Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes Calculators Education Engineering magazine articles Engineering software Engineering smorgasbord RF Cafe Archives RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising RF Cafe Forums Magazine USAF Radr Shop Sponsor RF Cafe RF Electronics Symbols for Visio RF Electronics Symbols for Office Word RF Electronics Stencils for Visio Thank you for visiting RF Cafe!
Copper Mountain Technologies (VNA) - RF Cafe
Berkeley Nucleonics Phase Noise Testing Seminar - RF Cafe
 

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024

Webmaster:

    Kirt Blattenberger,

    BSEE - KB3UON

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website:

AirplanesAndRockets.com

RF Electronics Shapes, Stencils for Office, Visio by RF Cafe

Receiver sensitivity with temperature - RF Cafe Forums

RF Cafe Forums closed its virtual doors in 2012 mainly due to other social media platforms dominating public commenting venues. RF Cafe Forums began sometime around August of 2003 and was quite well-attended for many years. By 2010, Facebook and Twitter were overwhelmingly dominating online personal interaction, and RF Cafe Forums activity dropped off precipitously. Regardless, there are still lots of great posts in the archive that ware worth looking at. Below are the old forum threads, including responses to the original posts.

-- Amateur Radio

-- Anecdotes, Gripes, & Humor

-- Antennas

-- CAE, CAD, & Software

-- Circuits & Components

-- Employment & Interviews

-- Miscellany

-- Swap Shop

-- Systems

-- Test & Measurement

-- Webmaster

Patrikc
 Post subject: Receiver sensitivity with temperature
Posted: Fri Nov 16, 2007 6:38 am 
 
Lieutenant

Joined: Fri Nov 16, 2007 5:06 am

Posts: 1

Hi ALL,

We have a debate in my company on how to calculate the receiver sensitivity with temperature.

Sensi = kTB + NF + C/N

C/N is demodulator requirement, and does not vary with temperature for a digital implementation

NF is the noise figure, and is referenced to 290K according IEEE standard (Friis proposed this temperature in 1944). NF varies with temperature of course.

My point is that, when you compute the sensitivity at different temperature, the "T" of kTB should remain equal to 290K, otherwise you account twice for the thermal noise change, once in the NF, and once in kTB.

What is your opinion on that?

Cheers, Patrikc


 
   
 
jaslovkel
 Post subject:
Posted: Fri Nov 16, 2007 2:42 pm 
 
Captain
User avatar

Joined: Tue Jun 26, 2007 10:27 am

Posts: 21

Location: Dallas, TX

Hi Patrikc,

Here is my take on the issue at hand.

Looking at the equation

Pin_mds(dB)=kT(dBm/Hz)+NF(dB)+B(dBHz)+C/N(dB)

we must first note that the bandwidth and the required C/N at the input of the demodulator usually do not change with temperature. Therefore, the only two terms which are in question are the NF and Pin_mds(or sensitivity). The NF is defined as the SNR(dB) at the input of the system minus the SNR(dB) at the output of the system. The NF may also be derived from a total integrated input referred voltage noise relative to the voltage noise produced by the source resistance (typically 50 Ohm). In the latter case, the integrated input referred noise does change with temperature, but the reference voltage noise is still calculated using the 290K number (~0.895nV/sqrt(Hz) for 50 Ohm @290K). Therefore, the NF does increase with temperature.

The term kT may be assumed only if the input impedance of the system is matched to the source resistance. This term should also be treated as a constant much like the noise of the source resistance. Then, the input referred voltage noise of the system will account for the noise floor variation inherently because of the kT noise associated with it.

In short, you are correct in your statement.

-J

Posted  11/12/2012

Triad RF Systems Amplifiers - RF Cafe
RF Cafe Sponsors
withwave microwave devices - RF Cafe
ConductRF Phased Matched RF Cables - RF Cafe

Please Support RF Cafe by purchasing my  ridiculously low−priced products, all of which I created.

These Are Available for Free