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#21
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315mhz/433mhz transmitter
On 7/23/2012 12:30 PM, Jeff Liebermann wrote:
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. From the document you posted, P*G/(4*Pi*D^2) = E^2/(120*Pi) Let G = 1, D = 3, E = 200uV then P*1/(4*3.14*3*3) = (200e-6)^2/377 and P/113 = 40e-9/377 so that P = 113 * 106e-12 giving P = 12e-9 This looks like NANOwatts to me. |
#22
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315mhz/433mhz transmitter
On 7/23/2012 12:30 PM, Jeff Liebermann wrote:
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. Please show your work. |
#23
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315mhz/433mhz transmitter
On 7/23/2012 12:30 PM, Jeff Liebermann wrote:
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. Oh, I see. You used 100 MILLIvolts (not MICROvolts) in your calculation! That's how you wound up with MILLIwatts rather than (NANOwatts). |
#24
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315mhz/433mhz transmitter
On 7/23/2012 12:30 PM, Jeff Liebermann wrote:
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. Oh, I see. You used 200 MILLIvolts (not MICROvolts) in your calculation! That's how you wound up with MILLIwatts rather than (NANOwatts). |
#25
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315mhz/433mhz transmitter
On Mon, 23 Jul 2012 12:41:32 -0500, John S
wrote: From the document you posted, P*G/(4*Pi*D^2) = E^2/(120*Pi) Let G = 1, D = 3, E = 200uV then P*1/(4*3.14*3*3) = (200e-6)^2/377 and P/113 = 40e-9/377 so that P = 113 * 106e-12 giving P = 12e-9 This looks like NANOwatts to me. Well, that looks right. I'll do the short version: From Pg 29. http://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet63/oet63rev.pdf Assuming a 0dBi gain antenna: Power = 0.3 FS^2 where FS = field strength in Volts/meter P = Watts Plugging in: Power = 0.3 * (200 uV/m)^2 = 0.3 * (200*10^-6 V/m)^2 Power = 0.3 * 4*10^-8 = 12*10-9 = 12 nano watts. Argh... You're right. However, that can't be the correct maximum power. It's much too low to be useful. Digging out a cheat sheet from: http://www.ti.com/lit/an/swra090/swra090.pdf CEPT (European) 1e and 1e1 are 10mw and 1mw respectively. However, digging down to the FCC stuff on Pg 11, I find that the specs are really in FCC 15.231(b). http://louise.hallikainen.org/FCC/FccRules/2012/15/231/ and are approx 11,000 uV/meter. Grinding the numbers again... Assuming a 0dBi gain antenna: Power = 0.3 FS^2 where FS = field strength in Volts/meter P = Watts Plugging in: Power = 0.3 * (11000 uV/m)^2 = 0.3 * (11000*10^-6 V/m)^2 Power = 0.3 * 0.000121 = 36 milliwatts. Thanks for catching my mistake and I'll double check the numbers (again) when I get home from some service calls. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#26
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315mhz/433mhz transmitter
On 7/23/2012 4:03 PM, Jeff Liebermann wrote:
On Mon, 23 Jul 2012 12:41:32 -0500, John S wrote: From the document you posted, P*G/(4*Pi*D^2) = E^2/(120*Pi) Let G = 1, D = 3, E = 200uV then P*1/(4*3.14*3*3) = (200e-6)^2/377 and P/113 = 40e-9/377 so that P = 113 * 106e-12 giving P = 12e-9 This looks like NANOwatts to me. Well, that looks right. I'll do the short version: From Pg 29. http://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet63/oet63rev.pdf Assuming a 0dBi gain antenna: Power = 0.3 FS^2 where FS = field strength in Volts/meter P = Watts Plugging in: Power = 0.3 * (200 uV/m)^2 = 0.3 * (200*10^-6 V/m)^2 Power = 0.3 * 4*10^-8 = 12*10-9 = 12 nano watts. Argh... You're right. Thanks for that concession. However, that can't be the correct maximum power. It's much too low to be useful. Well, maybe. Digging out a cheat sheet from: http://www.ti.com/lit/an/swra090/swra090.pdf CEPT (European) 1e and 1e1 are 10mw and 1mw respectively. However, digging down to the FCC stuff on Pg 11, I find that the specs are really in FCC 15.231(b). http://louise.hallikainen.org/FCC/FccRules/2012/15/231/ and are approx 11,000 uV/meter. Grinding the numbers again... Yes, but you are reading only part of the regulations. These are PERIODIC radiators. Please read the whole thing and tell me how often and for what period you can transmit. Thanks for catching my mistake and I'll double check the numbers (again) when I get home from some service calls. Very well. Please point out the pertinent parts that allow this (undisclosed) mode of operation. |
#27
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315mhz/433mhz transmitter
On Mon, 23 Jul 2012 19:14:28 -0500, John S
wrote: However, digging down to the FCC stuff on Pg 11, I find that the specs are really in FCC 15.231(b). http://louise.hallikainen.org/FCC/FccRules/2012/15/231/ and are approx 11,000 uV/meter. Grinding the numbers again... Yes, but you are reading only part of the regulations. These are PERIODIC radiators. Please read the whole thing and tell me how often and for what period you can transmit. Ummm... let's set some ground rules first. With all due respect, if your interest is learning something about FCC rules-n-regs, how the stuff works, how to make it all play together, how to grind the numbers, and where to find pieces, I'll bust my posterior to supply you with direction and/or answers. However, if your intent is make me jump through hoops, burn my time, or supply information that you could easily excavate on your own, please find someone else to play your game. I don't mind being wrong, being told I'm clueless, or doing research. I do mind wasting my time. See the last paragraph of 15.231 http://louise.hallikainen.org/FCC/FccRules/2012/15/231/ In addition, devices operated under the provisions of this paragraph shall be provided with a means for automatically limiting operation so that the duration of each transmission shall not be greater than one second and the silent period between transmissions shall be at least 30 times the duration of the transmission but in no case less than 10 seconds. The method of modulation is not specified. Whatever modulation method is chosen must comply with 15.231(b)(3)(c) The bandwidth of the emission shall be no wider than 0.25% of the center frequency for devices operating above 70 MHz and below 900 MHz. For devices operating above 900 MHz, the emission shall be no wider than 0.5% of the center frequency. Bandwidth is determined at the points 20 dB down from the modulated carrier. At 433MHz, that yields about 1MHz bandwidth which is adequate for most anything between on-off keying to perhaps frequency hopping spread spectrum. Thanks for catching my mistake and I'll double check the numbers (again) when I get home from some service calls. Very well. Please point out the pertinent parts that allow this (undisclosed) mode of operation. Sorry, but undisclosed modes are by definition undefined and therefore not codified in the FCC rules-n-regs. -- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831-336-2558 # http://802.11junk.com # http://www.LearnByDestroying.com AE6KS |
#28
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315mhz/433mhz transmitter
On 7/23/2012 4:03 PM, Jeff Liebermann wrote:
On Mon, 23 Jul 2012 12:41:32 -0500, John S wrote: From the document you posted, P*G/(4*Pi*D^2) = E^2/(120*Pi) Let G = 1, D = 3, E = 200uV then P*1/(4*3.14*3*3) = (200e-6)^2/377 and P/113 = 40e-9/377 so that P = 113 * 106e-12 giving P = 12e-9 This looks like NANOwatts to me. Well, that looks right. I'll do the short version: From Pg 29. http://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet63/oet63rev.pdf Assuming a 0dBi gain antenna: Power = 0.3 FS^2 where FS = field strength in Volts/meter P = Watts Plugging in: Power = 0.3 * (200 uV/m)^2 = 0.3 * (200*10^-6 V/m)^2 Power = 0.3 * 4*10^-8 = 12*10-9 = 12 nano watts. Argh... You're right. However, that can't be the correct maximum power. It's much too low to be useful. Digging out a cheat sheet from: http://www.ti.com/lit/an/swra090/swra090.pdf CEPT (European) 1e and 1e1 are 10mw and 1mw respectively. However, digging down to the FCC stuff on Pg 11, I find that the specs are really in FCC 15.231(b). http://louise.hallikainen.org/FCC/FccRules/2012/15/231/ and are approx 11,000 uV/meter. Grinding the numbers again... Assuming a 0dBi gain antenna: Power = 0.3 FS^2 where FS = field strength in Volts/meter P = Watts Plugging in: Power = 0.3 * (11000 uV/m)^2 = 0.3 * (11000*10^-6 V/m)^2 Power = 0.3 * 0.000121 = 36 milliwatts. ..3 * .000121 = .000036 or 36 MICROwatts. Thanks for catching my mistake and I'll double check the numbers (again) when I get home from some service calls. You're welcome again. |
#29
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315mhz/433mhz transmitter
On 7/23/2012 10:38 PM, Jeff Liebermann wrote:
On Mon, 23 Jul 2012 19:14:28 -0500, John S wrote: However, digging down to the FCC stuff on Pg 11, I find that the specs are really in FCC 15.231(b). http://louise.hallikainen.org/FCC/FccRules/2012/15/231/ and are approx 11,000 uV/meter. Grinding the numbers again... Yes, but you are reading only part of the regulations. These are PERIODIC radiators. Please read the whole thing and tell me how often and for what period you can transmit. Ummm... let's set some ground rules first. With all due respect, if your interest is learning something about FCC rules-n-regs, how the stuff works, how to make it all play together, how to grind the numbers, and where to find pieces, I'll bust my posterior to supply you with direction and/or answers. However, if your intent is make me jump through hoops, burn my time, or supply information that you could easily excavate on your own, please find someone else to play your game. I don't mind being wrong, being told I'm clueless, or doing research. I do mind wasting my time. Your condescending attitude is noted. See the last paragraph of 15.231 http://louise.hallikainen.org/FCC/FccRules/2012/15/231/ In addition, devices operated under the provisions of this paragraph shall be provided with a means for automatically limiting operation so that the duration of each transmission shall not be greater than one second and the silent period between transmissions shall be at least 30 times the duration of the transmission but in no case less than 10 seconds. This paragraph is part of paragraph (e) which allows only 260-470 1,500 to 5,000^1 150 to 500^1 ^1Linear interpolations. so that, with interpolation to 433, it works out to about 4383 uV/m. This, then, allows .3*(4383e-6)^2 or about 5.76 microwatts for 1 second out of every 30 seconds. Or, for 1/3 second out of every 10 seconds, but never more frequently. Thanks for catching my mistake and I'll double check the numbers (again) when I get home from some service calls. You're welcome (again). |
#30
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315mhz/433mhz transmitter
On 7/23/2012 11:21 AM, Jeff Liebermann wrote:
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. Well, I can't argue with the fact that they are being produced. If they really meet the FCC regulations, I have been unable to prove it. I have looked all over the FCC site under part 15 and never found an area that allows such power. If you ever find it, I would appreciate a link to it. |
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