Incoming Water at www.japanese-home-gardens.com

The local oscillator frequency is tuned in conjunction with the tuning for the incoming signal to produce a constant output frequency, called the intermediate frequency. This intermediate (or difference) frequency often is 456 kHz. In this case to receive a 1,000-kHz signal, the local oscillator would be operated at 1,456 kHz (1,456 - 1,000 kHz = 456 kHz). For an incoming 550-kHz signal the local oscillator would be operated at 1,006 kHz. Similarly, all incoming signals are converted to the intermediate frequency of 456 kHz.

This conversion of the incoming signal frequency to a lower frequency is accomplished by heterodyning, or beating, the incoming signal frequency against the frequency generated by the local oscillator. However, the mixer produces not only a lower frequency equal to the difference between the incoming signal frequency and the local oscillator frequency but also a higher frequency equal to their sum. The undesired sum frequency is suppressed by tuning the output circuit of the mixer to the desired difference frequency.

Modern gractice favors upward flow rather than horizontal ow basins, with skimming troughs closely spaced to pick up the cleanest water at the top. Mechanisms are installed to remove sludge before it mingles with the incoming water; this ensures greater silting depth and removes the sediment without periodically taking the basin out of service to hose out the mud. The addition of a coagulant chemical to the water brings about an agglomeration of colloidal and fine suspended matter into larger masses which will settle more readily.