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#1 2020-Jun-15 14:17:49

Lavender
Member
Registered: 2020-Apr-07
Posts: 20

How to calculate the time of signal

I ran the wl_example_siso_ofdm_txrx.m sample code and set:
N_OFDM_SYMS=500;
SAMP_FREQ=40MHz;
The final received signal is 1*81445 complex double, so the time corresponding to this signal is (1/40000000*81445) s, is this calculation correct?

Similarly, I set wl_basebandCmd (nodes,'tx_delay', 1000), so the packet sending interval is (1/40000000*1000) s, is this calculation correct?

Thank you.

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#2 2020-Jun-15 14:53:33

Lavender
Member
Registered: 2020-Apr-07
Posts: 20

Re: How to calculate the time of signal

From the sample code, we can see that the preamble is 1*1280 complex double. According to the calculation method above, the length of the preamble is (1/40000000*1280)s, which is 32μs.
However, the 802.11g protocol specifies a preamble of 16μs, so I wonder where I made a mistake?

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#3 2020-Jun-17 21:02:13

murphpo
Administrator
From: Mango Communications
Registered: 2006-Jul-03
Posts: 5159

Re: How to calculate the time of signal

The OFDM example script uses a longer preamble for extra AGC settling time.

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#4 2020-Jun-19 08:00:33

Lavender
Member
Registered: 2020-Apr-07
Posts: 20

Re: How to calculate the time of signal

I see, thank you.

So is the above method of calculating time correct, ie sampling interval * points?

And I am not sure, the value 1000 of 'tx_delay' represents 1000 sampling points or time, such as ms, μs, ns?
wl_basebandCmd (nodes,'tx_delay', 1000)

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#5 2020-Jun-19 08:13:53

murphpo
Administrator
From: Mango Communications
Registered: 2006-Jul-03
Posts: 5159

Re: How to calculate the time of signal

Refer to the user guide

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