response 96 of 210:

Sep 16 22:18 UTC 1998

Found it!!!  I got this from the FCC's web site, by searching on the 
terms "digital radio canada".  The actual URL is too long and painful 
to type in...   I am reformatting it for 80 column width.
It sounds like the USA and Canada are going to implement two different
services.  
----------
                                
Report No. IN 98-50     INTERNATIONAL ACTION         September 3, 1998
                                
                                
      THE UNITED STATES AND CANADA AGREE ON CONDITIONS FOR
                       IMPLEMENTATION OF  
      U.S. SATELLITE DIGITAL AUDIO RADIO SERVICES (DARS) 
                              AND 
 CANADIAN TERRESTRIAL DIGITAL RADIO BROADCAST SERVICES (T-DRB)
               ALONG THE U.S./CANADA BORDER AREA  


     The United States and Canada have agreed on technical conditions 
for implementation of Terrestrial Digital Radio Broadcasting (T-DRB) 
services in Canada in the 1452-1492 MHz band and Satellite Digital 
Audio Radio Services (DARS) in the United States in the 2320-2345 MHz band.  
As a result, T-DRB service can be implemented immediately, and the 
launch of DARS can occur after a transition period.  
Coordination discussions regarding DARS are continuing with countries 
other than Canada.  

     These agreed upon conditions are the result of negotiations that 
took place over several years and involved complex inter-service 
frequency sharing considerations unique to the U.S. and Canada
in these two bands.  Although these bands are used for different 
services in Canada and the U.S., new applications of digital technology 
will be introduced by Canadian and U.S. providers.  It is important to
note that the continued operation of U.S. aeronautical telemetry 
stations was a paramount concern in these discussions.  
Looking to the future, FCC Chairman William E. Kennard, stated, 
"This successful negotiation will provide U.S.consumers access to 
innovative CD quality audio programming and will promote new 
communications services using innovative satellite-delivered 
digital technologies."

     U.S. Ambassador Vonya McCann and Canadian Assistant Deputy Minister 
Michael Binder exchanged letters that will allow both countries to 
begin to implement by September 1, 1998 the technical conditions for the 
introduction of these new digital sound broadcasting services 
on either side of the border.  Both the United States and Canada 
have pledged to work swiftly to convert these technical
conditions into binding international agreements. 

     In the interim both countries will implement these mutually 
agreeable conditions on an interim basis, beginning on September 1, 1998.  
Details of the conditions are available on the FCC internet
site for the International Bureau (http//www.fcc.gov/ib).

     For further information, contact Ronald Repasi, (202) 418-0768, 
Rosalee Chiara  (202) 418-0754 or  
Larry Olson at (202) 418-2142, of the International Bureau. 

                             - FCC -

response 98 of 210:

Sep 17 11:01 UTC 1998

You can't inject a digital signal at the volume control, Scott.  All
you would get is buzzing.  Besides, the digital signal would be at least
8 bits.  Where would you put them all when tapping into a stereo receiver?
(The signal that comes out of your CD player is really analog.  The
digital signal on the CD didn't spend much time being digital once it
was read by the laser.  from there it goes to a digital to analog converter
(A to D) and the rest is all old fashioned analog circuitry.)

Cool! 2320-2345 MHz is not far from the 2.4 GHz microwave oven band!
Perhaps I can re-tune the cavity on my $5 garage sale special microwave
and be the first on the block transmitting digital audio!  ;-)

response 100 of 210:

Sep 17 15:11 UTC 1998

Sure. Back when I was a teenager I was tapping audio signals into the
volume controls of (tube) radios, as a convenient amplifier. Had to watch
out, though, as those radios had no power transformers and plugs weren't
polarized, so the 'hot' side of the line could be on the chassis and
circuit ground.

response 102 of 210:

Sep 17 20:34 UTC 1998

So can you somehow pick up digital signals with some sort of antenna and then
feed them into the CD player, at the point where it is about to convert the
digital to analog?  Would it be efficient to make a combination CD player cum
digital receiver?  Maybe also combined with a digital tape reader?

response 104 of 210:

Sep 18 04:02 UTC 1998

Sindi:  "digital" is just a generic description for the technique of 
sampling data and storing it as a computer file.  There are lots and 
lots of digital formats out there; the audio CD standard is just one.
Each format has its own software for decoding and playing the computer 
files -- in a home CD player, that's usually packaged in a chip.
But a CD player chip is going to be useless for decoding the Real 
Audio format, or a .WAV file, or a MP3 file.   It's only good for 
decoding the CD Audio format. 
 
It's unlikely to be easy or cost-effective to build a digital 
radio receiver by hacking a CD player and a conventional radio.
It's not likely to be possible at all; you'd probably be better off 
buying the chips, when the standards are announced, and assembling
the radio yourself as a hobbyist project.  The chips are going to 
be very cheap, if digital radio gets off the ground..

response 106 of 210:

Sep 18 15:36 UTC 1998

Gack! (Excuse me.) Read that Radio Amateur's Handbook - there is probably
an old one in the Kiwanis books for sale. All radios use variable capacitors
and/or inductors to "tune", but there is a wide variety of ways to do this.
You'll find schematics in - YES! - the Radio Amateur's Handbook.

response 108 of 210:

Sep 18 17:16 UTC 1998

schematics for a digital tuner?  In an old handbook?  omni gave us one.
Kiwanis tends not to get such valuable books.  I made an AM radio once in
physical chem lab, with a 9 volt battery in it.  What are the parts for a
digital tuner likely to cost new, and which ones are available in used tuners?
Maybe Kiwanis could be the first in town to sell digital tuners!

response 110 of 210:

Sep 18 21:16 UTC 1998

I know a radio engineer from Bosnia who could help by email.  We don't plan
on actually designing the tuner, just following a schematic and maybe
modifying it a bit to use the parts we already have (dead receivers, an
occasional dead CD player, VCR, must be something useful in them).
Seriously, would someone want to take a crack at explaining how tuners work?
We have been repairing only the amplifier parts of receivers.  I could not
understand enough of the vocabulary in several books I looked at to figure
out the tuner part, other than that somehow the carrier signal has to be
subtracted to leave the information part, and I think the signal got amplified
a bit before reaching the volume control.  And how would digital tuners differ
from analog?

response 112 of 210:

Sep 19 12:20 UTC 1998

My prediction is that a complete tuner will be cheaper than the individual
parts.  THere are precendents for that...

Seriously, unless you plan to become an electronics engineer with computer
engineering skills, the most you'll be able to do is an easy change like
adding a line out to a digital "walkman" style portable tuner.

response 114 of 210:

Sep 22 20:36 UTC 1998

Yup, cheaper new.  You'd be suprised what economies of scale vs. cost of small
parts distribution adds up to.  For a laugh, try addingup the cost of a new
transmission for acar vs. cost of all the parts to build the same tranny.

response 116 of 210:

Sep 23 10:36 UTC 1998

In part because many of the parts are custom made for the manufacturer and
pinouts and specifications are not available to the public.  In part because
the part you salvage may be out of spec., physically of the wrong size, or
have leads too short. Because the equipment to test and align what you made
will cost many thousands.  Because the parts you need may not be available
form the surplus on hand.  Heathkit went out of the kit business because
it was cheaper to buy all done and ready to play than to build it from
a kit.  To top it off, often what you wound up with was an inferior product.

response 118 of 210:

Sep 24 09:51 UTC 1998

Don't feel bad.  I have a pretty extensive knowledge of electronics and
even I will wait to buy one rather than build one.  If you want to listen
to more free audio, look into one of those 6' to 8' dishes used to receive
satellite TV.  Many of the TV channels carry audio on one of several 
subcarriers.  All you need to decode them is a stereo decoder, designed for
the task, or a good HF receiver added to the TV system.  BTW, does Kiwanis
have used satellite TV equipment?