Abstract: An apparatus is disclosed for a spaceborne or aerial platform having a frequency demultiplexer for frequency demultiplexing a signal corresponding to a range line or an azimuth line of SAR data, and including information about a plurality of target points, into a plurality of frequency channels, and a compression device for performing compression on each frequency channel, each frequency channel signal having information about the same target points. The frequency demultiplexer and the compression device can be implemented in hardware. The apparatus may be used for either or both of the range compression and the azimuth compression of a SAR arrangement on board a spaceborne or aerial platform and the SAR arrangement may generate a plurality of sub-images corresponding to the frequency channels from the SAR raw data. The sub-images may be combined by averaging in order to reduce the volume of memory required to store the SAR data.

Abstract: An apparatus is disclosed for processing a sequence of samples of a received signal R reflected by a target surface and having a delay and a frequency shift relative to a reference signal D to obtain a delay Doppler map for the reflected signal. A first correlation module can obtain partial correlations z(n?, k) between samples corresponding to the reflected signal R and a samples corresponding to the reference signal D, across a set of delays. An inverse discrete fourier transform (DFT) of a sequence of samples can be derived from at least DFTs of a first reflected signal sequence and second reference signal sequence.

Abstract: An apparatus is disclosed for a spaceborne or aerial platform having a frequency demultiplexer for frequency demultiplexing a signal corresponding to a range line or an azimuth line of SAR data, and including information about a plurality of target points, into a plurality of frequency channels, and a compression device for performing compression on each frequency channel, each frequency channel signal having information about the same target points. The frequency demultiplexer and the compression device can be implemented in hardware. The apparatus may be used for either or both of the range compression and the azimuth compression of a SAR arrangement on board a spaceborne or aerial platform and the SAR arrangement may generate a plurality of sub-images corresponding to the frequency channels from the SAR raw data. The sub-images may be combined by averaging in order to reduce the volume of memory required to store the SAR data.

Abstract: An apparatus is disclosed for processing a sequence of samples of a received signal R reflected by a target surface and having a delay and a frequency shift relative to a reference signal D to obtain a delay Doppler map for the reflected signal. A first correlation module can obtain partial correlations z(n?, k) between samples corresponding to the reflected signal R and a samples corresponding to the reference signal D, across a set of delays. An inverse discrete fourier transform (DFT) of a sequence of samples can be derived from at least DFTs of a first reflected signal sequence and second reference signal sequence.

Abstract: A payload of a communications satellite includes several receive chains connected to respective antennas 1 to 4. Each receive chain 6 is hybrid in that analogue filtering is carried out at the front end in order to remove the unwanted input spectrum beyond that of a broadband within which a narrowband signal is frequency hopped. Thereafter the filtered signal is digitized and the hopping pattern removed by using successive segments of a control word which determines the hopping frequencies to successively select progressively narrower sub-bands which contain the wanted signal on each hop.

Abstract: Digital signal processing apparatus for frequency demultiplexing a wide band channel which converts the data stream into parallel branches by means of serial-to-parallel conversion, and demultiplexing which consists of low pass and high pass fine filtering stages and a coarse filtering stage split among processors across parallel branches. Wideband signals arc processed without expensive processors because of the slower rate in the parallel channels. This may also be used for the inverse function of multiplexing.

Abstract: A digital signal processing apparatus for frequency multiplexing and demultiplexing of narrow band FDM signals has a first block fine processing stage (11) connected in series to a first block coarse processing stage (16, 17) and in parallel therewith a second block fine processing stage (11a) connected in series to a second block coarse processing stage (16, 17). The two stages 11 and 11a are coupled together at one side remote from the two coarse processing stages (16, 17) to provide a first port (14) and the stages (16 and 17) at the side remote from the port (14) provide a plurality of ports (15). Each stage (11, 11a) is a FIR lowpass filter and each stage (16, 17) incorporates a polyphase filter (16) in connection with a Fast Fourier Transform Unit (17).