QBL-MSK mapping for time of arrival (TOA) applications
View Patent ↗A transmitter is configured to transmit a time of arrival (TOA) message to a receiver applying a quadrature multiple frequency ranging (QMFR) algorithm for separating multiple path signal components. The transmitter includes (1) a modulator for generating a quasi-band limited minimum shift keyed (QBL-MSK) signal, (2) a serial formatter for generating a serial QBL-MSK (SQBL-MSK) signal, and (3) a switch for disabling the serial formatter, during a time that the TOA message is being transmitted to the receiver. The receiver includes (1) a matched filter for separating a data packet with the TOA message into in-phase (I) and quadrature (Q) spreading sequences, (2) an even sample mapping section, coupled to the matched filter, for outputting the even samples of the I and Q spreading sequences, (3) an odd sample mapping section, coupled to the matched filter, for outputting the odd samples of the I and Q spreading sequences, and (4) sliding correlator banks for receiving the even samples of the I and Q spreading sequences and the odd samples of the I and Q spreading sequences and outputting despread even I and Q samples and despread odd I and Q samples to a QMFR algorithm for separating multiple path signal components.
1. A transmitter configured to transmit a time of arrival (TOA) message to a receiver applying a quadrature multiple frequency ranging (QMFR) algorithm for separating multiple path signal components, the transmitter comprising:
a modulator for applying a spreading sequence to the TOA message to generate a quasi-band limited minimum shift keyed (QBL-MSK) signal,
a serial formatter for applying a serial formatting operation to the QBL-MSK signal to generate a serial quasi-band limited minimum shift keyed (SQBL-MSK) signal, and
a switch for disabling the serial formatter, during a time the TOA message is being transmitted to the receiver.
2. The transmitter of claim 1 including
a transmitter section for transmitting the SQBL-MSK signal or the QBL-MSK signal, and
the switch includes a processing module for enabling or disabling the serial formatter,
wherein when the switch enables the serial formatter, the transmitter section is configured to transmit the SQBL-MSK signal, and
when the switch disables the serial formatter, the transmitter section is configured to transmit the QBL-MSK signal.
3. The transmitter of claim 1 wherein
the switch is configured for disabling the serial formatter during a time the TOA message or a power amplifier (PA) ramp down message is being transmitted to the receiver, and
the switch is configured for enabling the serial formatter during a time a PA ramp up message, an automatic gain control (AGC) message, a multipath window message, a synchronization message, or a data message is being transmitted to the receiver.
4. The transmitter of claim 1 wherein
a structure for the QBL-MSK signal and the SQBL-MSK signal includes the following
s
(
t
)
=
[
∑
i
=
0
M
f
(
i
)
·
c
2
i
·
p
(
t
-
2
iT
c
)
]
cos
(
2
π
f
o
t
)
+
[
∑
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=
0
M
f
(
i
)
·
c
2
i
+
1
·
p
(
t
-
[
2
i
+
1
]
T
c
)
]
sin
(
2
π
f
o
t
)
where:
T c is the chip period,
c i is the chip value
M+1 is the number of chips,
p(t) is the QBL pulse-shaping function,
f o is the center frequency,
p
(
t
)
=
{
[
sin
(
π
t
2
T
c
)
(
π
t
2
T
c
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]
3
;
-
2
T
c
≤
t
≤
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T
c
0
;
elsewhere.
and
f
(
i
)
=
{
(
-
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)
i
;
for
SQBL
-
MSK
1
;
for
QBL
-
MSK
.
5. A method of separating multiple path signal components between a receiver and a transmitter comprising the steps of:
(a) modulating, by a transmitter, a data packet including a time of arrival (TOA) message using a spreading sequence;
(b) formatting, by the transmitter, the TOA message using quasi-band limited minimum shift keyed (QBL-MSK) modulation;
(c) formatting, by the transmitter, other portions of the data packet using serial quasi-band limited minimum shift keyed (QBL-MSK) modulation; and
(d) transmitting the TOA message modulated by quasi-band limited minimum shift keyed (QBL-MSK) and the other portions of the data packet modulated by serial quasi-band limited minimum shift keyed (QBL-MSK),
wherein the TOA message is configured for a receiver to separate multiple path signal components.
6. The method of claim 5 including the following step:
switching a serial formatter ON/OFF to enable or disable the serial formatter,
wherein when the serial formatter is switched OFF, the TOA message is modulated by QBL-MSK, and
when the serial formatter is switched ON, the other portions of the data packet are modulated by SQBL-MSK.
7. The method of claim 5 wherein
the step of formatting the other portions of the data packet includes formatting a PA ramp up message, an automatic gain control (AGC) message, a multipath window message, a synchronization message, or a data message using SQBL-MSK modulation.