(Richard Harrison) wrote:
Floyd Davidson wrote:
"Did you actually do very many?"

I`ve done single-hops, several-hop systems, and transcontinental
systems. I`ve done them on-shore, off-shore, and in a multi-hop loop
system on-shore and off-shore. I`ve done several systems with paths
sandwiched between tall buildings. I`ve done 960 radio, 2-GHz, and 6-GHz
systems. I`ve done space-diversity systems, hot-standby, and unprotected
systems. I`ve done solid-state systems, vacuum-tube systems, etc., etc.

I have no reason to say anything which is untrue. Floyd knows of an
anomalous hop in the desert. The path suffers reflections, else it would
not have great variation of signal with height. I know of many anomalous
systems, but I never built one. All of mine worked as designed.

As I pointed out, that was the most _interesting_ example that I
know of.

However, you've just stated something that I can't quite get my
arms around. "All of mine worked as designed." is stated as if
the "anomalous systems" that have a path which "suffers
reflections" are somehow not common, or not well designed, or
not normal.

Yet you mentioned "on shore" and "off shore" each twice above,
and I'm having a real difficult time thinking you've ever
designed a microwave shot across tidal waters without having
"reflections" which could not specifically be calculated. And
there is simply no way that it "worked as designed" unless you
mean you just allowed for a large enough fudge factor to account
for signal swings from day to day. The original claim that they
*all* came in within 1 dB is just hilarious.

My bet is that you have hung around and do know how these paths
function over time, and I'll bet you just exaggerated a little,
that's all.

--
Floyd L. Davidson http://web.newsguy.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

Floyd Davidson wrote:
"---I`ll bet you just exagerated a little, that`s all."

Too many hours of daylight on Floyd are taking their toll.

Everything you work with is known. precisely, including path attenuation
under normal propagation conditions. Normally, you don`t have a path
grazing at a highly reflective point. Your path survey discloses path
detractions and you adjust for the possibility of distructive
interference. You may opt for a high / low antenna placement for the
path ends, diversity, more clearance, shorter paths, and brute-force
fade margins. The high / low option lets you move the reflection point
and the reflection. Long microwave systems must have huge fade margins
anyway due to noise buildup from individual path contributions. A
receiver not too much below the overload signal point is a very quiet
receiver and contributes almost no noise to a system.

When the path design is right, the as-built numbers are almost exactly
as calculated, whether you believe it or not.

Best regards, Richard Harrison, KB5WZI

(Richard Harrison) wrote:
Floyd Davidson wrote:
"---I`ll bet you just exagerated a little, that`s all."

Too many hours of daylight on Floyd are taking their toll.

Look like you need some daylight.

Everything you work with is known. precisely, including path attenuation
under normal propagation conditions. Normally, you don`t have a path
grazing at a highly reflective point. Your path survey discloses path
detractions and you adjust for the possibility of distructive
interference. You may opt for a high / low antenna placement for the
path ends, diversity, more clearance, shorter paths, and brute-force
fade margins. The high / low option lets you move the reflection point
and the reflection. Long microwave systems must have huge fade margins
anyway due to noise buildup from individual path contributions. A
receiver not too much below the overload signal point is a very quiet
receiver and contributes almost no noise to a system.

When the path design is right, the as-built numbers are almost exactly
as calculated, whether you believe it or not.

Lets see, now you are saying that you go out and *measure* the
path, rather than calculate it.

And of course you measure it, *every* *single* *time*, on a day
when you *know* whether it is giving you the best path, the
worst path, or some specific point in between.

Richard you can cut the bull**** out. I've been measuring
microwave paths for 40 years. You don't calculate them to
within 1 dB. You might find out what that is after measuring it
on a regular basis for a year. (I've done *continous* path
measurements of several paths for over a year, and on two for
10 years.)

--
Floyd L. Davidson http://web.newsguy.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

Floyd Davidson wrote:
"Richard you can cut the bull**** out."

Floyd claims to have measured microwave paths for 40 years. I`ve been
doing it since 1960, so that`s about as long.

I`ve made repeated measurements over a number of years on the same
repeaters. During normal propagation, which is by far most of the time,
path loss like other system losses is very constant.

Of course there are periods of anomalous propagation. It depends on
location, season, and time of day. It`s worse when the atmosphere is
stagnant.

I`m sure that marginal paths with insufficient clearance and other
problems may have propagation which comes and goes. I`ve seen some, but
I haven`t built any like that.

Best regards, Richard Harrison, KB5WZI

(Richard Harrison) wrote:
Floyd Davidson wrote:
"Richard you can cut the bull**** out."

Floyd claims to have measured microwave paths for 40 years. I`ve been
doing it since 1960, so that`s about as long.

I`ve made repeated measurements over a number of years on the same
repeaters. During normal propagation, which is by far most of the time,
path loss like other system losses is very constant.

Of course there are periods of anomalous propagation. It depends on
location, season, and time of day. It`s worse when the atmosphere is
stagnant.

So now you say it's constant except for when it's not! Your designs
are within 1 dB except when they aren't.

I *am* impressed.

I`m sure that marginal paths with insufficient clearance and other
problems may have propagation which comes and goes. I`ve seen some, but
I haven`t built any like that.

That's why I asked if you'd built many.

In fact it is quit common, and most paths have anomalies. Most of
course aren't very interesting. But others are. Suggesting your
designs have never collided with such an anomaly just means you
either didn't really do many or you're failing to recall them.

--
Floyd L. Davidson http://web.newsguy.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

Floyd Davidson wrote:
"Suggesting your designs have never collided with such an anomaly just
means you didn`t do many or you`re failing to recall them."

It means care was taken in path planning. Microwave propagation is very
predictable. The only variable is the atmosphere and long statistical
records are available which allow a design for a percent reliability,
99.99 out to the limit of your budget.

Of course, on any particular path, there will be fades on some foggy
morning, but that doesn`t guarantee failure if you`ve planned for it.
The phone company uses alternate routing. I`ve designed similar systems.

What I said was, the as-built hops performed as designed during normal
propagation. That`s nearly all of the time. The received carrier power
measures remarkably close to the predicted value nearly every time and
if it doesn`t when the the alignment is complete, in my experience, it
has been always due to a defect in the system, not in its design..

I have never had to go back and "beef up" a hop to obtain reliability,
and I`ve put some hops in tough territory. The arithmetic is simple and
so are the criteria.

Best regards, Richard Harrison, KB5WZI