RadioBanter - View Single Post

July 8th 05, 04:58 AM

From: on Wed 6 Jul 2005 15:54

wrote:
From: on Tues 5 Jul 2005 16:41
John Smith wrote:
N2EY:

First, you can run duplex, simply use two modems and a separate
transmitter and receiver.

Uh-huh. Got it. The reciever listens while the transmitter transmits.
On the same frequency. 'Way to go "John", slap a patent on it!

Did John say "on the same frequency?" I don't think so.

He didn't say *not* on the same frequency either Sweetums. Now what?

Two questions:

1. What ELSE did John "*not* say?"

2. What are you going to say he "really said?" :-)

This is all very clever of you, but it really boils down to
YOU saying a lot of snit (that another didn't say) and then
trying to tap-dance around admitting you fudged things up.

Next time just accept being caught and hang up.

Do NOT try to MAKE UP STORIES to try and snow-job everybody.
It doesn't work and it annoys the other pigs.

FULL duplex IS possible using SEPARATE frequencies for
transmit and receive.

No kidding Sweetums I've done it several times myself. With my own
equipment operated under my own operators and station license.

Mostly I think you "did it" with only your own computer and
more literary license than you ever earned. :-)

But, that's just my opinion...and with some considerable
thinking about HF operations that hardly EVER go FULL duplex,
senior. For one thing, the rather large near field at HF
wavelengths mean you NEED considerable separation of antennas
or the most bodaciously-many-section-dual-filter to keep the
unwanted frequencies (transmitter leaking into receiver) OUT.
That attenuation has to be VERY large in order to keep the
receiver input from overloading.

Now, WHY would you want to go FULL duplex "operating under any
license?" for personal use? You would need someone at the other
end of the circuit doing the same thing...and that is an almost-
extreme rarity.

Telephone Cell sites operate 24/7 at FULL duplex. They HAVE to
and the equipment is designed to do that...such as separate
transmitting and receiving bands with plenty of diplexing filter
connecting the transmitter(s) and receiver(s).

The General Electric microwave terminals I've described used a
(approximately) 5-foot long dual waveguide bandpass filter to
keep separate transmit and receive frequencies from interfering
with one another. The pulse-position-modulation pulse trains
were not synchronous with one another, thus aiding in isolation.
The peak power output of the transmitter was only 12 Watts (at
base of antenna tower) yet the receiver was about as sensitive
as one could get (using radar receiver techniques) of the 1950s.

If you are going to mumble about "your own moonbounce" (what is
mistakenly called "EME" by hams), then you need not worry about
mutual interference. A return signal won't return from the moon
for about 2.5 seconds, long enough for you to manually swtich
coax or waveguide between transmit and receive (as one of the
early ham moonbouncers did and pictured in CQ long ago).

Or, you could go into broadband BS about using morse and auto-
switchover Tx/Rx by fancy diode T/R switching...so much so that
you could "read the other station between dots and dashes" like
your buddie Jimmie once said in here. :-)

But in your case of course . . sigh

In "my case" you are resentful/insulted/irritated because another
had LONG AGO experience in something YOU DID NOT. shrug I've
come to expect that in here from the self-propelled wunderkinder
of the PCTA extra crowd. It's practically a given. :-)