[Tagging] Radio telescopes

Joseph Eisenberg joseph.eisenberg at gmail.com
Thu Oct 25 22:56:38 UTC 2018


man_made=tower has an option for tower:structure=dish which is used with
tower:type=communication for tall communication dishes aka satellite
dishes, and we even render is at a dish with signals, in the
openstreetmap-carto style.

But I agree that this is an odd way to do it, and it also doesn’t work for
small dishes that are too short to be a tower or are on the ground.

There area a few man_made=satellite_dish and man_made=communications_dish
but no wiki or proposal.

I would make a proposal, but I wouldn’t like to add further confusion, and
my experience with the proposal process is discouraging so far.
On Fri, Oct 26, 2018 at 7:45 AM Graeme Fitzpatrick <graemefitz1 at gmail.com>
wrote:

> & to throw another spanner in the works :-), what do you call satellite
> dishes, either bubby ones for home use https://goo.gl/images/qaDzSX  or
> big commercial versions  https://goo.gl/images/44ZhNd?
>
> They're certainly not towers, but they definitely are for communication
> purposes.
>
> Thanks
>
> Graeme
>
>
> On Fri, 26 Oct 2018 at 07:45, Kevin Kenny <kevin.b.kenny at gmail.com> wrote:
>
>> On Thu, Oct 25, 2018 at 4:46 PM Warin <61sundowner at gmail.com> wrote:
>>
>>> On 25/10/18 23:56, Paul Allen wrote:
>>>
>>> BTW, these days few radio telescopes are dishes.  Most of them are
>>> phased arrays and not on towers
>>> or masts.
>>>
>>>
>>> That depends on the frequency of operation.
>>>
>>> New dish reflecting ones are being build. They simply perform the best
>>> for the intended frequencies.
>>>
>>
>> And there are dishes with phased arrays at the feed point, for beam
>> forming, and phased arrays of dishes, for long-baseline interferometry.  It
>> all depends on what frequency, SNR, polarization and angular resolution you
>> need. Paul is right that larger phased arrays are now practicable because
>> of better electronics, giving dishes less of an advantage, but phased
>> arrays are as old as radio astronomy. Jansky built his "merry-go-round"
>> Bruce antenna (20.5 MHz) in 1932, while Reber didn't build his first dish
>> until 1937. Jocelyn Bell discovered pulsars on a phased array built at
>> Cambridge by Ryle and Hewish (which also produced the 3C catalog of radio
>> sources - including 3C273, the first known quasar).
>>
>> The conclusion is either, "Life is full of tradeoffs," or "you really
>> don't want to know!"
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