[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: Failed attempt on FO-29.



At 09:36 PM 4/19/2005 -0700, Jim Walls wrote:
>George Henry wrote:
>
>> While the practice of leaving one's uplink frequency constant and 
>> adjusting the downlink for doppler may be the only practical way to 
>> operate in half-duplex, it is not good operating practice, in that your 
>> downlink signal can drift into an on-going QSO, causing interference 
>> that you are REQUIRED BY LAW to avoid.  This is PRECISELY the reason 
>> that the recommended procedure has always been to adjust one's UPLINK to 
>> maintain a constant downlink frequency.
>
>On a mode V/U (or mode J if you prefer), or any other mode where the 
>downlink frequency is higher in frequency than the uplink, this is 
>neither the preferred nor secondary method.
>
>The preferred method is full doppler tuning wherein the uplink and 
>downlink frequencies are constantly adjusted to maintain the frequency 
>constant at the satellite.  This is almost impossible to do unless all 
>stations involved in the conversation are running computer control of 
>the doppler.  If that is not possible, then the higher frequency should 
>be adjusted and the lower frequency should be left alone.  In the case 
>of FO-29, that means, adjust the downling frequency.  If AO-10 every 
>comes back, then adjust the uplink frequency.
>
>With that said however, there are others that will argue the opposite. 
>I will tell you that in my opinion, even though the recommendation is to 
>adjust the higher frequency, I personally find that it is much easier if 
>the downlink only is adjusted.  The reason I say that is that by 
>adjusting the receive frequency, you (not the other guy) has control of 
>how you like to listen to SSB (not everyone is the same).
>
>I will also tell you that in either case, there will in the real world 
>times when the opposite frequency is adjusted.  This is primarily 
>because the different operators in the conversation are not in the same 
>place and the dopplers are different.
>
>
>-- 
>73
>-------------------------------------
>Jim Walls - K6CCC
>k6ccc@amsat.org
>Ofc:  818-548-4804
>http://home.earthlink.net/~k6ccc
>AMSAT Member 32537 - WSWSS Member 395

My experience on AO-10, AO-40 on modes U/V and U/S is that most will adjust
there transmit frequency to keep netted with the orther station, even
though he is drifting with doppler.  Before you switch to transmit your
receiver has been tuned to keep with the other station, then when you start
transmitting you hear your offset and retune to bring it on freq with the
receiver.  What kind of rule is this?  I suppose tuning both freq.

Since FO-29 and AO-7 are so lightly populated I would say that keeping yout
transmit fixed is not likely to cause  interference if you start at a
frequency sufficiently separate any existing QSO's.  But one should be
vigilant to the fact that over time youo will drift considerably, so you
must be careful not to slide over another QSO...that's the FCC rule.

I think since there has been talk of setting up calling frequencies then
perhaps a sub-band for simplex stations would not be out of order.  Just a
gentlemen's aggreement...not cast in concrete  for eternity kind of rule.

What do y'all think about that idea?

I agree the one-true-rule is best...only practical with computer tuning,
however. 

73's
Ed - KL7UW  <new call>
===================================
BP40iq,  Nikiski, AK      http://www.qsl.net/al7eb
50-144-432-1296-2400-3456*-10368-24192* MHz
*Under construction
===================================
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home