Abstract: A digital speech coder includes a long-term filter (124) having an improved sub-sample resolution long-term predictor (FIG. 5 ) which allows for subsample resolution for the lag parameter L. A frame of N samples of input speech vector s(n) is applied to an adder (510). The output of the adder (510) produces the output vector b(n) for the long term filter (124). The output vector b(n) is fed back to a delayed vector generator block (530) of the long-term predictor. The nominal long-term predictor lag parameter L is also input to the delayed vector generator block (530). The long-term predictor lag parameter L can take on non-integer values, which may be multiples of one half, one third, one fourth or any other rational fraction. The delayed vector generator (530) includes a memory which holds past samples of b(n).

Abstract: The present disclosure includes a discussion of a bit error rate detection method for use in a digital radio communication system. The digital radio communication system contains multiple radios which transmit and receive radio frequency (RF) signals. The RF signals are formatted into multiple frames, each frame has a predetermined number of data bits, a subset of which have known values. A first frame of data is transmitted. The first frame is received and the subset of known data bits are extracted. Each data bit of the received subset of known data bits are compared to the known set of data bits and a counter is incremented in response to each comparison which results in difference between the received bit and the set of known bits. The counter value is used to determine a bit error rate of the received first frame at a predetermined confidence level.

Abstract: The present patent application discusses a low profile information card chamber (107) used in a radiotelephone (101). The information card chamber accepts, retains and makes electrical contact to an information card (105). The information card chamber (107) makes electrical contact to the information card when the information card is properly inserted (105). The electrical contacts are located on the lower platform (213) of the information card chamber (107). Upon inserting the information card (105) into the information card chamber (107), the information card (105) is translated away from the electrical contacts (205). Prior to being fully inserted, the information card (105) is translated towards the electrical contacts (205). The two translational devices allow an information card (105) to be inserted into the information card chamber (107) without excessive wiping of the electrical contacts (205) by the information card (105).

Abstract: The present disclosure includes a discussion of a method of and apparatus for channel quality estimation (CQE) in a receiver. Each channel is divided into observation intervals and sub-intervals. The duration of the sub-interval is chosen as the largest interval in which the channel is essentially static. The CQE collects error information for each symbol of the sub-interval, forming a sub-interval error value. The CQE maps the sub-interval error value into a sub-interval bit error rate (BER) estimate. The mapping is a non-linear function dependent on the specific radio system. Then, the CQE averages the sub-interval BER estimates over the entire observation interval, forming an interval BER estimate. Finally, the CQE compares the interval BER estimate to a predetermined threshold, forming a channel quality estimation decision for each observation interval.

Abstract: The battery pack retention apparatus, described herein, is an injection molded part. The injection molded part includes a rear housing (200) for a radiotelephone (100), two rails (201, 203) for a battery pack (101) to slide along and six guide bars (207, 209, 211, 213, 215, 217) for retaining the battery pack (101) on the radiotelephone (100). Four of the six guide bars are the compliance-type. The compliance-type guide bars (207, 211, 213, 217) have a U-shape and are coupled to the rails. A channel (401) is cored out from the rails under the compliance-type guide bars to allow for deflection of the guide bars. Deflection is caused by the bullets (409) of the battery pack (101) when the battery pack (101) is fully inserted. The deflection(y) of the guide bars provides a calculated force upon the battery pack (101). This calculated force ensures a high quality electrical connection between the contacts of the battery pack and the contacts of the radiotelephone.

Abstract: A method of and apparatus for compensating a received signal's phase compensates for the distortion caused by the asymmetrical characteristics of a voltage limiter. This compensation allows the received signal to be sampled at the positive and negative zero-crossings reducing the requirements of a local oscillator in a radiotelephone system. First, the phase of the received signal is sampled at the positive and negative zero-crossings, forming a corresponding positive-crossing and a negative-crossing phase value for the received signal. Second, the negative-crossing and positive-crossing phase values are combined, forming a first difference signal. Third, an estimated error signal is formed using the first difference signal. Fourth, the estimated error signal is combined with the positive or negative zero-crossing phase signals, substantially eliminating the asymmetrical distortion.

Abstract: The present patent application discusses a frequency translation apparatus for altering the effective frequency of the phase information of an input signal (115). The input signal (115) has a first phase (.theta.(t)) and a first frequency (f.sub.i). The phase of the input signal is extracted and digitized at a second frequency (f.sub.o), forming a second N-bit digital phase signal (.theta.'(t))(311). The frequency translation apparatus generates a third digital phase signal (319) which approximates the difference between .theta.(t) and .theta.'(t). Then, the frequency translation apparatus combines the second digital phase signal and the third digital phase signal, forming a fourth digital phase signal (307) substantially approximating the first phase signal.