[time-nuts] Near-perfect chip for Loran-C frequency receiver

Poul-Henning Kamp phk at phk.freebsd.dk
Thu Jul 3 15:53:41 EDT 2008


ST microelectronics have made a new ARM chip: ST32M* and it almost
fits the bill for a single-chip Loran-C frequency receiver: it has
a 1 million samples per second A/D converter.

Olimex has an eval-board costing EUR 46:
	http://olimex.com/dev/stm32-p103.html
(Check sparkfun for US pricing)

Unfortunately, the clock-circuit in the chip prevents use of the
USB port at 1Msps A/D sampling rate, or if your input clock is
10MHz, but it has a serial port as well.

I have played with various low-cpu/low-ram reception scenarios as
part of my SDR experiements, and I think we can fit it comfortably
into the available flash/ram of the chip.

I wrote 280 lines of simulation code in C yesterday, and using my
spectrum recording from the 2006-01-01 leapsecond, I was able to
detect the existence of signals as far away as GRI 8830, 7980 and
7270 in just 2 minutes integration time and get good clean signals
from 7499, 6731, 9007, 8000 and 7001.

Anybody interested in doing a little group-project to complement
all the disciplined GPS oscillators we've see recently ?

Poul-Henning

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.




More information about the time-nuts mailing list