Spurious signals and intermodulation products detection enhancement circuit

Claim 2

A testing circuit wherein the improvement comprises signal means; adjustable phase shifted means; unit means; combining means; said adjustable phase shifting means and said unit means each having one end connected to said signal means to recieve at least one signal therefrom; said adjustable phase shifting means and said unit means having their other end connected to said combining means; utilization means connected to the output of said combining means; said adjustable phase shifting means being adjusted such that the phase of the signal presented by said signal means through the phase shifting means to the combining means is 180* out of phase with respect to the phase of the signal presented by the signal means to the combining means by way of said unit means; an isolator means connected between said adjustable phase shifting means and said combining meAns; at least first and second frequency signal producing means make up said signal means; coupling means; a plurality of isolating means connecting said frequency signal producing means to said coupling means; and said coupling means being connected to said unit means and said adjustable phase shifting means.

Claim 3

A testing circuit as set forth in claim 1 further comprising switching means connected to the frequency signal producing means whereby one or more frequency signal producing means may be selectively connected to said coupling means; signal level adjustment means having an input and two outputs; filter means connected between said coupling means and the input of said signal level adjustment means; one output of said signal level adjustment means being connected to said adjustable phase shifting means and the other output being connected to said unit means; said unit means being the unit which is to be tested; said combining means being an adjustable amplitude balancing means having two inputs and one output; said adjustable phase shifting means and said adjustable amplitude balancing means each being adjusted such that the signals from said frequency signal producing means are canceled and only a spurious signal produced by said unit means is presented to the output of said adjustable balancing means; the electrical path through said phase shifting means and said isolator means being equal to the electrical path through said unit means; and said utilization means being at least one indicating device.

Claim 4

A testing circuit wherein the improvement comprises signal means; adjustable phase shifted means; unit means; combining means; said adjustable phase shifting means and said unit means each having one end connected to said signal means to receive at least one signal therefrom; said adjustable phase shifting means and said unit means having their other end connected to said combining means; utilization means connected to the output of said combining means; said adjustable phase shifting means being adjusted such that the phase of the signal presented by said signal means through the phase shifting means to the combining means is 180* out of phase with respect to the phase of the signal presented by the signal means to the combining means by way of said unit means; an isolator means connected between said adjustable phase shifting means and said combining means; said signal means is made up of a plurality of frequency signal producing means; first connecting means connecting the signal from said plurality of frequency signal producing means to said unit means; additional adjustable phase shifting means; second connecting means connecting said plurality of frequency signal producing means individually to the adjustable phase shifting means; and third connecting means connecting each of the adjustable phase shifting means to said isolating means.

Claim 5

A testing circuit wherein the improvement comprises signal means; adjustable phase shifted means; unit means; combining means; said adjustable phase shifting means and said unit means each having one end connected to said signal means to receive at least one signal therefrom; said adjustable phase shifting means and said unit means having their other end connected to said combining means; utilization means connected to the output of said combining means; said adjustable phase shifting means being adjusted such that the phase of the signal presented by said signal means through the phase shifting means to the combining means is 180* out of phase with respect to the phase of the signal presented by the signal means to the combining means by way of said unit means; an isolator means connected between said adjustable phase shifting means and said combining means; said signal means is made up of a plurality of frequency signal producing means; first connecting means connecting the signal from said plurality of frequency signal producing means to said unit means; additional adjustable phase shifting means; second connecting means connecting said plurality of frequency signal producing means individually to the adjustable phase shifting means; and third connecting means connecting each of the adjustable phase shifting means to said isolating means.

Claim 6

A testing circuit as set forth in claim 3 further comprising a plurality of switch means; a plurality of isolating means; said plurality of switching means and isolating means being series connected between the plurality of frequency signal producing means and first and second connecting means; a signal level adjusting means connected between said first connecting means and said unit means; a plurality of adjustable amplitude balancing means connected between said plurality of adjustable phase shifting means and said third connecting means; said combining means being an adjustable amplitude balancing means having two inputs and an output; each adjustable phase shifting means and adjustable amplitude balancing means being adjusted such that the individual frequency signals produced by said plurality of frequency producing means are canceled in said combining means and the output of the combining means being only the spurious signals produced by the unit means; and said utilization means being at least one indicating device.