Return to the archive index

Re: Off the Shelf Solutions? CF and 900MHz

Ok first of all a CF card is just like a floppy drive, zip drive, hard
drive... you actually format the card for use as a drive. as for the
interface, I'm unsure almost all cf card adaptors I have seen use a pcmcia
hardware adaptor to use it (either a cable that comes off the pcmcia
hardware to the cf slot.

as for 900mhz wireless data links...   what range do you want?  1-1000ft
you can get some hardware from most hamfests or ham radio suppliers.  if
you want more than that or "city wide" it is cheaper to get cellular cpcd
service or wireless modem service. It costs upwards of thousands (I paid
$5,000.00 for my 144mhz repeater,tower,controller,antennas, feedline,
etc...) for each repeater station. plus if you want high bandwidth data you
need controllers, interlink systems, multiple stations (in chicago for
example you would need a minimum of 20 of these repeaters) and each hop
from repeater to repeater to get to your internet port will add latency and
drop the data bandwidth. (you can add a 128K fractional T-1 line to each
repeater plus line costs, access costs, etc...) which would bring the cost
of your 900mhz city wide data link to about $100K plus about $3K per month
for leased lines, access fees,etc...   Now of you dont care that everything
that you transmit can be recieved and recorded by everyone that owns a
scanner you can go the amateur radio route, get a ham license and try to
achieve 56K with spotty access in the far reaching areas, no business
transmissions allowed, no encryption allowed.. you can do this for much
much less (Around $3K) and expect others to use your repeater as they
stumble upon it. 

Sorry for being a doomsayer but radio technology coupled with government
regulations severely cripples ones ability to do this cheaply.

----------
> From: Jay Prince <>
> To: Wear hard <>
> Subject: Off the Shelf Solutions? CF and 900MHz
> Date: Tuesday, December 08, 1998 7:27 PM
> 
> 
> 
> Hi All-
> 
> After a long absense from hardware hacking where I spent my time writing 
> code, I'm getting back into the hardware for a wearable I want to build. 

> (I thought this was  a software project when I started, but I see that I 
> need to do custom hardware too.)  So, In order to shorten development 
> time, I'm trying to use off the shelf solutions for most things.
> 
> This has lead me to plan on using an IDE drive to run my OS from.  (I 
> need at least 100 Meg of Application space for my plans.)  But it would 
> be nice to use Compact flash if I could, instead.   As I understand it, 
> the CF is electrically just like a Flash card for PCMCIA, right? (That 
> is, the CF PC Card adapters are just pass thru?)  So, does that mean in 
> order to interface with CF cards, you need a PCMCIA controller?
> 
> Or is it more simple than that?  (Suppose, say, I ahve a StrongARM 
> processor, would interfacing with CF work in a way that I could put it in

> the CPU's memory space with a few bridge chips and address 
> decoding/mangling?)
> 
> I'd like to use 3 or 4 64MB CF cards to hold the OS, Applications and 
> Applications data, plus an additional 64MB RAM.
> 
> Second question-  does anyone know of a off the shelf 900MHz (or 2.4GHz, 
> or the other range cordless phones use) transmit/recieve boards?  
> Ideally, audio in one end and out the other would be the interface, but I

> can give it digital values... or I can send data instead of the audio if 
> the boards are designed for that.  900-MHz phones are so common and the 
> frequency is relatively unregulated, so I am assuming this is around.  
> Would be great for a tether to the net without resorting to the expensive

> wireless solutions....
> 
> Thanks for any clues!
> 
> Jay
> 
> PS- Wearhard is very hard, but then, that's cause its close to the edge. 

> I'd hoped to use off the shelf hardware and software, and just be 
> focusing on my ideas for a new UI, but before I can get to the UI, it 
> looks like I'll be building custom hardware, developing the right drivers

> in Linux, and then a speech recognizer, etc.
> 
> --
> Subcription/unsubscription/info requests: send e-mail with subject of
> "subscribe", "unsubscribe", or "info" to 
> Wear-Hard Mailing List Archive (searchable): http://wearables.ml.org

--
Subcription/unsubscription/info requests: send e-mail with subject of
"subscribe", "unsubscribe", or "info" to 
Wear-Hard Mailing List Archive (searchable): http://wearables.ml.org

From Wear-Hard Mailing list Archive (WH)
Maintained by R. Paul McCarty

Archive created with babymail