What is the problem here? _REAL_ Radio Hams work with
signals that are deep in the noise all the time. There might be
a concern here by CBers who want S9 BBC quality, but
not for Radio Hams!

"Thierry" see my website wrote in message ...
Do you remember the problem caused by broadcasting tests via the power
line?
A lot of radio amateur have to support the RFI causes by these tests
everywhere in Europe.
All hope is not lost.
ITU officially recognized this was unacceptable...

"Airy R. Bean" wrote in message
...
What is the problem here? _REAL_ Radio Hams work with
signals that are deep in the noise all the time. There might be
a concern here by CBers who want S9 BBC quality, but
not for Radio Hams!

The problem is that this particular noise source produces 40dB OVER S-9 QRM
at 150 feet from the source... IIRC what I have read correctly..

"Airy R. Bean" wrote in message
...
What is the problem here? _REAL_ Radio Hams work with
signals that are deep in the noise all the time. There might be
a concern here by CBers who want S9 BBC quality, but
not for Radio Hams!

The problem is that this particular noise source produces 40dB OVER S-9 QRM
at 150 feet from the source... IIRC what I have read correctly..

Even so, would not the modulation characteristic be known, and therefore
a noise blanker developable, very much the way that Radio Hams do things?

Brenda Ann wrote in message
...
"Airy R. Bean" wrote in message
...
What is the problem here? _REAL_ Radio Hams work with
signals that are deep in the noise all the time. There might be
a concern here by CBers who want S9 BBC quality, but
not for Radio Hams!
The problem is that this particular noise source produces 40dB OVER S-9
QRM
at 150 feet from the source... IIRC what I have read correctly..

Even so, would not the modulation characteristic be known, and therefore
a noise blanker developable, very much the way that Radio Hams do things?

Brenda Ann wrote in message
...
"Airy R. Bean" wrote in message
...
What is the problem here? _REAL_ Radio Hams work with
signals that are deep in the noise all the time. There might be
a concern here by CBers who want S9 BBC quality, but
not for Radio Hams!
The problem is that this particular noise source produces 40dB OVER S-9
QRM
at 150 feet from the source... IIRC what I have read correctly..

"Brenda Ann" wrote in message ...

The problem is that this particular noise source produces 40dB OVER S-9 QRM
at 150 feet from the source... IIRC what I have read correctly..


to which, "Airy R. Bean" replied, in his usual,
unhelpful, childish, and predictably boring, repetitive manner...


What is the problem here? _REAL_ Radio Hams work with
signals that are deep in the noise all the time. There might be
a concern here by CBers who want S9 BBC quality, butnot for Radio Hams!


....which is really the NG equivalent of a noise source of 40dB over S9
QRM.


Dave

"Brenda Ann" wrote in message ...

The problem is that this particular noise source produces 40dB OVER S-9 QRM
at 150 feet from the source... IIRC what I have read correctly..


to which, "Airy R. Bean" replied, in his usual,
unhelpful, childish, and predictably boring, repetitive manner...


What is the problem here? _REAL_ Radio Hams work with
signals that are deep in the noise all the time. There might be
a concern here by CBers who want S9 BBC quality, butnot for Radio Hams!


....which is really the NG equivalent of a noise source of 40dB over S9
QRM.


Dave

Airy R. Bean wrote:

Even so, would not the modulation characteristic be known, and therefore
a noise blanker developable, very much the way that Radio Hams do things?



I'm not sure that it would possible Gareth to the extent needed.
The problem is that local noise depends on the activity of local PLC
modems, each of which is going to produce an additive but independent QRM.
You wouldn't know beforehand when data was going to be requested or sent.
It just sounds like random data bursts spread over a wide spectrum.
Yes, some suppression might be possible by taking a wide bandwidth and
somehow using cancellation. But getting 40dB or more of rejection I
think would be very difficult.

The galling thing about PLC/BPL is that the vested interests (i.e. the
power companies) seem to think that they can ignore all other spectrum
users. Yet the bandwidth they're offering will soon be insufficient
to meet the broadband demands. At least with ADSL line bandwidth can be
shared among a small number of subscribers. Greater bandwidth can be
achieved by reducing that contention ratio. But I wonder how many houses
are served by the same power substation on average. IMO, PLC/BPL is
the wrong technology too late. Even ADSL is going to struggle to meet
the bandwidth for on-demand video streaming.

As a final irony, now that the ITU has dropped mandatory CW, CW with
its much lower bandwidth offers the best chance in the presence of
such wide spectrum noise. Looks like my pursuit of CW as a mode was
worth it after all ;-)

David, M0DHO

Airy R. Bean wrote:

Even so, would not the modulation characteristic be known, and therefore
a noise blanker developable, very much the way that Radio Hams do things?



I'm not sure that it would possible Gareth to the extent needed.
The problem is that local noise depends on the activity of local PLC
modems, each of which is going to produce an additive but independent QRM.
You wouldn't know beforehand when data was going to be requested or sent.
It just sounds like random data bursts spread over a wide spectrum.
Yes, some suppression might be possible by taking a wide bandwidth and
somehow using cancellation. But getting 40dB or more of rejection I
think would be very difficult.

The galling thing about PLC/BPL is that the vested interests (i.e. the
power companies) seem to think that they can ignore all other spectrum
users. Yet the bandwidth they're offering will soon be insufficient
to meet the broadband demands. At least with ADSL line bandwidth can be
shared among a small number of subscribers. Greater bandwidth can be
achieved by reducing that contention ratio. But I wonder how many houses
are served by the same power substation on average. IMO, PLC/BPL is
the wrong technology too late. Even ADSL is going to struggle to meet
the bandwidth for on-demand video streaming.

As a final irony, now that the ITU has dropped mandatory CW, CW with
its much lower bandwidth offers the best chance in the presence of
such wide spectrum noise. Looks like my pursuit of CW as a mode was
worth it after all ;-)

David, M0DHO

"RVMJ" wrote in message
...

As the result of a deliberate manoeuvre, the Galileo spacecraft
collided with the planet Jupiter at an estimated time of 12:49:36 PDT
on September 21st this year. Signal had been lost at 12:43:14 pm as
Galileo passed behind Jupiter at a height of 5768 miles. Descent angle
was 22 degrees and the impact speed 108,000 mph, a little more than
the 106,500 mph of the Galileo probe, which entered Jupiter's
atmosphere in December 1995.

Galileo's transmitter had an output power of between 15 to 20 watts to
an antenna having 7 db of gain. Received power at the Deep Space Net
was -167 dBm.

The DSN receivers track frequencies with extreme precision. The
frequency gate for Galileo was normally about 0.3 Hz for a carrier
frequency of 2295 MHz, but could be widened to 3 Hz for a moon flyby
or planetary impact.

Normally, Galileo put all the transmitter power into data sidebands
plus or minus 360 kHz from the nominal carrier. This is called
suppressed-carrier working, or a modulation index of 90 degrees.
However, a pure-tone carrier would be less-difficult to track near
impact, so 5.5 hr before impact the modulation index was shifted to 60
degrees. This has the effect of putting more power into the carrier at
the expense of that in the data sidebands.

Four hours before impact the data rate was changed from 20 bps to 32
bps in order to gather as much science. However, Galileo's engineers
noticed that their real-time displays had stopped working.
Wide-spectrum recorders had captured the raw signals, and the
engineers are now using special decoders to find the data, which is 5
dB below the noise level. Obviously a bunch of Amateurs.....NOT.


And all without Gareth's "Big K" ;-)

--
73
Brian
G8OSN
www.g8osn.org.uk
www.amateurradiotraining.org.uk for FREE training material for the UK
Foundation and Intermediate Licences
www.phoenixradioclub.org.uk - a RADIO club specifically for those wishing
to learn more about amateur radio