Re: [Paparazzi-devel] telemetry messages on request

[Christophe De Wagter]

For the xbee868 you best can group messages (e.g. 1 burst per second) and you must limit it to about 180/200 bytes per second (incl the 8byte overhead per message). Then it can work non-stop. But since the range is so huge and there is only 1 frequency they do not want you to block the entire band for a quarter of the country (netherlands size).

-Christophe 

On Tue, Oct 6, 2015 at 11:19 PM, Refik Sever <address@hidden> wrote:

Hi Felix,

 

Thanks for your email.

 

Xbee868 stops sending messages if the duty cycle exceeds a threshold. I don't know their exact formula. If the data rate is too low, it stops sending after 45minutes and starts again after 5-10 minutes. If data rate is high, it stops after 8-10 minutes.

 

We will work on synchonizing the telemetry/telecommand messages.

 

Does anybody know a long range serial modem and low cost cofdm video transmitter?

 

Cheers,

Refik

 

From: paparazzi-devel-bounces+refiksever=address@hidden [mailto:paparazzi-devel-bounces+refiksever=address@hidden] On Behalf Of Felix Ruess
Sent: Tuesday, October 6, 2015 10:11 PM
To: Paparazzi UAV devel list
Subject: Re: [Paparazzi-devel] telemetry messages on request

 

Hi Refik,

that is a good question, unfortunately I don't know of a good way to solve this (like how to assign different time slots to up/down link).

You are not the first to have this problem, so any ideas on how to solve this would be welcome.

On a side note: IIRC the 868MHz modems only have a 10% duty cycle and there are times where the xbee will not send messages to respect that.

But since I never had a 868MHz xbee, I'm not quite sure how they handle this....

 

Cheers, Felix

 

On Mon, Oct 5, 2015 at 4:12 PM, Refik Sever <address@hidden> wrote:

Hello,

 

We are using Xbee 868 modem. The downlink and uplink shares the same frequency. Sometimes, we send a command from GCS but it does not make any difference and it dissappears. I think that it corrupts with the telemetry messages coming from airframe.

 

Is it possible to synchronize the telemetry and telecommand messages for Xbee? Telemetry messages may be send upon periodical request from GCS.  There may be different timeslots for telecommand and telemetry.

 

Does anybody have any suggestion for that?

 

Do you recommend a better serial modem other than Xbee?

 

Cheers,

Refik

 

 

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