There have been lots of questions lately on Communications and Positioning,
what's going on, and who has to do what with what. Here are some salient
points that will undoubtedly prove helpful, that Sue talked a little about
this afternoon. If you have any questions, feel free to email me back
(or find Sue. She's *really* good at this stuff). Thanks.
Lesson 1: To communicate, both devices must speak the same language.
Sue's first point was that, to transmit any information, the device
sending the info and the device receiving the info must both be using
the same frequency.
Remotes: Transmit Only. 15 Hz*.
Sharp Tranceivers: Receive or Transmit. 500 Hz.
Newtons: (have sharp tranceivers inside of them.) Receive/Transmit @ 500 Hz.
The above are non-configurable. They cannot be changed.
The Motorola hardware device that currently sits atop the Newton to
give it positioning info, however, is (according to Chris Atkenson)
configurable. The code should be modifiable, so that someone can tell
it what frequency to expect when it is receiving data.
Currently it receives 15 Hz, the same as the remotes. This was originally
built to get around the fact that the Newtons can't receive the remote
control signals, due to the speed differences.
Sue had some suggestions for both teams.
Newton:
Idea #1:
You have a choice. You can do positioning the way it is currently
implemented (that is, keep the Motorola hardware with the Newton
to read the remote control positioning signals). Then, you could use
sharp tranceivers to send communications data at 500 Hz, which the
Newton could use its internal sharp tranceiver to receive.
<OR>
Idea #2:
Or you could scrap the Motorola and the remotes and do everything with
the transceivers. (See below for more info on how **)
PC:
Idea #1:
To deal with positioning, Sues first suggestion was that you look at the
positioning code built in Visual Basic, and just port it into Delphi.
Then, use the Sharp tranceivers (one for sending, another attached to
the pc for receiving) for communications.
<OR>
Idea #2:
Just like the newton team, you could use the tranceivers to send both
positioning and communications info. (Again, see below **)
ADVANTAGES: of using the tranceivers
1) If both systems were using the tranceivers for positioning and communications,
then both could use the same sending system (how's that for platform
independance). Ie, we have one system of transceivers that broadcasts
positioning/communications, and all of the Cyberguides, regardless of
platform, pick up the same signals, then do with them as they will.
Cool, huh! Of course, this assumes that both groups agree with what the
tranceivers are sending (ie one group doesn't want just positioning info,
and one group just communications)...
2) This also means that the Newtons and PCs could talk to each other, as
well as get signals from the broadcasting system. (Again, a plus for
platform independance).
... just some ideas!
(BELOW)
* Hz -- Sue wasn't exactly sure on this. Hz, MHz, whatever ... that's
not the important part. The speeds are different (the important part)!
** On mixing Positioning/Communicatins --
Sues two suggestions on this idea, was that it may be possible to either
1) Have a prefix bit that indicates what the rest of the message is
2) Always include positioning info, even in comm. messages.
Thanks.
Nancy