# [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)

tosca005@umn.edu tosca005 at umn.edu
Wed Apr 21 15:04:55 PDT 2010

```Domenico: I suspect that the difference of opinion has to do with the
difference in punctuation (',' vs. '.') used with large numbers.

In typical American usage,
243,902,443 Million Watts = 243,902,443,000,000 watts = 243.9 trillion watts
243.902 443 million watts = 243,902,443 watts =         243.9 million watts

without the punctuation ->

243 902 443 million watts = 243 902 443 000 000 watts = almost 244 trillion
watts.

So, I think that if the comma is used as a 3-decade separator and not a
decimal point, that the original posting was in fact a million times
overstated. I hope that clarifies it.

If not, then think of it this way.

400 watts x  0 dB = 400 watts
400 watts x 10 dB = 4000 watts = 4 kilowatts
400 watts x 20 dB = 40000 watts = 40 kilowatts
400 watts x 30 dB = 400000 watts = 400 kilowatts
400 watts x 40 dB = 4000000 watts = 4000 kilowatts = 4 megawatts
400 watts x 50 dB = 40000000 watts = 40000 kilowatts = 40 megawatts
400 watts x 60 dB = 400000000 watts = 400000 kilowatts = 400 megawatts

They were nowhere close to 400 000 000 (400 million) megawatts of ERP.

400,000,000 million = 400 million million = 400 terawatts
400.000.000 million = 400 million         = 400 megawatts

73 de W0JT

On Apr 21 2010, i8cvs wrote:

>----- Original Message -----
>From: "Nigel Gunn G8IFF/W8IFF" <nigel at ngunn.net>
>To: "i8cvs" <domenico.i8cvs at tin.it>
> Cc: "Fabio A" <iw8qku at amsat.org>; "AMSAT-BB" <amsat-bb at amsat.org>;
> "Mateusz"
><sq7dqx at poczta.onet.pl>
>Sent: Wednesday, April 21, 2010 9:07 PM
>Subject: Re: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some
>calculations)
>
>> Of course, this ia all rubbish as the stated power of 243TeraWatts (READ
>BELOW CAREFULLY) is clearly not true.
>> That would require an antenna gain of, in the regeon of, 120dB.
>>
>> On 21-Apr-10 17:49, i8cvs wrote:
>>
>> >
>> > The only official data given for Arecibo by WF1F are the following :
>> >
>> >> The 1,000 foot dish has 60 dBi on 432 mc and 400 watts.
>> >> That comes out to be approximately 243,902,443 Million Watts ERP.
>> >>
>
>Hi Nigel, G8IFF/W8IFF
>
>
>1 tera watt =1 TW = 1 x 10^12 watt or 1,000,000,000,000 watt
>
>1 mega watt = 1MW = 1 x 10^6 watt or 1,000,000 watt or 1 million watt
>
>So 243,902,443 million watt ERP = 243,902,443 MW ERP as WF1F
>writes is CORRECT
>
>By the way  the gain of Arecibo is 60 dBi or 1.000.000 time in power
>and not 120 dB = 1. x 10^12 or 1.000.000.000.000 time in power
>
>73" de
>
>i8CVS Domenico

```