[time-nuts] New NTBW50AA

EB4APL eb4apl at cembreros.jazztel.es
Tue Sep 10 15:57:55 UTC 2013


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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