revisiting the 434 MHz band

Ron K. Jeffries rjeffries at
Sat Jul 24 12:17:43 EDT 2010

The discussion of alternatives to add some
form of wireless to Nanonote is interesting,
but is missing fundamental information.

What user problem do we wish to solve?
Ron K. Jeffries

On Fri, Jul 23, 2010 at 23:13, Werner Almesberger <werner at>wrote:

> Wolfgang Spraul wrote:
> > No no, not hookup to an FPGA.
> I think a CPLD would be sufficient to beat the bitstream into
> shape. This wouldn't have to be a large chip. What it would do is
> just find out where the packet starts and ends, find byte
> boundaries, and do a bit of buffering so that the CPU has
> something it can work with.
> You may be able to do those bit-level operations at low speeds
> (802.11b) also entirely in software, but you'd really spend a lot
> of resources for a task hardware is much much better at.
> Maybe the DSP could do it, though. Also, maybe there are some
> chips that integrate some of these functions.
> > I definitely want to hook this up to a regular ASIC XBurst CPU.
> I think this would be quite wasteful, even if it works. Kinda
> like the ZX81, where the CPU spent most of its time refreshing
> the screen, instead of running your program.
> > I was encouraged to look into SiGe chips by Henry Hallam
> > (, who says he works on a solution with a
> > Blackfin DSP and SiGe SE4120L to implement the GPS stack,
> Okay, but the SE4102L outputs a digital Q/I stream. Even with
> the MAX2830, you still need the ADC. Plus, unlike GPS, you also
> have a transmit stream to take care of.
> Regarding the ADC/DAC, in case you were thinking of using the
> things you find inside the CPU: they only do a few kilosamples/s,
> which is too slow as well. I don't know what sample rate 802.11b
> or even 802.11g need, but I would be surprised if it was less
> than a few hundred kSa/s, even if you do tricks like scaling
> 802.11b down to 1 Mbps. (Would be nice for Lies and Dece..., err,
> marketing, though. Much like all those "USB 2.0" devices that
> only do full-speed :-)
> Last but not least, unlike WLAN, the GPS data stream moves at an
> unhurried 50 bps.
> > The one thing that worries me about IEEE 802.15.4 is the range. Only a
> > few meters? That's what I still like about 433 Mhz - it seems to work
> over
> > hundreds of meters, possibly even more...
> Yes, range may be a problem. You can use more power, see e.g.,
> [1], but then you're adding extra chips and you go deep into
> RF design land. They also say they've achieved 378 m without
> such aids [2].
> [1]
> [2]
> 433/434 MHz can go a long distance, but at least in the lands
> under FCC's harsh rule only with crippling duty cycle
> restrictions.
> - Werner
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