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Re: Small ISM circuits interresting for small hamsats ?



The Stensat Group has been using ISM type chips for some satellite radios.
We are building radios for Stanford University and a starting one for a
Texas University. We also sell a cansat kit that includes a radio board
measuring 1x0.8 inches that is an AX.25 1200 baud transmitter. Send it
data via UART up to 64 characters and it will generate an AX.25 packet.
The power output is +7dBm. This is done with an 8 pin PIC and an atmel
transmitter chip. The neat thing about the atmel transmitter is their 900
MHz version drops in the same circuit. We only have to change the crystal,
one capacitor, and one inductor.

There is a picture of our transmitter and one of our 2m FM receivers on
www.katysat.org (look under communications). The cansat can be seen at
http://www.pratthobbies.com/proddetail.asp?prod=CANSAT%2D1

These are some examples of ISM hardware used in amateur frequencies. The
cansats are being sold to high schools and universities. I run a cansat
summer camp in Chantilly every year. The kids get a kick when they work
with the radios.

I'm not advocating the sales of any items, just trying to show what is
being done with ISM radios.

Ivan


On Wed, Mar 1, 2006, William Leijenaar <pe1rah@hotmail.com> said:

> Hi AMSATs,
> 
> We all know that on 433MHz there is also ISM low power device radio usage.
> Today there are quiet a lot off integrated circuits for this band.
> 
> Some of them are quit interresting and very small and low power usage.
> This is transmitter as receiver as also transceiver with data slicers etc 
> integrated...
> 
> For example check the ATMEL AT86RF211S device.
> http://www.atmel.com/dyn/products/product_card.asp?part_id=3662
> 
> I just wonder if someone ever tried to use them for 70cm FSK packet radio 
> ???
> With these devices you need only a small final PA and you have an ultra 
> small packet satellite in the format of a credit card size and in receive 
> mode they can last for weeks, maybe months on a small battery...
> 
> Propably they are not RF "clean" enough as most of them use crystal 
> capacitor switching to get the FSK frequency shift. When I remember right 
> the ham TNC's have Raised Cosine Filter to reduce inter-symbol 
> interference... maybe that might be a problem ?
> 
> Just wondered if it might be interresting for future ham satellites...
> 
> 73
> William Leijenaar
> ---
> ----
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