[time-nuts] Choke Ring Pictures

[Brian Kirby]

I can't do any antenna comparisons.  The choke ring was at my house - I 
now live in a apartment and the landlord allowed me to put a patch 
antenna on the edge of the roof (and his rules are no external antenna - 
got his permission before moving in).

I would expect the average patch antenna with a ground plane would be 
good enough for any gps receiver as long as the antenna has enough gain 
and transmission line loss is acceptable.

I showed the pictures, because somebody ask me about them a couple of 
years ago and I forgot.  And they were made for a multi path problem, 
and it stopped it.  The reason I made the other two was for testing 
carrier phase surveying with the Motorola Oncore VPZ receiver.  I was 
able to get down to the inch level with these units - maybe if they were 
commercial they may have done better.  It was an experiment for myself.

As with any hobby, you can spend what you want, your choice.

WarrenS wrote:
> Brian wrote:
>
>> "There were also comments about surveying and timing antennas."
> Those may of been from me, unsuccessfully trying to make a point of 
> the difference between what is 'Best' and what is 'GOOD enough'.
>
>> "about every national timing laboratory uses choke ring antennas.   
>> ... for timing stability reasons."
> Then again they also have multiple CS and Just their Antenna budget is 
> likely more than the annual income of most time nuts.
> Can you do a test to show IF there is ANY improvement for the AVERAGE 
> time nut when compared to a well setup (Tbolt) GPSDO using a TacoSalad 
> antenna?
>
> Would be interesting to see a plot of cost vs. performance for the 
> various antenna types,
> Scaled to show the performance improvement that the average Time nut 
> would see.
> The TacoSalad antenna, originally cost me a total of $7.95, And took 
> under 30 seconds to build.
> That cost should be discounted because those parts had been considered 
> just throw away junk up until now.
>
> ws
>
> **********************
>
> ----- Original Message ----- From: "Brian Kirby" 
> <kilodelta4foxmike at gmail.com>
> To: "Discussion of precise time and frequency measurement" 
> <time-nuts at febo.com>
> Sent: Monday, March 15, 2010 2:09 PM
> Subject: Re: [time-nuts] Choke Ring Pictures
>
>
>> Dr. Clark passed on a tip that I used.  Put the funnel in a microwave 
>> oven and run it and see if the funnel warms up.  If it warms up, you 
>> do not use it.  I do not know what type of plastic the funnel was 
>> made out of; it was white, semi-transparent.
>>
>> There were also comments about surveying and timing antennas.  If you 
>> investigate about every national timing laboratory uses choke ring 
>> antennas.  Some enclose the antenna unit and they temperature control 
>> it. They do this for timing stability reasons.
>>
>> The commercial timing antenna is bullet shaped and is operated 
>> without a ground plane.  They are patch antennas.  When there is not 
>> ground plane, the antenna picks up best from the overhead and less 
>> towards the horizon. These antennas usually have a lot more gain 
>> (30-50 db vs most normal antennas in the 15-25 db range).
>> Also in surveying, we cut off the horizon at 15 degrees in software.  
>> A free Army Corp of Engineering manual on GPS Surveying is at 
>> http://140.194.76.129/publications/eng-manuals/em1110-1-1003/toc.htm
>> The main difference in surveying and timing is in surveying they use 
>> the carrier phase method, were in timing most use a solution derived 
>> from the processing of the coarse acquisition code, in were the 
>> receiver is in a fixed over-determined position .  Some timing labs 
>> are using carrier phase method, when they need more resolution.
>>
>> Brian - KD4FM
>>
> ****************
>>> warrens wrote:
> ...
>>> Preliminary results for the Taco Dish GPS antenna as an indoor 
>>> antenna are  looking good.
>>> Certainly worth considering if your GPS antenna is stuck indoors, 
>>> 'Out of the rain in the living room'.
>>> I find it best to rise it up near the ceiling such as on an upper 
>>> shelf with nothing above it.
>>> It would be hard to tell the difference between the GPSDO 
>>> performance obtained from this or the Best outdoor antenna if using 
>>> a Tbolt set to the  standard default settings.
>>> Picture attached
>>>
>>> ws
>>>
>> **************
>
>
>
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