What would this receiver be called?

Question

I'm looking at a phase measuring system that uses an amplitude limited version of the received RF signal as a local oscillator to down convert the signal. I've been trying to find a name for this method, along the lines of hetrodyne, homodyne, and autodyne, but none of these seem to fit this configuration.

The input RF is received from multiple elements of a phased array, and one of these elements drives a limiter. (It's assumed that the signal to noise ratio is high enough for this to work.) The limiter output is offset by some fixed frequency and the result is used as a local oscillator to down convert the outputs of each of the antenna elements to the frequency of the offset.

Is there a name for this type of receiver?

@KevinWhite I'd say it's rather heterodyne, because the target frequency is not 0 Hz — Marcus Müller, Jun 29 '21 at 06:59
Sounds a bit like a Wadley loop that offsets the incoming RF frequency to cancel out oscillator drift. — , Jun 29 '21 at 12:10
@MarcusMüller - OK. The first and second paragraphs ask slightly different questions. The first one doesn't mention offsetting the frequency. — Kevin White, Jun 29 '21 at 17:32
@MarcusMüller Yes. The detail with the offset is the actual implementation. The result is that all signals down convert to that offset frequency (rather than baseband). — Jim, Jun 29 '21 at 18:47

score 1 · Answer 1 · answered Jun 29 '21 at 07:02

It's a bit of question of perspective:

From a point of outcome, and the existence of an intermediate frequency oscillator (limited signal·fixed frequency oscillation), it's an heterodyne receiver
The fact that you're using a nonlinearly distorted reception itself to mix down, and then preserve the IF through filtering it's kind of an envelope detector (but that is a very high-level comparison)
From my point of implementation view, your single branch that you use for mixing is used to find the exact RF frequency, so that your receiver can work with a local oscillator that doesn't "know" the transmit frequency. From that point of view, it's a heterodyne receiver with carrier-recovery frequency correction.

What would this receiver be called?

1 Answers1