US3927373A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Paging system
Assignee: US Philips Corp
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Filing: 1973-11-20
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Granted: 1975-12-16
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Expires: 1993-11-20
Abstract
Abstract A paging system for transmitting calls to receivers. The paging signals are modulated on the carriers of a number of transmitters which have the same transmitter frequency. One of the transmitters synchronizes the other transmitters. A transmitter is switched on if a call is to be transmitted, and is switched off after the call has been transmitted. The synchronization unit of a controlled transmitter comprises an auxiliary oscillator having a frequency which lies between the frequency of the synchronization signal and the transmitter frequency. The auxiliary oscillator is synchronized to a multiple of the synchronization frequency, and the transmitter frequency is synchronized to a multiple of the frequency of the auxiliary oscillator.
Inventors
- 👤 Abraham Janssens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 02:11
CPC Classifications
H; H04; H04W; H04W84/00; H04W84/02; H04W84/022; G; G08; G08B; G08B3/00; G08B3/10; G08B3/1008; G08B3/1016; H03; H03L; H03L7/00; H03L7/06; H03L7/16; H03L7/22; H03L7/23
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
320 words
A paging system comprising a plurality of controlled transmitters each having an main oscillator means for generating carriers in the same frequency channel, the carriers being modulated by the same information, a controlling transmitter coupled to apply a synchronization signal to the controlled transmitters, the controlled transmitters each having a synchronization unit means for synchronizing the transmitter frequency to a multiple of the frequency of the synchronization signal, the synchronization unit of each of said controlled transmitters comprises an auxiliary oscillator, the frequency of which is lower by a factor n than the transmitter main oscillator frequency and is higher by a factor m than the frequency of the synchronization signal, a first frequency control circuit means coupled to said auxiliary oscillator for synchronizing the frequency of the auxiliary oscillator to the m-tiple of the frequency of the synchronization signal, said first control circuit comprising a first frequency divider which has the dividing factor m coupled to the output of said auxiliary oscillator, a first phase detector having a first input means for receiving the synchronization signal and a second input coupled to the first frequency divider output, and a first low pass filter coupled between the output of the phase detector and a control input of the auxiliary oscillator, and a second frequency control circuit means cascaded and independent with respect to said first control circuit means and coupled to said main oscillator for synchronizing the transmitter main oscillator frequency to the n-tiple of the frequency of the auxiliary oscillator, said second control circuit comprising a second frequency divider having the dividing factor n coupled to said main oscillator, a second phase detector which is coupled to the auxiliary oscillator and to said second divider, and a second low pass filter coupled between the output of the second phase detector and a frequency control input of the transmitter main oscillator, m and n being integer numbers larger than one.
Claim 2
Dependent Claim
320 words
A paging system comprising a plurality of controlled transmitters each having an main oscillator means for generating carriers in the same frequency channel, the carriers being modulated by the same information, a controlling transmitter coupled to apply a synchronization signal to the controlled transmitters, the controlled transmitters each having a synchronization unit means for synchronizing the transmitter frequency to a multiple of the frequency of the synchronization signal, the synchronization unit of each of said controlled transmitters comprises an auxiliary oscillator, the frequency of which is lower by a factor n than the transmitter main oscillator frequency and is higher by a factor m than the frequency of the synchronization signal, a first frequency control circuit means coupled to said auxiliary oscillator for synchronizing the frequency of the auxiliary oscillator to the m-tiple of the frequency of the synchronization signal, said first control circuit comprising a first frequency divider which has the dividing factor m coupled to the output of said auxiliary oscillator, a first phase detector having a first input means for receiving the synchronization signal and a second input coupled to the first frequency divider output, and a first low pass filter coupled between the output of the phase detector and a control input of the auxiliary oscillator, and a second frequency control circuit means cascaded and independent with respect to said first control circuit means and coupled to said main oscillator for synchronizing the transmitter main oscillator frequency to the n-tiple of the frequency of the auxiliary oscillator, said second control circuit comprising a second frequency divider having the dividing factor n coupled to said main oscillator, a second phase detector which is coupled to the auxiliary oscillator and to said second divider, and a second low pass filter coupled between the output of the second phase detector and a frequency control input of the transmitter main oscillator, m and n being integer numbers larger than one.
Claim 3
Dependent Claim
29 words
A paging system as claimed in claim 1, further comprising audio transmission lines coupled between the controlling transmitter and the controlled transmitters for the transmission of the synchronization signal.
References Cited (Backward Citations)
US2033237A
Cited
US3600683A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-15 | 1979-06-16 | 1979-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-15 | 1983-06-16 | 1983-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-15 | 1987-06-16 | 1987-12-16 | $7700.00 | Window Closed / Lapsed |