Test technique for set-top boxes
View Patent ↗A test system ( 200 ) for testing for missing or shorted parts within a tuner circuit includes a signal generator ( 202 ) for applying a harmonic-containing baseband time varying RF test signal to the tuner circuit. The tuner circuit is tuned to a harmonic of test signal. A detector 208 coupled to the baseband IF output of the tuner circuit detects the voltage generated in response to the applied RF test signal. A voltage measurement device ( 210 ) measures voltage detected by detector to provide an indication of the gain. Significant changes in the gain indicate missing part(s) or short circuits.
1. A method for testing for one of a missing or shorted part within a tuner circuit, comprising the steps of:
applying a harmonic-containing baseband time varying RF test signal to the tuner circuit;
tuning the tuner circuit to a harmonic of test signal; and
detecting a change in gain measured at a baseband IF output of the tuner circuit indicative of one of a missing part or short circuit.
2. The method according to claim 1 wherein the time-varying RF test signal comprises a square wave signal.
3. The method according to claim 2 wherein the square wave signal has a frequency of 10 MHz.
4. The method according to claim 1 wherein the comparing step comprises the steps of:
(a) converting a voltage generated at the baseband IF output to a logarithmic value:
(b) measuring the logarithmic value to establish the gain.
5. The method according to claim 4 wherein the steps (a) and (b) are repeated multiple times to yield an average gain value.
6. A method for testing for one of a missing or shorted part within a tuner circuit, comprising the steps of:
applying a harmonic-containing baseband time varying RF test signal to the tuner circuit;
tuning the tuner circuit to a harmonic of test signal;
detecting a change in gain measured at a baseband IF output of the tuner circuit, and
comparing the change in gain to a change in gain associated with a specific missing or shorted part to determine whether that specific part is missing or shorted.
7. The method according to claim 6 wherein the time-varying RF test signal comprises a square wave signal.
8. The method according to claim 7 wherein the square wave signal has a frequency of 10 MHz.
9. The method according to claim 6 wherein the comparing step comprises the steps of:
(a) converting a voltage generated at the baseband IF output to a logarithmic value:
(b) measuring the logarithmic value to establish the gain.
10. The method according to claim 9 wherein the steps (a) and (b) are repeated multiple times to yield an average gain value.
11. A test system to detect one of a missing or shorted part within a tuner circuit, comprising:
a signal generator for applying a harmonic-containing baseband time varying RF test signal to the tuner circuit tuned to receive to a harmonic of test signal; and
a detector for detecting a voltage at a baseband IF output of the tuner circuit in response to application of the harmonic-containing baseband time varying RF test signal to the tuner circuit; and
a voltage measurement device for measuring voltage output by the detector to establish gain indicative of a missing component or short circuit.
12. The test system according to claim 1 wherein the signal generator generates a square wave signal.
13. The test system according to claim 12 wherein the square wave signal has a frequency of 10 MHz.
14. The test system according to claim 1 wherein the detector yields a logarithmically varying output voltage.
15. The test system of claim 11 wherein the voltage measurement device comprises a multi-meter.