Audacity Forum

I am trying to record from FM radio using a Hauppauge USB Win-TV Hybrid device - I have connected the phono leads from the FM tuner to the Composite connection on the USB Stick. I then playback through the Wintv7 software for viewing TV.

There seems to be a lot of noise showing in Audacity if I press record before I start the FM playback. Is there anyway of eliminating this noise or is this an unavoidable end product of effectively having to record from the soundcard?

I'm trying to do lossless FM captures and am concerned that this renders the job irrelevant as removing it after with the noise removal software will presumably damage the sound file.

Thanks for any help.

not sure that i can correctly picture the signal chain from device to device the way you described it

if you are recording with no signal
but can see noise then your sound card is noisy
and the problem has nothing to do with audacity

if you are getting noise with the fm then it could be the tuner

i have bought several cheap fm radios recently and found that
all the cheap ones are very noisy even on fm band and pick up few stations. apparently all done with a single ic chip to cut costs.
you used to be able to buy a cheap fm radio and it would work the way you expected.

a third possibility is the usb connection
many messages here lately with noise via usb
connect directly to the pc do not use an expansion device
have a good cable and connector
could help or it could be inherent to the pc

now if you are connecting via a tv composite signal input
instead of a separate line input the noise could be in that device

why not just use a real fm radio (good quality) and record to the line input of your sound card? even better use an external sound card.

now if by fm you mean a tv sound signal then you may be having problems with the flaky digital tv service we got stuck with. on many stations and with bad weather ours is always dropping out and is noisy when it does not drop out and some stations cannot be received at all even with an external amplifying antenna.

Does the USB device get its power from the computer? It's unfortunate that the fashion is to have everything run from the power in the USB port and it's not unusual for that power to be noisy. Sometimes you can get around problems like this by running the signal through a USB hub that gets its power from the wall instead of the computer. Don't use the hub for anything else.

Another possibility if the noise is "rain in the trees" hiss, is that's the way FM radio works. FM took a critical hit when they went stereo because they chose a simple multiplex system for the stereo signals that was enormously noisy. If your FM system allows you to drop back to mono, you may find most if not all of the show noise will vanish. When I was recording off-air, I always did it in mono. I have killer FM reception in Los Angeles, and my stereo was always noisy.

Koz

maybe
maybe not
IN the city is a tougher job for fm with the reflections off buildings

i am in the burbs
my old fm receivers are still 100% noise free on stereo
am can be noisy but that is am for you

my car fm is absolutely quiet
am band is poor like an afterthought to the designers

my older portable ($100-150 range) is noise free on fm
am and ssb has some noise on weak stations

my newer portable fm am/sw radio ($50-80 range) is noise free
even with the built in whip antenna for fm

only noise i have found on fm was when i bought a cheap fm radio ($15-25 range) at the drug store. no external antenna.
bought 3 of them trying to find a usable one. all of the cheap ones are useless for fm. do not achieve full limiting and have low sensitivity. noise could be internal from the cheapstuff ic they use.

if there is noise on FM i would bet on a cheapstuff design that cut corners using one ic and never achieves full limiting.

Thanks for the reply guys. Gives me plenty to think about.

I went for the USB because it supposedly lets you record radio from Freeview and FM - both of which I want to be able to do. Unfortunately my Digital captures save as Mpeg2 Video when I want to do an "as is" capture to Mpeg2 Audio. I don't know how I can get around this - as it's primarily a TV recording device I suspect it assumes video rather than audio, but I can't see anything in the options in the WinTV7 program that I can tweak.

It soon became obvious that I couldn't get a .wav capture this way from FM radio except by recording from the USB in Audacity but there is too much noise through the Stereo Mix. It is almost certainly either the sound card or more likely the USB itself creating the noise, as I get the same thing trying to record the audio from a Sky+ box. So it's not FM signal / reception noise.

I suspect that ultimately I have merely over complicated things and clearly the way forward is going to have to be to forget about the USB device and just try a straight line in approach for recording FM. How I do an MP2 audio capture from digital radio is another mystery entirely at the moment...

Thanks again for the ideas!

Broadcast Digital Television is MPEG2. MPEG2 was designed to transmit high definition television into your home with the least damage. It's still the best way to watch "CSI." Both Cable and Satellite transmission restrict the quality of the picture in order to get as many different shows into your house as possible. KCBS (in the case of Los Angeles) uses the whole broadcast channel for each show and it's usually terrific quality.

Capture systems sometimes leave the show as MPEG2 as they capture it and tag on beginning and end caps for local playback in your system. I believe that's how my Eye-TV does it.

There should be Windows tools that can play MPEG2 or convert it to something else. Apple gets you two different ways with this conversion. There is a charge to make QuickTime Player export, and another charge to make QuickTime Player "understand" MPEG2. You can install QuickTime Player for Windows.

Koz

<<<my old fm receivers are still 100% noise free on stereo>>>

I doubt that. Stereo FM transmissions have about a 20dB noise hit or worse compared to mono broadcasting and it doesn't matter what city you're in. They way they engineered stereo broadcasting just does that. Stereo broadcasting is automatically 9%-10% noisier than mono just because of the stereo pilot. Then the straight, unprocessed stereo separation signals are way out at the noisy edges of the band making it worse.

http://www.ham-radio.com/k6sti/monster.htm

Sometimes you don't notice it's there until you listen critically and switch to mono. Suddenly a slightly "live" background becomes velvety quiet.

Car listening has its own problems.

Koz

most of the stations i listen to are local so would have strong signal and hence good snr even with modest gain for limiting
even if stereo cost some snr

but i do hear one fm station in the car that is just as good
it is about 40 miles away from the next city but am not sure if they aim their signal towards us or not

when we lived upstate ny we got a st louis station coming in over a big station from nyc whenever it rained even with a big yagi aimed south to the south. i guess one sidelobe and propagation factors made the receiver capture the station from the west.

i am positive that the cheap radios now sound like crap on everything
they cant even play a strong local station without static on FM
which tells me it is too little gain not any new FCC standards

as to the old stereo
it is mostly background
i never listen to anything to just listen to it
whether fm or cds it is just pleasant background to keep my
subconscious from wandering and mask annoying noises that
might distract me from what i am concentrating on

i will have to try the stereo/mono test. i can do that on the main receiver. not sure about the portables. car radio not possible unless it is hidden in some menu - at least no button or knob for it.