[time-nuts] Survey plot as art.

"Björn Gabrielsson" bg at lysator.liu.se
Mon Jan 9 16:06:34 EST 2017

Hi Gary,

>> >> My gut reaction is that "coupling" between the two antennas may
>> >> have some effect on some of the variation.
>> For high accuracy applications, I have been given the advice to keep
>> GPS antenna separation much higher. 1 meter separation was suggested.
> Clearly the Adafruit is not high accuracy.  I have played with some
> short baseline DGPS (cm level data) and not found any issue with antenna
> separation.

Good for you! Others have found issues.

>> For comparing GPS receiver behavior its a cleaner setup to use a GPS
>> signal splitter (or basic RF splitter with suitable DC-blocks).
> Care to recommend any that have SMA connectors?  I have found that
> a 3dB difference in antenna can degrade my data quality, it would be
> interesting to see how the 3dB loss of the splitter affects thins.

The ZAPD-2DC+ from Minicircuits are good value for money, if 2 ports are

The Colorado based "GPS Source" and "GPS Networking" both provide quality
products. They have versions with SMA, but also TNC or N.

Splitters build for GPS use can be passive, but they are often amplified.
They will also pass power up to the lna in the antenna.



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