Talk:Link budget

FSL Equation

FSL (dB) = 32.45 dB + 20*log[frequency(MHz)] + 20*log[distance(km)] FSL (dB) = 92.4 dB + 20*log[frequency(GHz)] + 20*log[distance(km)] FSL (dB) = 36.6 dB + 20*log[frequency(MHz)] + 20*log[distance(miles)]

Add By: e.Abdo Ballouk

FSL in meters

I disagree with this formula:

FSL (dB) = -27.55 dB + 20*log[frequency(MHz)] + 20*log[distance(m)]

it should read:

FSL (dB) = 29.45 dB + 20*log[frequency(MHz)] + 20*log[distance(m)] since log of 1000 (number of meters in a km) = 3.

Kgrr (talk) 14:06, 1 October 2008 (UTC)

The formula is correct. The formula, with lambda equal to c/f, is

FSPL = ((4 * pi * d * f)/c)^2

With d in meters, f in MHz (= 10^6) and c equal to 3 * 10^8, we obtain

FSPL = ((4 * pi * d * f * 1 * 10^6)/(3 * 10^8))^2 = ((4 * pi * d * f)/(3 * 10^2))^2 = (0.041887893 * d * f)^2

Expressing this in decibels gives us:

FSPL(dB) = 10 * log10(0.041887893 * d * f)^2 = 20 * log10(0.041887893 * d * f) = 20 * log10(d) + 20 * log10(f) - 27.56 dB

ParadiseLost711 (talk) 18:45, 4 January 2009 (UTC)

so for 100 meters at 2,400 Mhz using formula 1.

FSPL(dB) = 20*log[4*π*distance/wavelength] = 20 log [4π * 100 m / (300/2400)m ]

= 20 log (10053) = 80.5 dB

and for 100 meters at 2,400 Mhz using formula 2.

FSPL(dB) = 20 log (0.1 km) + 20 log (2400 mhz) + 32.45 dB = -20 + 67.60 + 32.45 = 80.05 dB

and for 100 meters at 2,400 Mhz using formula 3. (100 meters = 0.1 km)

FSPL(dB) = 20 log (100 m) + 20 log (2400 mhz) - 27.56 dB = 40 + 67.60 -27.56 = 80.04 dB

and for 0.0621 miles at 2,400 Mhz using formula 4. (100 meters = 0.0621 miles)

FSPL(dB) = 20 log (0.0621 mi) + 20 log (2400 mhz) + 36.6 dB = -24.14 + 67.60 + 36.6 = 80.05 dB

OK ... My bad. It checks.Kgrr (talk) 16:19, 5 January 2009 (UTC)

The link to "Point-to-Point Link budget calculator" is to http://www.ligowave.com/linkcalc/ which requires a login is there not free, and either that is noted, or removed. --144.243.4.103 (talk) 16:44, 28 June 2010 (UTC)

External links modified

Hello fellow Wikipedians,

I have just modified one external link on Link budget. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

• Added archive https://web.archive.org/web/20050901001655/http://people.deas.harvard.edu/~jones/es151/prop_models/propagation.html to http://people.deas.harvard.edu/~jones/es151/prop_models/propagation.html

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 5 June 2024).

• If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
• If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 11:48, 16 May 2017 (UTC)

Merge from Optical power budget

This topic could be handled as a new In optical communications section in this article. ~Kvng (talk) 14:24, 1 November 2024 (UTC)

Support. --Zac67 (talk) 15:21, 1 November 2024 (UTC)

Support. Kr0ndstat (talk) 00:07, 7 November 2024 (UTC)