Jason A Alexander wrote:

> What I am trying to do is to take a pic16c84 and transmit data across
> a transparent radio link.  What I need to do is to brodcast this
> information out this one radio and let several different devices
> listen in and receive the data.

> I am fairly new to Pic programing and am having a hard time.

  And no wonder, having "bitten off" quite a wide range of issues in one
go.  This general field is referred to as "packet radio" and quite a
popular aspect of Amateur Radio, at least for those sub-set of ops whose
mentation can get past a Morse key <G>.

  I shall presume that Jason is consideriang a LAN system using pre-
built class-licensed milliwatt modules from http://www.qwikradio.com or
similar.  I further presume he was not considering using full HDLC
protocol but rather asynchronous ASCII.  Nevertheless, software-wise, he
is looking at writing a full TNC (Terminal Node Controller) type system,
and should certainly examine the behaviour, if not the availability of
commercial systems such as the TAPR Pocket TNC or Micropower devices.
Search starting from  http://www.tapr.org./  and read awhile.

  In addition, he implies the possible use of a "broadcast" mode where
data is received by multiple devices simultaneously.  This is not to be
confused with the basic packet radio premise of multiple "conversations"
or "connections" sharing the channel by some means and achieving error-
free data transfer by checksums and acknowledgements with serial
numbering of packets.

  The problem of error correction in a broadcast mode is a thorny one
indeed, generally implemented by serialising broadcast packets with non-
cylic (non-modulo at least) identifiers and individual receivers issuing
numbered NAKs after a timeout rather than ACKs.  Even this is limited.
But I had best ask first, is this what Jason was asking, or does he just
want a "connected mode" Packet protocol?

  Cheers,
        Paul B.  (VK2BZC)