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US 5,963,589 AGranted
Digital signal modulation analysis device
AssigneeAdvantest Corporation
InventorsMasao Nagano, Hitoshi Takahashi
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AssigneeAdvantest Corporation
InventorsMasao Nagano, Hitoshi Takahashi
Estimating the term…
A digital signal modulation analysis device is to shorten the time for modulation analysis, and at the same time to structure a measurement device that is small in scale and inexpensive. A digital signal modulation analysis device includes a frequency convertor which converts a signal from a device under test to a first intermediate frequency signal, a sampling part which converts the first intermediate frequency signal to a second intermediate-frequency signal whose frequency is lower than that of the first intermediate frequency to store the second intermediate frequency signal in a memory, a Hilbert converter which converts an incoming signal into orthogonal component signals through a quadrant-modulate detection process, an initial synchronization part which determines a carrier center frequency, a symbol-demodulation/parameter-estimation part which determines optimal parameters to minimize a modulation error and demodulates all symbol data to determine reference data for the all symbol data, and a modulation-precision calculation component which calculates modulation-precision data and modulation-error data for each symbol.
A digital modulation analysis device for measuring modulation characteristics of a digital MCA (Multi The Channel Access) signal produced by a device under test (DUT) for a digital communication, comprising:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Arrangements specific to the receiver only: demodulators
Digital communication
Term ended 21 Apr 2015 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
This invention is related to the modulation measurement of the digital signals used in digital communication methods, such as digital multichannel access (DMCA).
In a digital communication system such as a private mobile communication system, M16QAM (multi-subcarrier 16 quadrature amplitude modulation, M=4), one of DMCA modulation method is used. The M16QAM transmits the 16QAM signal by using the multicarrier method, in which four subcarriers perform the transmissions at the same time. This communication method enables the transfer speed of 4K symbols/second for 64K bps (bits/second) data. "Digital Method MCA System Standard Regulations (RCR-STD-32)" is a document issued by the Electric Wave System Development Center Foundation, which discusses this subject. In this document the details of the modulation method, encoding method, sync/pilot insertion, fall/rise slot structural diagram, measurement method, and modulation-precision definitions are given.
The data is encoded in 16-bit units and then transmitted as shown in FIG. 14. This 16-bit data is split into four 4-bit segments and transmitted by the four subcarriers, ch. 1-4. Each subcarrier compresses the bandwidth using the roll-off=0.2 root Nyquist filter (bandwidth-compression filter). The interval between any two subcarriers is 4.5 KHz, and 18 KHz of bandwidth is used for the four channels. The four-channel subcarrier transmission system diagram is shown in FIG. 15 for reference.
FIG. 1 shows the measurement component 200 digital modulation analysis device for the first embodiment of this invention.
FIG. 2 (a) shows the structural diagram of the Hilbert converter 310 for this invention.
FIG. 2 (b) shows the structural diagram of the Hilbert converter 304 in the Hilbert converter 310 for this invention.
The description is given by referencing the first embodiment of this invention.
The first embodiment of this invention utilizes a frequency convertor 109. The description is made by referencing FIGS. 1, 2(a)-(b), 3(a)-(c), 4, 5, 6, 7(a)-(e) and 8.
The system structure is described first.