Hi,
I have a a small correction to my message, I was talking from memory.
After checking with the real thing I found that 2 commands are needed:
One for turning the yellow LED (Comm fault) off and other for turning
the Green one (Normal) on.
Ignacio EB4APL
On 10/09/2013 13:47, EB4APL wrote:
Dave,
I have a cousin of your GPSDO, a NTGS50AA whose main differences are
that in this unit the DB-9 connector and the LEDs are in a separate
board connected by a flat cable, and that this unit is meant for -48
volts systems only.
The yellow light indicates that it is not in communication with the
mainframe for about 30 seconds so it is labeled comm error. There are
two ways to turn it green:
- Emulate a small subset of the mainframe protocol with a
microcontroller and communicate with the board through the 110 pin
connector in the back. Nothing useful and quite complicated.
- Ask Mark Sims to include in LH a function to periodically send a
command to turn the lamp green. I verified with the Trimble-Nortel
installation tool (GPS_Monitor) that if you tick the box for
commanding the LED to green, it stays green until the program quits,
so it is periodically resetting the comm timeout counter. With this
function the LED would be green as long LH is in communication with
the box and would turn yellow if the program quits or the
communication is lost, like when the box is installed in a cell tower.
Just an idea,
Ignacio EB4APL
On 10/09/2013 4:31, quartz55 wrote:
OK, did a bit more reading. I already understand the difference
between accuracy and stability however.
I thought ADEV was some sort of measurement of accuracy, but I
understand now it is a measure of stability over time. I'm supposing
now that I can assume that the best frequency accuracy I can imagine
is what is specked in the book for the unit, <.8x10^-10. That should
be good enough for me. Although most seem to say the GPSDO units are
good for .1Hz at 10GHz which I think would be 10^-13 no?
Yeah, I've read through the h...cpp and a lot of it is greek to me,
I'm no programmer, but I can pull a bunch of stuff out of it. But it
doesn't explain the acronyms or the meanings of them.
I've lowered the el mask to 20 and I get plenty of sats now. When it
was at 43, lots of times it was down to 2, now it's generally up to
6. I'll see how it does, especially if it rains, and yes the trees
really cover the antenna. I am getting 30-40 or more dBc however
which is what I had when it was more in the clear. I can move it to
the west about 30' on the chimney where my UHF/VHF beams are and it's
a lot more open straight up and especially to the south. The
position where it is now is just real convenient and it's only maybe
25' from the unit. Plus I didn't have to get up on that part of the
roof that's 7 in 12.
Yes, I notice the gis for our county seems to have a slightly
different co-ordinate system, they don't line up with google or the
GPS which seem to agree as far as I can zoom in on our location. I'd
say the GPS and google are within a foot or 2.
I guess I can just turn off the temp chart if it's not going to
report right and stop looking/worrying about it. As long as the
green lock light is on. I wonder if I could trick the Nortel unit
into thinking it's seeing the CM though, so the top green light would
come on instead of the yellow one. But that doesn't matter.
Thanks for all your help, I'll hang around for a while.
Dave
N3DT
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