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J

Joerg

Jan 1, 1970
0
joseph2k said:
Michael Black wrote:



True but the C-QAM standard ia partially compatable. See:

http://en.wikipedia.org/wiki/AM_stereo

What has become of it? I remember that once upon a time almost all US
made rental cars had AM-Stereo receivers. Lately my rentals were all
Japanese and none of them had it. IIRC even a Saturn L300 I rented a
couple years ago didn't. The home stereo we bought about five years ago
doesn't either. AFAIR it was designed by the US company SonicBlue. It
has all the other bells and whistles so AM-Stereo must have been pretty
low on the feature pecking order. Or is it gone already?
 
M

Michael A. Terrell

Jan 1, 1970
0
Joerg said:
What has become of it? I remember that once upon a time almost all US
made rental cars had AM-Stereo receivers. Lately my rentals were all
Japanese and none of them had it. IIRC even a Saturn L300 I rented a
couple years ago didn't. The home stereo we bought about five years ago
doesn't either. AFAIR it was designed by the US company SonicBlue. It
has all the other bells and whistles so AM-Stereo must have been pretty
low on the feature pecking order. Or is it gone already?


Every station around here pulled the plug years ago. Minor problems
with the transmitter caused it to act up, but still allowed them to
operate in mono with no problems. Budgets are tight, so when they got
few, or no complaints, they didn't bother to turn the encoders back on.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
J

joseph2k

Jan 1, 1970
0
John said:
But that's a batch process, isn't it? Not suitable for continuous
speech. I think there are "rolling" FFT algorithms... I may even have
one around here somewhere.

John

I was giving a descriptive explanation of what i meant, not a recommended
implementation. The recommended implementation does not use DFTs, and is a
FIR implementation.
 
K

krw

Jan 1, 1970
0
Every station around here pulled the plug years ago. Minor problems
with the transmitter caused it to act up, but still allowed them to
operate in mono with no problems. Budgets are tight, so when they got
few, or no complaints, they didn't bother to turn the encoders back on.
Encoders? I thought stereo AM required a second transmitter for
L-R.
 
M

Michael A. Terrell

Jan 1, 1970
0
krw said:
Encoders? I thought stereo AM required a second transmitter for
L-R.


That is for HDTV, one for the analog channel, and one for the digital
channel. ;-)


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
K

krw

Jan 1, 1970
0
That is for HDTV, one for the analog channel, and one for the digital
channel. ;-)
Seriously, I remember when WLS-AM (Chicago) went stereo. They were
talking about how they had to reduce the power from one transmitter
when they brought the second on-line. There were other issues as
well, but it's been a long time though.
 
I

Ian

Jan 1, 1970
0
In case the OP (or others) are interested, I happened to come across
an article with the original phase quadrature network in it (I posted a
scan of the relevant page in a.b.s.e) in a tutorial article in Elektor in
1977.

The unusually wide bandwidth of 30Hz to 16kHz is because this
network is designed to provide the quadrature for an Ambisonic
surround sound coder/decoder rather than SSB.

Performance appears to be pretty good for the number of opamps used.

Regards
Ian
 
M

Michael A. Terrell

Jan 1, 1970
0
krw said:
Seriously, I remember when WLS-AM (Chicago) went stereo. They were
talking about how they had to reduce the power from one transmitter
when they brought the second on-line. There were other issues as
well, but it's been a long time though.


They may have had to reduce power because the transmitter couldn't
meet specs in stereo mode when they ran it at full power. Some
transmitters generated serious amounts of spurs and harmonics when
converted to stereo. A lot of AM stations have a second, or even third
transmitter for day/ night power levels, and emergency operations. Its
cheaper to use a timer to switch transmitters than to keep a full time
engineer at the station to make the adjustments when the power and
antenna patterns change for night time service.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
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