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Old February 7th 05, 03:29 PM
JJ
 
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I also live in the area and we get SCA transmissions from NYC and Philly.
Lots... readings from the NYT, WSJ, different languages, and digital. The
best directory is Bruce Elving's guide.

Joe

"DougSlug" wrote in message
...
I am in the Trenton area, not far from you, Doug...what SCA programming,

if
any, have you discovered at your location with this radio?
- Doug


"r392" wrote in message
news:hz2Kd.11237$Dz2.457@trndny09...
I bought a SCA radio AM FM radio with the upper and lower SCA setting for
cheap on Yahoo auctions about a month ago brand new in box here is a

link.
I do not have anything to do with the guy just thought it was a good

deal.
the radio is a cheap radio. It has good audio and great sensitivity.
for $30 well worth it.
Doug





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Old February 11th 05, 09:01 AM
 
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Cannot be done with sound card or software. These are subcarrier s in
the FM signal. One has to tap the receiver after the demodulator and
send through a separate LF FM receiver ("adapters"_. Note that there are
legalities to consider in the US.
----------------------------------------------------

hmm.... new question I'm now wondering about after reading the above.

Does this mean that any audio tape I recorded years ago of regular FM
stations that happened to broadcast subcarriers also have the
subcarrriers recorded on my old tapes????

And if I was able to buy an SCA decoder, I would be able to hear these
old SCA transmissions when listening to my old audio tapes?

or would my old audio tapes only have the regular FM station information
recorded on them, even though the FM station was broadcasting a
subcarrier that I was unaware of at the time?

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Old February 11th 05, 09:05 AM
 
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Note that there are legalities to consider in the US.
---------------------------------------

strange. I've seen SCA decoers at legal ham radio stores just last year
(2004),

and the hams say that hams never do anything illegal. That hams always
obey the law.

Thereforem how can it be illegal if hams never do anything illegal and
sell them to customers at legitimate stores?


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Old February 11th 05, 01:32 PM
David L. Wilson
 
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wrote in message
...
Cannot be done with sound card or software. These are subcarrier s in
the FM signal. One has to tap the receiver after the demodulator and
send through a separate LF FM receiver ("adapters"_. Note that there are
legalities to consider in the US.
----------------------------------------------------

hmm.... new question I'm now wondering about after reading the above.

Does this mean that any audio tape I recorded years ago of regular FM
stations that happened to broadcast subcarriers also have the
subcarrriers recorded on my old tapes????


No. It is certain that your recordings recorded frequencies of centered at
67 and 92 kHz where SCA is centered. Audio frequencies stop at about 18 kHz
and your recording do also as did the audio output of your receiver.

On the other hand, an old Beta video recorder could be modified and hooked
to the FM demodulator to do what you describe.

or would my old audio tapes only have the regular FM station information
recorded on them, even though the FM station was broadcasting a
subcarrier that I was unaware of at the time?


Yes.


  #15   Report Post  
Old February 11th 05, 01:36 PM
David L. Wilson
 
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wrote in message
...
Note that there are legalities to consider in the US.
---------------------------------------

strange. I've seen SCA decoders at legal ham radio stores just last year
(2004),

and the hams say that hams never do anything illegal. That hams always
obey the law.

Thereforem how can it be illegal if hams never do anything illegal and
sell them to customers at legitimate stores?


Listening to SCA has nothing to do with ham radio.

And also, selling the equipment is not a legal thing. If is what a person
does with it that involves legalities. You can buy SCA decoders, but you
can legally only listen to what you have permission to do nmaking some
purchases for legal purposes. Yes, there is a reallity gap--some laws are
simply stupid.

Similarly you used to be able to buy scanners that could receive cell
phones. It was illegal though to do that.




  #16   Report Post  
Old February 12th 05, 01:40 AM
DougSlug
 
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You're correct that the audo tapes would only have audio information, but
the SCA information is also in the baseband signal except that it's outside
the audio bandwidth that the tape recorder would have recorded due to AF
filtering in an ordinary FM receiver. As I understand it, the SCA
information is filtered from the demodulated signal before it is sent
through the AF filter normally used for the audio output of the "main"
(primary carrier) baseband signal.


"Bob Horvath" wrote in message
...
On Fri, 11 Feb 2005 03:01:21 -0500, Bob Horvath wrote:

Your tapes would only have "audio" information on them, not Radio
Frequencies, which is what contains the SA information.



  #17   Report Post  
Old February 12th 05, 02:20 AM
nana
 
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"DougSlug" wrote in message
...
You're correct that the audo tapes would only have audio information, but
the SCA information is also in the baseband signal except that it's
outside the audio bandwidth that the tape recorder would have recorded due
to AF filtering in an ordinary FM receiver. As I understand it, the SCA
information is filtered from the demodulated signal before it is sent
through the AF filter normally used for the audio output of the "main"
(primary carrier) baseband signal.


It is filtered out by the Stereo demultiplexer before it gets to any audio
stage. To receive SCA, you will need to tap into the receiver after the
product detector (discriminator, pll, whatever) and before it goes to the
demux.

An SCA receiver is effectivily a 67khz receiver plugged into your 100MHz
receiver.

There is a LOT of info out there from people doing the same mod for the
purpose of receiving data/pager transmissions. Search under " discriminator
tap" and see what comes up.


Nana


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