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Re: FD 2000



At 11:40 PM 6/10/2000 -0400, Bob Bruninga wrote:
>Please dont think that I am being recalcitrant, but I dont think that even
>2% of that number could get a word in edgewise on voice.  Do we have any
>statistics on how many exchanges are routinely made on UO14 or AO27 during
>an analog pass?

It depends on how many people are on the bird and who they are and what they
are trying to do and what part of the US the satellite is over.

  When the satellite  has over 20 users on the same pass and
5 or 6 are trying to work everyone then it is saturated.  It also gets 
saturated
when there are stations not hearing the bird that keep calling CQ and have
stations that are just barely hearing the bird keep trying to call them or call
with the wrong callsign or keep asking for the same info over and over until
they get it. The info was clear on the satellite but they could not hear it the
first second or third time.

Here a histogram of this months passes for my QSO's

QS0s     number of passes       qso X passes
  0 ****         4               0         1 pass I was the only one!
  1 **           2               2       2 passes just me and one other!
  2 *****        5               10
  3 *****        5               15
  4 **********   10              40
  5 ******       6               30
  6 ******       6               36
  7 ******       6               42
  8 ********     8               64
  9 *****        5               45
10 **           2               20
11 **           2               22
12 ***          3               36
-------------------------------------------------------------------
                      64 Passes       362 qsos  Average = 5.7 QSOs/pass

I have not been trying to work everyone and have stayed in the background for
a lot of the pass. [I knew the pass was being recorded ] So I am sure that 
a lot more exchanges than 6 per pass happen on the FM birds.

>  I figure in the absence of QRM, a typical exchange would
>take about 12 seconds.  But the "success rate" runs only about 25%?  THus
>in an average pass of say 12 minutes, there can be about 15 successful
>exchanges?  These are just guesses.....  has anyone counted them?

In 12 seconds I can get a lot of calls or first name out at the same time.

"Hi paul, john,chuck lee,leo,roy, chris, david,kevin,jeff " is 3 to 4 seconds.
If they each answer back it would be 40 seconds for 110 exchanges. We are
not contesting here but have acknowledged that we heard the other calls.
I know more time is needed so you can announce you are on the bird. But you
can do a lot of exchanges in the same time as someone gives out his call
phonetically and with three or four "CQ Satellite". You get to know who is
hearing the bird well all the time and who is not.

I soon will have enough real audio files of UO-14, AO-27 and SO-35 passes
to fill a CD.  It will be over 2 months worth of passes.  If someone wants to
do the counting I would burn them a CD.

>Does the success rate (total throughput) go up on the weekends or down?

It depends on how many "new comers" are trying.  It definitely goes down
just after a ham magazines come out with an article that says you can work
these birds with a HT and rubber duck.  It returns to normal after they 
give up,
get frustrated or are helped via phone or e-mail by one of the regular users.

Also this has happened after some mailing list postings.

I know that the birds can be worked by a HT and duck or whip. I have done it
may times including while skiing down a hill.  But it sure helps to know the
tricks to hear it and know not to transmit if you are not!

I am not complaining and want to new people on the bird so I can get those
last 30 grid squares in the lower 48 states.

>I have no idea what the success of a similar digital pass will be.  But I
>am hoping we get to try.  Theoretically, assuming a 20% ALOHA channel
>efficiency and 3 seconds per exchange, Im guessing that as many as 60
>stations could be successful per pass.

I suspect it might get as bad as the peak days of MIR.  You could get up and
listen to MIR and not hear a packet.  When you sent one up and one was
answered all ?*&?$ would break out when all the automated stations would
start sending their packets to MIR.


>I agree, we dont have that many people on the bird yet.  But everyone with
>a THD7 or a D700 can do it anytime, anywhere.  Presumably there are
>several thousand of them out there...

With more that getting out there  someday the packet QRM will be as bad as
the voice QRM.

I am not saying you shouldn't put up a ARPS bird but if you do then someday
it to may become like AO-27 and UO-14 and you will wish for the good old days
when only you and a few users knew about it.

73 Randy N7SFI

Who is working on a satellite for next year that will repeat 9K6 UI packets.

Also EN15 EN17 EN65 EM46 EM53 EM72 EM87 EM91, EM94. FM04 and
         FM13 are at the top of my current most wanted grid list. If you are
         in one of these grids please get active on the birds.  Feel free 
to E-Mail
         for help.
  
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