[time-nuts] 469357A

Bob Camp kb8tq at n1k.org
Thu Jul 2 11:47:17 UTC 2015


Hi

> On Jul 2, 2015, at 12:19 AM, Mary Crowson <crowson.one at sbcglobal.net> wrote:
> 
> Hi. I'm pretty new to time nuts. I'm pretty much a novice, but a novice in training. I subscribed to this group because I had reviewed pertinent information that was being shared, and I appreciate the acceptance. I'm not sure I can be of much immediate help to any others, but perhaps eventually. 
> Having said that, I come here, today, seeing some knowledge and advice. 

Welcome !!!

> I have a Lucent RFTGm-II-Rb/Lucent RFTGm-II-XO unit. I intend to convert the 15MHz output to 10MHz for use as a GPSDO for an external standard for my test equipment that I'm slowly acquiring and learning about, and learning about and acquiring. I've seen the project where the 15 MHz was converted to 10 MHz. Helpful. I have some questions about this specific unit, or set. They are combined on a common rack that is much larger than my test equipment, when coupled. There are some distribution hubs that are located on top of each, respectively. Combiner/splitter. One is the 15 pin D-sub connector type. The other is BNC. Does anybody have access to the operating manuals for these, as well as the software, if one wishes to marry it to a PC and another program? 

The Lucent boxes mostly speak SCPI. It’s more for monitoring them than operating them. If you dig into the archives, there are a couple of programs that
are worth looking at as well as information on the (likely) command set / baud rates for use with a terminal program.

> The next question is also GPSDO related. I have four of the 469357A GPS antennas that were utilized with this equipment. According to some sources, they have a gain of 20 dB. According to other sources, they have a gain of 30 dB. According to some sources, the gain is somewhere in between. Does anybody know for sure what the Nokia/Symmetricom ratings are, apart from their being 5V? 

The antennas came from a half dozen sources. They have gains from about 22 db to 28 db depending on the source. Given that the tolerance on the gain
is often +/- 3db, there may not be a lot of difference between the antennas.

> Finally, for now, does anybody have any recommendations as to how I could, in an affordable manner, without spending $350+ on a new GPS antenna combiner, combine the signals for these four GPS antennas, to be utilized by the single Lucent RFTGm-II-Rb/Lucent RFTGm-II-XO combined unit?

You very much do not want to do that. GPS is a one antenna sort of thing. It depends on all the signals arriving at a single point in space. With multiple
antennas, there would be no real way for the receiver to do it’s thing. You *can* run one antenna into multiple receivers. 

> As a measure to foil GOS spoofing, as well as giving a better chance of locking into satellites quicker, as well as maintaining connection, with multiple receivers located on each of four corners of a dwelling, since I don't have the best unobstructed location for optimal satellite signal, due to a canopy of trees, and other residential buildings with similar landscaping? 

If you are in the US, what you want is the single location that gives you the best view due south. That’s the one most likely to give you a good population of sat’s in view.

Bob

> One more finally. This address says Mary. Long story. I'm Brian. I started using this address long ago, and have remained in the habit of it. I've still managed to remain in the habit of heterosexuality, despite. Just wanted to let others know this is a guy and not some potentially unbelievably good looking chick who is into ultimate geekery. 
> Any help would be appreciated. 
> 
> Brian
> 
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