Re: Arecibo on 432 MHz Moon Bounce (some calculations)
Hello all, just a curiosity, how did you found that the ERP is "... 243,902,443 Million Watts".
Thanks
73s Fabio iw8qku
----- Original Message ----- From: "MM" [email protected] To: [email protected] Sent: Wednesday, April 07, 2010 3:06 PM Subject: [amsat-bb] Arecibo on 432 MHz Moon Bounce
Hi all: Here is a EME event you cant miss. Dust off your CW key, its time for Satellite, QRP EME.
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.
enjoy
wf1f www.marexgm.org
(thanks to KB1MGI for passing on this data)
Arecibo on 432 MHz Moon Bounce
The Arecibo Observatory Amateur Radio Club will be putting the 1000-foot radio telescope on the air for 432 MHz EME from April 16-18.
It can be heard with a small hand-held yagi pointed at the moon
The scheduled times of operation are:
April 16: 1645 - 1930 UTC
April 17: 1740 - 2020 UTC
April 18: 1840 - 2125 UTC
Callsign: KP4AO
Tx Frequency: 432.045 MHz
Rx Frequency: 432.050 to 432.060+
Tx power: 400 W
Antenna gain: 60 dBi
System noise temp: 120 K (cold sky)
System noise temp: 330 K (when pointed at moon)
KP4AO can be heard with a small hand-held yagi pointed at the moon and a good receiver. A 15 dBi antenna and 100 W will be enough to work us on CW.
Operators at KP4AO will do their best to work as many stations as possible. Each session will start with a brief announcement and CQ in SSB. SSB QSOs may continue for 30 minutes to an hour, if the QSO rate remains high.
The mode will be shifted to CW as soon as it is judged that higher QSO rates would result.
We will listen for calls at frequencies 5-15 kHz higher than our own, and even higher if QRM warrants. Callers who s-p-r-e-a-d o-u-t are more likely to be copied.
If you've already worked us in any mode, please do not call again -- give others a chance.
If we call "CQ QRP", we will listen for stations running 100 W or less to a single yagi. Please do not answer such a CQ if you are running more power or have a larger antenna.
On April 18, if we reach a condition where most calling stations have been worked, and we judge that operating in the digital mode JT65B would produce a higher QSO rate, we will switch to JT65B.
Note that any of these planned operating strategies may be changed as circumstances dictate.
We are extremely fortunate to have been granted access to the world's largest radio telescope for this amateur radio good-will event. We look forward to working as many stations as possible in the alloted time!
From QRZ.COM
KB1MGI
...snip...
60dBi is abt 57dB It means 10exp5,7 ERP was 400x10exp5,7 W
----- Original Message ----- From: "Fabio A" [email protected] To: [email protected] Sent: Tuesday, April 20, 2010 8:26 PM Subject: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
Hello all, just a curiosity, how did you found that the ERP is "... 243,902,443 Million Watts".
Thanks
73s Fabio iw8qku
----- Original Message ----- From: "MM" [email protected] To: [email protected] Sent: Wednesday, April 07, 2010 3:06 PM Subject: [amsat-bb] Arecibo on 432 MHz Moon Bounce
Hi all: Here is a EME event you cant miss. Dust off your CW key, its time for Satellite, QRP EME.
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.
enjoy
wf1f www.marexgm.org
(thanks to KB1MGI for passing on this data)
Arecibo on 432 MHz Moon Bounce
The Arecibo Observatory Amateur Radio Club will be putting the 1000-foot radio telescope on the air for 432 MHz EME from April 16-18.
It can be heard with a small hand-held yagi pointed at the moon
The scheduled times of operation are:
April 16: 1645 - 1930 UTC
April 17: 1740 - 2020 UTC
April 18: 1840 - 2125 UTC
Callsign: KP4AO
Tx Frequency: 432.045 MHz
Rx Frequency: 432.050 to 432.060+
Tx power: 400 W
Antenna gain: 60 dBi
System noise temp: 120 K (cold sky)
System noise temp: 330 K (when pointed at moon)
KP4AO can be heard with a small hand-held yagi pointed at the moon and a good receiver. A 15 dBi antenna and 100 W will be enough to work us on CW.
Operators at KP4AO will do their best to work as many stations as possible. Each session will start with a brief announcement and CQ in SSB. SSB QSOs may continue for 30 minutes to an hour, if the QSO rate remains high.
The mode will be shifted to CW as soon as it is judged that higher QSO rates would result.
We will listen for calls at frequencies 5-15 kHz higher than our own, and even higher if QRM warrants. Callers who s-p-r-e-a-d o-u-t are more likely to be copied.
If you've already worked us in any mode, please do not call again -- give others a chance.
If we call "CQ QRP", we will listen for stations running 100 W or less to a single yagi. Please do not answer such a CQ if you are running more power or have a larger antenna.
On April 18, if we reach a condition where most calling stations have been worked, and we judge that operating in the digital mode JT65B would produce a higher QSO rate, we will switch to JT65B.
Note that any of these planned operating strategies may be changed as circumstances dictate.
We are extremely fortunate to have been granted access to the world's largest radio telescope for this amateur radio good-will event. We look forward to working as many stations as possible in the alloted time!
From QRZ.COM
KB1MGI
...snip... _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Hello, thanks for the reply, but now I have another question. I'm not good enough with those numbers!
If the calculated ERP is about 243 MW... which derives from changing from dBi to dBd (60dBi - 2.14), the part I don't understand is:
"*Since the given ERP is 243,902,443 Million Watts (see below) and since 60 dB is equivalent to 1000000 (one Million) time in power it comes out that the power reaching the feed of the dish is: 243902443 / 1000000 = 243 watt
The rest of the power 400-243 = 157 watt is lost in the feed line.*"
How do they have feeder losses? thanks in advance,
73s Fabio iw8qku
On Wed, Apr 21, 2010 at 8:45 AM, Mateusz [email protected] wrote:
60dBi is abt 57dB It means 10exp5,7 ERP was 400x10exp5,7 W
----- Original Message ----- From: "Fabio A" [email protected] To: [email protected] Sent: Tuesday, April 20, 2010 8:26 PM Subject: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
Hello all,
just a curiosity, how did you found that the ERP is "... 243,902,443 Million Watts".
Thanks
73s Fabio iw8qku
----- Original Message ----- From: "MM" [email protected] To: [email protected] Sent: Wednesday, April 07, 2010 3:06 PM Subject: [amsat-bb] Arecibo on 432 MHz Moon Bounce
Hi all:
Here is a EME event you cant miss. Dust off your CW key, its time for Satellite, QRP EME.
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.
enjoy
wf1f www.marexgm.org
(thanks to KB1MGI for passing on this data) ... snip ...
The anomoly you see is because the 60dB gain given is dBi and the "real" gain used to calculate the power is dBd (gain referenced to a dipole and not isotropic). The difference is around 2.4dB.
On 21-Apr-10 11:46, Fabio Azzarello wrote:
Hello, thanks for the reply, but now I have another question. I'm not good enough with those numbers!
If the calculated ERP is about 243 MW... which derives from changing from dBi to dBd (60dBi - 2.14), the part I don't understand is:
"*Since the given ERP is 243,902,443 Million Watts (see below) and since 60 dB is equivalent to 1000000 (one Million) time in power it comes out that the power reaching the feed of the dish is: 243902443 / 1000000 = 243 watt
The rest of the power 400-243 = 157 watt is lost in the feed line.*"
How do they have feeder losses? thanks in advance,
73s Fabio iw8qku
On Wed, Apr 21, 2010 at 8:45 AM, Mateusz[email protected] wrote:
60dBi is abt 57dB It means 10exp5,7 ERP was 400x10exp5,7 W
----- Original Message ----- From: "Fabio A"[email protected] To:[email protected] Sent: Tuesday, April 20, 2010 8:26 PM Subject: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
Hello all,
just a curiosity, how did you found that the ERP is "... 243,902,443 Million Watts".
Thanks
73s Fabio iw8qku
----- Original Message ----- From: "MM"[email protected] To:[email protected] Sent: Wednesday, April 07, 2010 3:06 PM Subject: [amsat-bb] Arecibo on 432 MHz Moon Bounce
Hi all:
Here is a EME event you cant miss. Dust off your CW key, its time for Satellite, QRP EME.
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.
enjoy
wf1f www.marexgm.org
(thanks to KB1MGI for passing on this data) ... snip ...
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.814 / Virus Database: 271.1.1/2825 - Release Date: 04/21/10 06:31:00
Hi all, I'm pleased of all those replies... but as I wrote in my previous email ( I agree with Mr. Bruninga ) "ERP is about 243 MW" and that comes from the conversion from dBi to dBd. That's all. No Losses. No difference in decimals punctuation.
That's my conclusion... think it is the right one. Thanks for the comments.
73s Fabio IW8QKU
On Wed, Apr 21, 2010 at 1:46 PM, Fabio Azzarello [email protected] wrote:
Hello, thanks for the reply, but now I have another question. I'm not good enough with those numbers!
If the calculated ERP is about 243 MW... which derives from changing from dBi to dBd (60dBi - 2.14), the part I don't understand is:
"*Since the given ERP is 243,902,443 Million Watts (see below) and since 60 dB is equivalent to 1000000 (one Million) time in power it comes out that the power reaching the feed of the dish is: 243902443 / 1000000 = 243 watt
The rest of the power 400-243 = 157 watt is lost in the feed line.*"
How do they have feeder losses? thanks in advance,
73s Fabio iw8qku
On Wed, Apr 21, 2010 at 8:45 AM, Mateusz [email protected] wrote:
60dBi is abt 57dB It means 10exp5,7 ERP was 400x10exp5,7 W
----- Original Message ----- From: "Fabio A" [email protected] To: [email protected] Sent: Tuesday, April 20, 2010 8:26 PM Subject: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
Hello all,
just a curiosity, how did you found that the ERP is "... 243,902,443 Million Watts".
Thanks
73s Fabio iw8qku
... snip ...
----- Original Message ----- From: "Fabio A" [email protected] To: [email protected] Sent: Tuesday, April 20, 2010 8:26 PM Subject: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
Hello all, just a curiosity, how did you found that the ERP is "... 243,902,443 Million Watts".
Thanks
73s Fabio iw8qku
Hi Fabio, IW8QKU
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.
enjoy
wf1f
To answere your question:
"how did WF1F found that the ERP is "... 243,902,443 Million Watts".
THERE ARE TWO POSSIBLE OUTCOMES:
Outcome Nr 1 or first possibility:
Since the given ERP is 243,902,443 Million Watts (see the WF1F above statement ) and since 60 dB is equivalent to 1000000 (one Million) time in power it comes out that the power reaching the feed of the dish must be:
243902443 / 1000000 = 243 watt
The rest of the power 400-243 = 157 watt must be losted in the feed line because the 400 watt amplifier is non mounted inside the feet but there should be a feed line long half the diameter of the dish from the feed and the operating point made of low loss big coax cable almost 150 or 200 meters long wich attenuation is 10 log (400/ 243) = 2.16 dB 10
Outcome Nr 2 or second possibility:
The 243,902,443 Million Watt ERP has been calculated in a wrong way considering the gain of the dish not 60 dBi or 60 dB over the isotropic antenna but 60 -2.14 = 57.86 dB wich is the gain over the dipole or 57.86 dBd and infact the wrong calculation showes: 10^ 5.786 = 610942 Million time in power and 400 watt x 610942 = 244,376,810 Million Watt ERP wich match very close with the value " 243,902,443 Million Watt" given by WF1F but it is a wrong value because it has been calculated with a gain of 57.86 dB instead of 60 dB
In order to know the real numbars a more informative clearification from the Arecibo Observatory Amateur Radio Club is welcome and necessary.
I hope this helps
73" de
i8CVS Domenico
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.
----- Original Message ----- From: "Nigel Gunn G8IFF/W8IFF" [email protected] To: "i8cvs" [email protected] Cc: "Fabio A" [email protected]; "AMSAT-BB" [email protected]; "Mateusz" [email protected] 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
I disagree with your numbars:
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
What was written was (243 million, 902 thousand, 443 units) million watts. That's 243 Terawatts.
On 21-Apr-10 21:23, i8cvs wrote:
I disagree with your numbars:
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
----- Original Message ----- From: "Nigel Gunn G8IFF/W8IFF" [email protected] To: "i8cvs" [email protected] Cc: "Fabio A" [email protected]; "AMSAT-BB" [email protected]; "Mateusz" [email protected] Sent: Wednesday, April 21, 2010 11:37 PM Subject: Re: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
What was written was (243 million, 902 thousand, 443 units) million watts. That's 243 Terawatts.
On 21-Apr-10 21:23, i8cvs wrote:
I disagree with your numbars:
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
Hi Nigel, G8IFF/W8IFF
Wath make confusion in the WF1F statements are the comma he writes between numbars.
He writes "That comes out to be approximately 243,902,443 Million Watts ERP."
Since the gain of Arecibo is 60 dBi = 1000000 time in power it is more correct to write 243902443 watt ERP or 243,902443 million watt ERP or 243,902443 MW ERP or better approximate to 244 MW ERP
73" de
i8CVS Domenico
Agreed.
The only thing, other than for times and dates, that I write between numbers is a decimal point. Commas and dots to split numbers into groups of three have no use.
OK, I might write 5 megawatts as 5E6 watts.
On 21-Apr-10 22:22, i8cvs wrote:
Wath make confusion in the WF1F statements are the comma he writes between numbars.
That because we English do it that way. The rest of the Europe, Germany and France for instance, seem to like inserting a comma instead!
:-D
David KG4ZLB
On 4/21/2010 18:45, Nigel Gunn G8IFF/W8IFF wrote:
Agreed.
The only thing, other than for times and dates, that I write between numbers is a decimal point. Commas and dots to split numbers into groups of three have no use.
OK, I might write 5 megawatts as 5E6 watts.
On 21-Apr-10 22:22, i8cvs wrote:
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Comma or no comma, shouldn't matter 1000 mega watts or 1,000 Mega watts is still one thousand million watts! NOT one thousands watts. true?
The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com
On 4/21/2010 6:14 PM, David - KG4ZLB wrote:
That because we English do it that way. The rest of the Europe, Germany and France for instance, seem to like inserting a comma instead!
:-D
David KG4ZLB
On 4/21/2010 18:45, Nigel Gunn G8IFF/W8IFF wrote:
Agreed.
The only thing, other than for times and dates, that I write between numbers is a decimal point. Commas and dots to split numbers into groups of three have no use.
OK, I might write 5 megawatts as 5E6 watts.
On 21-Apr-10 22:22, i8cvs wrote:
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Is it the original?
I had a mass produced plastic one (with a 50Hz motor) back in the early 1980's (or earlier). Unfortunately, your web site doesn't appear to give dates.
On 21-Apr-10 23:28, Idle-Tyme wrote:
The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com
Yes this is the original made by the person that made and trained most of the assemblers all those years ago. Read the history page it's pretty interesting.
The plastic junk one was a license on our patent. We thought of it like a Mc Donalds quarter pounder with cheese vs a nice sirloin steak at a 5 star steak house. They are both Beef. but there IS a big difference.
Joe
The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com
On 4/21/2010 7:08 PM, Nigel Gunn G8IFF/W8IFF wrote:
Is it the original?
I had a mass produced plastic one (with a 50Hz motor) back in the early 1980's (or earlier). Unfortunately, your web site doesn't appear to give dates.
On 21-Apr-10 23:28, Idle-Tyme wrote:
The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com
----- Original Message ----- From: "Idle-Tyme" [email protected] To: [email protected] Sent: Thursday, April 22, 2010 1:28 AM Subject: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
Comma or no comma, shouldn't matter 1000 mega watts or 1,000 Mega watts is still one thousand million watts! NOT one thousands watts. true?
The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com
Hi Idle-Tyme
I don't agree with your statement:
1000 mega watt are one thousand million watt 1,000 mega watt or 1.000 mega watt is only one million watt because zero after the comma means nothing like 1,0000000000000 is still one million watt or 1 MW
In addition writing the measuring units the plural must not be used as an example:
1 watt is correct 2 watt is correct 2 watts is wrong
The same for Ampere, ohm and so on.
1 ampere is correct 2 ampere is correct 2 amperes is wrong
In addition writing the measuring units be careful with the capital letters
1 watt is correct 1 W is correct 1 Watt is wrong
1 ampere is correct 1 A is correct 1 Ampere is wrong
73" de
i8CVS Domenico
On 4/21/2010 8:25 PM, i8cvs wrote:
Comma or no comma, shouldn't matter 1000 mega watts or 1,000 Mega watts is still one thousand million watts! NOT one thousands watts. true?
The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com
Hi Idle-Tyme
I don't agree with your statement:
1000 mega watt are one thousand million watt 1,000 mega watt or 1.000 mega watt is only one million watt because zero after the comma means nothing like 1,0000000000000 is still one million watt or 1 MW
NO! it's a comma, not a decimal point! it's one thousand, one thousand written 1000 or 1,000 is still one thousand they are exactly the same.
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" [email protected] To: "i8cvs" [email protected] Cc: "Fabio A" [email protected]; "AMSAT-BB" [email protected]; "Mateusz" [email protected] 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
I disagree with your numbars:
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
People need to learn engineering significance. Just because a calculator spits out 9 digits of precision, using them all shows a lack of understanding. The value is 244 million watts. The significance of all the other digits is absolutely meaningless!
The original post was about 400 watts and 60dBi gain. Neither of those numbers has more than 3 significant digits, Throw in the gain of a dipole over isotropic which is also a round number of about 2.14 therefore the answer CANNOT HAVE MORE THAN 3 digits of precision or it is WRONG. The answer given implies a precision that does not exist. And if you ask me, the 400 Watts is probably only significant to maybe 2 digits and from their experience with their Power Amp, I'd say that they only knew their TX power to ONE significant digit. So I would not even use the number 244. I would say "about 200 million Watts" because that is all the precision we can know from the inputs.
When an engineering student gives me such an answer I shoot them down hard! Numbers convey not only VALUE but PRECISION. And implying PRECISION where it does not exist is wrong.
Sorry, but everyone else has given their opinion, so I may as well say mine ;-)
Bob, Wb4aPR
And, as usual, your opinion is absolutely true. Only needs to be to the precision that you can measure or the nearest "preferred value".
On 21-Apr-10 22:57, Robert Bruninga wrote:
People need to learn engineering significance. Just because a calculator spits out 9 digits of precision, using them all shows a lack of understanding. The value is 244 million watts. The significance of all the other digits is absolutely meaningless!
----- Original Message ----- From: [email protected] To: "i8cvs" [email protected] Cc: "Nigel Gunn G8IFF/W8IFF" [email protected]; "AMSAT-BB" [email protected]; "Fabio A" [email protected] Sent: Thursday, April 22, 2010 12:04 AM Subject: Re: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
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
Hi , W0JT
I agree with you that the difference of opinion has to do with the difference in punctuation (',' vs. '.') used respectively in typical American and European usage with large numbers so that
400,000,000 million = 400 million million = 400 terawatt in American usage 400.000.000 million = 400 million = 400 megawatt in European usage like in Germany France and Italy
Tanks and
73" de
i8CVS Domenico
participants (9)
-
David - KG4ZLB -
Fabio A -
Fabio Azzarello
-
i8cvs -
Idle-Tyme -
Mateusz -
Nigel Gunn G8IFF/W8IFF -
Robert Bruninga -
tosca005＠umn.edu