I ended up buying a pre-cooked Trimble plus a missilehead-like GPS antenna:
http://www.ebay.it/itm/252162780444?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
http://www.ebay.it/itm/262679152903?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
This should limit the chance it would be a DOA(well I hope at least), it
comes already boxed, has somewhat a wide power supply voltage range, no
pigtails to play with, and the antenna is new.
Now I just need to prepare the cable for the antenna, the mounting pole
and wait them to arrive through snail mail.
Many thanks to all but especially to Larry McDavid W6FUB that helped me
a lot to decide.
Now, while I wait...
1) I am reading the thread on EEVBlog(Thanks Bob and Bryan), (I have
like one month before I receive the unit so I could have spent more, I
admit) but I have several questions:
a) Is this a board or a puzzle? seems that brings reverse
engineering to a whole new level. 32 pages of forum posts looking for
missing parts...LOL
b) which is the difference between the Symmetrical and Trimble
unit? I am mostly interested in interfacing, like the ability to get
also NMEA sentences (if possible) and the ability to add the KOBB
display. In the thread there are a lot of information but really not
sure how much is common between the two. Only sure thing I have
understood seems that Trimble does not initiate a Survey at power on.
c) since I *may* like to use the GPS antenna also for the clock
kit(I WANT a DISPLAY!), I would like to build/buy a *simple* spitter.
Just a second output. I hope that a passive cheap schematic would do.
BTW, on which frequencies this unit receive data? Just 1575.42MHz? Would
it be possible to build a Wilkinson splitter?
d) still confused about the number of serial ports available, their
expected usage and voltage levels.
e) Which is the antenna signal level (dBm) that this unit require
to operate properly?
Giuseppe Marullo
IW2JWW - JN45RQ
On 10/24/2016 1:05 AM, Giuseppe Marullo wrote:
Hello Attila,
not cheap at that point, and I already have that ST board(I live few
km from ST headquarters, BTW)!.
Still licking my wounds from Eclipse-whatever chaintool, ouch, no way
I am going to mess with that again anytime soon.
I am not in the mood to start another endless project, way too many
unfinished stull in my drawers(as many others I guess).
I like the qrp-kit kit, but I will have a good look at eevb for the
"thunderbolt in disguise" and then I will decide.
Thanks.
Giuseppe Marullo
IW2JWW - JN45RQ
On 10/23/2016 5:52 PM, Attila Kinali wrote:
On Sun, 23 Oct 2016 15:32:33 +0200
Giuseppe Marullo <[email protected]> wrote:
I am puzzled about what to do, still the total cost of it for a OXCO +
GPS(unit with antenna) + control mcu is 67usd, I doubt I could find
anything like this for a cheaper price new.
Yes, it's cheap for a kit, but it is not that cheap if you want to be
cheap. :-)
You can get GPS modules for as low as $5 on ebay (these are new),
a uC board for another $10-30 (even cheaper on ebay) and a quite good
OCXO for $10-30, also from ebay. A few wires, a bit of programming and
you have an GPSDO that beats the progrock. So, by buying the right stuff
you can stay below $30 and have something that will get you a long way
for experimenting.
Just for the fun of it:
http://www.ebay.com/itm/STM32F030F4P6-ARM-CORTEX-M0-Core-Mini-System-Development-Board-5V-3-3V-/371769616187?hash=item568f32273b:g:seAAAOSwXeJYCx63
$1.40
http://www.ebay.com/itm/MCP4725-I2C-DAC-Breakout-Development-Board-12Bit-Resolution-/401209928223?hash=item5d69f9aa1f:g:j5gAAOSw34FVH5b1
$1
http://www.ebay.com/itm/Aircraft-Flight-Controller-w-Ublox-NEO-6M-GPS-Module-for-Arduino-APM2-/182318966076?hash=item2a730ea53c:g:QuoAAOSwOVpXc3K~
$5.04
http://www.ebay.com/itm/1-USED-ISOTEMP-OCXO-143-141-10-MHz-5V-SC-CUT-Square-Wave-Crystal-Oscillator-/331997554003?hash=item4d4c98a553:g:w~sAAOSwCGVX~g24
$16
Total cost: ~$25 including shipping and all but the OCXO are new.
You will need programmer for the uC board, if you don't have that,
change
the uC board for an STM32F0DISCOVERY board:
http://eu.mouser.com/ProductDetail/STMicroelectronics/STM32F0DISCOVERY
Of course, any "real" GPSDO will beat this one by orders of magnitude
in phase noise and stability, but they are also much less fun to
build :-)
Attila Kinali
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