Method and apparatus for implementing signal quality metrics and antenna diversity switching control
View Patent ↗A method for detecting the digital quality of a radio signal includes: receiving a radio signal including an analog modulated portion; digitally sampling an analog modulated portion of the radio signal to produce a plurality of samples; using a ratio between an average magnitude and an RMS magnitude of a block of the samples to compute an analog signal quality metric. Receivers that implement the method are also provided.
1. A method comprising:
receiving a radio signal including an analog modulated portion;
digitally sampling an analog modulated portion of the radio signal to produce a plurality of samples; and
using a ratio between an average magnitude and an RMS magnitude of a block of the samples to compute an analog signal quality metric.
2. The method of claim 1 , wherein the radio signal further includes a digitally modulated portion and the block of samples spans about 1 OFDM symbol in the digitally modulated portion.
3. The method of claim 2 , wherein the analog signal quality metric is determined using samples from 16 symbols.
4. The method of claim 1 , wherein the ratio is raised to a power p such that subsequent averaging of analog signal quality metric values over time is not biased from the nominal threshold of about 0.5.
5. The method of claim 4 , wherein the value of p is 8.
6. The method of claim 1 , wherein the analog signal quality metric (ASQM) is calculated as:
ASQM
=
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2
·
(
∑
k
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0
K
-
1
[
Re
{
x
k
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2
+
Im
{
x
k
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2
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)
2
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∑
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8
where x k is the k th sample of the block of samples, and k is sample index from 0 to K−1.
7. The method of claim 1 , wherein the analog signal quality metric has a value in a range of 0 to 1.
8. The method of claim 1 , further comprising:
using the analog signal quality metric to select one or more antenna elements to be connected to a receiver input.
9. An apparatus comprising:
a radio receiver including an input for receiving a radio signal having an analog modulated portion; and a processor for digitally sampling the analog modulated portion to produce a plurality of samples, and using a ratio between an average magnitude and an RMS magnitude of a block of the samples to compute an analog signal quality metric.
10. The apparatus of claim 9 , further comprising:
a plurality of antenna elements for receiving the radio signal; and
a switch for connecting one or more of the antenna elements to the receiver input in response to the analog signal quality metric.
11. The apparatus of claim 9 , wherein the radio signal further includes a digitally modulated portion and the block of samples spans about 1 OFDM symbol in the digitally modulated portion.
12. The apparatus of claim 11 , wherein the analog signal quality metric is determined using samples from 16 symbols.
13. The apparatus of claim 9 , wherein the ratio is raised to a power p such that subsequent averaging of analog signal quality metric values over time is not biased from the nominal threshold of about 0.5.
14. The apparatus of claim 13 , wherein the value of p is 8.
15. The apparatus of claim 9 , wherein the analog signal quality metric (ASQM) is calculated as:
ASQM
=
(
2
·
(
∑
k
=
0
K
-
1
[
Re
{
x
k
}
2
+
Im
{
x
k
}
2
]
)
2
K
·
∑
k
=
0
K
-
1
[
Re
{
x
k
}
2
+
Im
{
x
k
}
2
]
2
-
1
)
8
where x k is the k th sample of the block of samples, and k is sample index from 0 to K−1.
16. The apparatus of claim 9 , wherein the analog signal quality metric has a value in a range of 0 to 1.