how to increase NFM bandwidth
i know i can just use WFM to have a large amount of bandwidth but WFM at max volume is still much less than NFM. is there a way to make NFM have a huge bandwidth (or increase the output volume of WFM)?
no i'm saying in the program SDRSharp NFM mode really cranks the volume while WFM is softer even at max volume. i understand both modes are basically the same
Im hearing imapired and sdrsharp is too quiet even at 50 db but NFM is LOUD at 50 db.... annoying
If the volume changes when you change between WFM and NFM it is simply down the the way it's being demodulated and is entirely co-incidence.
Actually, that's how it works with FM. When public service frequencies with to nbfm, most radio manufacturers didn't want to redesign their radios to have a narrower bandwidth receiver, so they simply bump up the volume instead. With FM, as you increase your reciever's bandwidth beyond the actual width of the signal, it gets quieter and quieter. In the opposite sense, going narrower than the signal causes clipping. That's because, with FM, the signal width gives you the dynamic range of the audio (unlike with AM where the signal width gives you the frequency range).
The bandwidth of the demodulator should match the width of the actual signal. If audio is still low, you are better off amplifying the audio than further decreasing the demodulator bandwidth, as that would cause clipping.
yes.. the optimal s/n is at the full deviation value.
All the info related to the transmitting format is in here;
http://noaasis.noaa.gov/NOAASIS/pubs/Users_Guide-Building_Receive_Stations_March_2009.pdf
Also satellites current operational status is here: http://www.ospo.noaa.gov/Operations/POES/status.html
In the SDRSharp config file (sdrsharp.exe.config) you will find this line: <add key="minOutputSampleRate" value="32000" /> Change the value to 48000. Now you can increase bandwidth for NFM to 34000 for your APT images.
I use a super old version of SDR# and on it (different computer than I am on now) the setting is "filter bandwidth" but a number of other settings are also important in optimizing the filter characteristics.
One setting which I wish was available is baseband filter BW.
all i want to do is either manually increase the nfm bw limit OR increase the volume output by wfm. wxtoimg keeps turning up crap images because of low volume with wfm and nfm is 2khz short of the 34khz i need for apt
Can't you use WFM with a narrow filter bandwidth? The crucial factor is the S/N ratio- Somewhere in the signal chain you must surely be able to turn up the volume.
My own knowledge is on Linux, so its not the same with windows once it leaves the software. What i would do is look for a mixer setting somewhere between the two that is turned down, which you have forgotten about. Something like that. On any modern OS there are innumerable settings between various sound devices and sometimes having more inputs open than you need can lower the system volume. Look for a obscure master volume setting. If all else fails, simply use an external sound card and route the outputs to the inputs and turn up the gain on that pathway and use it when you want to use the external input.
i cant really make it any plainer than this. NFM mode in SDRSharp has a much greater volume than WFM mode, i want to use WFM because of the greater BW available but since the volume ceiling is lower APT images suffer. i want to find a way to increase either the NFM bandwidth or increase the WFM mode volume. all my volume settings are maxed and there's a clear difference
the big question is why- when you turn down the WFM filter bandwidth to 34 KHz, the actual FM demodulator isnt really adjusting to 34 KHz
You should look at the SDRSharp.exe.config file
Maybe the bandwidth settings can be changed.
unhandled exception, says it needs to be a value between minimum and maximum.
just want to increase volume. dont want to install a billion different programs to solve minor issues
I just had a good pass here and listening with SDRSharp, I see exactly what you mean, i have the same problem.
the next pass I am going to try with GQRX which has a specific APT setting to see if the signal to noise ratio is better.
I am using an indoor antenna and there is snow on my roof so the signal drops down when it goes directly overhead- its okay when the angle to my (indoor) antenna is under the snow. -Still, that gives me enough time to see what you mean. the audio level is a great deal lower with WFM in narrowband setting than it is with NFM in its widest setting, 32 KHz.
Have you tried HDSDR? (http://HDSDR.de) I would definitely try HDSDR first.
Also, rtl_fm , which may be the best for scripted control.
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