What appears to be a third party reskinned version of SDR# has been released on the *removed* Facebook discussion page. The modified software is called “sdr sharper” and changes the look and feel of SDR#. The software also includes several plugins ready to go including a scope, audio notch filters, audio equalizer, audio waterfall and s-meter. The sdr sharper software call be downloaded from the file *removed* over at *removed*.
Important Note: We are currently unsure of the legality of this software as it seems to be based on the licensed SDR# code base. If it turns out to be illegal software we will remove all download links.
Update 28/01/2015: As suspected SDRSharper is illegal and infringes on SDR#’s licensed code and trademark as pointed out by Youssef, the author of SDR# in the comments section of this post. In response we have removed the direct download link. Please respect the SDR# licence and Youssef’s hard work by not using illegal copies.
The IF Processor plugin is designed to upgrade the Zoom FFT plugin that comes standard with a fresh install of SDR#. The IF processor plugin comes with a tracking notch filter and an asymmetric filter controls. These features will allow you to easily remove interfering signals that appear on top of your signal of interest.
The Audio Processor plugin allows you to improve the audio output using a controllable graphical audio bandpass filter. This feature can help you to remove any hiss or other undesirable sounds in the output audio.
The two new SDR# plugins demonstrated on an AM signal
MPX Output plugin. Allows programs like RDS Spy to work with the audio output from SDR#
Aviation band 8.33 calculator. Automatically converts the current frequency input to an aviation one according to the standard 8.33 kHz channel spacing.
Frequency Lock. Simply locks the frequency change settings in SDR# to prevent accidental changes.
SDR Update Script. Not a plugin, but a script that automatically updates SDR# and installs most of Vasilli’s plugins all at once. To use this script, it must be placed in a subdirectory of the SDR# folder.
Here’s an example video of SDR# running the MPX plugin so that RDS Spy can be used.
Adds a new display that shows a compressed image of the entire waterfall and shows where in time the playback is up to.
Allows you to modify the waterfall play time position with the mouse.
Adds a stop and pause button.
Note that to install this plugin you do not add the magicline to the plugins.xml file. Instead you need to add it to the <frontendPlugins> section of the SDRSharp.exe.Config text file.
Recently the popular Frequency Manager + Scanner plugin set for SDR# has been upgraded and renamed to the “Frequency Manager Suite”. The plugin can be downloaded from their new website at www.freqmgrsuite.com. The plugin suite includes a frequency scanner and manager, a scanner metrics recorder, a scheduler, an activity logger and a frequency entry plugin.
Apart from plugins the suite also now includes a plugin manager program called “Pluginator” which can help you to install and delete plugins without needing to edit the Plugins.xml file directly. There is also a new database manager tool which can help you to import frequency databases from online or other sources.
We have posted the full feature release below:
The Frequency Manager Suite (FMS) adds 4 more plugins to the previous set of 3:
Scheduler – allows you to schedule listening activities by date and time.
Activity Logger – records scanner activity to a file for later use.
Scanner Decisions – now a first-class plugin and also available as the classic stand-alone window. And you can change the position of the plugin without restarting SDR#.
Frequency Details – displays details about a frequency from your database. And you can change the position of the plugin without restarting SDR#.
New standalone applications also come with FMS:
Data Tools – this significantly upgraded import/export application lets you import data from 6 popular internet databases as well as generically-formatted files, and permits you to export your FMS databases to standard file format.
The Pluginator – an application that lets you add, delete, and change the order of plugins without ever having to hand-edit the SDR# file Plugins.xml. Just fill in the blanks.
New features in Frequency Manager + Scanner:
The new Preferences dialog allows customization without hand-editing a configuration file.
FMS configurations are now kept in a file separate from those of SDR#, permitting easier upgrades to SDR#.
You can have multiple frequency databases, and can change to a different database without restarting SDR#.
When tuning manually you can optionally change the radio settings (mode, BW, etc.) according to what’s in the database for the tuned frequency.
Scan resolution – high-res or low-res to favor speed over accuracy or vice versa.
Adjacent Frequency Rejection now displays its bandwidth on the spectrum analyzer.
SDR# (SDRSharp) is probably the most popular software program that is used with the RTL-SDR. It is free, fast and fairly easy to use.
SDR# is coded in C# and so runs on the Microsoft .NET runtime. SDR# has always used the 3.5 version of the .NET runtime, however recently the programmers have made the decision to upgrade the runtime used to the latest 4.6 version of .NET. For non-programmers this means that compatibility with newer operating system such as Windows 10 is enhanced, performance and stability is improved and that SDR# can now be run on Linux and OSX with Mono 4.0. The downside is that Windows XP and Vista are no longer supported operating systems (Vista SP2 is supported). An OS compatibility list for .NET 4.6 can be found here.
If you are an SDR# user and run an older operating system such as XP or Vista we suggest that you either upgrade your OS, or simply continue to run the older versions of SDR#.
In addition to the new changes, the install procedure has also changed. Firstly, the old sdrsharp.com website now redirects to airspy.com. To install SDR# now, simply download SDR# zip file from airspy.com/download. Unzip it to any folder on your PC. Next, to download the RTL-SDR drivers simply run the install-rtlsdr.bat file. We will soon be updating our Quickstart guide to incorporate these changes.
We have been relying on the .NET Framework 3.5 for quite some time until it’s no longer installed by default into the new operating systems. Microsoft also provides minimalist support of this version of the Framework on Windows 10 which handicaped the core and plugin developers in many ways. This also resulted in obscure bugs in the user base. So we moved recently the entire code base to the .NET 4.6 in order to refresh the software and make it compatible with modern operating systems like Windows 10.
This has many implications:
Better performance
Better programming API
Support of Windows 10
Support of Linux and Mac with Mono 4.0 and up
End of support of Windows XP and Vista
End of support of the ExtIO interface (not portable)
We coordinated this migration with all the plugins and front-ends developers so no body misses the boat. The installation procedure has also changed and now the main package contains a batch file to download the dependencies required to run RTL-SDR. This might be disturbing for a few, but the overall impact was judged positive and a better investment for the future, especially with the new API offered by .NET 4.6.
The old audio waterfall plugin for SDR# seems to be no longer available for download anywhere (it may have gone out of date and is no longer compatible with the latest versions of SDR#). Alan Duffy decided to write his own version of the audio waterfall plugin and make it available for download. An audio waterfall shows the demodulated audio in waterfall form, essentially creating an audio spectrum analyzer. This can be useful for understanding the demodulated frequency structure of a signal.
To install the plugin simply download the dll from his website and place it in the SDR# folder. Note that for us Chrome detected this file as malicious, but this is a false alarm as Chrome does this often with unknown .dll files. To recover the file we had to go to the Chrome menu -> Downloads, then select “Recover File” to download the file. (If you still have problems with the download then check out the comments as some users have kindly mirrored it). Then open plugins.xml file with a text editor, and add the magicline specified on his page.
Alan’s Audio waterfall shown together with the built in audio spectrum analyzer in SDR#.
Edit: If you downloaded an older version of the plugin please note that it has now been updated. The update fixes some stability issues which would previously hang SDR#. The updated .dll file can be downloaded directly from https://goo.gl/VQlH9E.
Radio-Sky Spectrograph is a radio astronomy software program which is often used together with the RTL-SDR or other similar SDRs. It is best explained by the author:
Radio-Sky Spectrograph displays a waterfall spectrum. It is not so different from other programs that produce these displays except that it saves the spectra at a manageable data rate and provides channel widths that are consistent with many natural radio signal bandwidths. For terrestrial , solar flare, Jupiter decametric, or emission/absorption observations you might want to use RSS.
Usually to interface an RTL-SDR with Radio-Sky Specrtograph a program called RTL-Bridge is used. However, now SDR# plugin programmer Alan Duffy has created a new plugin that allows SDR# to interface with Radio-Sky Spectrograph via a network stream. This allows it to work with any SDR that is supported by SDR# plugins. Alan Duffy writes:
I wrote the plugin after becoming interested in amateur radio astronomy. The plugin allows you to use any of the software defined radios supported by SDR# to feed the Radio-Sky Spectrograph program with wide-band data. The plugin shows the frequency, bandwidth, and FFT resolution and has a user selected “Number of Channels” that are sent to the spectrograph program with an allowable range of 100 to 500. This number can only be edited when the data stream is not enabled. Also if certain key parameters change, such as the frequency or decimation, the network stream will stop as the spectrograph would no longer be capturing the same data. If this happens, simply click the start button on client side software (i.e. Radio-Sky Spectrograph). As long as the Enable box is checked on the server side, the plugin will listen for a connection and start transmitting data after RSS makes a new request for data.
We note that the software might also be useful for simply capturing a long term waterfall for finding active frequencies or looking for meteor scatter or aircraft scatter echoes.
Over on his site rtl-sdr.ru, Vasilli has been back at work creating new plugins for SDR#. The latest plugin is a TCP server that takes the demodulated mono audio stream from SDR# and sends it over TCP (note that the site is in Russian but the Google translate button on the right can be used). This can be used to easily stream audio over the internet or a network, or even locally on the same PC to another program. If enough programs support TCP audio streams, then the plugin could potentially replace the need for software like Virtual Audio Cable or VBCable by allowing another method for piping the audio from SDR# into a decoding program.
Installing the plugin is the same as usual. Just extract the SDRSharp.TcpServer.dll file to the SDRSharp folder, open plugins.xml with a text editor and paste in the 'magic line' specified in MagicLine.txt.
To test the server you can connect to it with VLC media player. Some special commands need to be specified to VLC in order for it to understand the audio format. To enter them go to Media->Open Network Stream and make sure 'Show more options' is checked. Enter the network URL as 'TCP://127.0.0.1:20022' (without quotes), and enter the Edit Options field as ':demux=rawaud :rawaud-channels=1 :rawaud-samplerate=48000 :rawaud-fourcc=s16l' (without quotes). Ensure the first colon in the line is copied over properly. Then enable the TCP server in the SDR# plugin, and click Play in VLC. Ensure the SDR# is muted, and the volume in VLC turned up. Audio should now begin streaming through TCP.
Hopefully in the future we can see some audio compression algorithms and more decoding software supporting TCP audio connections.
Vasilli has also updated many of his other plugins too, including creating a DSD_TCP plugin which allows you to transmit the digital audio directly to DSD+ via a TCP connection.
Recently Eddie MacDonald has been pumping out simple but useful plugins for SDR# including the SDR# Dark Mode and Visual Tuner Knob plugins. Recently he released a new plugin called "FFT Window Screen Grabber". This plugin simply helps you to easily take a screenshot of the FFT and waterfall displays in SDR#. It could be a useful plugin if you are constantly finding interesting signals that you want to document, or upload to sigidwiki.com.
Recently we've posted about Eddie MacDonald's several releases of new plugins for the popular SDR# software. Recently he's released a tuner knob plugin which provides a visual frequency tuning knob that is useful for those running on touchscreen hardware, a 'dark mode' plugin which reduces the brightness of SDR# and compresses the UI a little, and an FFT grabber plugin which allows for easy screenshots of the FFT and waterfall spectrum's to be taken.
Eddie notes that all his plugins now have an actual home website at https://sdrplugins.com. This is where he will release updates and new plugins from now on.
If you are interested in discovering more SDR# plugins, we have a large list available here.
Thanks to Alex for submitting news about his new SDR# plugin called "SDRSharp.GpredictConnector". This plugin allows SDR# to interface with GPredict which is a tool used for tracking the orbit of satellites. Just like with the DDE Tracking plugin and the Orbitron satellite tracking program this plugin could be used to automatically tune SDR# to the frequency of a passing satellite using GPredict. It should also be able to compensate for any doppler shift frequency offset.
To use with SDR# simply download the zip file and move the .dll file into the SDR# folder. Then add the 'magicline' to the plugins.xml file using a text editor. In GPredict you can then add a radio interface from the preferences, and then use the 'Radio Connect' interface to connect to the plugin.
Connecting to GPredict using the GPredictConnector SDR# Plugin
Eddie Mac has just released another useful plugin for SDR# called "Toolbar Plugin". This is an accessibility improvement plugin that simply puts many of the plugin controls on the SDR# toolbar. This eliminates the need to constantly open and close plugin panels on the left.
The plugin includes controls for setting the demodulation mode, changing the FFT display settings, a direct frequency entry text box, frequency stepper buttons, an SNR level meter, squelch controls, analog/digital preset buttons, screen grabber controls, and time slot selectors for the TETRA decoder plugin. The analog/digital preset buttons are quite interesting as they allow you to set presets for either analog or digital signals. For example for a digital signal you could set the preset to use NFM demodulation, and to launch the DSD+ application automatically.
More information about this and Eddie's other plugins can be found on his site, and on this forum post.
Some toolbar plugin selections.Analog/Digital Preset Settings
This is an excerpt from our book on RTL-SDR which we've decided to post given that many new users struggle to understand all the settings in SDR#.
SDR# is currently the most popular SDR program used with the RTL-SDR. It's easy to set up and use. To install SDR#, go through our Quickstart Guide. Below we explain some of the settings and displays in SDR#.
Upon opening SDR# you'll be greeted with the screen shown below. Here we have highlighted the main parts of SDR#
After opening SDR# for the first time, we suggest that you immediately remember to perform the following steps (if you don’t know what some of these steps are, continue reading further below for more information):
Increase the RF gain from zero to a higher value in the configure menu.
Reduce the range slider on the right of the SDR# window to about -70 (for RTL-SDR dongles).
Enable the “Correct IQ” setting to remove the center spike if using an R820T/R820T2, or enable “Offset Tuning” in the configure menu if using an E4000/FC0012/13.
Turn off the “Snap to grid” setting, or adjust the PPM offset accordingly.
Set the 'Mode' to the correct setting for the signal that you are listing to.
Main Settings and Windows
Note that there is a distinction in SDR# between settings that affect the software side, and settings that affect the hardware side. All hardware side settings can be found in the Configure Menu window which can be accessed with the cog icon . In here are settings to control things like the RF gain and sample rate / bandwidth of the RTL-SDR. To optimize reception, you need to adjust settings in this window.
Most of the settings found in the main windows of SDR# affect the software digital signal processing (DSP) side of things. To optimize processing of the signal you need to adjust these DSP settings.
Control/View
Explanation
Play Button / Stop Button
This button is used to start and stop the SDR.
Source
This is a drop down menu which is used to select the SDR input device being used. If you are using an RTL-SDR, select RTL-SDR/USB. Be sure to NOT select RTL-SDR/TCP unless you are using a remote server with rtl_tcp.
Configure Menu
Clicking this button opens up the configure menu. In here you can change settings like the sample rate (bandwidth) and RF gain. See further down for more information about these settings.
Frequency Input
Use the mouse to set the desired frequency you wish to listen to here. You can either click on the tops and bottoms of each individual number to increase or decrease the value, or simply hover over the number you want to change and use the mouse wheel to alter the value.
The frequency input is divided into 4 sections with each section containing 3 values (e.g. 000.000.000.000). The first section represents GHz frequency values, the second MHz, the third kHz and the last Hz. For example to tune to a radio station at 88.6 MHz we would enter 000.088.600.000 into the frequency input. To tune to 861.5475 MHz we would enter 000.861.547.500. To tune to 1.575 GHz we would enter 001.575.000.000. To tune to 500 kHz (with an upconverter and appropriate offset shift set (discussed later)) we would tune to 000.000.500.000.
Volume
Set the volume level of your output speakers or audio piping device here.
RF Spectrum / FFT Display
This part of the window shows the RF spectrum as a graph in real time visually. Active signals will appear as peaks on this graph.
RF Waterfall
This part of the window shows the RF spectrum graph spread over time with new data at the top and old data at the bottom, just like a waterfall.
Tuning Bar
The vertical red line in the RF spectrum graph shows where on the RF spectrum the RTL-SDR is currently tuned to. Within the currently active chunk of instantaneous bandwidth the tuning can be altered by simply using the mouse to click and drag the red line, or just by clicking elsewhere in the RF spectrum.
The shaded rectangular area around the red line shows the bandwidth of the tuned area (don’t confuse this with the bandwidth/sample rate that is set in the configure menu). The bandwidth should be set so that it covers the area of the signal that is tuned. The bandwidth can be adjusted by using the mouse to simply drag the edges of the shaded area in or out.
Radio Tab
Here you can choose what type of demodulation mode the signal at your currently tuned frequency should use.
Mode
Acronym Expansion
Explanation
NFM
Narrowband Frequency Modulation
Commonly used mode used by walkie talkie radios, weather radio and most VHF/UHF digital signals.
WFM
Wideband Frequency Modulation
This is the mode that broadcast FM stations use (e.g. radio music stations).
AM
Amplitude Modulation
Used by broadcast AM stations that are receivable by normal shortwave radios and also used by air band voice frequencies used by aircraft and air traffic control. Some digital signals also use AM.
LSB/USB
Lower Side Band / Upper Sideband
Used in the HF band by ham radio users to transmit voice and data efficiently with small bandwidths.
CW
Continuous Wave
Used for listening to Morse code.
DSB
Double Side Band
Similar use to AM, but requires centered tuning.
RAW
Raw IQ signal
Used for listening or recording RAW IQ data
Setting
Suggested Default
Explanation
Shift
0 (No upconverter used)
This box offsets the tuned frequency by the amount entered. This is useful if you are using an upconverter. For example if you have an upconverter with a 100 MHz oscillator, you would set the shift to be -100,000,000 (don’t forget the minus sign). Without the shift, when using an upconverter to tune to a signal at 9 MHz you would need to actually tune to 100 + 9 = 109 MHz. With the shift set, you can tune to 9 MHz as normal. If you have an upconverter with a 125 MHz oscillator you would tune to 125 + 9 = 134 MHz, or set the shift to -125,000,000.
Bandwidth
NFM/AM: 12500, WFM: 250000
This is the width of the shaded part of the tunable area. You can set it manually here, or by dragging the edges with the mouse as described under the tuning bar description.
Filter
Blackman-Harris 4
Changes the filter type used. Different filters have different shapes. The filter is used to select the highlighted signal in the RF window. Blackman-Harris is usually the best filter to choose and this setting almost never needs to be changed.
Order
500
Changes the filter order. You may notice when using low filter orders that signals outside of the tuned bandwidth can still be heard. Larger filter orders “tighten” or “sharpen” the band pass filter used within the tuned bandwidth/IF thus preventing signals outside of the tuned bandwidth from being heard. You will want to increase the filter order when there are strong signals near to your tuned area. Using higher filter orders can cause a greater load on the CPU, so slow PCs may need to reduce this value.
Squelch
OFF
Squelch is used to mute the audio when the signal strength is below the specified value. A larger value requires a stronger signal to unmute the audio. It is useful for when listening to speech as the sound of static when no one is talking will be muted.
CW Shift
600
Mainly useful for when receiving CW (Morse code) as it specifies the offset between CW transmit and receive frequencies.
FM Stereo
OFF
Will enable stereo output for broadcast radio WFM signals, but can make weak stations sound worse.
Snap to Grid / Step size
OFF or set to band spacing
In many bands frequencies are allocated at a fixed distance apart. For instance in most countries air band signals are spaced 25 kHz apart (or 8.33 kHz in some countries). Turning on snap to grid can help with tuning by causing the tuning bar to snap directly to a signal. However, to use this with a non-TCXO RTL-SDR the PPM frequency offset correction must be set correctly, otherwise the frequencies may not line up. The snap to step size can be set in the “Step Size” pull down menu.
Correct IQ
ON
Should usually be selected as ON. This setting removes the small but annoying center spike that is present with R820T/R820T2 RTL-SDR dongles.
Lock Carrier
OFF
Only active in AM or DSB mode. Allows for synchronous AM which can significantly improve reception and also automatically centers the signal on the carrier. Turn this on for better AM reception, but may increase CPU usage.
Anti-Fading
OFF
Can be used when “Lock Carrier” is activated. Takes advantage of the symmetry of AM signals which helps with weak signals when they may be fading in and out. Turn this on for better AM reception, but may increase CPU usage.
Swap I & Q
OFF
If you are using SDR# as a panadapter, some hardware radios may have the I & Q signals swapped and need this option checked.
Mark Peaks
OFF
Simply marks any peak in the RF spectrum with a circle.
Audio Tab
This tab allows you to adjust settings related to the audio processing.
Setting
Suggested Default
Explanation
Sample Rate
48000
Sets the sample rate of your sound card. Some decoding software may require a specific sample rate to be set. Usually the default value should be fine for general listening. This is normally greyed out unless using a sound card based SDR.
Input
A Sound Card
Specifies the input sound card when using SDR# with the “Other (Sound Card)” source. Used mainly with sound card based software defined radios. In normal use with an RTL-SDR this does not need to be set.
Output
Speakers
Sets the audio output device. By default it is set to your speakers. If you are passing the audio to a decoder program here you would choose your virtual audio pipe (VAC/VB Cable) to send the audio to.
Unity Gain
OFF
Should normally be unchecked as it sets the audio gain to 0 dB.
Filter Audio
ON
Improves voice signals by filtering the audio, removing high pitched hiss and DC noise. Should normally be off if decoding digital signals, but may actually help in some cases if there is significant DC offset.
AGC (Automatic Gain Control) Tab
Note that in some modes the AGC tab will be greyed out.
Setting
Suggested Default
Explanation
Use AGC
ON
Turns on the audio automatic gain control. The AGC will attempt control the audio volume level so that loud sounds are not too loud and quiet sounds are not too quiet. The default settings work well for voice audio signals. It is especially useful to turn this on when listening to AM/USB/LSB signals as strong signals in these modes may sound distorted otherwise.
Use Hang / Threshold / Decay / Slope
-50, 100, 0
Allows you to modify the default AGC behavior, though in most cases the defaults are fine.
FFT Display
The FFT display settings adjust options related to the spectrum analyzer screen and the waterfall.
Setting
Suggested Default
Explanation
View
Both
Set it to view both the RF spectrum and the waterfall, or only one of them, or none at all. Removing the waterfall may be useful on older PCs with slow processing hardware.
Window
Blackman-Harris 4
Sets the type of windowing algorithm to use on the FFT, the default of Blackman-Harris 4 is the best in most cases.
Resolution
32768
Increasing the resolution will increase the quality of how the signal looks in the RF display and waterfall. Using a higher resolution may be useful when fine tuning, as high resolutions will allow you to see the peaks and structure of a signal much more clearly. Beware that high resolutions can slow your PC down and can cause trouble especially with single core machines. Generally, a value of at least 32768 should be used if your PC can handle it.
Time Markers
OFF
Adds time markers on the waterfall display, so you know at what time a particular signal was broadcasting.
Gradient
Allows you to customize the colors used in the waterfall display.
Mark Peaks
OFF
Adds a circular marker on every signal peak on the RF spectrum.
S-Attack / S-Decay
Changes the amount of smoothing and averaging done in the RF spectrum display.
W-Attack / W-Decay
Changes the amount of smoothing and averaging done in the waterfall display.
Speed
Changes how fast the RF spectrum and waterfall updates.
Zoom FFT
Zoom FFT is a plugin that comes by default with SDR#. It creates a zoomed in RF spectrum display of the tuned IF bandwidth at the bottom of SDR#.
Setting
Explanation
Enable IF
Opens a “zoomed in” RF spectrum graph around the area of your tuned IF bandwidth. Allows you to see the signal structure with much greater resolution.
Enable Filter
If Enable IF is checked, then you can enable a special adjustable IF filter. This filter allows you to filter the left and right side of the tuned IF bandwidth individually.
Enable MPX
Enables you to see the MPX spectrum of a broadcast FM radio station. Broadcast FM is encoded in a special baseband audio format called MPX. It contains a mono section, a pilot tone and a stereo section, as well as sometimes subcarrier sections for data like RDS and special radio services like SCA. If you were to try and view the audio baseband with the “Enable Audio” button, you wouldn’t see the MPX structure because SDR# would have processed it into normal audio, and discarded the subcarriers and other sections.
Enable Audio
Allows you to see the audio (baseband) spectrum.
SDR# Digital Noise Reduction
It is useful to turn on digital noise reduction when listening to weak and noisy analogue voice signals. This setting will attempt to reduce the background ‘hiss’ sound. There are two DNR options available, IF and Audio. The IF uses the noise reduction algorithm on the IF signal and the Audio option does it on the output audio signal. Usually the IF digital noise reduction works best and should be tried first, though a combination of both may work best. The sliders control the strength of the algorithm applied, and the profile can be optimized for the type of audio you are listening to. The profile options are Hi-Fi, Talk, Speech, Narrow Band and custom.
Noise Blanker
The noise blanker is an algorithm that can be turned on to help reduce impulsive and pulsing like noise from sources like spark gaps. Examples of this type of noise may come from motors, electricity lines, power over Ethernet and switching power supplies. Carefully using this option can really help when receiving a weak signal amongst pulsating noise, which is mostly common on the HF bands. The noise blanker works by simply removing any samples that have large pulses of energy in them.
In SDR# there are two different types of noise blanker. The baseband noise blanker works on the entire spectrum and will remove pulses from the FFT and waterfall, whereas the demodulator noise blanker only works within the tuned area that is currently being demodulated. Tuning the settings is mainly an exercise in trial an error. Move the sliders until the pulsating noise goes away, whilst trying to keep the signal active.
Recording Tab
The recording tab allows you to make I/Q and Audio recordings. The sample format allows you to choose the level of recording quality needed. Since the RTL-SDR is only about 8-bits, we can select the lowest 8 Bit PCM option. Using only 8-bits saves a significant amount of disk space.
An I/Q recording is a recording of the entire ~2 MHz bandwidth that you are currently tuned to. It saves the RF data within the bandwidth so you can replay it at a later time. An I/Q recording can be made by checking the “Baseband” check box. Note that I/Q recordings can use up a lot of disk space, so make sure to watch the File Size and Duration status counters. I/Q recordings can be played back in SDR# by selecting IQ File (*.wav) from the source menu. If you receive a lot of dropped buffers, then your PC or disk may simply not be fast enough to process the recording. Remember that baseband recordings use a lot of disk space.
The audio coming out of the speakers can be recorded by checking the “Audio” check box. This will record audio to a standard audio .wav file. All recorded files are stored in the same folder as the SDR# executable.
Frequency Manager Tab
The frequency manager allows you to save any frequencies of interest in a database. A new frequency can be added to the database by clicking in the New button. This will add a frequency with the current tuned frequency and settings like bandwidth. You can edit the frequencies name and put it into a group for easy management. Double clicking on a stored entry will instantly tune SDR# to that frequency, and set the stored mode and bandwidth.
If you check the “Show on spectrum” check box then your saved frequencies will be displayed in the RF spectrum.
Right hand side sliders
The sliders on the right adjust the graph display settings for the RF spectrum and waterfall.
Setting
Suggested Default
Explanation
Zoom
Zoomed out
Moving this slider will cause the RF spectrum and waterfall to zoom in on your tuned IF bandwidth area in order to see a signal closeup. However, the more you zoom in, the lower the resolution will seem. An alternative to zooming is to either reduce the sample rate, or to use the special decimation drivers. These alternative methods will preserve the visual resolution and allow you to see the signal structure much more clearly.
Contrast
Adjusts the contrast of the waterfall. Adjust it so that signals clearly stand out from the background noise.
Range
-70
Modifies the dB level range shown on the left (vertical) axis of the RF spectrum window. You should adjust this so that the noise floor sits near the bottom of the RF spectrum window. This will allow signals to be more visible in the FFT RF spectrum and waterfall displays. As the RTL-SDR has a dynamic range of approximately 50 dB (plus a little more after oversampling/decimation), you will not need a range much higher than 0 to -70 dB. This setting will also affect the contrast in the waterfall and may help make weak signals easier to spot.
Offset
0
Adds an offset to the dB level range in the RF spectrum window. The offset is added to the top value on the dB level range in the RF spectrum. Usually there is no need to adjust this, but if you want to get really good contrast on weak signals, adjust this along with the range so that the signal height is the same height as the vertical axis. This setting will also affect the contrast in the waterfall and may help make weak signals easier to spot.
Configure Window / RTL-SDR Controller
The SDR# configure window can be accessed by clicking on the cog icon at the top of the SDR# window. The settings in this window affect the actual RF performance of the RTL-SDR, and should be set correctly to optimize the signal to noise ratio (SNR). The configure window has several options which are described below.
Remember that some options may be greyed out until you press stop in SDR#.
Setting
Suggested Default
Explanation
Device
Your RTL-SDR
If you have multiple RTL-SDR dongles plugged in, the device drop down menu allows you to choose between them.
Sample Rate
2.048 or 2.4 MSPS
Lets you choose the size of the instantaneous bandwidth the RTL-SDR should display. Generally settings of up to 2.8 MSPS work well on most PCs, but if you have a slow PC you may want to reduce this. We recommend a default rate of 2.048 or 2.4 MSPS.
Sampling Mode
Quadrature Sampling
Use Quadrature sampling for normal operation. The direct sampling selections should be used when using an RTL-SDR that supports it.
Offset Tuning
R820T/2 : OFF
E4000/FC0012/13 : ON
Only useful for the E4000/FC0012/13 tuners. Selecting this will get rid of the large spike in the center of the spectrum that is present with the E4000/FC0012/13 zero IF tuners.
RTL AGC
OFF
Enables automatic gain control on the RTL2832U chip. This is normally not useful as selecting this usually degrades reception.
Tuner AGC
OFF
Enables the automatic gain control system on the tuner chip. Can be useful for general browsing, but it is almost always better to set the gain manually.
RF Gain
Adjust for best signal to noise ratio
This slider can be used to set the tuner RF gain manually. Will not be active if Tuner AGC is checked.
Frequency correction (ppm)
TCXO Dongle: 0
Standard Dongle: Adjust for freq. accuracy.
Allows you to correct the frequency offset that RTL-SDRs have from having low quality crystal oscillators.
Setting the RF Gain
There are three RF gain settings that can be found by clicking on the Configure button. RTL AGC turns on the RTL2832U chips internal automatic gain control (AGC) algorithm. Tuner AGC enables the RTL-SDR tuners AGC. The AGC’s attempt to automatically optimize the SNR of the signals. Finally, the gain slider can be used to manually set the gain.
The AGCs used in the RTL-SDR are designed to be used with wideband DVB-T signals, and do not work very well with narrowband signals. We recommend using manual gain control at all times to optimize the gain of a signal, however for casual browsing turning on Tuner AGC may suffice. RTL AGC is almost never used as it tends to just introduce a lot of unwanted noise.
The goal when setting the RF gain manually is to try and get the signal to noise ratio (SNR) as high as possible. This means that the maximum signal strength should be high, but the noise floor should also be as low as possible.
When increasing the gain, there will come a point at which the noise floor begins to rise faster than the signal strength rises. This is the point at which you should stop increasing the gain.
You can calculate the signal to noise ratio by subtracting the peak signal height from the height of the noise floor.
What Overload Looks Like
In SDR's (and all radio's for that matter), overload is when a signal that is too strong enters the radio and causes “saturation”. An analogy might be trying to listen to your friend talking to you at a loud concert. The music from the speakers is so loud that you can't hear what they are saying. The same thing can happen in radios. For example if the SDR cannot cope with a strong signal and starts overloading, weaker signals will no longer be able to be heard. This can happen even if there is a strong signal hundreds of MHz away from your target signal, though the closer in frequency it is the more problematic it will be. The biggest causes of overload are broadcast FM signals, pagers, TV broadcasts, DAB radio and GSM signals.
The first solution to overload is to simply turn the gain down. But turning the gain down can also make your desired signal weaker, so ideally you'd use a filter to remove those unwanted strong signals, or buy a more expensive 12-bit or higher SDR which can handle strong signals much better. In this section we'll show you what overload looks like on SDR#, so you'll know when to recognize if there is a problem.
Overload can manifest itself as images of the strong signal at frequencies where they're not meant to be. For example in the image below there are broadcast FM stations at 206 MHz, and they definitely should not be there. Simply turning down the gain causes them to disappear.
BCFM Images
It can also manifest as a rise in the noise floor. For example in the image below a strong pager signal is causing the noise floor to rise whenever it transmits, and then fall again when it stops.
Pager Causing Noise Floor Rises
If you are tuned only a few MHz away from a very strong signal it can cause all sorts of weird images to show up . For example in this image below, whenever the pager transmits it causes strange signal spikes all over this part of the spectrum.
Of course overload can also cause the noise floor to rise so high that the signal is no longer visible at all.
Pager Overload
SDR Sharp Plugins
There are many plugins available for SDR# that extend its functionality. We recommend visiting rtl-sdr.com/sdrsharp-plugins for a list and brief overview of these plugins.
To install plugins you will most often need to copy a .dll file to the SDR# directory and add a 'magic line' text entry to the Plugins.xml text file which can be found in the SDR# directory. You will need to open this file in Notepad or another text editor to read it. The readme file that usually comes in the plugin zip file will usually tell you what the 'magic line' is. The line should be added between the <sharpPlugins> </sharpPlugins> tags.
Note that some older plugin readme files may still instruct you to add the line to the SDRSharp.exe.config file. This was used in older SDR# versions and is now incorrect. The line should be added to the plugins.xml file now.
If you enjoyed this tutorial you may like our eBook available on Amazon.
SDR# plugin developer Eddie Mac has again released a new plugin for SDR# called "SDR# Plugin Manager". This plugin is designed to make it easy to install, remove and re-order other SDR# plugins. Also included is a repository browser. This is a repository of many known SDR# plugin links which can be used to download and install a plugin with a simple click of a button.
If you are interested in programming your own plugins, Eddie also offers the following advice which he posted in our forum:
A good place to get started programming plugins is to download the express version of .NET (free for personal use) and install at least the C# pack. Then go to the Airspy website and download Youssef's zipped examples on coding plugins. While they are not documented you can use them as an example of the steps involved.
If you know a bit of c++ that is great it should be a good spring board to learn C#. In fact, you can even program simple plugins (like my tuner knob) in Visual Basic. Both C# and VB.NET compile to Common Language Run time anyway so to SDR# it's not much difference. The only caveat is that if you want to create any plugins to do processing on signals of any sort you MUST use C# as it supports the data types SDR# uses and VB does not. As well, VB does not allow unsafe code which C# can be instructed to allow.
Another great resource for learning to program plugins for SDR# is GitHUb and another great place is Andrej Mohar's website where he actually has a tutorial and an good explanation of the plugin coding process. You can find it here http://www.andrej-mohar.com/plugin-basics-for-sdr
If you would like an example of a "stencil" as you call it - a template, I would be happy to share a template in both VB and C# for you to use to start to learn. However, I would suggest begginning with C# from the start.
The basics of it is that the "plugin" is actually in interface that is called while SDR# loads. The "Plugins.xml" file tells SDR# what your dll is called and what the name of the plugin is. Once it has initialized your plugin, SDR# sharp asks the plugin for a "panel" control which contains the controls for your plugin. In also returns to you a "control" object interface that allows you to receive notifications of program value changes or to set program values. There are more complex things you can do but the basics are simple.
In the new version the 'Net Info' button is now functioning and it is possible to see the current calls, groups, and meta information on the current cell and neighbour cell. It also appears that it has been updated to allow for multiple SDR# TETRA decoder instances to be opened simultaneously now for wider band monitoring.
Thanks to Stephen 'Tag' Loomis (N0TTL) for submitting news about his new plugin called 'CalicoCAT' which is a serial CAT control plugin for SDR#. The plugin emulates the Kenwood TS-2000 CAT control command set, and is used to allow SDR# to communicate with other software running on the PC via a virtual serial port. To create a virtual serial port you can use free software like com0com.
Stephen notes that the plugin could be used to allow software like WSJT-X to control SDR#. For example you could use it to automatically change bands at certain times.
Thanks to VE3NEA for letting us know about his new RTL-SDR compatible heatmap generator plugin for SDR#. To use the plugin you first need to generate some heatmap CSV data by using the rtl_power software. You can then open the CSV file in the plugin and it will generate a heatmap image. A frequency heatmap shows a wideband waterfall image of detected frequency activity.
RTL-SDR heatmap tools are nothing new, but the convenience of having it as a SDR# plugin is that you can click on the heatmap image to instantly tune to a frequency where activity was recorded during the initial rtl_power scan.
Over on YouTube user TheGazLab has uploaded a video that reviews the Airspy HF+, and also shows how to use the HF+ with SDR# and WSJT-X in order to create a FT8 monitor. The Airspy HF+ is high dynamic range HF/VHF receiver designed for DXing.
In the video TheGazLab demonstrates to us the decoding in real time, and explains the CAT control SDR# plugin that he's using. The CAT control plugin when combined with a virtual serial port driver allows the WSJT-X program to automatically tune SDR# to the FT8 frequency selected in WSJT-X.
Later in the video he also discusses the SpyServer network which allows SDR# users to connect to remote public Airspy and RTL-SDR units over the internet. He demonstrates connecting to a public server in the UK, and decoding FT8 via the remote server. The video also shows the new SpyServer interface by @zakhttp which nicely lays out the world SpyServer network on a map, making it easy to choose a desired location to listen to.
Airspy HFPlus, SDR# and WSJT-X with full CAT control decoding FT-8
The Contour Shuttle Express and Pro V2 are USB controller accessories for PCs. They consist of a knob-like wheel with multiple buttons and they are designed as a keyboard replacement for improving the productivity of video/photo editors. However, several people have found them useful for controlling software defined radio receiver programs like SDR#.
There was no wrapper available for Contours Windows SDK so I created a managed .NET wrapper around contours dll. If anyone wants to develop their own software for these devices I will happily provide them with my .NET wrapper for free as well as a demo app to instruct on its usage.
. In here are settings to control things like the RF gain and sample rate / bandwidth of the RTL-SDR. To optimize reception, you need to adjust settings in this window.
