“Injection locking and injection pulling are the frequency effects that can occur when a harmonic oscillator is disturbed by a second oscillator operating at a nearby frequency. When the coupling is strong enough and the frequencies near enough, the second oscillator can capture the first oscillator, causing it to have essentially identical frequency as the second oscillator. This is injection locking. When the second oscillator merely disturbs the first but does not capture it, the effect is called injection pulling”. https://en.wikipedia.org/wiki/Injection_locking

The IC9700 uses a Temperature Compensated Crystal Oscillator (TCXO) running at 49.152MHz to generate the frequencies for conversion of the 1296MHz transmitter / receiver to an IF and to provide the frequencies required for the Software Defined Radio (SDR). The TCXO is a small, 2.5 x 2.0 x 1.0 mm L x W x H SMD component. The TCXO is also voltage controlled from the radio’s synchronization functions. This allow manual setting of the frequency of the radio and with later firmware upgrade, allow automatic
synchronization to an external 10MHz reference such as the GPSD-2 (https://brisbaneradiosociety.net/10-mhz-reference-by-vk4amg/)

Due to the latency in frequency adjustment with temperature changes in the radio and due to steps noticeable in the automatic synchronization function, digital communication, particularly at 1296MHz may be affected. Without automatic synchronization, the receive waterfall for a digital mode may look like a banana and prevent decoding. Because of the complexity and the SMD construction of the IC9700, it is difficult to sample the TCXO frequency and apply control voltage to provide stable and accurate frequency. The IC9700 automatic synchronization function ensures the TCXO is within injection lock range.

While the setup of other frequency locking solutions require computer programming and adjustment using an accurate and stable radio beacon or other signal, the RefGen-9700 with the IC9700 automatic synchronization sets automatically. Further adjustment is not required under any radio operating conditions.