Modem with pilot symbol synchronization
First Claim
1. A modem having a transmission section and a reception section, each of the sections having a signal input port and a signal output port, wherein the transmission section comprises:
- signal formatting circuitry located between the input port and the output port of the transmission section for formatting a signal applied to the input port with a desired format prior to an outputting of the signal from the output port of the transmission section; and
circuitry for insertion of a sequence of pilot symbols into a sequence of data symbols outputted by the formatting circuitry, the insertion circuitry being located between the formatting circuitry and the output port of the transmission section, the sequence of pilot symbols serving as a time reference useful in detection of a signal transmitted by the transmission section;
wherein the reception section receives a composite signal of data symbols having a prescribed format and a sequence of pilot symbols having a prescribed format which may be the same as or different from the format of the data symbols, the reception section comprising;
means for extracting the sequence of pilot symbols from the composite signal, and timing means for establishing a time base based on a time of reception of the sequence of pilot symbols; and
decoding circuitry employing the time base of the timing means for decoding the format of the received composite signal to extract data from the composite signal.
1 Assignment
0 Petitions
Accused Products
Abstract
A modem, or a communication system, in its transmission section, has signal-formatting circuitry followed by circuitry for insertion of a sequence of pilot symbols into a sequence of data symbols outputted by the formatting circuitry. Placement of the insertion circuitry after the formatting circuitry permits a variety of formatting options without effecting the sequence of pilot symbols that serves as a time reference useful in detection of a signal transmitted by the modem. The reception section of the modem is equipped correspondingly to process a received composite signal of data symbols having a prescribed format and a sequence of pilot symbols. The reception section extracts the sequence of pilot symbols from the composite signal, and employs the pilot symbols to develop a time base for operation of circuitry for decoding the format of the received composite signal to extract data from the composite signal.
58 Citations
26 Claims
-
1. A modem having a transmission section and a reception section, each of the sections having a signal input port and a signal output port, wherein the transmission section comprises:
-
signal formatting circuitry located between the input port and the output port of the transmission section for formatting a signal applied to the input port with a desired format prior to an outputting of the signal from the output port of the transmission section; and
circuitry for insertion of a sequence of pilot symbols into a sequence of data symbols outputted by the formatting circuitry, the insertion circuitry being located between the formatting circuitry and the output port of the transmission section, the sequence of pilot symbols serving as a time reference useful in detection of a signal transmitted by the transmission section;
wherein the reception section receives a composite signal of data symbols having a prescribed format and a sequence of pilot symbols having a prescribed format which may be the same as or different from the format of the data symbols, the reception section comprising;
means for extracting the sequence of pilot symbols from the composite signal, and timing means for establishing a time base based on a time of reception of the sequence of pilot symbols; and
decoding circuitry employing the time base of the timing means for decoding the format of the received composite signal to extract data from the composite signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A communication system having a transmission station and a reception station, each of the stations having a signal input port and a signal output port, wherein the transmission station comprises:
-
signal formatting circuitry located between the input port and the output port of the transmission station for formatting a signal applied to the input port with a desired format prior to an outputting of the signal from the output port of the transmission station; and
circuitry for insertion of a sequence of pilot symbols into a sequence of data symbols outputted by the formatting circuitry, the insertion circuitry being located between the formatting circuitry and the output port of the transmission station, the sequence of pilot symbols serving as a time reference useful in detection of a signal transmitted by the transmission station;
wherein the reception station receives a composite signal of data symbols having a prescribed format and a sequence of pilot symbols, the reception station comprising;
means for extracting the sequence of pilot symbols from the composite signal, and timing means for establishing a time base based on a time of reception of the sequence of pilot symbols, wherein the time base is suitable to train an equalization filter, to extract signal strength, and to obtain information on data modulation format for switching between formats; and
decoding circuitry employing the time base of the timing means for decoding the format of the received composite signal to extract data from the composite signal. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
-
-
17. A modulator, suitable for use in the transmission section of a modem and in the transmission station of a communication system to prepare a signal for subsequent transmission and reception, the modulator comprising:
-
circuitry for encoding a signal input upon the modulator with a desired format, data of the signal being outputted by the coding circuitry as a sequence of data symbols;
circuitry coupled to an output terminal of the coding circuitry for inserting a sequence of pilot symbols into the sequence of data symbols, the sequence of pilot symbols constituting a time synchronization signal for facilitating a reception of the data symbols; and
wherein the sequence of pilot symbols is established for use in a detector at a location of reception of the data symbols, the detector operating by means of a filter matched to the sequence of pilot symbols or by a correlation of a received sequence of the pilot symbols against a replica of the sequence of the pilot symbols. - View Dependent Claims (18, 19, 20, 21)
-
-
22. A demodulator, suitable for use in the reception section of a modem and in the reception station of a communication system, wherein a signal received at the demodulator has a predetermined format and is composed of a sequence of data symbols interleaved with a sequence of pilot symbols, the sequence of pilot symbols constituting a time synchronization signal for facilitating a reception of the data symbols, the modulator comprising:
-
circuitry for decoding the formatted signal received at the demodulator, data of the signal being outputted by the decoding circuitry as a sequence of the data symbols;
circuitry coupled to an input terminal of the decoding circuitry for extracting the sequence of pilot symbols from the interleaved sequences of pilot and data symbols, wherein the extracting circuitry has a detector for detecting the sequence of pilot symbols, the detector operating by means of a filter matched to the sequence of pilot symbols or by a correlation of a received sequence of the pilot symbols against a replica of the sequence of the pilot symbols; and
timing circuitry responsive to the sequence of pilot symbols provided by the extracting circuitry for establishing timing signals to operate the decoding circuitry. - View Dependent Claims (23, 24, 25, 26)
-
Specification