2. about.me
• Born in Kaohsiung, 1994
• FHCRC.102nd
• Studying EE @ FJU
• Joined Arduino.Taipei ( since 2013 )
•
•
• / Maker
My Blog : http://davidchensbase.blogspot.tw
9. A collection of early quartz crystal frequency standard units used in crystal oscillators, produced by Bell Labs/AT&T/Vectron International. ( via wiki )
10. A pair of 1968 Heathkit vibrators ( via wiki )
11. Architectures of Radio Receivers
• Crystal Radio ( )
• Tuned radio frequency ( TRF ) –
• Reflex receiver –
• Homodyne ( Direct-Conversion ) –
• ( Super ) regenerative – ( )
• Autodyne –
• ( Super ) heterodyne – ( )
• ( heterodyne / regenerative / autodyne ) detection
• / /
Image : A drawing of an early vacuum tube radio receiver and horn loudspeaker, from an advertisement in a radio magazine around 1922. ( via wiki )
12. Crystal Radio
• Crystal Radio ( )
• Cat's whisker detector ( Galena )
• Germanium transistors
• Crystal earpiece
• Needs well grounding
• Variable L/C
• Easy to make
• Sensitivity : Poor
• Selectivity : Poor
• Signal to noise ratio ( SNR ) : Poor
Image : Sketch of crystal radio set. ( via wiki )
14. A circuit of an inductively-coupled crystal radio receiver with impedance matching. ( via wiki )
15. Crystal radio diagram in 1922.
This circuit did not use a tuning capacitor, but used the capacitance of the antenna to form the tuned circuit with the coil. ( via wiki )
18. Tuned radio frequency ( TRF ) receiver
• Tuned radio frequency ( TRF ) receiver
• by Ernst Alexanderson, 1916
• RF Amplifiers / Active Filters
• IC ZN414 / MK484 / TA7642
• Neutrodyne receiver –
• by Louis Hazeltine, 1922
• Preventing oscillations
• Reflex receiver –
• by Wilhelm Schloemilch and Otto von Bronk, 1914
• Feedback loop
Image : Top view of the Leutz Transoceanic "Phantom" radio receiver with its cover removed, from 1927. ( via wiki )
19. Tuned radio frequency ( TRF ) receiver
• Pros
• Active band pass filter
• Cons
• Hard tuning, hard to build, large
• Sensitivity : Medium
• Selectivity : Poor
• Signal to noise ratio ( SNR ) : Medium
Image : The first Neutrodyne radio receiver, built by Louis Hazeltine and presented at the March 2, 1923 meeting of the Radio Society of America ( via wiki )
26. The first neutrodyne radio receiver, presented by Louis Alan Hazeltine in a lecture on March 2, 1923
titled "Tuned radio frequency amplification with neutralization of capacity coupling" to the Radio Club of America at Columbia University. ( via wiki )
27. Block diagram of a simple single-tube reflex radio receiver ( via wiki )
28. Circuit diagram of a reflex receiver. One transistor amplifies both high frequency and low frequency. ( via wiki )
30. Homodyne Receivers
• Homodyne receiver ( Direct-Conversion / Zero-IF )
• Mixer + Local Oscillator
• Low convert to DC
• Regenerative receiver
• by Edwin Armstrong, 1912
• No significant Mixer and LO
• Autodyne mixer ( Mixer / LO 2 in 1 )
• Hartley / Colpitts configuration
• Hysteresis –
• Nearly self-oscillating
• Regenerative control
Image : An early vacuum tube regenerative radio receiver from 1922. ( via wiki )
31. Super-regenerative Receivers
• Super-regenerative
• by Edwin Armstrong, 1922
• Quench oscillator in supersonic ( 30~100kHz )
• Oscillations were interrupted periodically
• Pros
• Simple, easy to make
• Cons
• Oscillator signal propagates through antenna
• Signal interfered by flicker noise
• Sensitivity : Excellent
• Selectivity : Medium
• Signal to noise ratio ( SNR ) : Poor
Image : American radio researcher Edwin H. Armstrong and his new invention, the superregenerative receiver in 1922. ( via wiki )
41. Superheterodyne Receivers
• Heterodyne receiver
• by Reginald Fessenden, 1901
• Failed on the stability of LO ( ppt accuracy ) [wiki]
• Continuous Wave ( CW ) receiver
• Heterodyning Animation [link]
• Super-heterodyne receiver
• by Edwin Armstrong, 1918
• Supersonic IF stage ( 455kHz, 10.7MHz…etc )
• Stable, reliable until the transistor era [wiki]
• Regency TR-1
• Sony TR-52 / TR-55
Image : One of the first prototype superheterodyne radio receivers built by inventor Edwin Armstrong. ( via wiki )
42. Superheterodyne Receivers
• Pros
• Simple / stable enough to commercialize
• Excellent performance
• Cons
• More stages than a regen radio
• Tracking LO and Image filter
• Sensitivity : Excellent
• Selectivity : Excellent
• Signal to noise ratio ( SNR ) : Excellent
Image : American engineer Edwin with his new wife and a portable superheterodyne radio receiver. ( via wiki )
58. • FM
•
• FM / AM
•
• ( RTL-SDR )
• 60MHz
• Manhattan-style Circuit Construction [Link]
• A Simple Regen Radio for Beginners – ARRL [Link]
Image : IC – CD9088 AM / FM
64. A Simple Regen Radio for Beginners
By Charles Kitchin, N1TEV
• BJT ( 2N2222 )
• LM386
• Hartley : 2L1C
• Fine Tune
• FM !?
•
• 5.6~11.9MHz ( Pi-FM-RDS )