JPS5675792A - Reception system for multifrequency signal - Google Patents
Reception system for multifrequency signalInfo
- Publication number
- JPS5675792A JPS5675792A JP15210479A JP15210479A JPS5675792A JP S5675792 A JPS5675792 A JP S5675792A JP 15210479 A JP15210479 A JP 15210479A JP 15210479 A JP15210479 A JP 15210479A JP S5675792 A JPS5675792 A JP S5675792A
- Authority
- JP
- Japan
- Prior art keywords
- threshold value
- circuit
- signal
- detection
- level
- 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.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q1/00—Details of selecting apparatus or arrangements
- H04Q1/18—Electrical details
- H04Q1/30—Signalling arrangements; Manipulation of signalling currents
- H04Q1/44—Signalling arrangements; Manipulation of signalling currents using alternate current
- H04Q1/444—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies
- H04Q1/45—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using multi-frequency signalling
- H04Q1/457—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using multi-frequency signalling with conversion of multifrequency signals into digital signals
- H04Q1/4575—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using multi-frequency signalling with conversion of multifrequency signals into digital signals which are transmitted in digital form
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
Abstract
PURPOSE:To increase the protective characteristics for momentary interruption, by performing signal detection with the fixed threshold value of comparatively high level, then switching the threshold value after detection to the value of low level performing the signal detection afterward. CONSTITUTION:A multifrequency signal input is converted into a linear PCM code and fed to an adder 16 after being frequency spectral. In this case, since the preceding input signal is absent, the first fixed threshold value of a selection circuit 15 is selected and the 1st threshold value is fed to the adder 16 from a threshold value generating circuit 13. Then, the output level of a discrete Fourier transformation operating circuit 12 is compared with the 1st fixed threshold value for signal detection. Next, from the result of detection, the selector circuit 15 is switched to select the second fixed threshold value lower in the level than the 1st threshold value. After that, the output of the circuit 12 is compared with the 2nd threshold value to detect the signal. If momentary interruption is caused, when the time width of the monentary interruption is within a permissible range, the output level of the circuit 12 is not lowered than the 2nd threshold value.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP54152104A JPS592233B2 (en) | 1979-11-26 | 1979-11-26 | Multi-frequency signal reception method |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP54152104A JPS592233B2 (en) | 1979-11-26 | 1979-11-26 | Multi-frequency signal reception method |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS5675792A true JPS5675792A (en) | 1981-06-23 |
JPS592233B2 JPS592233B2 (en) | 1984-01-17 |
Family
ID=15533134
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP54152104A Expired JPS592233B2 (en) | 1979-11-26 | 1979-11-26 | Multi-frequency signal reception method |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS592233B2 (en) |
-
1979
- 1979-11-26 JP JP54152104A patent/JPS592233B2/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
JPS592233B2 (en) | 1984-01-17 |
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