Bulletins from the Pacific Packet Radio Society - page 175

when everyone will be pretty much forced into using newly designed optimal demodulators to get good results. People might fight adding this feature to already-designed modems \Bell 202s all over creation, recently- introduced TAPR TNCs with on-board XR modem} which could work on the above circuits when signals are good. There may be a logical rationale out of this mess, however. We've already much agreed not to use Bell 202 modems \and the TAPR XR modem falls in this category} on the satellite. So when you logically rule out everything that Bell 202 modems should not be used for, you are left with only our present type of application: i.e., for local-area applications where afsk over 2-meter fm is used. For afsk on fm, we can live without preframe sync. But if you generate it, nothing is harmed, and it can do some good when the circuit is a bit noisy.)

Those are the apparent options. Here are my tentative conclusions:

We should standardize, as soon as possible, on always sending 16 reversals of preframe sync.

Generating preframe sync on the modem is possible. However, the mixture that we will have of existing and (yet-to-be-produced) modems makes this a non universal, and therefore an undesirable, solution.

It is desirable to generate 16-reversal preframe sync on the TNC/PAD (not the modem).

That leaves us with:

(a) the fact that the 8273 is already happily generating preframe sync,

(b) a belief that the 8530 can be tricked into doing it, and

(c) a problem getting the 1933 to do it.

I'd appreciate any comments, particularly any thoughts on whether anyone can think of a way to make the 1933 generate preframe reversals.

73, Paul, W4RI

FILE QST.83.02.2l.0.NK6K

Subj: Some thoughts on PACSAT software

Although there is little here that will directly effect initial hard ware design, I think it would be a good idea to start getting a picture of what it is that all the hardware is up there for. The purpose of this document is to set down some ideas about the

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