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#11
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315mhz/433mhz transmitter
On Mon, 23 Jul 2012 00:08:53 +0000, foxbrain
wrote: BTW i'm making a project for my own not any kind of homework. Ok, you're off the hook. i have one more question : if i wanted to make my device have a bigger range like 500-1000meters should i put an amplifer before the antenna? i should change the antenna in to yagi shouldn't i? FCC 15.209 http://louise.hallikainen.org/FCC/FccRules/2012/15/209/ 200 uv/meter maximum, measured at 3 meters. That works out to about -46dBm ERP or about 12 milliwatts into a unity gain antenna. This should explain how it all works: http://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet63/oet63rev.pdf See the calcs on Pg 29. Claims 500 meters: http://www.sparkfun.com/products/155 At 10mw, this is close to maximum legal. Anything more than that and you're going to start interfering with wireless weather stations, car alarms, etc. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#12
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315mhz/433mhz transmitter
On Sun, 22 Jul 2012 23:21:12 -0700, Jeff Liebermann
wrote: FCC 15.209 http://louise.hallikainen.org/FCC/FccRules/2012/15/209/ 200 uv/meter maximum, measured at 3 meters. That works out to about -46dBm ERP or about 12 milliwatts into a unity gain antenna. Sorry, brain damage. The -46dBm should be 10.8dBm ERP -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#13
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so depending on the equation in :
http://transition.fcc.gov/Bureaus/En...3/oet63rev.pdf i should make the power the much larger i can but not more than 10mw and so for the gain , and decrease the E (v/meter).... thanks |
#14
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315mhz/433mhz transmitter
On 7/23/2012 1:28 AM, Jeff Liebermann wrote:
On Sun, 22 Jul 2012 23:21:12 -0700, Jeff Liebermann wrote: FCC 15.209 http://louise.hallikainen.org/FCC/FccRules/2012/15/209/ 200 uv/meter maximum, measured at 3 meters. That works out to about -46dBm ERP or about 12 milliwatts into a unity gain antenna. Sorry, brain damage. The -46dBm should be 10.8dBm ERP Hmmm... my calculator says P = 12 nanowatts. |
#15
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315mhz/433mhz transmitter
John S wrote:
On 7/23/2012 1:28 AM, Jeff Liebermann wrote: On Sun, 22 Jul 2012 23:21:12 -0700, Jeff Liebermann wrote: FCC 15.209 http://louise.hallikainen.org/FCC/FccRules/2012/15/209/ 200 uv/meter maximum, measured at 3 meters. That works out to about -46dBm ERP or about 12 milliwatts into a unity gain antenna. Sorry, brain damage. The -46dBm should be 10.8dBm ERP Hmmm... my calculator says P = 12 nanowatts. That is wrong, 10mW ERP is what these lowpower devices are allowed to transmit. |
#16
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315mhz/433mhz transmitter
On 7/23/2012 9:12 AM, Rob wrote:
John S wrote: On 7/23/2012 1:28 AM, Jeff Liebermann wrote: On Sun, 22 Jul 2012 23:21:12 -0700, Jeff Liebermann wrote: FCC 15.209 http://louise.hallikainen.org/FCC/FccRules/2012/15/209/ 200 uv/meter maximum, measured at 3 meters. That works out to about -46dBm ERP or about 12 milliwatts into a unity gain antenna. Sorry, brain damage. The -46dBm should be 10.8dBm ERP Hmmm... my calculator says P = 12 nanowatts. That is wrong, 10mW ERP is what these lowpower devices are allowed to transmit. If so, then more than 200uV/m is allowed. Do the calculation as Jeff supplied: quote This should explain how it all works: http://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet63/oet63rev.pdf See the calcs on Pg 29. /quote |
#17
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315mhz/433mhz transmitter
On Mon, 23 Jul 2012 08:56:41 -0500, John S
wrote: On 7/23/2012 1:28 AM, Jeff Liebermann wrote: On Sun, 22 Jul 2012 23:21:12 -0700, Jeff Liebermann wrote: FCC 15.209 http://louise.hallikainen.org/FCC/FccRules/2012/15/209/ 200 uv/meter maximum, measured at 3 meters. That works out to about -46dBm ERP or about 12 milliwatts into a unity gain antenna. Sorry, brain damage. The -46dBm should be 10.8dBm ERP Hmmm... my calculator says P = 12 nanowatts. Your calculator is correct. My -46dBm is wrong. It was late, I was multitasking, the phone range, I was tired, etc. Sorry for the muddle. +10.8dBm converts to 12 mw. http://www.rapidtables.com/convert/power/dBm_to_mW.htm Then... I find a 433MHz radio that delivers +20dBm (100mw). http://www.sparkfun.com/products/10153 By my reading of 15.209, that's overpowered unless operating with a miserable -9dB gain antenna. From the manufacturers web pile at: http://www.hoperf.com/rf_fsk/ they offer +10, +13, and +20dBm outputs and claim they all meet ETSI and FCC regs. I dunno about that. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#18
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315mhz/433mhz transmitter
On 7/23/2012 11:21 AM, Jeff Liebermann wrote:
On Mon, 23 Jul 2012 08:56:41 -0500, John S wrote: On 7/23/2012 1:28 AM, Jeff Liebermann wrote: On Sun, 22 Jul 2012 23:21:12 -0700, Jeff Liebermann wrote: FCC 15.209 http://louise.hallikainen.org/FCC/FccRules/2012/15/209/ 200 uv/meter maximum, measured at 3 meters. That works out to about -46dBm ERP or about 12 milliwatts into a unity gain antenna. Sorry, brain damage. The -46dBm should be 10.8dBm ERP Hmmm... my calculator says P = 12 nanowatts. Your calculator is correct. My -46dBm is wrong. It was late, I was multitasking, the phone range, I was tired, etc. Sorry for the muddle. +10.8dBm converts to 12 mw. 12 nw is -49 dBm. Why are you still using 12 mw? http://www.rapidtables.com/convert/power/dBm_to_mW.htm Then... I find a 433MHz radio that delivers +20dBm (100mw). http://www.sparkfun.com/products/10153 By my reading of 15.209, that's overpowered unless operating with a miserable -9dB gain antenna. The antenna would have to have -69 dB gain for 100 mw to radiate 12 NANOwatts. From the manufacturers web pile at: http://www.hoperf.com/rf_fsk/ they offer +10, +13, and +20dBm outputs and claim they all meet ETSI and FCC regs. I dunno about that. I don't either. This is a question I've had for years. |
#19
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315mhz/433mhz transmitter
On Mon, 23 Jul 2012 12:53:12 +0000, foxbrain
wrote: so depending on the equation in : http://tinyurl.com/c86y6q6 i should make the power the much larger i can but not more than 10mw and so for the gain , and decrease the E (v/meter).... Not exactly. When adding a bigger antenna, you will need to decrease the transmit power to keep the field strength (V/meter) constant. For example, assume that +12dBm tx power and 0dBm (unity) gain antenna is the maximum legal. If you replace the unity gain antenna with an +8dBi gain yagi, you will need to reduce the transmit power down to +4dBm output to stay withint the maximum field strength requirement. Note that you can calculate your maximum range if you know the various numbers. http://wireless.navas.us/index.php?title=Wi-Fi#Link_Calculations http://www.terabeam.com/support/calculations/som.php -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#20
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315mhz/433mhz transmitter
On Mon, 23 Jul 2012 11:54:01 -0500, John S
wrote: On 7/23/2012 11:21 AM, Jeff Liebermann wrote: On Mon, 23 Jul 2012 08:56:41 -0500, John S wrote: On 7/23/2012 1:28 AM, Jeff Liebermann wrote: On Sun, 22 Jul 2012 23:21:12 -0700, Jeff Liebermann wrote: FCC 15.209 http://louise.hallikainen.org/FCC/FccRules/2012/15/209/ 200 uv/meter maximum, measured at 3 meters. That works out to about -46dBm ERP or about 12 milliwatts into a unity gain antenna. Sorry, brain damage. The -46dBm should be 10.8dBm ERP Hmmm... my calculator says P = 12 nanowatts. Your calculator is correct. My -46dBm is wrong. It was late, I was multitasking, the phone range, I was tired, etc. Sorry for the muddle. +10.8dBm converts to 12 mw. 12 nw is -49 dBm. Why are you still using 12 mw? The 12mw is correct. The -46dBm was my mistake. It should have been about +10.8dBm. http://www.rapidtables.com/convert/power/dBm_to_mW.htm Then... I find a 433MHz radio that delivers +20dBm (100mw). http://www.sparkfun.com/products/10153 By my reading of 15.209, that's overpowered unless operating with a miserable -9dB gain antenna. The antenna would have to have -69 dB gain for 100 mw to radiate 12 NANOwatts. Nope. Use 12 milliwatts or 10.8dBm please. Loose the -46/49dBm. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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