Topic: Mono to stereo converter.

[wuhu_software]

I am just curious if those streaming to WU have a mono to stereo plug converter between the radio and the sound card's line-in?

Usually the output connector from the radio will be a 2 conductor mono plug. Most sounds cards have a 3 conductor stereo line-in connector. It is necessary to converter the mono to stereo using a converter plug (available at radio shack for a couple of bucks).  

Some cards do offer mono inputs such as AUX and TAD. Using those inputs would be preferable if you are not converting to stereo.

I have noticed a few of the streams have a bit of a hum.

Is this the possible cause?

Thanks.

[ncpilot]

I am using a mono to stereo converter...

I'll bet the hum has more to do with the quality of the radio, and the quality of the earphone output circuitry, rather than a mono to stereo conversion...

I'll bet (#2) that most audio input cards in computers have better circuitry, and will only serve to magnify poor audio from the radio...

Could be that powering the radio on AC adds hum?

Being close to the computer could induce hum?

Don't the installation instructions for Oddcast caution about mis-matching the input on the computer card? Different sensitivities? Potential problems with overload, etc...? Would the AUX input have a different sensitivity than MIC?

Hey, I'm bored here at work... let me spew some more stuff!!  

My radio quality isn't so great to begin with... also, I sometimes hear electronic sounds in the background rather than hum--could be interference from the computer itself...?

I guess it's obvious, but the feeds using 8kB don't sound near as good as 16kB--at least mine sucked at 8kB...

[kray1000]

My test radio apparently didn't have a very good receiver... there was always a little "snow" in the signal.  When I listened to my feed online, there was some "digitized" interference.

I went to Wal-Mart and picked up a $33 TV/radio (TV, AM/FM, CD player, weatherband) which does a very good job of pulling in the signal.  Not sure if the output jack or the signal quality was the difference, but the interference is now gone from my feed.  Everything else in my setup stayed the same.

http://audiostream.wunderground.com/roanokevalleyweather/roanoke.mp3

[SLOweather]

Hum is most likely caused by a sub-par AC adapter or power supply. If possible, try the receiver on batteries to see it this is the culprit.

The next cause, if you have an outdoor antenna on it, is a ground loop where the antenna is at a different ground potential than the radio or computer.

There's an outside chance that a ground loop could be caused by the radio and computer being plugged into different circuits.

And lastly, hum could induced if there is a break in the shield of the patch cable, or if the radio is too close to an electromagnetic device like a monitor, fluorescent light, motor, or something with a transformer in it.

As far as cables and connectors and adapters go, Rat Shack all manner of them.

Dubbing cables (top 2 at that link) have a built-in attenuator to match line-level outputs or earphone jacks to mic inputs. Sometimes these can also match a speaker jack to a line-level input.

To adapt a mono output to a stereo input, you need something like THIS.

Oddcast should be able to take a single channel input (or a stereo input) and mix it to a mono output without any adapter. I think the Shoutcast DSP can do that.  

Of course, the true technoweenie would keep the inputs separate, hook them to 2 different audio sources, and broadcast 2 feeds over the same stream to a stereo server. If you live where you can receive 2 different NOAA forecasts on 2 different channels (here I can get 3 on a good antenna), you could stream them in stereo. The listener would then adjust the balance on his computer or speakers to hear the desired forecast.

[carterlake]

Hum....

My hum is actually coming out of the radio but then, it is in the basement and NOAA radio is massively underpowered. Making my own antenna seemed to help quite a lot but it would be nice to have a hum filter in Oddcast.

What I've noticed is a buzzing noise occasionally which is NOT in my stream from computer to radio (if I listen to unmuted audio). So the buzzing comes from Oddcast?

[SLOweather]

You can try this to see if you can isolate the problem.

Unplug the radio cable from the computer and stream dead air. Then listen to the stream and see if the buzz goes away.

And for the hum, Google on Oddcast DSP plugins. Look for an equalizer (the more bands the better) or or maybe a notch filter. If your feeling lucky, try searching for Oddcast hum filter. Maybe you'll hit the jackpot.

[SLOweather]

What kind of antenna did you add to it?

[carterlake]

What kind of antenna did you add to it?

I designed my own, replacing the monopole that comes with the radio.

According to my math, the optimal antenna length for 162.4 mzh is 1.846 meters. Since I can't put an antenna in the house that's 6 feet long, I opted for 1/4 the wavelength or 46 centimeters... that equals almost exactly 18 inches. So I got out the 10 gauge wire and made a loop antenna in the shape of an elongated recetangle, with the top and bottom lengths of 18 inches. I also made the length of the pole from the loop to radio 9 inches (or 1/8th the wavelength).

I'm certainly open to suggestions though... in fact, now that I have to working well, I might have to just brave the wife's temper and get a weather radio with a digital tuner.

[SLOweather]

You are correct that 1/4 wavelength is the correct length to use.

There are a couple of  easy, effective, inexpensive antennas you can build.

One suitable for outdoor use is to get an SO-239 connector from Rat Shack http://www.radioshack.com/search/index.jsp?kwCatId=&kw=so-239&origkw=so-239,
and 5 lengths of stiff wire cut to your 1/4 wavelength. Brazing rod works well, but even 12-14 ga solid house wire might work. Copper-coated welding rod will work for a while.

Also, 4 ring terminals and 4 screws and nuts that will fit through the holes in the terminals and those in the corners of the connector.

Solder one wire to the center pin of the SO-239. Crimp or solder the ring terminals on one end of each of the remaining 4 wires. Screw one to each corner of the connector, pointing out at right angles from each other. With the center element pointed up, bend the 4 down at about a 45 degree angle.

Then use a PL-239 cable to connect to the antenna, weatherproof it unless you're mounting in the attic, and figurre out how to mount it. One way would be to run the cable through a piece of thinwall conduit into which the PL-259 just fits.

That's called a ground plane antenna, and is great for a single freq application like a weather radio. Use care around those rod ends. In the past I've glued beads from the hoppby store onto them.

The second antenna is a collinear. Get a length pf coaxial cable like for a CB antenna. Strip off the outer jacket maybe an inch longer than your 1/4 wave. Be careful not to nick the braid.

Carefully pull the braid inside out back over itself down the cable until the insulated center conductor is fully exposed. Then you can put a layer of electrical tape or heat shrink over the braid. Form a small loop or eye in the end of the center cable for hanging. Yo could leave the insulation on and use a small double-wrapped zip tie to do it.

This antenna is harder to waterproof unless maybe you dunk the whole top in Plasti-Dip or something. It does roll up and become very portable, and again, is well suited for a single frequency.

[carterlake]

Interesting read...

http://www.crh.noaa.gov/mqt/nwr/nwrwebpg/antenna.php

By the way, I went back to my original home-made antenna (just a simple loop, no measuring or optimization)... seems to work best of all.