Bulletins from the Pacific Packet Radio Society - page 046

up with other lots.

Received your request for the FM-21s. I'll keep you posted on the status of the deal with Ed Clegg. We have had many problems running packet radio on 2-meters in the NYCINJ area. Seems that people treat frequencies as personal territory!!! It makes a lot of sense to expand into the 220 MHz band. One of us (AD71/2) is experimenting with direct FSK on 220. This brings up a key question - How fast will the TNC boards run when using your style software?

From an engineering standpoint, the lack of adequate buffering on the 8273 is a big headache. I suspect that transmit frame underruns and receive frame overruns will result if we push the speed to the hardware limitations of the 8273. That chip is meant to run in a DMA environment (where its performance is excellent. New designs for TNC boards here, and in other areas, have been considering the Zilog SIO (which is quad-buffered) or the Motorola MC6854 (triple-buffered). Both chips require an external DPLL, but this is traditionally the function of the modem! The clock recovery can be accomplished with a single chip. I guess we could still use the 82739 and install a hardware FIFO in the RX and TX data (buss) paths.

Again, the existence of hardware variants of the TNC board underscores the need for a high-level language approach to packet radio software.

Time for me to get off the soap-box. 73 for now! - Steve


To: Hank
From: Den

We've put three more of the Alpha boards together today, bringing to five the number of completed boards, with two more to be finished later this weekend. Our optimistic predictions still show:

Alpha proof-of-performance - 2 weeks (WA7GXD)
Beta layout - 3 weeks (NOADI,KD2S,WB7ESQ)
Beta PC boards (ass'y,test)- 6 weeks (WA7GXD,KD2S)
TAPR TNC (turnkey !) - 10 weeks (AG7H,WA7PXW,Baker)
TIP software - DONE (WA7PXW)
LIP software ( primitives - 3 weeks (N7AIG, WA7PXW)
NCS software - 4 weeks (KD2S)
TAPR LIP - 6 weeks (WA7PXW,N7AIG)
VADCG LIP - 6 weeks (KC7MA,KD2S)
TAPR/VADCG (auto interface)- 10 weeks (N0ADI,WA7PXW,KD2S,KC7MA)

We have a great deal of information on the VADCG/AMRAD station and digipeater protocols, but would like to have the current version of protocols in use at your site. This information will allow Margaret, Chuck and myself to be operating on correct

Click for Original Graphic Image of this page.

Previous Index Next