Abstract: A method for determining the switching frequency of a DC-to-DC power supply for a portable radio transceiver (300) includes determining a first group of switching frequencies (301) and then determining the switching harmonics based on that group of switching frequencies (305). These switching harmonics are then compared to a group of desired radio channels (311) where it is then determined if the switching frequencies interfere with the group of desired radio channels (313). Based on these results, a second group of switching frequencies is selected if the first set of switching frequencies provides an undesired level of interference (317, 319, 321).

Abstract: A mail delivery indicator assembly (100) for a mailbox (102) with a door (105) includes a signal holder bracket (101) attached to a mailbox door (105). A signal ball (108) is attached by a tether (110) to the signal holder bracket (101) for indicating when the mailbox door is opened. The signal holder bracket (101) attaches within a holder receptacle (109) attached to the mailbox door (105) which allows the signal holder bracket (101) to be removed. The signal holder bracket (101) may further include an offset section (103) for allowing the bracket to be attached to a recessed door. Additionally, the signal holder bracket may include one or more guards (112, 114) which prevent snow other debris from inadvertently removing the signal ball (108) from the ring section (107).

Abstract: A voltage controlled oscillator (VCO) for use in a personal area network synthesizer includes a delay cell (100), a first current amplifier (201, 203) for amplifying an input current, a resister capacitor (RC) tuning network (207, 209, 211) for varying the amount of amplification and delay of an output of the first current amplifier. A second current amplifier (213, 215) is then used for amplifying an output current from the RC tuning network. The invention includes a unique composite voltage variable capacitor (CVVC) (300) for precisely tuning the amount of delay presented by the delay cell. The unique topology of the delay cell (100) allows it to be readily used in voltage controlled oscillators (VCOs) operable at frequencies above 1 GHz.

Abstract: A resistor capacitor (RC) tracking loop includes a parasitic insensitive integrator (211) charged by a buffer (207) with offset compensation. The integrator (211) operates to provide an accurate ramped voltage proportional to a measured RC time constant. A single comparator (213) is used for sensing the voltage ramp rate by detecting two multiplexed reference voltages (VREFLO VREFHI). A timer within controller (201) is triggered by the VREFLO crossing at comparator (213). The timer counts the number of precision reference clock periods (FREF) that occur between the VREFLO and VREFHI crossings and adjusts an accumulator within controller (201) to a value (M). This value (M) is directly used to adjust a resistor and/or capacitor array used in a continuous time filter whose bandwidth and corner frequency can be precisely tuned.