Signal Combining Apparatus

• US 20130250781A1
• Filed: 03/07/2013
• Published: 09/26/2013
• Est. Priority Date: 03/21/2012
• Status: Active Grant

• Current Assignee: Viavi Solutions Licensing LLC (Lumentum Holdings Inc.)
• Original Assignee: Aeroflex Ltd (Lumentum Holdings Inc.)
• Inventors: Gilmartin, David
• Granted Patent: US 9,288,131 B2
• Time in Patent Office: Days
• US Class Current: 370/250
• CPC Class Codes: H04B 17/0085 using test signal generators
• CPC Class Codes: H04B 17/17 Detection of non-compliance or faulty performance, e.g. response deviations H04B17/18 takes precedence
• CPC Class Codes: H04B 17/20 of receivers
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements
• CPC Class Codes: H04L 43/50 Testing arrangements

Abstract

The present application relates to a signal combining apparatus (12) having an input for receiving a signal from a signal generator (14) and an output for outputting a signal to a signal analyser (16). The input signal is split into a plurality of identical signals by a high isolation splitter (20) and the plurality of signals are transmitted via a plurality of transmit paths (22), which can be selectively enabled or disabled, to inputs a plurality of duplex combiners (24), each of which has an input/output port to which a device under test (18) can be connected. Outputs of the plurality of duplex combiners (24) are connected to a plurality of receive paths (26), which can be selectively enabled and disabled, whose outputs are connected to a signal relay (28) which is operative to receive one or more signals received through the plurality of receive paths (26). An output of the signal relay (28) is connected to the output of the signal combining apparatus (12), such that a composite signal output by the signal relay containing the signals received through the plurality of receive paths can be analysed by the signal analyser (16).

Claims

1. Signal combining apparatus comprising:

an input port for receiving an input signal from a signal generator;

an output port for outputting a signal to a signal analyser;

a plurality of test ports for connecting the apparatus to a plurality of devices under test (DUTs), the apparatus further comprising;

a splitter for dividing a signal received at the input port into a plurality of signals;

a plurality of transmit signal paths;

a plurality of receive paths;

a signal relay, the signal relay being configured to receive a signal through one or more of the plurality of receive paths and to output a signal to the output port, the signal output to the output port containing the signals received from the one or more of the plurality of receive paths wherein the apparatus further comprises a plurality of duplex combiners which are each configured to;

receive a signal from one of the plurality of transmit paths;

transmit the signal from the one of the plurality of transmit paths to one of the plurality of test ports;

receive a signal from one of the plurality of test ports; and

transmit the signal received from the one of the plurality of test ports to one of the plurality of receive paths.

2. Signal combining apparatus according to claim 1 wherein the plurality of transmit paths each comprise a switchable gain stage.

3. Signal combining apparatus according to claim 1 wherein the plurality of receive paths each comprise a switchable gain stage.

4. Signal combining apparatus according to claim 2 wherein the switchable gain stage comprises an amplifier for amplifying a signal received at an input of the switchable gain stage and switching means for switching between the amplifier and a conductor.

5. Signal combining apparatus according to claim 2 wherein the switchable gain stage comprises an amplifier for amplifying a signal received at an input of the switchable gain stage, an attenuator for attenuating the signal received at the input of the switchable gain stage and switching means for switching between the amplifier and the attenuator such that the switchable gain stage is operative selectively to amplify or attenuate the signal received at the input of the switchable gain stage.

6. Signal combining apparatus according to claim 1 wherein each of the plurality of transmit paths comprises a fine level control.

7. Signal combining apparatus according to claim 1 wherein each of the plurality of receive paths comprises a fine level control.

8. Signal combining apparatus according to claim 6 wherein the fine level control comprises a variable attenuator.

9. Signal combining apparatus according to claim 1 wherein each of the plurality of transmit paths further comprises an isolator for selectively enabling or disabling the transmit path.

10. Signal combining apparatus according to claim 9 wherein the isolator comprises switch means and a resistive termination, the switch means being operative to selectively connect an input of one of the plurality of duplex combiners to an output of one of the plurality of transmit paths or to the resistive termination.

11. Signal combining apparatus according to claim 1 wherein each of the plurality of receive paths further comprises an isolator for selectively enabling or disabling the receive path.

12. Signal combining apparatus according to claim 11 wherein the isolator comprises switch means and a resistive termination, the switch means being operative to selectively connect an output of one of the plurality of duplex combiners to an input of one of the plurality of receive paths or to the resistive termination.

13. Signal combining apparatus according to claim 1 further comprising a switchable feedback path for selectively connecting an output of one of the plurality of transmit paths to an input of one of the plurality of receive paths.

14. Signal combining apparatus according to claim 13 wherein the feedback path includes a power sensor for measuring signal power in the one of the plurality of transmit paths.

15. Signal combining apparatus according to claim 14 further comprising heating means for maintaining the power sensor at a constant temperature.

16. Signal combining apparatus according to claim 1 further comprising:

a power sensor for measuring the power of a signal output by one of the plurality of duplex combiners to one of the plurality of receive paths;

a threshold detector for detecting whether the power of the signal output by the one of the plurality of duplex combiners meets a predetermined threshold; and

control means for controlling a switchable attenuation such that if the power of the signal output by the one of the plurality of duplex combiners meets the threshold, the signal output by the one of the plurality of duplex combiners is attenuated.

17. Signal combining apparatus according to claim 16 wherein the control means is operative to control an isolator of the receive path such that when the power of the signal output by the one of the plurality of duplex combiners meets the threshold the output of the one of the plurality of duplex combiners is connected to a resistive termination.

18. A method for calibrating signal combining apparatus according to claim 1, the method comprising:

transmitting a signal of known power along one of the plurality of transmit paths;

measuring the power of the transmitted signal at an output port of the signal combining apparatus using an external measuring device;

measuring the power of the transmitted signal at an output of the one of the plurality of transmit paths using an internal measuring device;

storing the measurement taken by the internal measuring device as a target power measurement;

subsequently transmitting a signal of the known power along the one of the plurality of transmit paths;

measuring the power of the transmitted signal at the output of the one of the plurality of transmit paths using the internal measuring device;

comparing the measured power of the transmitted signal to the target power; and

adjusting a gain of the one of the plurality of transmit paths until that the measured power corresponds to the target power.