think about it !!!

[Sonar]

Wanna talk about noise sources?

Think about these common and loud noises:

1. Neighbor using an electric drill, grinder, saw, etc.
2. Neighbor using an arc/mig/tig welder - nasty!
3. Neighbor has a cheap DC to AC converter for their solar panel array.
4. Most common is often right under your nose - a cheap and unfiltered 12v switching-type power supply.

I agree 100%. You left out the infamous plasma TV. I'm fortunate enough not to have to deal with a noise issue. As I mentioned in a previous post, I had a three month period where I went through and intermittent S3 - 5 noise level. It was definitely and outside source. And it drove me crazy. I couldn't hear anybody whose signal wasn't above an S3 or 5. And with my IMAX only 10 feet off the ground, that takes care of about 75% of the stations I receive. I never figured out what it was. but the West Mountain DSP speaker I purchased took care of the problem. And even though the problem subsided and never came back I kept the speaker, and enjoyed it for about two months after that. Those external DSP speakers, and the clear speech filters work wonders for that type of interference. I'm assuming it doesn't work for everyone (depending on the type of interference,) but if you're at the end of your rope, and can't resolve a noise issue on your receive, the stand alone filter or speaker itself is definitely an option. Even without an interference problem those speakers at least in my experience turned the receive on the Madison into an incredible listening experience. That's why I'm going to purchase another. I just need to correct some issues that are more pressing then improving my receive, which isn't actually all that bad. The sonar FS 2340 receives very nicely, as does the Uniden Madison. 73 Robb and a Happy New Year.

 

[Captain Kilowatt]

Sonar......the problem with DSP that is done at the audio level is that you still cannot detect a signal below the noise level. It only allows you to make signals clearer if they are already marginally above the noise. When DSP is done at the RF level, typically at an IF stage, the results are MUCH more dramatic. It allows a signal to be detected that is actually below the noise by separating the noise from the signal to put it in laymans terms. I have used both and there is a big difference. The older Yaesu FT-857D radios )like mine) have audio level DSP and the new ones use RF (or IF) DSP and it works much better. Similarily my Kenwood TS-820S has a speech processor that works at the IF level. It has MUCH more punch while still retaining decent fidelity and clarity than newer radios that simply use a form of audio processing. Not saying that audio DSP does not work because it does but you have to first detect a signal from the noise before you can process it Unfortunately audio processing is cheaper and easier to use therefore it is more commonplace.

 

[Captain Kilowatt]

Wanna talk about noise sources?

Think about these common and loud noises:

1. Neighbor using an electric drill, grinder, saw, etc.
2. Neighbor using an arc/mig/tig welder - nasty!
3. Neighbor has a cheap DC to AC converter for their solar panel array.
4. Most common is often right under your nose - a cheap and unfiltered 12v switching-type power supply.

And mobile cell phone chargers. I had a charger that would wipe out my FM radio in the car except on strong local stations and my 2m radio was useless when the charger was plugged into the lighter socket.

 

[309hellinois]

And mobile cell phone chargers. I had a charger that would wipe out my FM radio in the car except on strong local stations and my 2m radio was useless when the charger was plugged into the lighter socket.

I had that problem with 3 after market mobile chargers. I bought a Samsung charger and the noise is gone.

 

[Captain Kilowatt]

I had that problem with 3 after market mobile chargers. I bought a Samsung charger and the noise is gone.

Mine was a Nokia at the time. Now I just charge my Samsung phone directly from the USB port in my dash. No problem at all.

 

[Sonar]

Sonar......the problem with DSP that is done at the audio level is that you still cannot detect a signal below the noise level. It only allows you to make signals clearer if they are already marginally above the noise. When DSP is done at the RF level, typically at an IF stage, the results are MUCH more dramatic. It allows a signal to be detected that is actually below the noise by separating the noise from the signal to put it in laymans terms. I have used both and there is a big difference. The older Yaesu FT-857D radios )like mine) have audio level DSP and the new ones use RF (or IF) DSP and it works much better. Similarily my Kenwood TS-820S has a speech processor that works at the IF level. It has MUCH more punch while still retaining decent fidelity and clarity than newer radios that simply use a form of audio processing. Not saying that audio DSP does not work because it does but you have to first detect a signal from the noise before you can process it Unfortunately audio processing is cheaper and easier to use therefore it is more commonplace.

Thank you. That was a great description. Especially for someone like myself with little to no knowledge about the way the items that we use to enjoy our hobby work. You could imagine the difference it made for me. To my knowledge that unitthe Uniden Madison has a double conversion front end. Although my noise level doesn't include any outside interference it's still only a double conversion receive, and the West Mountain DSP speaker made a tremendous difference in making it possible to have that static that I'm assuming everyone gets on every CB radio receive, almost totally disappear, and actually debt to clearly hear that station that was at or below the same static level. That West Mountain DSP speaker actually made it possible for me too clearly hear stations that were at or below an s-1 unit on mine either. That s one unit on my meter is where I usually received that static and even the noise blanker isn't enough to eliminate anywhere near enough of that static to make it possible to hear that station. Not only did it do that, but it made the receive much more enjoyable even with stations below and S5. It worked great and truly made my Uniden Madison receive like a totally different radio. I didn't get that mechanical or metallic sound that some people who have used these type of speakers have described. I'm looking forward to purchasing another, as I previously mentioned I had swapped my DSP speaker for a bunch of other equipment, and I've missed the West Mountain DSP speaker ever since. I have a few other more pressing station issues to correct before moving on to purchase another West Mountain, but as soon as those issues are addressed it will be the first thing I will do. Once again thanks for the lesson and for someone like myself your description fits the layman's terms to the T. Anyone reading it no matter how inexperienced or unknowledgeable would probably get the idea on exactly how those speakers work. Thanks again my friend. Much appreciated. 73's

 

[Cold War Vet]

well its the new year and after all the lights have been taken down my noise level has dropped 3 db
I know that there are several million noise sources that cause rfi but those i can account for so the christmas lights in my area were causing some of my rfi and trust me almost every house in my neighborhood was lit up like a laser designator as seen by a laser guided gbu paveway

 

[Cold War Vet]

And mobile cell phone chargers. I had a charger that would wipe out my FM radio in the car except on strong local stations and my 2m radio was useless when the charger was plugged into the lighter socket.

my wifes ipad charger is a noisy wall wart when she plugs it in i know it

 

[Shadetree Mechanic]

I have heard about people putting Shotkey diodes in the receive to lower the noise floor. Would this help with RFI or is this for something different?

 

[N0NB]

I have heard about people putting Shotkey diodes in the receive to lower the noise floor. Would this help with RFI or is this for something different?

Different noise sources.

The noise floor (NF) is generated inside your radio by its circuitry, also known as thermal noise. It is the noise that is heard when the antenna is disconnected/connected to a dummy load. If the noise level rises when the antenna is connected on a "dead" band such as 10m at night, the radio's NF is probably low enough. This noise is only really a concern above 14 MHz as the lower bands have enough atmospheric noise that is much stronger than that generated in the radio.

Replacing the diodes may have another benefit if they reduce the intermodulation distortion (IMD) suffered by the receiver in presence of strong signals. Again that sounds like additional noise in the speaker but is generated by poor linearity of the devices.

RFI is anything that is received when the antenna is connected. Other than IMD, the diodes don't have anything to do with that. RFI requires other mitigation techniques.