WWVB BPSK Receiver Project?
I was not concerned about processing power on a PC (or Mac for that matter) but for the uC that was used in PHK's project.
Didier KO4BB
Sent from my BlackBerry Wireless thingy while I do other things...
-----Original Message-----
From: Chris Albertson albertson.chris@gmail.com
Sender: time-nuts-bounces@febo.com
Date: Thu, 15 Mar 2012 15:48:41
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] WWVB BPSK Receiver Project?
On Thu, Mar 15, 2012 at 3:13 PM, Poul-Henning Kamp phk@phk.freebsd.dk wrote:
In message 20120315152620.8347488e049854218aed4aa6@kinali.ch, Attila Kinali w
rites:
Do you need 16 bits or can you get by with a 12 bit ADC?
In general: The more the merrier, for a digital dude like me, having
more bits is easier than getting AGC working correctly :-)
Have you considered using an FPGA for signal processing? It seems
you need a fairly serious CPU to handle that much data.
"That much data" we are talking about 192K samples per second. I can
routinely record multiple tracks of 192K audio and do processing in
real time and the CPU meter hardly moves the bottom. Even a
gigabit per second Ethernet port is not "a lot of data" on a modern
computer.
FPGAs and DSP come into play if you are talking about tens of millions
of samples per second with data rates above say 200Mb/Sec But the
rate from an audio interface running 192K and 24-bits is still under
one megabyte per second. An interesting ratio is the number of CPU
cycles available to process one sample. On my Apple iMac that would
be about roughly 200,000 operations per data sample.
In real life SDR receivers even an older CPU can process the I and Q
channels and maintain a large graphic screen and send and receive data
over a network and still not be "maxed out"
Chris Albertson
Redondo Beach, California
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In message <595370411-1332118092-cardhu_decombobulator_blackberry.rim.net-18097
4826-@b1.c24.bise6.blackberry>, shalimr9@gmail.com writes:
I was not concerned about processing power on a PC (or Mac for
that matter) but for the uC that was used in PHK's project.
That was sort of the entire point about the "aducLoran": to show that
for time-nuttery, you don't need much CPU.
If you wanted to extract a real-time modulation of any kind, the situation
is very different, but as long as you just want to extract a carrier
phase/frequency, averaging is the way to go and that is cheap.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@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.
Looks like this bounced as I sent from the wrong address. Better late
than never.
On Wed, 14 Mar 2012 15:46:48 -0700, Chuck Forsberg WA7KGX N2469R caf@omen.com wrote:
Asus has a $30 Xonar PCI soundcard that should do the job.
I have two of the the more expensive pci-e versions. Some motherboards
can do a/d at 192 but not as well as the Xonar.
Even better: a USB DVB card [1]. For $30 you have a few million 8-bit
I/Q samples per second and an interface to Gnu Radio. The possibilities
are nearly endless.
Cheers,
- Ben