the scaling of the approximation the division by 256 the correct scaling value would be 10313 8192 u00d7 256 322 but this would result in a rather cumbersome hardware implementation this leads to a small error in the approximation which in fact is partly cancelled by the fact that a larger error may exist for negative gain changes than for positive gain changes in summary it is preferred to provide two inputs to the filter 38b so as to enable a relatively large step size in the rxagc to be able to cancel fast changes in the input signal level on the other hand the txagc is required to be slower and more accurate if the txagc followed only the rxagc the resolution of the txagc would not be adequate however by introducing the linear power value from block 34a and its equivalently shifted linear power reference value block 39c it becomes possible to increase the accuracy of the txagc to the required level while the above description serves to describe the operation of the invention it should be noted that a number of possible implementations exist for example fig5 illustrates a presently preferred implementation where blocks 38a and 38b are integrated thus enabling a substantial hardware savings the embodiment of fig5 includes a 5 to 1 multiplexer 50 a 1 x scaling.