WORLDWIDE DX CLUB Weekly Top News

are doing, processors multi-band, compression, optimized for AM signal a
bit less than 5 kHz bandwidth, mono only.
DRM moves up to stereo, and bandwidth 12 kHz audio available. So no
processor on chain, none optimized for it available. Content server does
the final audio bandwidth limiting.
Signal leaving tx is mono, right? Neither mono nor stereo, as in analog.
Transmitter acting more like computer modem, ones and zeroes with complex
digital modulation scheme. Depends on how digital signal is composed.
Person receiving signal is getting true stereo? There are three possible
modes: simple mono; stereo with less compression, and the other is
parametric: for very small amount of total signal sent, includes very
efficient info about differences between left and right. Don't get as good
replication of stereo at other end, but is very good. Throws away a lot of
things, but still sends relevant things to fool ears. Programs prepared in
raw audio, wav format and stereo, except for last week's DXPL, generated
>from mono into a stereo signal but with no difference between channels.
What do terms like 16 qam and 64 qam mean? Quadrature amplitude
modulation. Is used in digital satellite txion, and now DRM too, to encode
a number of bits. Looks both at phase and amplitude of carrier, and from
that can gather 16 or 64 data points. At higher rate, get more info packed
into one single carrier. In DRM mode contrary to analog, many many
carriers going out on same tx.
Why ever use 16 qam? Gets easier definition, square divided into 16
pieces. If divided into 64 pieces, if there is noise, you start getting
confusion. What difference does it make to end user? Noise comes thru as
dropped out signals, silence or garbles. Use 16 when there is more noise
in atmosphere, or doing farther distance. But at 16 qam, cannot do stereo
broadcasting.
Looking for more opportunities to do test txions. Can only do on highly
linear Siemens 10 kW txs. At Pifo also are 100 kW txs designed almost 20
years ago; want to retrofit those for DRM, working with Elkhart
engineering center to do so. Waiting to see how DRM really takes off,
especially in Latin America. Hope to participate in more tests, perhaps in
conjunxion with some other broadcasters. Also upcoming tests for NASB in
mid-May.
Two websites to learn bout DRM: the main one, and
for those who have DRM receivers with some great
forums, a fun site. Or even if you don't have a receiver.
(HCJB DX PL April 29, notes by Glenn Hauser for dxld)
ECUADOR HCJB Pifo dismantling Yesterday's program of HCJB German sce,
heard here in local-like quality (well ... via Wertachtal) contained a
studio talk about impressions from the Pifo site.
Summary:
The place is no longer the forest of masts it used to be. A lot of them
are already dismantled, people are busy disconnecting wires and bringing
them down. It's a scary sight: These were the antennas we used to
broadcast to Europe. On the other hand it's a big difference to the scenes
at other abandoned sites where they just cut the wires, let anything
collapse and a scrap dealer picked up the remains. At Pifo they instead
carefully prevent the masts from falling over while they dismantle the
guys, and once they have an antenna down it will be packed for later use.
An engineer said that they hope to find grounds for a new station.
However, "no decision has been made yet" according official information
>from the mission's leadership.
(Kai Ludwig-D, dxld Apr 30)