Date post: | 06-Apr-2018 |
Category: |
Documents |
Upload: | subrata-saha |
View: | 225 times |
Download: | 0 times |
of 25
8/3/2019 Austein Concept
1/25
Tuned Radio Frequency
Superheterodyning
Cell Phones
SuperheterodyningHow Radios and Cell Phones Tune to Varying Frequencies
Matthew Goldstein, KB1NCS
MIT UHF/VHF Repeater Association
October 16, 2008
Matthew Goldstein Superheterodyning
http://goforward/http://find/http://goback/8/3/2019 Austein Concept
2/25
Tuned Radio Frequency
Superheterodyning
Cell Phones
Theory
Example
Problem
How to Tune to a Station
Start with an antennaElectronic "Filters" can select frequency ranges
Amplify the result
Repeat until you have just your station
100.6 100.7 100.8 100.9 101 101.1 101.2 101.3 101.4 101.50
5
10
15
20
25
30
35
40
45
50
Frequency (MHz)
Filters applied to a signal
Matthew Goldstein Superheterodyning
http://find/http://goback/8/3/2019 Austein Concept
3/25
Tuned Radio Frequency
Superheterodyning
Cell Phones
Theory
Example
Problem
How to Tune to a Station
Start with an antennaElectronic "Filters" can select frequency ranges
Amplify the result
Repeat until you have just your station
100.6 100.7 100.8 100.9 101 101.1 101.2 101.3 101.4 101.50
5
10
15
20
25
30
35
40
45
50
Frequency (MHz)
Filters applied to a signal
Matthew Goldstein Superheterodyning
http://find/http://goback/8/3/2019 Austein Concept
4/25
Tuned Radio Frequency
Superheterodyning
Cell Phones
Theory
Example
Problem
How to Tune to a Station
Start with an antennaElectronic "Filters" can select frequency ranges
Amplify the result
Repeat until you have just your station
100.6 100.7 100.8 100.9 101 101.1 101.2 101.3 101.4 101.50
10
20
30
40
50
60
70
80
90
100
Frequency (MHz)
Filters applied to a signal
Matthew Goldstein Superheterodyning
http://find/http://goback/8/3/2019 Austein Concept
5/25
Tuned Radio Frequency
Superheterodyning
Cell Phones
Theory
Example
Problem
How to Tune to a Station
Start with an antennaElectronic "Filters" can select frequency ranges
Amplify the result
Repeat until you have just your station
100.6 100.7 100.8 100.9 101 101.1 101.2 101.3 101.4 101.50
10
20
30
40
50
60
70
80
90
100
Frequency (MHz)
Filters applied to a signal
Matthew Goldstein Superheterodyning
T d R di F Th
http://find/http://goback/8/3/2019 Austein Concept
6/25
Tuned Radio Frequency
Superheterodyning
Cell Phones
Theory
Example
Problem
How to Tune to a Station
Start with an antennaElectronic "Filters" can select frequency ranges
Amplify the result
Repeat until you have just your station
100.6 100.7 100.8 100.9 101 101.1 101.2 101.3 101.4 101.50
10
20
30
40
50
60
70
80
90
100
Frequency (MHz)
Filters applied to a signal
Matthew Goldstein Superheterodyning
T d R di F Th
http://find/http://goback/8/3/2019 Austein Concept
7/25
Tuned Radio Frequency
Superheterodyning
Cell Phones
Theory
Example
Problem
A Tuning Example
Matthew Goldstein Superheterodyning
Tuned Radio Frequency Theory
http://find/http://goback/8/3/2019 Austein Concept
8/25
Tuned Radio Frequency
Superheterodyning
Cell Phones
Theory
Example
Problem
A Tuning Example
Matthew Goldstein Superheterodyning
Tuned Radio Frequency Theory
http://find/http://goback/8/3/2019 Austein Concept
9/25
Tuned Radio Frequency
Superheterodyning
Cell Phones
Theory
Example
Problem
A Tuning Example
Matthew Goldstein Superheterodyning
Tuned Radio Frequency Theory
http://find/http://goback/8/3/2019 Austein Concept
10/25
Tuned Radio Frequency
Superheterodyning
Cell Phones
Theory
Example
Problem
A Tuning Example
Matthew Goldstein Superheterodyning
Tuned Radio Frequency Theory
http://find/http://goback/8/3/2019 Austein Concept
11/25
Tuned Radio Frequency
Superheterodyning
Cell Phones
Theory
Example
Problem
A Tuning Example
Matthew Goldstein Superheterodyning
Tuned Radio Frequency Theory
http://find/http://goback/8/3/2019 Austein Concept
12/25
Tuned Radio Frequency
Superheterodyning
Cell Phones
Theory
Example
Problem
A Tuning Example
Matthew Goldstein Superheterodyning
Tuned Radio Frequency Theory
http://find/http://goback/8/3/2019 Austein Concept
13/25
q y
Superheterodyning
Cell Phones
y
Example
Problem
A Tuning Example
Matthew Goldstein Superheterodyning
Tuned Radio Frequency Theory
http://find/http://goback/8/3/2019 Austein Concept
14/25
q y
Superheterodyning
Cell Phones
y
Example
Problem
A Tuning Example
Matthew Goldstein Superheterodyning
Tuned Radio Frequency Theory
http://find/http://goback/8/3/2019 Austein Concept
15/25
Superheterodyning
Cell Phones
Example
Problem
A Tuning Example
Matthew Goldstein Superheterodyning
http://find/http://goback/8/3/2019 Austein Concept
16/25
Tuned Radio Frequency
S h d i
Theory
E l
8/3/2019 Austein Concept
17/25
Superheterodyning
Cell Phones
Example
Problem
What if we Change Frequencies?
Have to adjust every FilterFilters change selection range
If only the frequency to the Filters never changed
Matthew Goldstein Superheterodyning
Tuned Radio Frequency
S h t d i
Theory
E l
http://find/http://goback/8/3/2019 Austein Concept
18/25
Superheterodyning
Cell Phones
Example
Problem
What if we Change Frequencies?
Have to adjust every FilterFilters change selection range
If only the frequency to the Filters never changed
Matthew Goldstein Superheterodyning
Tuned Radio Frequency
SuperheterodyningTheory
http://find/http://goback/8/3/2019 Austein Concept
19/25
Superheterodyning
Cell Phones
y
FM Example
How to Move the Frequencies
Superheterodyning - Mixing
Vacuum Tubes and Transistors Mix FrequenciesProduce Sum and Difference Frequencies
Generate a Local Frequency with Constant Offset
Filter the Mixed Difference
Matthew Goldstein Superheterodyning
Tuned Radio Frequency
SuperheterodyningTheory
http://find/http://goback/8/3/2019 Austein Concept
20/25
Superheterodyning
Cell PhonesFM Example
How to Move the Frequencies
Superheterodyning - Mixing
Vacuum Tubes and Transistors Mix FrequenciesProduce Sum and Difference Frequencies
Generate a Local Frequency with Constant Offset
Filter the Mixed Difference
Matthew Goldstein Superheterodyning
Tuned Radio FrequencySuperheterodyning
Theory
http://find/http://goback/8/3/2019 Austein Concept
21/25
Superheterodyning
Cell PhonesFM Example
How to Move the Frequencies
Superheterodyning - Mixing
Vacuum Tubes and Transistors Mix FrequenciesProduce Sum and Difference Frequencies
Generate a Local Frequency with Constant Offset
Filter the Mixed Difference
Matthew Goldstein Superheterodyning
Tuned Radio FrequencySuperheterodyning
Theory
http://find/http://goback/8/3/2019 Austein Concept
22/25
Superheterodyning
Cell PhonesFM Example
What does this give us?
Lets Tune again to 101.1
Only have to set Local Frequency to 90.4
Filters are already tuned to 10.7
Matthew Goldstein Superheterodyning
Tuned Radio FrequencySuperheterodyning
Theory
FM E l
http://find/http://goback/8/3/2019 Austein Concept
23/25
Superheterodyning
Cell PhonesFM Example
What does this give us?
Lets Tune again to 101.1
Only have to set Local Frequency to 90.4
Filters are already tuned to 10.7
Matthew Goldstein Superheterodyning
Tuned Radio FrequencySuperheterodyning Processing High Frequencies
http://find/http://goback/8/3/2019 Austein Concept
24/25
p y g
Cell Phones
g g q
Cell Phone Processors
Cell phone signal frequencies are around 2GHz
Fast processors are expensiveTo makeLower battery life
Matthew Goldstein Superheterodyning
Tuned Radio FrequencySuperheterodyning Processing High Frequencies
http://find/http://goback/8/3/2019 Austein Concept
25/25
p y g
Cell Phones
g g q
How Superheterodyning Helps
It is often impractical to use frequencies as they are given.
Particularly when they move or are too high
Superheterodyning pretends you were given something else
Matthew Goldstein Superheterodyning
http://find/http://goback/