEE floating point samples at the sample rate. It is possible to record all three sources at once, but this is not usually useful. Normally you would record the mic to create a CQ message such as "CQ contest this is N2ADR". You would record speaker audio to create a record of operations to review at a later time. You would record IQ samples so you could record a slice of the band to tune in different stations later. Note that a WAV file has a maximum size of 4 gigabytes, but Quisk can record and play files with an unlimited size.

Quisk can play the files it created, as well as other WAV files in the proper format. Choose the file name of the source on the Config/Config screen, and check the box. Then press "FilePlay" to begin playing and release it to stop. Playing a file replaces the usual samples with the file samples, so it is necessary to have working sound sources at the same sample rates as the recording. Playing an audio file just plays the file on the speakers. When the file is finished, normal speaker audio resumes. Playing a CQ message is similar, but will press the PTT button as it plays. You can specify a repeat time to keep repeating the message. When a station answers, press FilePlay or PTT to stop the message so you can answer.

To play an IQ sample file, first make sure the sample rate and VFO frequency are the same as the recording. This will ensure the frequency readout is correct. It is a good idea to name files with this information, such as "IQ192k7100.wav" for a file recorded at 192 ksps and a VFO (center) frequency of 7100 kHz. Then press "FilePlay". The band samples will be replaced with the file samples, and you will be able to tune around in the band and receive different stations. Do not press band up/down as that will change the band center (VFO).

Tuning in Stations

First select CW, USB etc. with the mode buttons. This is a master button on the small screen layout. On the Graph or Waterfall screens, you tune in a CW signal by left-clicking above the X axis directly on the signal. You tune in an SSB signal by clicking on the upper edge (lower sideband) or the lower edge (upper sideband). That is, you always click where the carrier goes. You can also click, hold down the mouse button and drag the tuning line. The speed of tuning is lowest close to the X axis, and increases as you move up. Try it. If you hold the Shift key down when you click, the Rx filter will be centered at the frequency. In this case, you would click in the center of an SSB signal.

If you click below the X axis, tuning will not jump to that frequency, but you can still hold the button and drag. That is useful for small adjustments. The mouse wheel will move the frequency up and down and round the frequency to multiples of 50 Hertz.

If you right-click a signal, Quisk tunes to the signal as before, and also changes the VFO to move the signal to the center of the screen.

Station Window and Dx Cluster

There is a station window below the frequency axis (X axis) to display stations of interest. This feature was added by Christof, DJ4CM. It consists of zero or more lines containing an M-Circle symbol Ⓜ for memory stations, a Star symbol ★ for favorite stations and a Dx symbol for Dx Cluster stations. The default number of lines is one, but you can add more lines if the display becomes too crowded. If you move your mouse near the marked frequency, a popup window will appear with station details. Left-click the symbol to tune to it. There are Dx Cluster telnet servers available that provide real time information on Dx station activity. You must configure the host name, the port and your call sign to use this feature. This feature will run continuously unless the host is the null string. The Dx stations will appear in the station window as they become available from the server.

Configuration Screens

The Configuration screen shows a group of sub-screens that give status information, and that adjust various Quisk control parameters. The Status screen shows Quisk status information. The Favorites screen allows you to enter frequencies and modes for stations, nets, etc. To add a line, right-click the left label and select Insert or Append. To tune to a station, select Tune.

The Config screen controls features that apply to all radios. There is a band plan button to control the colors shown for the CW and phone segmants of each band. The Config screen can pop up an amplitude and phase correction window for SoftRock and similar receivers. If you use the sound card for input, you may need to correct for small errors in the I and Q amplitude and phase. First change to the correct band, because corrections are saved for each band. Press the button on the config screen to bring up a correction screen. Then feed a test signal to your hardware (or use a strong available signal) and look at the signal image. Adjust the slider controls to reduce the image. The upper slider is the fine adjustment, and the lower is the coarse. You will need to adjust both amplitude and phase as they will interact. The amount of available adjustment range can be configured. When you have a final correction, it is a good idea to write it down. The correction point is saved based on the VFO frequency, and you will probably need two or three correction points per band.

The Tx Audio screen controls the transmit audio, and enables you to record and play it back for test purposes. To have good transmit audio, you must start start with a clean audio source. You can plug in a USB mic or headset as a source. Or you can connect an analog mic to the mic input of your sound card. Or you can connect your mic to a preamp, and then to the line input of your sound card. The mic should be directly in front of your mouth when you speak. Try to avoid headsets that cause you to speak across the mic. The idea is to make your voice as loud as possible relative to the background noise in your shack.

You need to adjust the mic sound level as high as possible, but without too much clipping. Speak normally and try to get a level a few dB below zero (clipping). The peak level should be at least -20 dB, and preferably above -10 dB. Infrequent clipping (above 0 dB) is OK, because Quisk will clip the audio anyway when it processes it. It may be difficult to figure out how to adjust the mic level. For Linux, figure out the correct control number and use mixer_settings or use one of the Linux mixer apps. For Windows, use the level control on the audio control screen in Control Panel, but be careful that another application does not change it after you set it for Quisk. Quisk will attempt to adjust the audio level with its AGC, but it helps to start with a good level.

Refer to the "Tx Audio" tab. Clip is the amount of audio clipping from zero to 20 dB. There is actually some clipping at zero dB due to the mic AGC. Preemphasis boosts the high frequencies in your voice. Zero is no boost, and 1.0 is 6 dB per octave. Use the record and playback buttons to test for the best control settings. Notice that your voice will become louder with more clipping. Note that SSB, AM, FM and FDV each have their own settings, so change to the correct mode before you start. Audio processing is most useful for SSB, so if you are a DX enthusiast, use aggressive settings. I only use AM for rag chewing, so I use zero preemphasis and 4 dB clipping. For FM, I use zero clipping and preemphasis.

Digital Modes DGT-*

These modes are used for digital signals, and require an external program such as Fldigi or WSJT-X to decode the signals. First, connect your digital program to quisk using Hamlib or XML-RPC so that frequency changes are recognized. See "Hamlib Control" below. Next you need a way to transfer digital samples between the programs. For Windows, install a Virtual Audio Cable (VAC) and connect Quisk to one end and the digital program to the other. For Linux, Quisk can create a VAC itself by using PulseAudio. Digital data is only sent when one of the "DGT-" modes is in use. See the documentation for more information.

Hamlib Control

Most digital and logging programs use Hamlib to control a rig so that frequency changes in one program are recognized in the other. Quisk has three options for external control: Hamlib, XML-RPC and a serial port emulating the "Flex" protocol. See the documentation for more information.

Multiple Receivers

Quisk can tune in two frequencies in the same band by using the "Split" button. This is meant for working DX split, but it can be used anywhere in the band. But if you want to receive in two different bands at once, you need SDR hardware that can support multiple sub-receivers. The Hermes-Lite and other Hermes hardware can do this. Press the "Add Rx" button to add additional receivers. You will get multiple receiver screens with their own control buttons and menus. The main buttons in Quisk still control the main receiver and transmitter. The menu button on the "Add Rx" button controls where the sub-receiver sound goes. When a sub-receiver "Play" button is pressed, you can play the sound alone, or together with the main receiver sound. There is an additional device on the sound screen that can direct the sound from sub-receiver 1 to an external digital program. There is a limit to how many sub-receivers your hardware can support. Quisk may not know this limit, so please do not request more sub-receivers than actually exist.