US4013949A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Return loss test set
Assignee: AG Communication Systems Corp
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Filing: 1976-02-09
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Granted: 1977-03-22
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Expires: 1996-02-09
Abstract
Abstract In this test set, each one of a pair of resistive bridges has one node thereof connected to ground, one of the arms of each bridge that is adjacent the one nodes being open. Each one of a pair of ungrounded terminals of a balanced circuit under test is connected to a different one of the ungrounded nodes associated with the open arms of the bridges. Any center ground terminal of the test circuit is connected to the one nodes, which are grounded. Equal amplitude test signals of the same phase are applied to the pair of nodes on the two bridges that are adjacent to the one nodes thereof. A reflected signal coupled from the pair of nodes on the two bridges that are opposite the one nodes thereof is applied to a VTVM which provides an indication of the return loss of the test set, in relation to the individual bridge resistances which are the same values.
Inventors
- 👤 George E. Ice
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:40
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/04
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
235 words
Apparatus for testing the return loss of a balanced circuit under test having at least a pair of terminals which are ungrounded and are to operate into a load having a prescribed impedance, some balanced circuits under test also having a grounded center terminal, said apparatus comprising: a pair of resistive bridges each having a bridge resistance which is equal to one half of the value of the prescribed impedance, one nodes of each of said bridges being electrically connected together and to a ground reference potential, one arm between said one node and an other node of each of said bridges being open; first means connecting the pair of ungrounded output terminals of the test circuit to associated ones of said other nodes of said bridges, any center ground terminal of the test circuit being connected to said one nodes of said bridges; second means for producing an indication which is a measure of the return loss of the circuit under test; third means producing an AC test signal; fourth means responsive to the output of said third means for coupling equal amplitude test signals of the same phase to said bridges; and fifth means coupling a reflected output signal from the two nodes of said bridges that are opposite said one nodes and applying this reflected signal to said second means for providing an indication of the return loss of the test circuit.
Claim 2
Dependent Claim
235 words
Apparatus for testing the return loss of a balanced circuit under test having at least a pair of terminals which are ungrounded and are to operate into a load having a prescribed impedance, some balanced circuits under test also having a grounded center terminal, said apparatus comprising: a pair of resistive bridges each having a bridge resistance which is equal to one half of the value of the prescribed impedance, one nodes of each of said bridges being electrically connected together and to a ground reference potential, one arm between said one node and an other node of each of said bridges being open; first means connecting the pair of ungrounded output terminals of the test circuit to associated ones of said other nodes of said bridges, any center ground terminal of the test circuit being connected to said one nodes of said bridges; second means for producing an indication which is a measure of the return loss of the circuit under test; third means producing an AC test signal; fourth means responsive to the output of said third means for coupling equal amplitude test signals of the same phase to said bridges; and fifth means coupling a reflected output signal from the two nodes of said bridges that are opposite said one nodes and applying this reflected signal to said second means for providing an indication of the return loss of the test circuit.
Claim 3
Dependent Claim
24 words
Apparatus according to claim 1 wherein said third means is tunable for varying the frequency of the test signal over a band of frequencies.
Claim 4
Dependent Claim
148 words
Apparatus according to claim 2 wherein said fourth (coupling) means comprises: a pair of balanced input transformers each having a primary and a secondary winding; the impedances of said secondary windings thereof both being equal to one half the value of the prescribed impedance; the impedances of said primary windings thereof having the same values; said secondary windings thereof being electrically connected to associated ones of said bridges; and a four-port resistive hybrid having a value equal to the values of the impedances of the primary windings of said input transformers, one port of said hybrid being electrically connected to the output of said third means, the hybrid port opposite said one port being electrically connected to a balancing network having an impedance equal to that of said hybrid; the other pair of ports of said hybrid being electrically connected to associated primary windings of said input transformers.
Claim 5
Dependent Claim
21 words
Apparatus according to claim 3 wherein each of said input transformers includes an electrostatic shield which is electrically connected to ground.
Claim 6
Dependent Claim
82 words
Apparatus according to claim 2 wherein said fifth means comprises a balanced output transformer having a primary and a secondary winding, the impedance of said secondary winding being equal to twice the impedance of one of said bridges, the impedance of said primary winding being equal to that of said second means; said output secondary winding being coupled to the nodes of said bridges that are opposite said one nodes thereof, said output primary winding being coupled to said second (measuring) means.
Claim 7
Dependent Claim
23 words
Apparatus according to claim 5 wherein the secondary winding of said output transformer includes a center tap which is electrically connected to ground.
Claim 8
Dependent Claim
19 words
Apparatus according to claim 6 wherein said output transformer includes an electrostatic shield which is electrically connected to ground.
Claim 9
Dependent Claim
94 words
Apparatus according to claim 2 wherein said fourth means comprises a balanced input transformer having a primary winding electrically connected to said third means and receiving the AC test signal, and having a pair of secondary windings, each of said secondary windings being electrically connected to a different one of said pair of resistive bridges; the impedances of both of said secondary windings of said input transformer being equal to the impedance of the associated bridge; the impedance of the primary winding of said input transformer being matched to that of said third means.
Claim 10
Dependent Claim
19 words
Apparatus according to claim 8 wherein said input transformer includes an electrostatic shield which is electrically connected to ground.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-03-21 | 1980-09-20 | 1981-03-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-03-21 | 1984-09-20 | 1985-03-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-03-21 | 1988-09-20 | 1989-03-22 | $7700.00 | Window Closed / Lapsed |