CCS/CC1310: Question about preamble of Antenna Diversity

Please refer to 2.3 in www.ti.com/.../swra523a.pdf. You have as a minimum send the number of preamble given in this section but you can send longer preamble if you so wish.

Hi TER,

Thank you for your reply.
Finally, please let me confirm that my understanding is correct.

-Even if the preamble setting of the transmitter is 8 bytes or more, there is no problem.
-The preamble setting of the receiver is related only to SyncTimeout,
and the preamble setting of the receiver and the transmitter do not have to be the same value.
-PER does not increase even if the preamble setting of the receiver and the transmitter are different values.

Sorry to hear it over and over.
Please correct it if my understanding is wrong.

Best Regards,
Miyashiro

Hi Siri,

I'm sorry I'm asking you questions many times.
Thanks to you I understand about the preamble.

However, my customer has several TX systems, each with various preamble settings, such as 6 bytes, 8 bytes, 10 bytes and so on.
Their receiver are planning to communicate with such various preamble TX systems.
Therefore, it is undesirable for them that the preamble on the RX side must be set to the same preamble length with the TX side.
If you have any good solutions, please let me know.
Or is TI planning to improve these functions in the future?

I would appreciate it if you could answer my questions.

Best Regards,
Miyashiro

Hi Siri,

I interpreted your comment as following.
If my recognition is wrong, please correct it.
If there is no problem, I will answer to my customer.

"Basically, it is necessary to match preamble setting between TX and RX.
 However, if the length of the preamble on the TX side is undefined like "8bytes or more",
 I suggest a method to set the preamble on the RX side to the maximum preamble length of the system."

I would like to ask additionally, what kind of inconvenience is there if the Sync Search state becomes longer?
I expect the PER to increase.

> Why are they using different preamble lengths on the TX side?

They are trying to make a receiver that enters the network of transmitters with different vendor chips(various preamble) and communicates with them.
Besides, for example, when a TX system is used in an urban area,the preamble may be shortened to increase the data rate,
on the other hand when the TX system is used in a country area, the preamble may be lengthened to realize long distance communication.

Best Regards,
Miyashiro

Hi Miyashiro

There will always be a chance that the radio enters sync search state based on noise/an interferer and not the real packet. The longer the syncTimeout is, the longer the radio will be in this state (maybe with the “wrong” antenna selected) and hence miss the real sync word when it comes along.

Not sure if this will be a very big problem.

I understand that different protocols or vendors uses different preamble length, but usually they use different packet format, sync word, CRC, modulation format etc. also. Do not know how many different systems you will find from different vendors where the only difference in their RF settings are the preamble length.

If all RF parameters are the same, they are most likely using the same standard, and in this case, the preamble length will be set by the standard as well.

Preamble is usually used for bit synchronization and for settling of the AGC on the receiver, and is not used to realize longer range.

BR

Siri

Hi Siri,

Thank you for explaining in detail.
I will reply to my customer.
I was very helpful to you and I sincerely thank you.

> I understand that different protocols or vendors uses different preamble length, but usually they use different packet format,
> sync word, CRC, modulation format etc. also. Do not know how many different systems you will find from different vendors
> where the only difference in their RF settings are the preamble length.

I have heard that in already constructed networks (eg in the field of smart meter, vending machine etc.),
preamble is different only, other sync words etc. may be the same .
My customer would like to make a receiver for such networks.

Best Regards,
Miyashiro