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

[Tom Miller]

How about a laser diode and pin photo detector? You should be able to get 
nanosecond resolution with light.


----- Original Message ----- 
From: "Tim Shoppa" <tshoppa at gmail.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Thursday, May 07, 2015 2:43 PM
Subject: Re: [time-nuts] Important parameters for a GPS/GNSS antenna


> 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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