[time-nuts] Injection locking

[Lux, Jim (337C)]

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Kit Scally
> Sent: Wednesday, February 10, 2010 3:55 PM
> To: time-nuts at febo.com
> Cc: Kit Scally
> Subject: [time-nuts] Injection locking
> 
> Hi,
> 
> 
> As others have already noted, there's a paucity of circuits or down to
> earth advice on this topic - unless your poison is "millimetre wave"
> technology.
> I set out to GPS-lock my Icom 706 transceiver some while ago.  This uses
> a (single) hi-stability master 30MHz xtal oscillator.  With support from
> Murray (ZL1BPU), I decided to IL rather than generate an external
> GPS-locked 30MHz source.
> 
> The only reference other than that by Uzunoglu to IL oscillator design I
> managed to find was in Jessop, 4th Ed, 1994 (p9.50) which stated:
> 
> P1/P2 = [2Q*deltaF/F]^2
> 
> where:
> P1   = pwr of injected signal
> P2   = Oscillator (to be controlled) power
> Q    = loaded Q of cavity (ie: xtal osc)
> F    = oscillator frequency
> delta F = locking range
> 
> 

Since Q of the oscillator is basically F(center)/BW(cavity) your equation could reduce to 
2* F(center)/BW(cavity) * deltaF/F(center) = 2 * deltaF/BW(cavity)

Or, the power ratio is roughly the square of how far the signal is from the 3dB point of the oscillator.

That is, if the 3dB point of the closein sidebands extend 10 Hz, and your signal is 10Hz away, the injection power would have to equal the carrier power?

There's an interesting article out there where a whole raft of microwave oven magnetrons were harnessed together to make a microwave weed killer, and they comment that they all tend to lock together.

When it comes to coupled oscillator arrays, there's a whole lot of literature. Look for York and Pogorzelski as authors (Pogo is just down the hall from me at work.)  I don't know if he's done work with coupling at a subharmonic of the output frequency.  No reason why it wouldn't work.