Abstract: A method and system for detecting PIM signals in a wireless communication base station are disclosed. According to one aspect, a method includes receiving radio frequency, RF, signals over a frequency band spanning a plurality of frequencies of signals transmitted by at least a first transmitter external to the base station and at least a second transmitter. The method includes determining frequencies at which signals are present among the received radio frequency signals. PIM signal frequencies are calculated based on the determined frequencies at which signals are present. The method includes determining whether the calculated PIM signal frequencies interfere with selected uplink channels.

Abstract: A method and system for detecting PIM signals in a wireless communication base station are disclosed. According to one aspect, a method includes receiving radio frequency, RF, signals over a frequency band spanning a plurality of frequencies of signals transmitted by at least a first transmitter external to the base station and at least a second transmitter. The method includes determining frequencies at which signals are present among the received radio frequency signals. PIM signal frequencies are calculated based on the determined frequencies at which signals are present. The method includes determining whether the calculated PIM signal frequencies interfere with selected uplink channels.

Abstract: Techniques for the selection of signals from multiple sources are disclosed. For instance, an apparatus may include a first tuner module, a second tuner module, and a multiplexer. The first tuner module generates a first tuned signal from a first RF signal, and the second tuner module generates a second tuned signal from a second RF signal. The first RF signal corresponds to a first signal source, and the second RF signal corresponds to a second signal source. Based on a selection signal, the multiplexer selects one of the first tuned signal and the second tuned signal.

Abstract: A radio frequency tuner is provided having inputs for receiving signals in common or overlapping frequency ranges from distribution networks. Each input is connected to a respective first converter, for example performing upconversion to a first intermediate frequency above the RF frequency ranges of the incoming signals. The first frequency changers are arranged to be active one at a time. The outputs of the first frequency changers are supplied to a second frequency changer which performs downconversion on the output signal of the active first converter to convert a selected channel from one of the distribution networks to a second intermediate frequency. Sufficient RF isolation may therefore be provided without requiring mechanical switching components such as RF relays.

Abstract: A digital terrestrial tuner has an RF input connected to a filter arrangement, whose output signal is supplied to a zero intermediate frequency frequency changer. The filter arrangement comprises a plurality of signal paths of different frequency responses. The signal paths are selectable one at a time for insertion between the tuner input and the frequency changer. At least one of the signal paths comprises a non-tracking filter which provides attenuation of out-of-band signals so as to reduce harmonic mixing caused by harmonics of the frequency changer commutating signal or by harmonics of spurious signals at lower frequencies.

Abstract: A tuner is provided for selecting a channel from a broadband radio frequency input signal containing a plurality of channels, such as a terrestrial broadcast signal. The tuner has an input which supplies the broadband signal to a filter. The output of the filter is connected to a mixer of a single frequency changer, which converts the selected channel to a predetermined non-zero intermediate frequency. The filter is a tracking radio frequency filter which tracks the frequency of the selected channel so as to attenuate the image channel. A controller receives from a demodulator a signal representing reception quality, such as bit error rate, and adjusts the tracking of the filter so as to achieve acceptable reception quality, such as an adequately low bit error rate. Alignment of the filter during manufacture is not, therefore, required.

Abstract: A multi-channel tuner apparatus is provided which is capable of simultaneously and independently selecting a plurality of channels for reception. The apparatus comprises a plurality of tuners, each of which converts a selected channel to a near-zero intermediate frequency. The output signals from the tuners are supplied to respective sample/hold circuits, whose outputs are supplied to a single analogue/digital converter for multiplexing the tuner signals and converting them to the digital domain. A common demodulator arrangement processes the digital domain signal to extract the information from all of the selected channels.

Abstract: A tuner is provided for permitting independent reception of a plurality of channels from a multiple channel radio frequency input signal. A first analog converter of the upconverter type block-converts the radio frequency band to an intermediate frequency band. Several second analog frequency converters, such as quadrature ZIF downconverters, are independently controllable for independently selecting respective channels for reception from the intermediate frequency band at the output of the first converter. Each of the second converters converts the respective selected channel to the desired intermediate frequency. A voltage-driven interface is provided between the first converter and the second converters.

Abstract: A radio frequency tuner is provided having inputs for receiving signals in common or overlapping frequency ranges from distribution networks. Each input is connected to a respective first converter, for example performing upconversion to a first intermediate frequency above the RF frequency ranges of the incoming signals. The first frequency changers are arranged to be active one at a time. The outputs of the first frequency changers are supplied to a second frequency changer which performs downconversion on the output signal of the active first converter to convert a selected channel from one of the distribution networks to a second intermediate frequency. Sufficient RF isolation may therefore be provided without requiring mechanical switching components such as RF relays.

Abstract: A digital terrestrial tuner has an RF input connected to a filter arrangement, whose output signal is supplied to a zero intermediate frequency frequency changer. The filter arrangement comprises a plurality of signal paths of different frequency responses. The signal paths are selectable one at a time for insertion between the tuner input and the frequency changer. At least one of the signal paths comprises a non-tracking filter which provides attenuation of out-of-band signals so as to reduce harmonic mixing caused by harmonics of the frequency changer commutating signal or by harmonics of spurious signals at lower frequencies.

Abstract: A tuner is provided for selecting a channel from a broadband radio frequency input signal containing a plurality of channels, such as a terrestrial broadcast signal. The tuner has an input which supplies the broadband signal to a filter. The output of the filter is connected to a mixer of a single frequency changer, which converts the selected channel to a predetermined non-zero intermediate frequency. The filter is a tracking radio frequency filter which tracks the frequency of the selected channel so as to attenuate the image channel. A controller receives from a demodulator a signal representing reception quality, such as bit error rate, and adjusts the tracking of the filter so as to achieve acceptable reception quality, such as an adequately low bit error rate. Alignment of the filter during manufacture is not, therefore, required.

Abstract: A multi-channel tuner apparatus is provided which is capable of simultaneously and independently selecting a plurality of channels for reception. The apparatus comprises a plurality of tuners, each of which converts a selected channel to a near-zero intermediate frequency. The output signals from the tuners are supplied to respective sample/hold circuits, whose outputs are supplied to a single analogue/digital converter for multiplexing the tuner signals and converting them to the digital domain. A common demodulator arrangement processes the digital domain signal to extract the information from all of the selected channels.

Abstract: A method of depositing pipe on the seabed which includes providing a vessel of a length greater than the pipe, which vessel has a main winch on one end and an auxiliary winch on the other end, anchoring a cable from the main winch to the seabed, drawing the cable horizontally of the vessel utilizing the auxiliary winch, attaching trolleys carried by a length of pipe to the section of the cable overlying the vessel, using the auxiliary winch to let out the cable and suspend the pipe on the cable from the main winch, utilizing a third cable to lower the pipe, and repeating the process for each length of pipe.