We are a railway company and we use your PLL CD4046 in the acquisition of the speed of our trains.
An electronic board acquire impulses from speed sensors. There are 5 channels, as speed is acquired on 5 wheels.
The PLL deliver a stable (fo 2.5kHz) signal until the train reaches 25km/h. After this limit, the PLL deliver a frequency proportional to the speed.
Our problem is that every channel haven't a similar constant frequency under 25km/h even if every components are the same.
Our software reads the frequencies of the channels and regulates the electrical power. If the channels are too far away from the basic frequency the regulation doesn't work as the train starts.
Is there a way to have a constant frequency (fo) equal on every channel without trimming every channels for itself ?
Please have a look on our schematic (C5, C6, R19 and R20 are mounted on the board)
Thank you in advance for your help !