improving clarity of SDR recording

[ih784]

I have a high-pitched squeal in the background of my recordings and I can faintly hear people talking. What setting could I use to improve this? Sample rate?

 

[Enjoi19]

What software are you using?

 

[ih784]

What software are you using?

SDRTrunk and trunk recorder.

 

[Enjoi19]

Could you post your trunk recorder config? Which systems are you scanning?

 

[ih784]

Could you post your trunk recorder config? Which systems are you scanning?

I will when I get home. Im at work right now. I’m scanning marine vhf frequencies.

 

[ih784]

Here are the settings I’m using. The squelch is just above the point it breaks the squelch. The channel bandwidth is 12.5. These are all vhf frequencies. I’m wondering if it’s just faint calls that are barely coming in? Or, I need a better antenna?

 

[Enjoi19]

What's your antenna setup and how close to water are you? That's likely the big determining factor.

 

[ih784]

What's your antenna setup and how close to water are you? That's likely the big determining factor.

As the crow flies, about 15 miles.

 

[Enjoi19]

As the crow flies, about 15 miles.

Unless you have some crazy line of sight to water and a wicked VHF antenna, I would hazard to say it's a bit too far to get much.

 

[ih784]

Definitely not an issue lol. I currently only have the top of a (cheaper) 4’ antenna and a height of about 15’. Should I be at 7.5 or 12.5 bandwidth? Would it even matter?

 

[Enjoi19]

I'll have to leave this one to someone more expert in the marine VHF side of things - Hopefully there's some answers

 

[ih784]

I appreciate your responses! Setting this up was new to me. I’ve normally just imported from RR for P25/trunked systems.

 

[PDXh0b0]

Go to windows sound manager and disable your microphone?

 

[ih784]

Go to windows sound manager and disable your microphone?

I’ll check it out right now! Thanks!

 

[maus92]

View attachment 169154


View attachment 169155

Here are the settings I’m using. The squelch is just above the point it breaks the squelch. The channel bandwidth is 12.5. These are all vhf frequencies. I’m wondering if it’s just faint calls that are barely coming in? Or, I need a better antenna?

The highlighted marine channel in the pix - 157.4 - is a 25 kHz bw channel.

 

[ih784]

Thank you! Is there a list that would give me this information if they’re all unique or a rule of thumb?

 

[maus92]

12.5 kHz channels are allowed in the US for public use but are uncommon. Most marine channels in use are 25 kHz. Below is a chart that may be helpful:

Maritime VHF Narrowband Channels - 12.5 KHZ | Navigation Center

More general marine channel info can be found stating here:

U.S. VHF Channel Information | Navigation Center

 

[ih784]

Please bear with me. I’m hearing some people while I’m using 12.5. I can toggle it off and on and experiment. But, is there an advantage to using 12.5kHz vs 25kHz?

 

[maus92]

Please bear with me. I’m hearing some people while I’m using 12.5. I can toggle it off and on and experiment. But, is there an advantage to using 12.5kHz vs 25kHz?

There is no advantage to using 12.5 kHz when listening to a 25 kHz channel - it's probably one reason why you are experiencing poor audio quality. Use 25 kHz FM if SDRT gives you that option.

 

[ih784]

Awesome. I just switched them all over to 25 kHz. The Tx doesn’t sound as garbled. Plenty of static but, I think I can attribute that to poor signal.