LAUNCHXL-CC1310: LAUNCHXL-CC1310: Error Rate Engineering Demodulation Problem

Alex Zhang

Part Number: LAUNCHXL-CC1310

Hi team：

I have clients who have encountered the following issues：

I burned and wrote the rfPacketErrorRate code on the LAUNCHXL-CC1310 development board, and wanted to use a signal analyzer for demodulation, but encountered some issues.

Firstly, I selected HSM Mode in the code. Is this mode using 8FSK modulation in this code? What is the corresponding Symbol Rate?

Secondly, in order to better locate the sent package, I have modified the package content in the following location in tx. c,

 pPacket[dataOffset + 0] = packet[dataOffset + 0] = (uint8_t)(seqNumber >> 8);
    pPacket[dataOffset + 1] = packet[dataOffset + 1] = (uint8_t)(seqNumber++);
    uint16_t i;
    for (i = dataOffset + 2; i < config->payloadLength; i++)
    {
       // pPacket[i] = packet[i] = rand();
        pPacket[i] = packet[i] = 0xf0;
    }

May I ask if this modification takes effect?

Because I couldn't find the corresponding code words such as Preamble and sync demodulated on the signal analyzer, may I ask if the rfPacketErrorRate project will handle the data inside the package? How can I successfully achieve data demodulation?

over 2 years ago

0 Siri over 2 years ago

TI__Guru* 86071 points

The HSM is 4 mbps and uses 8FSK.

You are changing the payload in the correct place and should be able to verify this by looking at the received packet on the RX side.

The PHY is using FEC (Forward error Correction) so the data written to the packet will not be what is actually being sent on the air. It is encoded on the TX side and decoded on the RX side.

Siri

0 tian jun over 2 years ago in reply to Siri

Intellectual 390 points

what kind of FEC is used in The PHY of HSM?

0 Siri over 2 years ago in reply to tian jun

TI__Guru* 86071 points

This is not info we give out. The HSM is a proprietary PHY that runs on the CC13x0 devices, and you need a CC13x0 in both ends to use this PHY.

There are no parameters that you can tweak and tune when it comes to the RF performance, and we do not provide any info regarding the implementation of the PHY.

Siri

0 Alex Zhang over 2 years ago in reply to Siri

TI__Intellectual 1305 points

So what is the implementation method for positive error correction here?

0 Alex Zhang over 2 years ago in reply to Alex Zhang

TI__Intellectual 1305 points

and I want to ask what are the deviation and symbolRate at 4Mbps?

thank you

0 Siri over 2 years ago in reply to Alex Zhang

TI__Guru* 86071 points

I have already said that we are not giving out details on the FEC etc.

I am still not sure why the customer needs this information as there is nothing to tweak on etc.

What is relevant is how long time it takes to send a packet with this PHY.

There is a fixed preamble sync pattern that takes 130 us to transmit. In addition the PA needs about 50 us for ramp-up.

After that, the packet (payload) is sent at a bit rate of 4 mbps. That means that if you send 100 bytes in your packet, the payload takes 100 * 8 / 4000000 = 200 us

There is also a PA ramp down that takes 30 us.

That means that the TX time will be:

50 us + 130 us + 200 us + 30 us = 400 us

The effective data rate for a 100 byte long packet is then 2 mbps.

Siri

0 tian jun over 2 years ago in reply to Siri

Intellectual 390 points

Thanks for your reply,and I want to kown why the fixed preamble sync pattern takes 130us to transmit, if only considerate the transmit time in 4mbps state,32bit preamble and sync will takes 16us,whether the time include process the fix preamble sync pattern generated and transmitted in air

0 Siri over 2 years ago in reply to tian jun

TI__Guru* 86071 points

This PHY does not send a "normal" preamble or sync.

There is a fixed pattern consisting of 208 symbols that are sent before the payload. The symbol rate is 1.6 ksps, meaning that this takes 130 us.

Siri

0 Jhonson Anderson over 2 years ago in reply to Siri

Prodigy 20 points

Your continuous replies really helped a lot and I almost get my solution.You said there is a fixed pattern consisting of 208 symbols that are sent before the payload.Is there any chance I can acquire the accurate code,such as in some documents.Or if you konw the accurate code,plese just tell me about it.

regards

0 Siri over 2 years ago in reply to Jhonson Anderson

TI__Guru* 86071 points

We are not sharing this information.

Siri

0 Jhonson Anderson over 2 years ago in reply to Siri

Prodigy 20 points

OK. Is CRC(Cyclic Redundancy Check) used in high speed mode?

0 Siri over 2 years ago in reply to Jhonson Anderson

TI__Guru* 86071 points

Yes.

This is enabled through the API:

RF_cmdTxHS.pktConf.bUseCrc = 0x1;
RF_cmdRxHS.pktConf.bUseCrc = 0x1;

Siri

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LAUNCHXL-CC1310: LAUNCHXL-CC1310: Error Rate Engineering Demodulation Problem