Technical Information

Technical Specifications

Modulation	Offset-QPSK
Data Rate	24 kbits/sec
Pulse Shape	square-root raised cosine 100% excess bandwidth
Data Sequence	511-bit PN sequence download the MATLAB file containing this bit sequence
Radio Frequency (RF)	418 MHz
Differential Encoding	d(k) = b(k) XNOR d(k-1) d(k+1) = b(k+1) XOR d(k) for k even (assuming the index starts at 0)

The bit-to-symbol assignments refer to the differentially encoded bits.

Helpful Hints

Download a segment of C code that you should use to interface with the BERT.

Test Data Files

The test data files contain samples of the baseband I and Q outputs that your receiver front-end will be providing the A/D converters for the various scenarios described below. The sample rate is 48 ksamples/sec and each file represents approximately 2 seconds worth of data.

Name	Description
OQPSK_nde.mat	OQPSK_nde.mat contains samples of the baseband OQPSK modulated signal using the PN9 sequence with NO DIFFERENTIAL ENCODING. The data are stored in an L x 1 complex array X. The real part of X contains samples of the I output and the imaginary part of X contains samples of the Q output.
OQPSK_de.mat	OQPSK_de.mat contains samples of the baseband OQPSK modulated signal with the DIFFERENTIALLY ENCODED PN9 sequence. The data are stored in an L x 1 complex-valued vector where the real part contains samples of the I output and the imaginary part contains samples of the Q output.
OQPSK_de_rotate1.mat	OQPSK_de_rotate1.mat contains samples of the baseband OQPSK modulated signal with the DIFFERENTIALLY ENCODED PN9 sequence and a constant phase rotation. The data are stored in an L x 1 complex-valued vector where the real part contains samples of the I output and the imaginary part contains samples of the Q output.
OQPSK_de_rotate2.mat	OQPSK_de_rotate2.mat contains samples of the baseband OQPSK modulated signal with the DIFFERENTIALLY ENCODED PN9 sequence and a small frequency offset. The data are stored in an L x 1 complex-valued vector where the real part contains samples of the I output and the imaginary part contains samples of the Q output.
OQPSK_de_SNR20dB.mat	OQPSK_de_SNR20dB.mat contains samples of the baseband OQPSK modulated signal with the DIFFERENTIALLY ENCODED PN9 sequence with noise such that Eb/No = 20 dB. No carrier phase synchronization is presumed. The data are stored in an L x 1 complex-valued vector where the real part contains samples of the I output and the imaginary part contains samples of the Q output.
OQPSK_de_SNR10dB.mat	OQPSK_de_SNR10dB.mat contains samples of the baseband OQPSK modulated signal with the DIFFERENTIALLY ENCODED PN9 sequence with noise such that Eb/No = 10 dB. No carrier phase synchronization is presumed. The data are stored in an L x 1 complex-valued vector where the real part contains samples of the I output and the imaginary part contains samples of the Q output.