Amateur Radio Association of Nebraska
Amateur Radio News, Events and Information If you love Amateur Radio, this is the place for you.

January 23, 2018, 11:03:55 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length

News Alert: Notice:  The next meeting is January 17th, 2018 at Central Community College Dawson Building Room 132.  See Forum for More Information.  Notice:  Meeting will be at 7:30pm!!
 

Amateur Radio Association of Nebraska
Pages: [1]   Go Down
  Print  
Author Topic: NOISE BLANKERS/NEW AND OLD  (Read 3670 times)
K0YNE
IRLP Admin
Jr. Member
*
Offline Offline

Posts: 50


View ProfileK0YNE1959
« on: April 24, 2009, 11:12:50 AM »

BACK IN THE OLD DAYS, PROBABLY JUST TWO  OR THREE DECADES AGO, NOISE BLANKERS WERE
PRIMARILY DESIGNED TO ELIMINATE OR REDUCE THE EFFECTS FROM SPARK PLUG NOISE. FORD
VEHICLES WERE EXTREMELY BAD ABOUT SPARK PLUG INTERFERENCE IN MOBILE HAM RADIOS.
IN THOSE DAYS, THE NOISE BLANKER WAS GENERALLY FIXED AS TO THE TIME LENGTH OF THE SPARK.
THE NOISE BLANKER WAS FOUND IN THE AUDIO CHAIN AND COULD HAVE BEEN AFTER DETECTION.
THESE WERE GOOD TO EXCELLENT NOISE CANCELLING CIRCUITS, SO AN OPERATOR COULD ELIMINATE OR GREATLY REDUCE THE POP OF THE SPARK IN THE SPEAKER.
 IN LATER YEARS, THE CIRCUIT WAS MOVED FROM THE AUDIO AREA AND EMPLOYED NEAR THE RF AND MIXER STAGES, THUS REDUCING OR ELIMINATING SPARK PLUG NOISE AND OTHER LESS COMPLEX NOISE WAVE FORMS WITH ADJUSTMENTS TO SHORTEN OR LENGTHEN THE NOISE'S TIME PERIOD.  THIS WAS AND IS
NOW MUCH MORE BENEFICIAL , BECAUSE NOW THE DISRUPTING INTERFERENCE CAN BE REMOVED AND
THE "IF" AMPLIFIERS CAN RECOVER THE GAIN WITHIN THE CHAIN. AT THIS POINT THE AGC (AUTOMATIC GAIN CONTROL) WON'T BE MASKED BY THE ENGINES POPPING NOISE FROM SPARK PLUGS AND THE AGC CAN RESUME ITS RISE AND FALL WITHIN THE BAND PASS AND ALLOW GAIN THRU THE AMPS TO AMPLIFY WEAK SIGNALS AGAIN OR LOWER THE GAIN ON STRONG SIGNALS.

THE CIRCUITRY IS SIMILAR TO THE "GREEN SCREEN TECHNOLOGY"  WHEN SIGNALS ENTER THE RF AMP AND MIXER CIRCUITS TO BE PASSED DOWN THRU THE "IF" (INTERMEDIATE FREQUENCY) CHAIN , AND IF THERE IS A SPARK PLUG INTERFERING FOR EXAMPLE, THEN AS IT LEAVES THE RF AMP AND INTO THE MIXER, THE IF SIGNAL IS SAMPLED AND PASSED THRU AN INVERTER STAGE. THE INVERTER STAGE KEEPS THE AMPLITUDE OF THE INVERTED SIGNAL AND 180 DEGREES OUT OF PHASE  AS THE SIGNAL IS FOUND TRAVELING DOWN THE IF BANDPASS. SINCE THE SAMPLED INVERTED NOISE PULSE WILL BE BEHIND
IN "TIME" COMPARED TO THE SIGNAL IN THE BANDPASS OF THE "IF". A SLIGHT DELAY WILL HAVE TO
BE PLACED IN THE BAND PASS OF THE "IF" AT THE POINT WHERE THESE TWO SIGNALS THAT ARE 180
DEGREES OUT OF PHASE WITH EACH OTHER, BUT AT THE SAME AMPLITUDE AS EACH OTHER.
WHEN THE TWO ARE REJOINED ALONG THE "IF" BANDPASS CHAIN, THE TWO SIGNALS MET AND THE
180 DEGREE DIFFERENCE PROVIDED A CANCELLATION OF THE OFFENDING "POP" OF THE SPARK PLUGS.
PAUL K0YNE
 
Logged
Amateur Radio Association of Nebraska
   

 Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  



Explore ARAN ....
*
Website Search  
Call Sign Search
Resources

Calendar, Gallery, Links, IRLP Node Status, Help, Search, Bookstore, Classes/Training, Education, Account Signup, Membership Brochure, IRLP Information, Member Roster

Forums

General Category, -Web Site News -General Discussion -ARAN News -ARAN Member Information -Public Service -IRLP (Internet Radio Linking Project) -Repeaters Classifieds, -For Sale -Wanted Education, -Ham Classes/Licensing -Other Training On The Workbench, -Amps -Radios -Boat Anchors -DXing -Antennas -Contesting -Digital -Computers -Electronics

Login, Register
ARAN, Amateur Radio Association of Nebraska
1417 W. 4th St.
Hastings, NE 68901


Contact ARAN
Join ARAN
Sitemap


View Our Stats
Powered by MySQL Powered by PHP © 2010 Amateur Radio Association of Nebraska
Powered by SMF 1.1.20 | SMF © 2013, Simple Machines
Valid XHTML 1.0! Valid CSS!
SimplePortal 2.3.2 © 2008-2010, SimplePortal