GB787826A - Variable band width intermediate frequency system - Google Patents
Variable band width intermediate frequency systemInfo
- Publication number
- GB787826A GB787826A GB3729955A GB3729955A GB787826A GB 787826 A GB787826 A GB 787826A GB 3729955 A GB3729955 A GB 3729955A GB 3729955 A GB3729955 A GB 3729955A GB 787826 A GB787826 A GB 787826A
- Authority
- GB
- United Kingdom
- Prior art keywords
- frequency
- mixer
- oscillator
- oscillators
- band
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G5/00—Tone control or bandwidth control in amplifiers
- H03G5/16—Automatic control
- H03G5/24—Automatic control in frequency-selective amplifiers
- H03G5/26—Automatic control in frequency-selective amplifiers having discharge tubes
Landscapes
- Superheterodyne Receivers (AREA)
Abstract
787,826. Variable selectivity apparatus. COLLINS RADIO CO. Dec. 29, 1955, No. 37299/55. Class 40 (5). In a variable band width amplifier an input signal is applied in turn to mixers 11, 17, 24, Fig. 1, separated by highly selective band-pass filters 16, 23, the mixers 11, 24 being fed with oscillations from oscillators 12, 19 while the mixer 17 receives oscillations from a difference mixer 18 receiving oscillations from the oscillators 12, 19. The maximum (or minimum) frequency passed by the circuit may be lowered (or raised) by decreasing (or increasing) the frequency of either oscillator and by both maximum and minimum may be effected by adjustment of both oscillators in opposite directions. The filters are preferably of the mechanical type as described in Specifications 722,645 and 722,664, [both in Group XL (b)]. Assuming the input signal has a frequency of 470 kc/s. and the oscillator 12 a frequency of 720 kc/s., then the output passes through the filter 16 having a centre frequency of 250 kc/s. and a band-width of 4 kc/s. Assuming the response of filter 16 to be according to curve A, Fig. 2, then adjustment of the oscillator 12 to a frequency of 719 kc/s. will displace the output from the mixer 11 to the form of curve B, Fig. 2, so that part of the response is lost. Due to the change in frequency of oscillator 12 the output of the difference mixer 18 rises to 206 kc/s., but since the signal received at mixer 17 is only 3 kc/s. wide it passes unaffected through filter 23 to mixer 24 where it is restored to the input frequency. By variation of the frequency of oscillator 19 the band-width of the system may also be varied, Fig. 3 (not shown). The mixers 11, 17 and 24 are preferably of the heptode type, Fig. 4 (not shown), energized from oscillators of the cathodecoupled type, Figs. 5 and 6 (not shown).
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB3729955A GB787826A (en) | 1955-12-29 | 1955-12-29 | Variable band width intermediate frequency system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB3729955A GB787826A (en) | 1955-12-29 | 1955-12-29 | Variable band width intermediate frequency system |
Publications (1)
Publication Number | Publication Date |
---|---|
GB787826A true GB787826A (en) | 1957-12-18 |
Family
ID=10395367
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB3729955A Expired GB787826A (en) | 1955-12-29 | 1955-12-29 | Variable band width intermediate frequency system |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB787826A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2328814A (en) * | 1997-09-02 | 1999-03-03 | Sony Uk Ltd | Variable bandwidth filter |
-
1955
- 1955-12-29 GB GB3729955A patent/GB787826A/en not_active Expired
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2328814A (en) * | 1997-09-02 | 1999-03-03 | Sony Uk Ltd | Variable bandwidth filter |
GB2328814B (en) * | 1997-09-02 | 2001-09-26 | Sony Uk Ltd | Variable bandwidth filter |
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