[time-nuts] Important parameters for a GPS/GNSS antenna

Tim Shoppa tshoppa at gmail.com
Thu May 7 14:43:44 EDT 2015


 Personally I would be happy with PPS time resolution at 10 nanoseconds but
others would want better than a nanosecond.

Gotcha with modulating the PPS onto a RF carrier, is that for time
resolution of 1 nanosecond, you would end up using a Gigahertz of bandwidth.

Tim N3QE

On Thu, May 7, 2015 at 11:49 AM, John Ackermann N8UR <jra at febo.com> wrote:

> Just put the GPS antenna, receiver, battery, and a low power RF
> transmitter modulated by the PPS (wide bandwidth = fast edge time) on the
> turntable, then use an appropriate receiver to demodulate the PPS and feed
> it to the rest of the system.  Put the RX antenna directly above (or below)
> the turntable so the path length remains close to constant.  Using FM might
> also remove Doppler effects from the received pulse.
>
>
> On 5/7/2015 11:18 AM, Tom Van Baak wrote:
>
>> I wonder if anybody ever made a rotating GPS antenna to average out the
>>>> X-Y phase-center offset ?
>>>>
>>>
>>  Of course, this does not really work with a gps antenna, unless you
>>> put the whole receiver onto the rotary table. But then you shift
>>> the problem onto the PPS output (note: amplitude noise translates
>>> into phase noise).
>>>
>>
>> Attila,
>>
>> My thought was to put PHK's proposed experiment entirely on the rotating
>> table: antenna, receiver, local Cs standard, laptop, and battery. You could
>> also get interesting data if you slightly offset the antenna from the
>> center. It would make the ultimate GPS Spirograph. (for those of you under
>> 40, http://en.wikipedia.org/wiki/Spirograph will explain)
>>
>> /tvb
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