In telecommunication, the term frequency frogging has the following meanings:
1. The interchanging of the frequencies of carrier channels to accomplish specific purposes, such as to prevent feedback and oscillation, to reduce crosstalk, and to correct for a high frequency-response slope in the transmission line.
Note:Frequency frogging is accomplished by having modulators, which are integrated into specially designed repeaters, translate a low-frequency group to a high-frequency group, and vice versa. A channel will appear in the low group for one repeater section and will then be translated to the high group for the next section because of frequency frogging. This results in nearly constant attenuation with frequency over two successive repeater sections, and eliminates the need for large slope equalization and adjustments. Singing and crosstalk are minimized because the high-level output of a repeater is at a different frequency than the low-level input to other repeaters.
2. In microwave systems, the alternate use of two frequencies at repeater sites to prevent feedback and oscillation.
A froggingrepeater 36 is connected between the lines 33 and 35 and functions to translate the incoming high frequencygroup signals on the lines 33 and 35 to the low frequencygroup signals on the lines 35 and 33 respectively.
The incoming high frequencygroup of signals on the line 33 is received by the hybrid 41 and transmitted to a frequencyfrogging and slope correction circuit 43 on a line 44.
The oscillator frequency is determined by the values of the inductor 292 and the capacitors 288 and 291 and the amount of each cycle during which the capacitor 288 is switched in the tank circuit.
This froggingrepeater includes means for connecting additional circuitry, known as line build-out cards, between the incoming carrier cable and the froggingrepeater and between the froggingrepeater and the outgoing carrier cable.
This process of interchanging the frequency allocations of carrierchannels is known as frequencyfrogging.
Typically, the carrier signals are frequency spaced such that the lower sideband of one carrier signal is at the same frequency as the upper sideband of the next lower frequencycarrier signal.
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