Sound Quality from RTL-SDR

[dragon48]

I just configured this inexpensive SDR:

RTL-SDR Blog V3 R820T2 RTL2832U 1PPM TCXO HF Bias Tee SMA Software Defined Radio with Dipole Antenna Kit.

I'm using the latest version of SDR Sharp with Windows 10.

To be clear, I did not purchase this to listen to commercial radio and am not complaining; just curious if this is to be expected:

I tuned in to a strong local FM station. The reception is fine, but the audio quality is awful. It is very nasal and devoid of bass. I did click on the "WFM" detector and checked "FM Stereo." Also, I have a good ear and am reasonably sure that I'm not getting true stereo separation. Is this to be expected? If I uncheck "FM Stereo," the sound just get worse, with less treble.

Any way to get true stereo or improve the sound quality? Is the bad quality audio and lack of stereo separation normal, or is this indicative of something wrong with my setup and will I have problems with other functions?

Thanks

 

[BM82557]

For WFM set Filter BW (Bandwidth) to 250,000

 

[dragon48]

A little better quality, but not a ton. Default was either 150,000 or 200,000. Not a big deal, but I'm really curious as to what selecting and deselecting the "FM Stereo" is actually doing.

 

[wowologist]

Sounds more like you have the gain set too high. For a strong local FM station you don't need much really.

 

[DRL-XM43]

Yup sounds like too much gain and overdriving the front end.

 

[dragon48]

The gain was at the default (all the way to the left) 0 DB.

Appreciate The advice, but this isn't really big deal.

 

[boatbod]

To be clear, the RTLSDR hardware just receives and digitizes a chunk of RF spectrum. It's the software that is responsible for demodulation/decoding and the quality of reproduced audio. You could spend $25 or $2500 on the hardware, but if you use the same software and settings the results are going to be remarkably similar.

 

[dragon48]

To be clear, the RTLSDR hardware just receives and digitizes a chunk of RF spectrum. It's the software that is responsible for demodulation/decoding and the quality of reproduced audio. You could spend $25 or $2500 on the hardware, but if you use the same software and settings the results are going to be remarkably similar.

I am using SDR Sharp because the RTD-SDR site recommends it. Do you recommend anything else? Don't mind paying a little, but don't want to pay a lot.

 

[a417]

You shouldn't be paying anything, all the best stuff in this field is free. You are using a great, front-running program...you just need the settings tweaked.

...and maybe a little front-end attenuation.

 

[wowologist]

I am using SDR Sharp because the RTD-SDR site recommends it. Do you recommend anything else? Don't mind paying a little, but don't want to pay a lot.

www.sdr-radio.com ...if you like it, leave him a donation...if not...someone else might cover the dogfood for you. Its an ADVANCED program...but it's pretty much the state of the art in sdr software these days. If you stick with it and enjoy what youre getting into you may want to invest in a sdrplay down the road and throw up a 33' loop of speaker wire on the roof and listen to the world.

 

[mancow]

Is it the one with the precanned plugins? If so check the various audio processing options. I think some are set by default.

 

[hhca]

if your worrying about FM audio quality on a sdr then your missing the point...

 

[air-scan]

I just configured this inexpensive SDR:

RTL-SDR Blog V3 R820T2 RTL2832U 1PPM TCXO HF Bias Tee SMA Software Defined Radio with Dipole Antenna Kit.

I'm using the latest version of SDR Sharp with Windows 10.

To be clear, I did not purchase this to listen to commercial radio and am not complaining; just curious if this is to be expected:

I tuned in to a strong local FM station. The reception is fine, but the audio quality is awful. It is very nasal and devoid of bass. I did click on the "WFM" detector and checked "FM Stereo." Also, I have a good ear and am reasonably sure that I'm not getting true stereo separation. Is this to be expected? If I uncheck "FM Stereo," the sound just get worse, with less treble.

Any way to get true stereo or improve the sound quality? Is the bad quality audio and lack of stereo separation normal, or is this indicative of something wrong with my setup and will I have problems with other functions?

Thanks

Actually SDRuno will run RTL-SDR with the EXTIO dll driver for HDSDR. FM Stereo is full range rich. Just keep SDR# for as a reminder it's not all that!

 

[KE5MC]

No one has commented, so I'll add your computer's audio setting could be having a negative impact.

 

[wgbecks]

The suggestion to reduce RF Gain are important to prevent overload and spurious response to the normally large inband signals. But KE5MC likely hit the nail on the head... Check the sampling rate of the audio device in your computer and set the audio section in SDR# to match.

I get excellent FMBC Stereo audio quality on mine with the run of the mill RTL-SDR's. The default 200 KHZ bandwidth for WBFM is accurate and works well for stereophonic transmissions. I don't believe there is any deemphasis by default in SDR# so you might want to download and install one of the audio processor plug-in's that enable this feature.

Mine works so well that I can pipe the audio to Visual Analyzer and calibrate it as an FM modulation monitor against my professional instruments!
Just remember to include the de-emphasis if you wan to achieve accurate audio response for listening or measurements.

Bill

 

[peepoop]

I ran into this too.

The fix is an easy one, but you'd never know it because SDR# is really hard to use with zero in-app documentation.

On the left, open up the Audio Processor plugin and disable "Bandpass filter". It's enabled by default. Fixed.

 

[wgbecks]

One last thought... US FMBC frequencies are channelized on 200 KHz increments beginning at 87.9 MHz and ending at 107.7 MHz. It's easy to tune the SDR off frequency, especially when there is too much RF gain and the SDR overloads presenting spurious signals on the spectrum and waterfall scopes. And as peepoop posted, the documentation is sadly lacking and it will take some cut and try to learn how to setup SDR# to match the specific communications modes.

Have fun!

Bill

 

[k9wkj]

gain at 0 default means it is probably set to auto which is like 49db
distortion is very likely

 

[Ubbe]

At 0dB gain, that where the defualt when I installed SDR#, I get hardly no signal at all. Either crank it up to 30dB or plainly tick the RTL and Tuner AGC boxes, that will make the dB values dissapear and not be shown.
It's enough to use 1.024MSPS sample rate. Larger values makes you see a bigger range of MHz in the spectrum, if your PCs processor can handle it.

FM broadcasts are at 100KHz steps so set that step size and tick the snap to grid box.
As there's no deemphasis you can turn down the treble a bit on your stereo amp, if you feel that there's too much of it.

/Ubbe

 

[TailGator911]

Did the OP say if he was experiencing the same problem with other bands on the spectrum? Upon reading this, I fired up my SDR, as I am running all of the same software and hardware that the OP is, and my FM commercial stations are loud and clear. I run my PC audio thru a set of studio Mackies, and the FM sounds great thru SDR#.