Summary of the Main Window's controls


Device Tab
Output Tab
Storage Tab
Preferences Tab

Device Tab

The Device tab is the only tab that changes the controls it contains based on the type of device being opened. This is because depending on the type of device we open, Echoes loads a different Soapy support library, dedicated to the open device; this library can supply or request more or less information to the user.

Let's start by seeing what it looks like and what controls are available when you open an audio device, intended as a microphone input or line input.
device tab audio
Device tab after opening an audio device

If the device used in the last acquisition session is no longer present while starting a new one, the following message will be displayed:
mismatched dongle
Device not found at startup

This situation can happen when you open RTS files that come from other users, that carry the name and serial number of the device with which they have been created - likely different from yours. This consideration also concerns the example rts files that you will find under c:\program files\GABB\echoes (Windows) or under /usr/share/echoes (Linux). Anyway, this is not a big problem, simply open the Device selector and chose a new one.
device selector
Device selector listing all the connected devices

Device selector
It displays the available devices as seen by Soapy library. There may be two additional devices that are not managed by Soapy but are integrated into Echoes. These are the Test patterns and the UDP client which will be described later.

The program is not able to recognize new devices just plugged in. The devices detection is performed only at start-up, so in order to recognize new devices, the program must be restarted.

Sample Rate and Sample Rate Range
This control is available for every device except for UDP client. Depending of the device type, it can be chosen freely or picked from a range of fixed values (audio devices); in this case the control displayed is named Sample Rate Range.

SDRs devices instead tend to have both: there are some defined sample rate ranges and within these ranges a sample rate can be freely chosen. In RTL-SDR for instance there are two sample rate ranges 250..300k and 900..3200k. Once selected one of the two ranges, the Sample Rate control allows us to choose an arbitrary value within that range. Now let's introduce some new controls related to the radio functionalities of our device and therefore not visible when we open an audio device.
device tab rtl
Device tab after opening an RTL-SDR device

Tune and Frequency Range
Sets the device's tuning frequency, within the provided ranges. In case of RTL-SDR devices there is only an unique frequency range, and within this range, any frequency can be tuned. Other devices have more than one range to choose from, and in this case above the Tune control a Frequency Range selector appears, like in case of RSP1 (see below). The frequency can be selected by the up/down buttons or it can be entered directly by right-clicking above the LCD number.
edit tune
Entering a tuning frequency by typing

Please note that it's not needed to enter the thousands dots. The showed frequency can be entered by typing 107400100 but is displayed with dots for easier reading.

RF Gain and AGC
It's expressed as percentage, where 100% is the maximum gain supported by the device. It will be ignored if AGC is checked, since the gain in this case is self-regulated by the device itself.

Error Compensation
Enter a value only in case the frequency values on waterfall looks shifted versus a reference signal. A precise well known fixed frequency carrier can help to verify the accuracy of the frequency scale.
Shifts can be compensated by entering a value in ppm, that can be negative or positive and have two decimals precision. The integer part is managed by hardware, while the fractional part is used to apply a transparent offset correction to the waterfall for a finer centering.

Opening a RSP1 SDR, the Device tab shows another control:
device tab rsp1
Device tab after opening a RSP1 device

Bandwidth and Bandwidth Range
The Bandwidth control applies band filters to the input signal. In case of RSP1, these filters have fixed bandwidths and the control shows a list of provided values.
With other devices, it could appear a further control, Bandwidth range, that selects between filters ranges. In this case, the Bandwidth control allows to select an arbitrary bandwidth into the selected range.

Antenna Selector
The last control that can appear in device tab is the Antenna selector, in case a SDR provides more antenna inputs leaving the user to select between them.


This tab groups the controls that affect the quality of the spectrum displayed in the waterfall, by adjusting the FFT (Fast Fourier Transform algorythm) parameters.
FFT tab
FFT tab

Downsampling Frequency
This control is excluded by default, by checking the Downsampling Bypass box.

The downsampler allows to forward to the FFT a signal sampled at a lower frequency than the one set in the SDR. By default, downsampling is excluded because it causes a loss of information, as the FFT thus receives a signal with a narrower bandwidth than the sampled one.
In some cases, however, it can be useful because applying the FFT on a narrower bandwidth signal allows it to be transformed with a finer frequency resolution.
The Downsampling frequency drop-down lists up to 5 values, automatically generated by recursively divide by two the sample rate frequency. So, for instance, with a sample rate of 3 MHz, the allowed values will be 3 MHz, 1,5 MHz, 750 kHz, 375 kHz, 187500 Hz.
FFT Window
Shape of the window applied to FFT output. The default is Rectangle, that means none, since usually is not required to set a window for meteor scattering purposes, but it could help to limit the effects of interferences.
FFT windows
FFT windows

FFT Resolution
This value can be expressed both as Hz-per-point or as number of FFT points.
The FFT is applied to the input signal and produces a spectrum as wide as the sample rate (or downsampling frequency if set). The spectrum resolution increases with the number of points the FFT produces. The higher the number of points, the higher the resolution and the lower is the Hz-per-point.

The +/- pushbuttons are related to the Hz-per-point, so to increase the resolution, the button minus must be pressed to lower the Hz-per-point and increase the points. Vice-versa to decrease the resolution.

Output Tab

This tab groups the controls related to capturing functionalities.
Output tab
Output tab

Acquisition Mode
Continuous, Periodic and Automatic. In order to set one of these modes, the Stop After and Peak Upper Threshold must be set accordingly, otherwise when pressing Start, the acquisition won't start and a warning message appears in the lower part of Main window.
Mode Stop After Peak Upper Threshold
Continuous mode 0 0
Periodic mode >0 0
Automatic mode >0 >0
Continuous mode: when the acquisition starts, the waterfall runs continuously without automations. A CSV file records data related to every scan line showed on the waterfall. When acquisition is stopped, the file is closed, and a new empty one is created when restarting the acquisition. There is no provision for events detecting, every scan is treated and recorded as a single event. No automatic screenshots neither dumps will be produced, but is still possible to capture screenshots manually by pressing the button Manual shot on waterfall window. This is the default mode the first time Echoes is started.

Periodic mode: if this mode has been chosen, while acquisition is running, Echoes will capture screenshots and/or dumps on a fixed period basis. This period is set with the Data Dump Coverage control. By default, this control is set to zero seconds. By setting, for instance, 60 seconds, the program will generate a dump and a screenshot every 60 seconds. Please note that if the waterfall coverage is below 60 seconds, the screenshots and the dumps will remain time-aligned but screenshots won't cover the entire time. The CSV content is similar to Continuous mode with one column added that holds the name of the screenshot file where that scan has been plotted. This operating mode should be used to practice with the program and get to understand how to set the thresholds and other parameters that allow you to run t he program in automatic mode.

Automatic mode: when this mode is selected, the program tries to recognize meteor echoes in the spectrum. This try can be more or less successful depending of how some controls - those related to thresholds - are set to match your specific setup. When a peak is detected, a screenshot and/or dump can be generated immediately, but in most of cases is more useful to add some amount of delay to let the peak reach the lower part of the waterfall, scrolling downward. In this way, longer lasting echoes (overdense) can be fully captured in the screenshot. While taking the screenshot, the instantaneous power graph below the waterfall replays the power data recorded when the peak was detected, so the shot will simultaneously display the power peak in frequency domain, in time domain (Power history graph) and both (waterfall). For each event detected, 3 new rows are added to automatic_data table in DB.

Generate Screenshots
Check this if interested in producing screenshots automatically. This control has no effects on manual screenshots generated by pressing the dedicated button in waterfall window.

Generate Dump Files
Check this if interested in producing dump files.

Both the above checkboxes have effect in Periodic and Automatic modes.

Refresh Interval
Refresh Interval Required is the waterfall's refresh rate in milliseconds. Each n milliseconds, a scan is retrieved from the FFT output and placed at the top of the waterfall widget, scrolling all of its contents down.

Refresh Interval Measured is instead the effective time taken to update the waterfall. When this value does not follow the request anymore, it means that the FFT has become too slow to satisfy it, causing CPU time wasting. To solve this problem one can increase the interval required or reduce the FFT points, thus reducing the FFT resolution.

Delay Before Shot
Sets the delay to apply to screen capture after the event has been detected. This delay is expressed as percentage of waterfall's height and allows to catch in a screen most of the echo. For instance,
  • 20% means little delay, almost immediate shot,
  • 50% means the shot will be triggered at about half run,
  • 80% means the shot will be triggered at about end run. Such delay allows the waterfall to display that ionized tail resulting from the ablation of bigger objects before taking the shot
shot delay percentages
Shot delay percentages

Stop After
Sets the maximum number of automatic screenshots to be taken in the current day, usually set to a high value so there is no fear to exceed it, because if exceeded, the acquisition stops immediately.

Data Dump Coverage
The screenshot time coverage depends directly from the refresh interval. The smaller is the interval, the shorter will be the time covered. The dumps instead can last for an arbitrary number of seconds that can be set with this control. This means that dumps are ideal to capture and plot long overdense echoes; the drawback is that dumps have all the same length, even underdense ones.

Thresholds Behavior
Selects between Absolute, Differential and Automatic thresholds. They have been already covered here.

Peak Upper Threshold, Peak Lower Threshold : event detection thresholds. Expressed in dBfs - or percentage in case of Automatic behavior chosen. See here for further details.

Averaged Scans for N calc
This control allows to specify the number of scans to be considered for mobile averages calculations, to calculate N and the average S-N, so consequently for the automatic thresholds too.

Peak Detection Range
Specifies the width of the event detection interval in percentage of the waterfall width. 100% covers the entire width, 2% is the minimum value alloweed, because it must be symmetric referring to the center frequency. The interval can be dragged and resized with the mouse on Waterfall window, see also here

Join Events Closer Than
Specifies a time in ms for which, if two events occur in rapid succession, these events would be considered as a single event. See also here.

Pause Capture When N Exceeds
This feature is used to conserve disk space in case unexpected disturbances occur, causing many false positives to be detected. If the background noise N should rise above this threshold, the automatic captures are inhibited and the message TOO NOISY appears at the bottom of the waterfall window. The acquisition continues, waiting for the disturbance to stop, and when it does, the program captures again.

Waterfall Palette Style
Allows to select between the black/white palette and color palette for waterfall's representation.

Storage Tab

To keep the database within the size that the host computer can handle, there are two controls in the Storage tab which are:
Data Lasting
Defines how much time an event's information can persist in the automatic_data database table, expressed in days. More aged data will be removed from the table.

Images Lasting
Defines the time for which screenshots and dumps persist in the related automatic_shots and automatic_dumps, tables, both expressed as days. More aged files will be removed from the respective tables.

storage tab
Storage tab

Available Space on Disk
Free disk space in GigaBytes of the disk hosting the working directory.

Reserved Storage
Number of GB to keep free on the disk, stops the acquisition when the available space falls below this limit.

Create DB Snapshot Every
Creates a backup copy of the database every N days, at midnight UTC. A zero value disables this functionality.

Overwrite Latest Snapshot
When checked, a new snapshot always overwrites a previous one made. Otherwise each snapshot will be numbered progressively and kept on the disk.

Erase Shots and Dumps Before Start
Cleans the data directory from old screenshots before starting acquisition. Do not check if working in automatic mode.

Erase Old Statistics Before Start
Cleans the data directory from old CSV files before starting acquisition. Do not check if working in automatic mode.

Preferences tab

The last main window's tab is about user's preferences, a miscellaneous of controls that covers different customizable aspects of the program.

preferences tab
Preferences tab

Show Frequency [Hz] Tick Marks
Checked by default, uncheck to get rid of the frequency tick marks displayed on waterfall.

Show time [mS] Tick Marks
Checked by default, uncheck to get rid of the time tick marks displayed on waterfall.

Show Power [dBFs] Tick Marks
Checked by default, uncheck to get rid of the power tick marks from the instantaneous spectra and Power history side graphs.

Show Peak Detection Interval Boundaries
Checked by default, uncheck to get rid of the vertical lines that delimits, on the waterfall, the peak detection interval.

Disable Tooltips
This box is unchecked by default, allowing the display of the help messages that appear on every control when the mouse cursor hovers them. Once the user has become familiar with Echoes, they could result annoying, and can be hidden by checking this box.

Enable Event's Notification Sound
Checked by default, uncheck to get rid of the "ping" sound produced each time the program captures an event.

Enable the Acquisition Fault Notification Sound
Checked by default, uncheck to get rid of the "crash" sound produced each time the program detects an acquisition error.

Use Direct Buffers When Possible
Unchecked by default, this feature is only available for devices whose Soapy support library provides the ability to change the size and overall number of internal buffers; currently only RTL-SDR gives this ability. Its purpose is to use the same buffers used by Soapy to carry the radio samples from the support library up to the FFT. If not checked, Echoes copies the data coming from the support library into its own buffers, so this operation takes more time.

Generate DAT dumps instead of DATB
This checkbox gives the possibility of using the old ASCII format for dumps .DAT is given instead of the newer and more compact binary format .DATB, because the first one can be read with GNUplot and other math tools, while the latter is readable only with Ebrow.

dBfs Scale Offset and Gain
dBfs multiplier factor and offset. These controls are needed if you want to calibrate the signal displayed by Echoes to carry out actual measurements. It is necessary to use an RF generator producing a signal of known frequency and power, then act on the multiplier and/or offset controls until obtaining a signal on the spectrum with a power in dBfs corresponding to that in dBm produced by the generator.

UDP Server Address
By default is empty, or that means not used. When set to a valid IP address, a new pseudo-device will be created, that will be available on Device selector (a restart is needed after entering a new address). That address must be a computer running an Echoes instance, working with a physical device. See UDP client for more infos.

UDP Server Port
By default is 12345, defines the UDP port used by servers. There is no need to change it, unless you know that port is already used in your network to do other. See UDP client for more infos.

UDP Delay Between Packets
Delay in microseconds between the sending of subsequent UDP datagrams. This parameter is considered only when using the UDP device.

Cancel Events Lasting More Than
While testing the Echoes settings, might happen to catch events that never ends, due to wrong thresholds settings. This control specifies a maximum allowed lasting for an event, and if the CAPTURING label remains displayed for a longer time, the event will be canceled without leaving any trace on the system.

Scan Integration
This selector allows you to choose how the program should handle the case in which the waterfall refresh interval is slow, and in the time it takes to display one scan, the radio gets more than one.

This situation is not unusual, because the radio receive thread always sends to the graphical interface the maximum amount of data made possible by the hardware on which the program is running; while the scrolling of the waterfall can be set with the Refresh interval control.

Scan integration was essentially designed to be used on low performances hardware, like for example my Raspberry PI 3b+. When the program runs on a PC, there is no need to change its default setting, unless you desire to acquire waterfalls with low refresh rate.

The default setting is Last which corresponds to the way Echoes has always worked until now: if - when adding a new scan to the waterfall - there are data available for multiple scans, the oldest ones are discarded so as to always display the most recent data available.

With Average, the program calculates a scan that is the result of an average of the received scans and displays it.

With Max Hold, the program displays a scan that mixes the received scans by taking the highest values on each frequency point. Be warned that selecting this option will result in spectra with higher N.
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