Answers to Frequently Asked Questions
Bernard F6BVP raised a question of common interest regarding the ATEPRA SCC card and modem interfaces. As it may help others, I post this answer to fpaclist.
FPAC is an assembly of standard existing building blocks. Should we have selected to stick to standards as far as software and communication protocols of the OSI model, Open System Interconnction, the least was to ensure the same connectivity at hardware level. So we did.
ATEPRA Modems :
Audio side :
There was nothing to invent, the widely spread standard of the TNC2 wasadhered to. Din female 5 pins 180 deg. Pin usage as in TNC2. PTT active is aclosing to ground signal, open otherwise. Side effect benefits of above selection is two fold :
1- Any radio that was set to support a TNC2 connection can beconnected to the ATEPRA modems and is ready for FPAC.
2- For wiring you can purchase every where, supermarket, hi-fi shops, already made cords and accessories in all arrangements male, female; and also tee and conversion, for monitoring and measure.
Note : - 9600bps modem is kept the same standard for PTT and pins assignment while one knows that interface is no longer at microphone/speaker interface but at modulator/discriminator inside the rig.
- All ATEPRA modems have a built in watch-dog to avoid permanent transmit key-on in case of failure (feature sometimes called anti-streaming).
Serial side :
Like it has been done thoughout amateurs applications, the TTL signalling has been prefered to RS232 as a matter of simplicity and cost reduction. DB9 female connector with Pins assignement as set by IBM has been retained with the following provision :
For the 9600bps modem. As the ATEPRA modem has its own clock,
external clock
usage is only an option. This signal is not at all used on
1200bps modems.
ATEPRA SCC card interface.
Connector is a db37 male. Pin arrangement is such that a ribbon harness can be used to connect four DB9 male corresponding to the four channels of the SCC card. Signals and pin assignment correspond to above.
Softwarewise, DCD signal can be disabled, in this case data activity is scrutinized. DSR, CTS are not used. DTR is +12v.
Note : there is a provision on the printed circuit board for 1488/1489 converters TTL to RS232 levels. this option is not used for amateurs applications
73 Remy F6ABJ.
A 20L10 pal is used on the SCC card for addresses decoding. Two ranges exist 150 and 158. 150 is labelled 150 on a yellow sticker, 158 on a blue one. Anyone will do for a single board installation, provided you set the corresponding addressing in the configuration file FPAC.CFG. For a two board installation, you will need two different pals i.e.; 150 and 158.
73, Remy F6ABJ.
There haven't been many (yet) but the digests are all archived here on QSL.net. See the sidebar.
[This is the answer to the question.]
[This is the answer to the question.]
[This is the answer to the question.]