GB538795A - Modulating system for carrier frequency signalling and the like - Google Patents
Modulating system for carrier frequency signalling and the likeInfo
- Publication number
- GB538795A GB538795A GB2535/40A GB253540A GB538795A GB 538795 A GB538795 A GB 538795A GB 2535/40 A GB2535/40 A GB 2535/40A GB 253540 A GB253540 A GB 253540A GB 538795 A GB538795 A GB 538795A
- Authority
- GB
- United Kingdom
- Prior art keywords
- circuit
- modulating
- input
- carrier
- frequency
- 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
- H03C—MODULATION
- H03C1/00—Amplitude modulation
- H03C1/52—Modulators in which carrier or one sideband is wholly or partially suppressed
- H03C1/54—Balanced modulators, e.g. bridge type, ring type or double balanced type
- H03C1/56—Balanced modulators, e.g. bridge type, ring type or double balanced type comprising variable two-pole elements only
- H03C1/58—Balanced modulators, e.g. bridge type, ring type or double balanced type comprising variable two-pole elements only comprising diodes
Abstract
538,795. Modulating and demodulating systems. STANDARD TELEPHONES & CABLES, Ltd. Feb. 9, 1940, No. 2535. Convention date, April 5, 1939. [Class 40 (v)] The circuits of modulating, demodulating, and frequency-changing devices of the kind employing non-linear resistances are modified to reduce the production of harmonics of the modulating frequencies and to secure the same upper limit for the transmission of all modulating frequencies. Fig. 1 shows a bridge modulator with the input frequencies from a microphone 21 applied across one diagonal of the bridge, and the carrier from a source 28 applied across the other diagonal. The output is taken to line 22 through a filter BPF. The carrier input includes a series resistance 32, and a shunt 33 comprising an inductance and variable resistance. A rejector circuit 30 tuned to twice the carrier frequency is connected in the microphone input circuit, and a rejector 31 tuned to the mean input frequency is connected in the output circuit. In a modified circuit, Fig. 2, used as a demodulator, the sidebands are applied through a band-pass filter BPF<SP>1</SP>, resistance pad 49, and series condenser 70; and the demodulated output is taken through a series condenser 71 and low-pass filter LPF<SP>1</SP> to the telephone circuit 66. Specification 428,293 is referred to.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US266043A US2271078A (en) | 1939-04-05 | 1939-04-05 | Modulating system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB538795A true GB538795A (en) | 1941-08-18 |
Family
ID=23012926
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB2535/40A Expired GB538795A (en) | 1939-04-05 | 1940-02-09 | Modulating system for carrier frequency signalling and the like |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US2271078A (en) |
| FR (1) | FR864654A (en) |
| GB (1) | GB538795A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE941495C (en) * | 1942-08-20 | 1956-04-12 | Siemens Ag | Circuit arrangement for single sideband modulation |
| US2438948A (en) * | 1944-01-21 | 1948-04-06 | Bell Telephone Labor Inc | Modulating system |
| US4509202A (en) * | 1981-03-30 | 1985-04-02 | Kingery William L | Full-wave rectification of signals generated by radio frequency transmitting circuits |
-
1939
- 1939-04-05 US US266043A patent/US2271078A/en not_active Expired - Lifetime
-
1940
- 1940-02-09 GB GB2535/40A patent/GB538795A/en not_active Expired
- 1940-04-04 FR FR864654D patent/FR864654A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US2271078A (en) | 1942-01-27 |
| FR864654A (en) | 1941-05-02 |
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