I came across this: " rpitx " it is python software that enables a
RaspberryPi to transmit using a GPIO pin.
The links refer to using the Rpi to produce 2m Tx signal. Rpitx seems
able to produce most modulation schemes. I have not tried it so have no
idea if it would produce your need directly.
http://zr6aic.blogspot.co.nz/2016/11/creating-2m-fm-repeater-with-raspberry.html
http://zr6aic.blogspot.co.nz/2016/10/vhf-2m-low-pass-filter-design-for.html
Cheers,
Will
On 01/05/2017 09:53 PM, M. Simon via time-nuts wrote:
Paul,
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.
Simon
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 <paulsw...@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.
RegardsPaulWB8TSL
On Wed, Jan 4, 2017 at 2:48 AM, Chris Albertson <albertson.ch...@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.
<snip>
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.
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