Google is building an 100 kW transmitter.

[firewalker]

 

https://hackaday.com/2016/03/02/google-is-building-a-100kw-radio-transmitter-at-a-spaceport-and-no-one-knows-why/

Alexander.

[XOIIO]

Mind control.

[rolycat]

With the headline hyperbole removed:

Google is building a highly directional 0.5 watt transmitter and it's likely to be an experiment aimed at faster communications.

[PA0PBZ]

With the headline hyperbole removed:

Google is building a highly directional 0.5 watt transmitter and it's likely to be an experiment aimed at faster communications.

Exactly, a 0.6M dish will do that.

[Zero999]

Yes, where the heck did they get the 100kW from if it's only 0.5W?

[thm_w]

Yes, where the heck did they get the 100kW from if it's only 0.5W?

Of the few details listed in the documents, one thing does pop out as exceptionally odd: a 70-80 GHz transmitter with an effective radiated power (ERP) 96,411 W. That’s close enough to 100 kilowatts to call it as such. This is the maximum effective radiated power of the highest power FM stations in the US, but radio stations are omnidirectional, whereas Google is using very high gain antennas with a beam width of less than half a degree. The actual power output of this transmitter is a mere half watt.

For example, an FM radio station which advertises that it has 100,000 watts of power actually has 100,000 watts ERP, and not an actual 100,000-watt transmitter. The TPO of such a station typically may be 10,000 to 20,000 watts, with a gain factor of 5 to 10 (5× to 10×, or 7 to 10 dB). In most antenna designs, gain is realized primarily by concentrating power toward the horizontal plane and suppressing it at upward and downward angles, through the use of phased arrays of antenna elements. The distribution of power versus elevation angle is known as the vertical pattern. When an antenna is also directional horizontally, gain and ERP will vary with azimuth (compass direction). Rather than the average power over all directions, it is the apparent power in the direction of the antenna's main lobe that is quoted as a station's ERP (this statement is just another way of stating the definition of ERP). This is particularly applicable to the huge ERPs reported for shortwave broadcasting stations, which use very narrow beam widths to get their signals across continents and oceans.

https://en.wikipedia.org/wiki/Effective_radiated_power

Its an accepted industry term but applying it to narrow beams seems ridiculous and misleading.

[RobertoLG]

or comunication with aliens lol

[TheSteve]

Perhaps they plan to put a couple hundred thousand transceivers in space and run millimeter wave micro spotbeams all over the place. I don't see them using millimeter wave for any LEO applications though.

[T3sl4co1l]

ERP is the same reason one 20mA red superbright LED can be 100mcd or 50,000+.

Tim

[rs20]

Its an accepted industry term but applying it to narrow beams seems ridiculous and misleading.

Why? If you're sitting (or flying through) the beam, the ERP tells you exactly what you'll experience right there. Like T3sl4co1l points out, it's just like with LEDs. You can tell me all you want that the 50,000mcd LEDs are "misleading" because they put out the same number of lumens as a 100mcd LED, but you'll be singing tune if you stare down the barrel of one.

[thm_w]

Why? If you're sitting (or flying through) the beam, the ERP tells you exactly what you'll experience right there. Like T3sl4co1l points out, it's just like with LEDs. You can tell me all you want that the 50,000mcd LEDs are "misleading" because they put out the same number of lumens as a 100mcd LED, but you'll be singing tune if you stare down the barrel of one.

It tells you nothing about what you'll experience right there, without knowing radiation pattern and distance.
If you say 0.5W then you know that at most you would see that much power.

mcd is also useless unless beam angle is given as well.

[uncle_bob]

Hi

Using EIRP to confuse a 100KW device with a 0.5W device is one good example where EIRP leads one astray.

Bob

[vk6zgo]

Hi

Using EIRP to confuse a 100KW device with a 0.5W device is one good example where EIRP leads one astray.

Bob

And the amazing thing is that people who post on an EE forum & would laugh ideas of "over-unity" devices to scorn,still get sucked in by it.
If EIRP actually gave real power gain,our energy crisis would be over.

Bob,"they're all mad,but me & thee---& I'm not too sure about thee!"

[rs20]

Why? If you're sitting (or flying through) the beam, the ERP tells you exactly what you'll experience right there. Like T3sl4co1l points out, it's just like with LEDs. You can tell me all you want that the 50,000mcd LEDs are "misleading" because they put out the same number of lumens as a 100mcd LED, but you'll be singing tune if you stare down the barrel of one.

It tells you nothing about what you'll experience right there, without knowing radiation pattern and distance.
If you say 0.5W then you know that at most you would see that much power.

mcd is also useless unless beam angle is given as well.

If you place a photodetector in the brightest part of an LED's beam, the reading it registers can be found using mcd rating and distance alone. No need for radiation patterns. This is the whole point of the mcd unit.

If you place an RF detector at the "brightest" part of a satellite dish's radiation pattern, the readings you'll read are given by ERP/EIRP and distance alone. This is the whole point of ERP/EIRP.

Using EIRP to confuse a 100KW device with a 0.5W device is one good example where EIRP leads one astray.

That's dumb journalists confusing EIRP with power. If people stated EIRP in W/sr, that'd be fine to dissuade journalists from misusing it. But then it'd be harder to use for people working from dipole/isotropic formulae.

[profany]

wow, thats amazing