SdrDx Docs -> troubleshooting
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11.0 - Troubleshooting


The waterfall / spectrum goes bright on changing frequency, as if there's some kind of AGC being applied

There's no default spectrum / waterfall AGC. However, there are several switchable features that do implement waterfall AGC. Make sure that AWI, ANF, SNF, TRI and SBW are all off. In the case of using the memories, the MNO control tells the memory subsystem whether to change the waterfall intercept on memory recall. In the case of using VFOs, within the VFO dialog ( Right-click any VFO) the Spectrum, dB/Div, and   Max dB  and their associated   Ind.  checkboxes control the behavior of the VFO bandstack with regard to changing the spectrum and waterfall levels.


Audio distorted sometimes, or other random performance

Are you using Wifi to connect to the SDR? WiFi connections are subject to random delays as other devices demand bandwidth on the WiFi channel; Since WiFi can only carry one connected device at a time, once a device acquires the channel, everything else has to wait. Ethernet is much better at sharing time between devices. Several things can be done:

  1. Turn off all other WiFi devices.
  2. It's good to be close to the wifi station, as this increases throughput.
  3. Reduce your bandwidth as much as possible - the less data per second, the more likely you are to get all the packets you're supposed to get.
  4. Consider a USB-to-Ethernet adapter for your computer, so you can be directly connected to the network (these are not as reliable as actual ethernet ports, but they're way better than WiFi)


AFEDRI audio slow and draggy sounding

Look at the bottom left of the SdrDx window. Does it say SDR-IP there? If so, your AFEDRI is in RFSPACE Emulation mode. You need to open the AFEDRI-supplied control application and turn "Emulation ID" off. Then it will stop (badly) pretending it is an SDR-IP SDR.


SdrDx Won't let me set the gain on my AFEDRI SDR

Look at the bottom left of the SdrDx window. Does it say SDR-IP there? If so, your AFEDRI is in RFSPACE Emulation mode. You need to open the AFEDRI-supplied control application and turn "Emulation ID" off. Then it will stop (badly) pretending it is an SDR-IP SDR.


SdrDx crashes when I press Run

This can happen if there is no audio device set. If that's the problem, you can fix it this way: Start SdrDx, click SND, and select a valid audio output device. Click Okay. SdrDx will close. Changes take effect on next restart.


I get no sound

To clear off anything that might affect audio output, make sure one of FCD, Run or > is on, then that MUT, LSQ, AMS, HPF, SSP, NOI, NOT, -Ri, NBL, DNR, TDM, 60, 70 and LPF are all off. Make sure SND is set to the output on your machine that is actually connected to speakers, etc. Make sure that VOL is fully right, I/R is fully left, and you are tuned to an actual signal. Try a local AM BCB station.


The dB scale and/or grid are missing / black

Turn off ANF -- when Automatic Noise Floor is on, the dB and S notations no longer relate to real values, as the noise floor is locked to one vertical position on the display. For this reason, they are not displayed and the measuring grid is set to black. SdB is set to yellow as shown to let you know that the dB scales are disabled.


The scope display is black when I select the audio waterfall

This happens when there is no color palette selected for the waterfall. Press LAP and load one of the supplied audio palettes, or use EAP to create a palette of your own. You can then use SAP to save it under the name pal_defaulta.wfp if you would like this to load automatically when you start SdrDx. If you don't want it to load automatically, save it under a different name.


US CB channels out of order: 22, 24, 25, 23, 26?

This is actually not a problem. If you look at the US CB band below channel 20, you'll see there are gaps every four channels. Those gaps are actually non-voice channels that are intended for industrial and radio control use. Back when there were only 23 CB channels, there was an additional 20 KHz gap (room for two industrial / RC channels) between channels 22 and 23, also intended for that purpose. But years after the 23 channel spacing was finalized when the FCC decided to allow for 40 CB channels, they started just above 22, shoved 24 and 25 in there, skipped where 23 was, and the proceeded upwards at the usual 10 KHz spacing. There's some radio esoterica for you!


Need to get back to "square one?"

Under OS X, just delete ~/Library/Preferences/com.fyngyrz.sdrdx x.yy.plist where x.yy is the program version. If previous versions also exist, SdrDx will pick those up next time it starts, or, you can delete those as well.

Versions of Windows often change where they keep program's settings / preferences; so you're kind of on your own figuring that one out. Sorry.


Control-click not working to open dialogs under OS-X?

Check your mouse preferences and make sure that an actual right-click on the mouse is set to work. Then use mouse-right-click, not keyboardControl-left-mouse-click, to open the dialogs. The manual has recently begun to use Right-click BUT to indicate when you should right-click a button. Remember: a right-click is a right click. Not a control-click.


SDR-14 or SDR-IQ won't connect to server under OS X 10.11

See this note


Run or > or FCD is on, SdrDx looks like it's running, but I can't hear any audio

1) Ensure VOL is not at    0

2) Ensure I/R = -120

3) Ensure SQL =    0

4) Ensure LSQ (off)

5) Ensure AMS (off)

6) Ensure SSP (off)

7) Ensure AMS (off)

8) Ensure TXS (off)

9) Ensure LPF (off)

10) Ensure HPF (off)

11) Make sure the demodulator envelope is wide enough

12) Make sure you're in the proper demodulator mode for the signal

13) If in >, try pressing pause: ||

14) Is MUT blinking? If so, click it or press Spacebar

15) Do you have the correct audio output selected? Check the dialog opened with SND


With a network SDR, Run is Run and won't press

1) Does CUTESDR work in your machine? If not, follow the CUTESDR directions until it does.

2) Is > pressed? You can't be in Run *and* > .

3) Is FCD pressed? You can't receive on a network SDR and the FUNcube at the same time.


FCD is FCD and won't press

1) SdrDx can't find your FUNcube.

1a) Is the FUNcube plugged in?

1b) Does a virtual machine have a "grip" on it? One client at a time!

1c) Does your FUNcube have the 18j (or later) firmware installed?


FCD is dark green and won't turn FCD bright green

1) Perhaps the sample rate is set too high for some reason. For example, I can't run the full 96000 here on my XP virtual machine; this causes a failure to start. Qt (the development environment) forbids more than 48000 on Windows. But if I set it to 48000, it'll run. Whereas on the Mac, I can run full speed. Right-click FCD and adjust the sample rate.


FUNcube audio is distorted

1) The FUNcube seems to lose its mind now and then, especially when not used for a while, and a hard reset can often make it work again. Turn it off within SdrDx (click the bright green FCD so it turns dark green FCD), remove the FUNCube from its USB port ( FCD will turn FCD), wait 30 seconds, then plug the FUNCube back in. When SdrDx's FCD button again indicates dark green FCD, click it to re-start reception.

2) Sometimes the FUNcube needs to re-adjust its internal AGC. While it does this, it can produce distorted data.

3) Are you tuned to the same demod frequency as the FUNcube's center frequency? Try receiving off to the side. The best achievable DC I/Q balance on the FUNcube isn't great.

4) Make sure that the noise blanker is off: NBL, or, that NBT and NBW are both set to no more than 50. To start with the noise blanker, I recommend NBW=50 and NBT=30


 o  is red  o  and won't press

1) Is Run pressed, and green? Otherwise,  o  record won't work.


> is red > and won't press

1) Is Run pressed, and green? If so, > play won't work.

2) Is FCD pressed, and green? If so, > play won't work.


SWF won't press

1) Is Run or FCD pressed? You have to be receiving to save waterfalls


My recordings don't work?

1) Is your machine too slow? Try a narrower bandwidth (SDR / dialog)


My recording files are being split at 500 MB?

1) Right-click  o , and set the size you prefer.


It's difficult to set the sliders exactly?

1) Point at the slider knob and try using the mouse-wheel

2) Use TAB and  TAB to select the slider you want to change, then use and


I can't get the UDP communications going?

1) Make sure the port settings (NET dialog) match those in the client application(s.) Also make sure that there is only one UDP client running under OS X, as Apple has a flawed UDP implementation that can only handle one client at a time.



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