l 3 f l 4 however these degradations in snr are not as severe as those seen at the integer multiples and are not included in this discussion in the operation of a wireless communication device the operation frequency of the output may be at one of several frequencies within a specified spectrum for example the gsm operation mode has channel offsets every 200 kilohertz khz accordingly depending upon the operation of the base station the mobile wireless unit may in fact be tasked with operating at a sub optimum operation point such as that denoted by point a in fig2 thus when the transmitter 39 s operation is somehow specified to at the frequency denoted by point a the user of the mobile wireless unit will experience problems in the operation and or communications using such wireless communications device the same device operating at point b will encounter much better operation since point b is a frequency where the noise problems associated with sampling rates will not occur it should be noted that the operating i e output frequency can be set by many different means the way in which the operating frequency is set is not relevant for the purposes of this disclosure turning back to fig1 the wireless communications device 10 has an adjustable clock circuit 30 the adjustable clock circuit 30 is operable to accept a signal representative of the operating frequency of the output such as that delivered by the frequency detection circuit 26 the adjustable clock circuit 30 is operable to accept such a signal indicative of the frequency of the output signal and to determine whether to alter the sampling frequency of the loop filter 22 accordingly when the communications device 10 determines that the operating frequency.