I apologise for sending this to the list but it seems Justin's email address
failed for some reason.

-----Original Message-----
From: Kevin
Sent: March 18, 1999 10:35 PM
To: Justin Crooks
Subject: RE: RF applications (from piclist)


Justin,

Unfortunately what I'm doing is not useable at this time (read, not
finished). From what you have stated, my basic design targets would satisfy
your requirement but I have a couple of questions.

Are the Remote units also sending packets of 8 bytes?
By independent channels, do you mean frequencies?

In a nut shell, my modem does;

26 independent frequency's at a hop rate determined by packet length. There
is a bit of a caveat to this; you can set it up for a fixed number of
channels and/or fixed hop rate.
Output Power defaults to 500mW, but is adjustable from 100mw to 1 W

>From the site testing I have done it has a useable range of error free
communications of approx. 1.2 kms (at the default power level). Currently my
costs are sitting around $70 dollars, however I have few changes in the RF
which will bring this down slightly. At the present time I have this basic
design working in a customers product. I plan on re-doing artwork and
modifying some of the synchronization algorithms before I release it in my
own form . Physically the board is quite small ( 1.8"W x 3.5"L) but this was
spec'd by my present customer. I hope to reduce it somewhat and anticipate
approximately 1.5 x 3 (but may remain the same as above for RF reasons).

Anyway, that's it in a nutshell.

Cheers,

Kevin

> I have used several different RF transceivers, but none of them are quite
> right for my application.  Here is what I need:
> Data packets of 8 bytes come from a master unit, communicating to 250
> remote units.  They, in turn, respond one at a time.  I need this to occur
> on 8 independent channels, and the whole process needs to take no
> more than
> 4 seconds.
> The closest I've found is LINX, but their transmitters freak on me about
> 10% of the time, making 100% error-free communications very difficult.
> The best I've found is Radiometrix, but their 900 MHz series keeps getting
> delayed.  If you have a product that would fit, or know someone
> who does, I
> would love to know about it.  Also, they need a minimum range of 300 ft,
> and FCC-15 compliant, and under $100.
>