[time-nuts] WWVB Simulator
msimon6808 at yahoo.com
Thu Jan 5 03:53:25 EST 2017
The design of the - wwvb cheatn d-psk-r - is an excellent start. It is why I wanted a WWVB simulator. There are some points that need improvement though. To cover the full range of a VCXO the current design might require (in theory) as much as a +90 to -90 deg phase difference between the local oscillator and WWVB. I thought that should be reduced to +22.5 to -22.5 degrees ( in theory - actual will be less because the VCXO I'm using is active from about .5V to 2.5V instead of the full 0 to 3.3V). So that adds a voltage reference (for the offset), op amp and offset resistors to the frequency control loop.
I'm also doing full surface mount (designed for hand soldering) and rationalizing the parts values. A fast CMOS comparator (instead of the clunky LM311) etc. Power required will be +/-12V and +5. Local regulator(s) will supply parts that need 3.3V. I'm designing with low cost in mind.
I still have a lot more work to do but the general outline is more or less complete. I will publish when I get some testing done.
The AM detector is also not like any other I have seen. It may be overkill. But it is not very expensive.
Engineering is the art of making what you want from what you can get at a profit.
I like Polywell Fusion.
On Wednesday, January 4, 2017 7:29 PM, paul swed <paulswedb at gmail.com> wrote:
SimonLike you I tend to like hardware. But today complete micros are so cheap and powerful they make life easy. Heck a bit to complex use 2 or 3. I like to follow the "Get-er-done" philosophy.
That said search the time-nuts archive for the wwvb cheatn d-psk-r. It knows how to create the bpsk time stream aligned to wwvb then flips a BPSK switch to remove the BPSK. This allows all of the old phase tracking receivers work without modifications.I used an Arduino $8 maybe and shared all of the details and software with the group. It preserves the old AM for radios that need that modulation.So a corrected wwvb signal can be had for cheap and it works very well here on the east coast. As well as wwvb ever did.
Have fun and use whatever technology you like as you are the do-er, you get to choose.
On Wed, Jan 4, 2017 at 2:48 AM, Chris Albertson <albertson.chris at gmail.com> wrote:
You don't need to tie up a PC. It could likely output the WWVB
signal while it was also surfing the web and reading emails. 60KHz
is NOTHING compared to displaying a you-tube video
In fact I bet your 48MHz uP could directly synthesize the signal.
Look at the ratio of 48 MHz / 60 KHz. The uP can execute about 800
instructions during one cycle of a 60 KHz courier. Your PC can do
a million operations during that same one cycle.
But go ahead. I'm subscribed to another list dedicated to building
stuff with vacuum tubes. I kind of enjoy building with that
technology. I used to like building with 70'd vintage 74xxx TTL.
city is like lego blocks for big kids. But as a practical matter if
you just want something to work, 21st century technology gets the job
On Tue, Jan 3, 2017 at 6:49 PM, M. Simon via time-nuts
<time-nuts at febo.com> wrote:
> Sure. I considered software. But I'm a hardware guy. I like designing boards. The rig was designed to do amplitude and phase simply. The final design will have a $5 48 MHz microprocessor included. I'm using that one because of speed and memory. When that proves out I might redesign for a $2 24 MHz processor. Onesies prices at Mouser
> Besides the hardware better illustrates the concepts than software. And I don't have to tie up a PC if I don't want to.
> I haven't priced everything out yet because the design is not done. I'd be surprised if the cost was over $20 in parts for everything - power supply not included. PCB extra.
> Feel free to send this along to the list if you are inclined.
> Engineering is the art of making what you want from what you can get at a profit.
> I like Polywell Fusion.
> On Tuesday, January 3, 2017 5:53 AM, Hal Murray <hmurray at megapathdsl.net> wrote:
> time-nuts at febo.com said:
>> I have come up with a ridiculously simple WWVB simulator that simulates both
>> the AM modulation and the BPSK modulation.
> Did you consider software?
> Is the audio on a Raspberry Pi fast enough?
> I haven't looked at any details, but you can get ARM CPUs for ballpark of $5
> on eBay. There is a good chance that one of their IO devices will let you
> send raw bits via a DMA channel.
> These are my opinions. I hate spam.
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