This document defines and discusses various types of radio frequency (RF) interference. It begins by defining interference as the combination of two or more electromagnetic waveforms that results in a strengthened or cancelled signal. It then discusses specific types of RF phenomena that can cause interference, such as harmonics, noise floor, impulse noise, and passive inter-modulations. Sources of both short-range and long-range interference are identified. Methods for hunting down interference through monitoring with a spectrum analyzer are outlined. Finally, the document discusses how isolation techniques can resolve interference issues, including frequency isolation, physical isolation, and using various types of filters.

1. RF INTERFERENCE
SIMPLIFIED!
OPEYEMI PRAISE

2. CONTENT
• WHAT IS INTERFERENCE?
• RF PHENOMENA
A. NOISE FLOOR
B. HARMONICS
C. IMPULSE NOISE
C. PIM – PASSIVE INTER-MODULATIONS
D. NEAR AND FAR PROBLEM (TERRESTRIAL TELECOM NETWORK)
E. INTERNATIONAL INTERFERENCE (DSO, HUMANS HAVE GEOGRAPHICAL BORDERS, SIGNALS
DON’T)
• INTERFERENCE SOURCES
• HUNTING INTERFERENCE – INTERFERENCE MECHANISMS
• ISOLATION, THE OPPOSITE OF INTERFERENCE

3. WHAT IS INTERFERENCE?
• THE COMBINATION OF TWO OR MORE ELECTROMAGNETIC WAVEFORMS TO
FORM A RESULTANT WAVE IN WHICH THE DISPLACEMENT IS EITHER REINFORCED
OR CANCELLED.
• WHEN YOU HAVE UNWANTED SIGNALS COMBINING WITH YOUR INTELLIGENT
SIGNAL, YOU HAVE INTERFERENCE.
• USUALLY THE RESULTANT SIGNAL (YOUR SIGNAL + INTERFERING SIGNAL) IS
STRONGER!

4. HARMONICS
• HARMONICS ARE MULTIPLES OF AN RF CARRIER. FOR
INSTANCE, IF WE HAD A TRANSMITTER AT 100 MHZ, IT
MIGHT HAVE HARMONICS AT 200 MHZ, 300 MHZ, 400 MHZ,
500 MHZ, AND SO ON. TYPICALLY, THE ODD NUMBERED
HARMONICS (300 MHZ, 500 MHZ AND SO ON) ARE
STRONGER THAN THE EVEN HARMONICS. GOVERNING
BODIES NORMALLY REGULATE THE POWER LEVEL OF
HARMONICS. HOWEVER EQUIPMENT DOES FAIL OR GO OUT
OF SPECIFICATION.
• MOST RF SYSTEMS HAVE ACCEPTABLE LEVELS OF
HARMONICS – HARMONICS IS THE REASON YOU MIGHT
INTERFERE WITH A SYSTEM OUTSIDE YOUR BAND. THEY ARE
ALSO CONTRIBUTORS TO HIGH NOISE FLOORS.
• IF THE ORIGINAL BROADCAST IS AT A HIGH POWER LEVEL,
EVEN LEGAL HARMONICS CAN BE POWERFUL ENOUGH TO
CAUSE PROBLEMS.

5. NOISE AND NOISE FLOOR
• NOISE IS DEFINED AS ANY SIGNAL OTHER THAN THE ONE BEING MONITORED
• THE NOISE FLOOR IS THE MEASURE OF THE SIGNAL CREATED FROM THE SUM OF
ALL THE NOISE SOURCES AND UNWANTED SIGNALS WITHIN A BAND.

6. IMPULSE NOISE
• IMPULSE NOISE IS CREATED WHENEVER A FLOW OF ELECTRICITY IS ABRUPTLY
STARTED OR STOPPED. A SURPRISING VARIETY OF ITEMS CAN CREATE IMPULSE
NOISE:
• ELECTRICAL MOTORS FROM ELEVATORS, FLOOR BUFFERS OR EVEN FAX
MACHINES
• BAKERY OVENS
• WELDING
• ELECTRIC FENCES
• POWER LINES, WHICH MAY ARC AND SPARK
• LIGHT DIMMERS
• MOVING VEHICLES

7. PIM – PASSIVE INTER-MODULATIONS
• IT IS CAUSED WHEN TWO OR MORE STRONG RF SIGNALS COMBINE IN SOME
SORT OF NON-LINEAR DEVICE, SUCH AS A TRANSISTOR, DIODE, OR EVEN THE
CRYSTALS FOUND IN CORROSION OR RUST.
• IT’S ALSO POSSIBLE THAT LOOSE CONNECTORS IN AN ANTENNA FEED LINE OR
POORLY CONFIGURED TRANSMITTERS CAN BE THE CAUSE.

8. NEAR AND FAR PROBLEM (TERRESTRIAL TELECOM
NETWORK)
• WHY WE DO NOT INSTALL UE CLOSE TO THE BASE STATION.
• SELF-INTERFERENCE FROM CONNECTED DEVICES CAN OCCUR DEPENDING ON
THE DISTANCE FROM THE BASE STATION.

9. INTERNATIONAL INTERFERENCE
• HUMANS HAVE GEOGRAPHICAL BORDERS, ELECTROMAGNETIC SIGNALS DON’T.
TV/RADIO STATION MAY LIKELY ENTER INTO SEME, BENIN REPUBLIC.
• HENCE, ITU REGULATE INTERNATIONAL INTERFERENCE.
• REASON WHY DSO (DIGITAL SWITCH-OVER OF TV STATION) MIGRATION IS AN
INTERNATIONAL THING.

10. INTERFERENCE SOURCES
• SHORT-RANGE INTERFERENCE SOURCE

11. INTERFERENCE SOURCES
• LONG-RANGE INTERFERENCE SOURCE
1. TV STATIONS
2. BASE STATIONS
3. STRANGE TOWERS WITH RADIO
4. RADIO STATIONS
5. SATELLITE HUB
6. VSAT ANTENNAS

12. HUNTING INTERFERENCE – INTERFERENCE
MECHANISMS
• MONITOR THE SYSTEM (SPECTRUM ANALYZER) TO
ASCERTAIN EXISTENCE OF INTERFERENCE
• KNOW YOUR FREQUENCY, YOUR BANDWIDTH AND AN
IDEA OF SIGNAL STRENGTH WITHIN YOUR BAND.
MONITOR THAT!
• GET YOUR SPECTRUM ANALYZER, CONNECT IT A
DIRECTIONAL ANTENNA.
• SIGNAL LEVEL INCREASES IN THE DIRECTION OF THE
INTERFERENCE SOURCE.

13. HUNTING INTERFERENCE – INTERFERENCE
MECHANISMS
• IF IT IS LONG DISTANCE SOURCE, START BY USING OMNI-DIRECTION ANTENNA.
• WHEN YOU HAVE LOCATED AN AREA OF STRONG SIGNAL LEVEL, USE
DIRECTIONAL ANTENNA TO LOCATE THE EXACT SOURCE.

14. ISOLATION, THE OPPOSITE OF INTERFERENCE
• INTERFERENCE IS RESOLVED BY THE FOLLOWING;
• 1. FREQUENCY ISOLATION – MOVE TO A DIFFERENT FREQUENCY
• 2. PHYSICAL ISOLATION – ADJUST THE TWO SYSTEMS TO HAVE EITHER
VERTICAL SPACING OR HORIZONTAL SPACING OR BOTH.
• 3. SHUT-DOWN ROGUE TRANSMITTER
• 4. FILTERS
A. BAND PASS FILTERS
B. BAND REJECT FILTERS
C. HIGH PASS FILTERS
D. LOW PASS FILTERS

15. A CASE STUDY OR
QUESTIONS
INTERFERENCE ISSUE WITH GOVERNMENT AGENCY

16. THANK YOU